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The biosphere: humanity's home.

A planet as a home? Yes, that is our place in the cosmos. We know now that this small lost planet is something more than a space shared by all humanity. It is our home, "Heimat," our motherland, our Earth. It is here, our home, made of our dead, our lives, our children. We must look after it, we must serve Fatherland Earth.

Edgar Morin

Terre-Patrie (1993)

1 The development of thought

1. First impressions

1.1 The remote past

Imagine what human beings must have thought of the world around them roughly 12,000 years ago, shortly after the end of the last ice age. The current interglacial period was starting, and in the mid-latitudes of the Northern Hemisphere, for example, human settlements were slowly starting to spread through the birch, poplar, and pine forests. People knew and remembered a great deal about the most important game animals (wild goats, chamois, reindeer, and musk ox in the North; wild boar, aurochs, horses, and deer in the South), including their habits, the times of their migrations, and the routes they followed; this information formed the basis of the people's complex collective hunting strategies. Over time, humans accumulated surprisingly detailed information pertinent to hunting and other activities, among them gathering wild fruit and collecting invertebrates. When night fell, these people looked up at the sky and tried to make sense of the moon and stars--so familiar yet so strange. The phases of the moon were presumably known long, long ago. Human thought has developed cumulatively over the millennia and has given rise to the modern idea of the biosphere, a global entity that brings together in inseparable solidarity all the living things on the planet in a single functional unity.

A historical perspective

Ancient knowledge about animals and plants dealt with the same phenomena modern ecologists study; such information might seem a precursor to the modern-day ecological approach, just as ancient knowledge of the heavenly bodies might seem related to modern astronomy. But it is a mistake to consider ancient knowledge like this a distant forerunner of the modern idea of the biosphere. Of course, modern ideas have not simply emerged from nothingness; each idea has its own history. This makes it tempting to go back into the past from the present day to search for theories or data linked together to make a chain starting at the beginning and leading to contemporary knowledge, as if one could reconstruct the development of knowledge in the same way one traces a family tree. Interpreting the events of the past in the light of present knowledge is a risky endeavor, though, because current views cannot duplicate the ways in which problems were seen at an earlier time. When considering the history of the idea of the biosphere, this temptation would take the form of interpreting the gradual changes in people's ideas about nature as steps or stages toward the notion of the biosphere, as though the history of human understanding of nature had been moving in precisely that direction.

The history of the development of people's ideas about nature has not followed that path. Human societies have faced problems relating to nature in one way or another, and their practical and theoretical responses to these problems have had more or less success. What is under consideration here is the gradual development of these theoretical and practical responses to the problems that have arisen and to their underlying causes. Thus, the idea of the biosphere does not appear as the end of a historical process seeking to reach precisely this point but simply as the present stage in the ongoing development of humanity's conceptual and practical relationships with its surroundings.

Mythical representation to explain the origin of the world

The empirical knowledge accumulated over the time before written culture is a valuable inheritance that has allowed the development of human societies. For a long time, many events--such as illness, the death of mother or child in childbirth, hunting accidents, etc.--were totally unforeseeable. These uncontrollable phenomena were seen then (and in some cases still are) as inevitable and inexplicable.

It is important to try to understand things like these, not in order to control them, but to limit their effects. Human thought progresses by trying to explain the unknown starting from the basis of what is known, and so humans have attributed their tragic fates to desires like their own and to forces like their own, but on a much larger scale. The idea of the supernatural probably arose as a result of this intellectual habit, which is as old as humanity.

Little by little, every human group created divinities that presided over the simplest actions of everyday life. Much later, elaborate foundation myths developed, and gods made their appearance. Such tales helped to explain the basic mystery facing human beings--the origin of the world, that is, the planet Earth and the living things on it, as well as the stars shining in the sky. These ancient accounts were the first human references to Earth as such and what we, nearly 30 centuries later, refer to as the biosphere (a term derived from the Greek words bios, meaning life, and sphaira, meaning ball).

The Egyptians, for example, were polytheistic. They even had purely local gods. Some of these gods were incarnated as animals such as the sacred ibis (Thoth, the god of learning and writing), the falcon (Ra, the personification of the Sun, and Horus, the protector of the monarchy), and the jackal (Anubis, the god of the dead and of funeral rituals). Other gods were identified with a natural feature or object. Ra, for example, was identified with the Sun and was thought to cross the sky in his solar boat; the goddess Nut was identified with the sky, the vault of the heavens, and was separated from her husband, Geb, the Earth god, by Shu, who was the father of both, god of the air, and supporter of the sky; and Hapi was the personification of the annual Nile flood. The Egyptian empire had consolidated by the time of the rule of Akhenaton (Amenophis IV to the Greeks and king of Egypt from c. 1379-1362 B.C.), who imposed worship of a single deity, Aton (the disc of the Sun), but this monotheistic cult disappeared after Akhenaton's death.

The Greeks were also polytheistic. Gaia (or Gea) was regarded as the fundamental divinity, the Earth goddess, first to emerge out of primeval chaos. She was said to have borne and then married Uranus (the sky). Their offspring were the first divine beings and many monstrous divinities, including the Titans (e.g. Oceanus and Cronus) and the Cyclopes. The myth of Gaia suggested the name that James Ephraim Lovelock (b. 1919, see pp. 128-129) gave to his theory that Earth behaves like a single living system (but we should not expect there to be any relation between the Gaia myth and the Gaia hypothesis).

From myth to science

About 6,500 years ago, while foundation myths and mythologies were developing and becoming more complex, astronomy was becoming increasingly refined, probably because people sought answers to their questions through astrology. Later on, other competent schools of astronomy grew up, first in Egypt and then in Greece.

Yet people did not think of the planet Earth as a sphere. In Mesopotamia, the Sumerians thought the world was a mountain covered by a celestial sphere supported by metal pillars that none could approach. The Babylonians thought of the world as a mountain floating on the ocean; so did the people of Israel, who were influenced by Babylonian ideas. For the Egyptians, the universe was a rectangular parallelepiped, with Earth at its base: four peaks supported the sky, from which the stars hung. The poems of Homer (eighth century B.C.) teach us that the Greeks of the Archaic period thought that Earth was a disc surrounded by the ocean, the sky, and a primordial river that flowed into the sea at the horizon. The heavenly bodies were thought to rise above this horizon at dawn and sink below it at night.

The Babylonians, the Egyptians, and the Greeks all learned to measure time. They reconciled with more or less success the astronomical year of 365 days and a fraction to the cycle of the seasons. They learned to predict eclipses, after the observation that they repeated in a cycle of 18 years 11 days (known as saros), at which time Earth, the Sun, and the Moon returned to the same relative positions. They also found explanations for the apparently aberrant movement of the "wandering heavenly bodies" (the meaning in Greek of the word planetes), which move relative to the fixed stars.

Eudoxus of Cnidus (c. 409-356 B.C.), a Greek philosopher, mathematician, and astronomer, proposed a complex system of concentric spheres, each planet having a sphere of its own, in which Earth was the center of the universe (known as the geocentric theory of the universe). A century later Greek astronomer Aristarchus of Samos (c. 310-230 B.C.) became the first person to advance the theory that Earth rotates and that it revolves around the Sun. By the fifth century B.C., sufficient evidence was found to abandon previous cosmological ideas and affirm that the planet Earth is, indeed, round (the answer to the problem of what happened to the Sun and stars when they went below the horizon). The great Greek astronomer Hipparchus of Nicaea (c. 190-120 B.C.) was the first to postulate that Earth was round in shape; much later, in the second century A.D., so did astronomer, mathematician, and geographer Ptolemy (Claudius Ptolemy of Alexandria) in his work now known as Almagest. However, some compelling reason was needed to abandon mythical explanations in favor of more rational ones. The idea that predicting phenomena is the basic purpose of research was already widespread in antiquity. But, of course, one does not always need to understand something to predict it; eclipses, for example, could be predicted within the framework of astronomical ideas that placed Earth at the center of the solar system, even though this assumption was incorrect.

Greek civilization in the fifth century B.C. was based on the polis or city (Athens, Corinth, etc.). The Greek city consisted of the city itself and also the surrounding countryside. The city had to be administered and defended so that the free men living there--the citizens--could reach or maintain some degree of prosperity. Tyrannical regimes, in which power was restricted to a small number of people (oligarchic or aristocratic regimes) clearly hampered a city's growth and trade and became an obstacle to the prosperity desired by most citizens. This led cities to adopt different types of democracy (rule by the people) with varying degrees of success and duration. Under these new methods of government, political proposals were presented to the people, who discussed them and decided upon them. New intellectual procedures had to be invented to meet this new way of doing things.

Impediments to the spread of knowledge to the masses (mysticism, obscurantism, esotericism stemming from archaic myths, and supposed restriction of knowledge to initiates and oracles) were all gradually replaced by rigorous, coherent chains of thought and the idea that both the physical world and the living world can be understood by the use of reason. This incredibly fruitful intellectual revolution, the birth of rationalism (from the Latin word ratio, meaning reason), was dominated by Greek philosopher Socrates (c. 470-399 B.C.), the teacher of Plato (c. 427-347 B.C.). It has been called the "Greek miracle" and marked the emergence of organized abstract thought. This process did not take place suddenly. It was preceded by a long period of transformation, during which the earliest ideas about what is now called the biosphere underwent great changes and ideas about nature tended to shed their former religious bases.

The nature of things

This tremendous change in people's view of the world was due to the elaboration of systems based on the nature (physis in Greek) of things, that is to say their origin (arkhe in Greek), and the changes that gave rise to the phenomena of the universe. All the systems developed at this time sought to explain the true nature of the world, that which underlies its constant changes in appearance.

Greek mathematician and philosopher Thales of Miletus (c. 624-565 B.C.) thought that water was the essence of all things, as it can become solid to form ice, consolidates as soil in alluvial deposits, emerges from the ground as springs, and condenses in clouds from the air. He also taught that water was the origin of life, since it gives plants and animals their vital force. Thales was best known to his contemporaries for his prediction, presumably on the basis of the Chaldean priestly calendar, of the total eclipse of the Sun on May 28, 585 B.C., which, according to tradition, interrupted the battle between the Lydians and the Medians.

Later, Anaximenes (585-526 B.C., also from Miletus), advanced the idea that air, not water, was the basic building block of all matter, while Heraclitus of Ephesus (c. 540-475 B.C., also from Asia Minor) taught that fire was the basic material principle of an orderly universe. Even more remarkably, the Greek philosopher Anaximander of Miletus (c. 611-547 B.C.), a student of Thales, described the eternal cycle of the birth and death of worlds, which he thought were living things or deities. This eternal action, according to Anaximander, separated the opposites of the imperceptible primitive substance, the apeiron (the unlimited; the divine principle, both material and infinite), and gave rise to the worlds. Anaximander also outlined the major aspects of the development of life by adaptation to its environment. He postulated that animals originated in the sea, as fishes protected by a spiny shell, and they modified their form of life, when, once on dry land, this shell burst and gave rise to other animals by transmutation (the conversion of one form into another). Humans originated within sharks, and, when duly fed, they were thrown onto the shore and became able to survive there. Thus, a kind of early evolutionary theory was formulated.

Unlike Heraclitus of Ephesus and the philosophers of Miletus, contemporary philosophers in Elea (a Greek colony in southern Italy, on the shores of the Tyrrhenian Sea)--mainly Zeno of Elea (c. 490-430 B.C.) and Parmenides of Elea (c. 540-470 B.C.)--conceived philosophical systems that denied movement (or change) on the basis of reasoning such as the affirmation that if the world changed, it would already have totally disappeared in the infinity of time. Furthermore, Parmenides did not consider the movement of bodies, but rather that of the "system of the world" as a whole.

1.2 The time of reason and the time of faith

These conceptions represent one of the major advances in human thought over the course of history. They offered the first affirmations of the unity of the material world and the first attempts to give material explanations for the origin and development of the world. It became widely accepted that the essential nature of things persisted despite their apparent changes. The objects of the world, living and nonliving, were seen as ceaselessly turning from one thing to another, in the way that a plant becomes flesh when eaten by a herbivore. This line of thought marked the first step toward the idea of the unity of the world, a concept that is essential to the development of the idea of the biosphere.

Classical thought: Plato and Aristotle

The ideas of Athenian philosopher Plato are generally considered the foundation of Western philosophy. He stated that there was an ideal and perfect universe, an eternal world of "ideals" located "outside and beyond," an imperfect copy of which forms the inferior world of humans, which is subject to a constant process of degradation. This is a metaphysical approach, since the world of ideas, in the material meaning of the word, cannot be experienced, not even in theory. Even so, Plato is essentially a rationalist. According to his beliefs, ideas as a whole can be understood by reason, and the rigorous practice of philosophy makes it possible to become aware of the deceptive nature of appearances in the everyday world and perceive the true world of ideals. Such a philosophy is dualistic, as all aspects of the world boil down to two principles: the ideal and the material. This is a form of idealism in that the only true reality is the world of ideals, but it also reflects the principles of rationalism in that the world can be understood through the use of reason. Such dualism is recognizable in outline as the medieval Christian conception of the universe, with its references to "above" and "here below." Plato's philosophy did not attach value to the world experienced by humans, and so it did not favor the accumulation of a body of empirical knowledge about nature. To the contrary, Plato was fascinated by the formal disciplines such as logic and mathematics. The cosmology of one of his works, Timaeus--in which the demiurge forms the "body of the world" from fire and water--stems from a line of reasoning based on analogy with a geometric construction.

Aristotle of Stagira (ancient Macedonia; 384-322 B.C.), Plato's most famous and influential pupil, sought to reconcile the Platonic theory of ideals with empirical reality. Aristotle located the essence of things not in a world "beyond here," like Plato, but in things themselves. This way of looking at things allowed, and in fact required, the construction of a body of empirical knowledge. Just as Plato's approach led him to take an interest in mathematics, Aristotle's philosophical point of view greatly influenced the sort of things he chose to investigate. And this is because philosophy is closely related to how science is practiced--something that has been shown many times in the development of the idea of the biosphere. Aristotle's knowledge was very broad in its scope, positively encyclopedic. His many works on nature included Physics, On the Heavens, On Generation and Corruption, Meteorology, History of Animals, Parts of Animals, Generation of Animals, Motion of Animals, On the Soul, and several short texts known collectively as Parva naturalia. Aristotle's works thus deal with the major areas into which present-day research related to the biosphere is organized. In Plato's work Phaedrus, Socrates says that the planet Earth is spherical and occupies the center of the universe. Aristotle deduced that Earth is spherical from the fact that things weigh the same everywhere, as they all converge toward the center of the world from varying directions. Grasping the idea that our planet is round was another essential step on the path to the modern idea of the biosphere.

Aristotle's knowledge of nature was amazingly sound. Some of his observations, sometimes obtained by dissection, were not confirmed until the nineteenth century. In his History of Animals, he mentions more than 500 species, including 120 fish and 60 insects. Many of his observations deal with subjects we would now consider ecological or demographic. His metaphysical preoccupation with the essence of things (that is to say, that without which things would not be what they are) led him to seek in nature what the organisms in question have in common and what distinguishes them. This led him to group different species together in genera, a position that some historians consider taxonomic in nature.

Aristotle's conception of nature is often anthropocentric, as the human species represents the yardstick against which other animal species are measured. It is also teleological because it seeks to explain the differences between species as adaptations to defined ends (in other words, purposes) such as staying alive and growing. Trying to understand living things by reference to human beings--and considering that other organisms have a "purpose"--are ideas that have changed very slowly. Aristotle's influence pushed human thought in this direction for many centuries. In historical terms, his "mistakes" have been as influential as his many correct ideas.

The pessimistic materialism of Lucretius

After the pre-Socratic Democritus of Abdera (c. 470-400 B.C.) and Epicurus (341-271 B.C.), Roman poet and philosopher Lucretius (Titus Lucretius Carus, c. 98-55 B.C.) was one of the most illustrious representatives of materialist thought in antiquity. Lucretius clearly explained his ideas in his poem De rerum natura (On the Nature of Things). Like Democritus and Epicurus, he believed in the doctrine of atomism. This doctrine held that the material universe is composed of relatively simple and immutable particles too minute to be visible, which form ephemeral combinations--the objects of the universe. Atomism is not the ancestor of modern ideas about atoms, as it sought to disprove the idea that the order of the world was of divine origin.

Like Epicurus, Lucretius thought of Earth as a sea. This sea had given birth to the first animals, though the smallest ones were still being created continuously by spontaneous generation. Some of the animals that entered the world were monsters unable to survive. Only the strongest and best adapted could be considered the ancestors of present-day animals. Unlike the archaic myths (which held that a golden age had preceded the modern world), Lucretius thought that people had evolved from a brute state, when they survived by collecting wild berries, to civilization, as a result of the practice of agriculture. This idea of evolving development is present throughout Lucretius's writings. The Earth, like living things, was born, and was thus subject to aging and death, as was shown by erosive processes. Thus, in infinite space, the Earth, the "mother of gods" (and not the other way round), changes and declines, and "the pastures glad, which now today yet scarcely grow."

Medieval images of nature

The period between the fall of the Western Roman Empire (in 476) and the discovery of the New World (in 1492) is traditionally considered the medieval period. It is no longer seen as a dark age between two brilliant periods, classical antiquity and the Renaissance. Much of the learning of the Greeks and Romans was spread and developed by Arabic scholars. These scholars included al-Biruni (973-1048), who stated that the Earth is round because the shadow it casts on the Moon is round, Avicenna ('Ibn Sina; 980-1037), a doctor from Bukhara, and Averroes ('Ibn Rushd; 1126-1198) from Cordoba. Aristotle's ideas spread throughout the Christian world as a result of translations from Arabic.

Christian theology was based on the idea that God created the world. It did not inquire into the natural phenomena relating to living things. According to Christian thought, the order and harmony of the world and the impressive adaptations of animals revealed the perfection of God's creation. Without actually prohibiting it, religious dogma posed an obstacle to the study of material causes. The philosophy of Italian thinker Saint Thomas Aquinas (c. 1225-1274), known as Thomism, was a synthesis of the thought of Aristotle and that of Augustine and other early Church fathers, and it soon became dominant within scholasticism, the philosophical movement dominant in western Christianity from the ninth to the seventeenth centuries. This rationalist form of scholasticism sought the truth by logical deduction and was thus an impediment to the use of real data to decide a controversy. To learn if the uterus of a female rabbit was divided into two lobes, rather than killing one and dissecting it, people referred to Aristotle's works. The work of naturalists was thus reduced to engraving fantastic bestiaries, making herbals, and cultivating medicinal plants. The relation of humans to nature was one of domination, as ordered by Genesis (1:28): "Be fruitful and multiply and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth."

The "little Renaissance" of the twelfth century saw some changes with the writings on natural history of Abbess Hildegard of Bingen (1098-1179), Albertus Magnus (also known as Albert the Great; 1193-1280), and Frederick II of Hohenstaufen (1194-1250), king of Sicily who was crowned Holy Roman Emperor in Rome in 1220. Albert promoted the medical school in Salerno, where dissection of human bodies was performed; this was one of the reasons given for his later excommunication. Still, the general level of observations had barely changed.

1.3 The triumph of humanism and the mechanistic revolution

The cultural revolution known as the Renaissance took place in fifteenth century Italy and spread to the rest of Europe in the sixteenth century. Among other things, there was a significant change during this time in humans' perception of their relation to nature and their place in the world and in the universe. Many of the concepts underlying the modern idea of the biosphere have their origins in the Renaissance.

Factors contributing to an intellectual revolution

The Council of Florence (also known as Ferrara-Florence), a meeting seeking to reconcile the Roman and Greek churches, was addressed in 1439 by Byzantine emperor John VIII Palaeologus (1390-1448), who sought to alert the West to the threats facing Constantinople. He did not get the support he was looking for, and 14 years later, on May 29, 1453, Mehmed II (the Conqueror; 1432-1481) took Constantinople. The rediscovery of Greek and Roman culture (through manuscripts left in Italy by John VIII) and the emergence into the public forum of Jewish culture--two of the characteristic features of the Renaissance--were linked to John's visit to the Council of Florence. After Italian poet Petrarch's rediscovery of Cicero and Roman culture in the fourteenth century, the later great humanists Marsilio Ficino (1433-1499), Erasmus of Rotterdam (c. 1469-1536), and Sir Thomas More (1478-1535) tried to reconcile classical Greek thought (especially that of Plato) with Christian values, a process that gradually gave rise to notions like tolerance and the worth of the individual.

However, this rediscovery of classical thought was not the only factor contributing to the intellectual advances of the time. The invention of movable type and the printing press by Johannes Gutenberg (c. 1399-1468) led to the growth of printing and publishing. Largely due to the efforts of humanist printers and publishers like Aldus Manutius (or Aldo Manuzio; 1449-1515), this, in turn, led to the wide distribution of the classic texts and the Bible, which were translated from Greek and Latin and published in the languages of the common people. And so a new type of person--the reader--was created; by freely interpreting a text and making independent judgments on it, readers constructed their own individual personalities and adopted their own points of view. The Reformation triggered by Martin Luther (1483-1546) also played an important role in this change, since it promoted a personal interpretation of the scriptures by its adherents. The introduction and systematic adoption of perspective in painting was another cause and consequence of the intellectual changes of fifteenth century. The Italian painters of this century, the Quattrocento--among them Fra Angelico (1401-1455), Piero della Francesca (1416-1492), and Andrea Mantegna (1431-1506)--were largely responsible for the development of perspective. This major change legitimized the idea of the point of view, the aesthetic equivalent of the idea of tolerance in ethics. After all, doesn't perspective tell us that things look different from different points of view?

Understanding the universe in terms of geometry

The first globe intended to represent the planet Earth was made by German geographer Martin Behaim (c. 1436-1507) in 1492, the same year that Christopher Columbus (1451-1506) discovered the New World. Behaim made his globe almost 30 years before it was proved beyond all doubt that the world was round, as postulated by Hipparchus and Claudius Ptolemy of Alexandria in antiquity. Proof came with the first circumnavigation of the globe (1518-1522) by Ferdinand Magellan of Portugal (c. 1480-1521) and the Basque Juan Sebastian de Elcano (1486-1526), in the service of the kings of Spain. In 1497-1498 Portuguese navigator Vasco da Gama (c. 1460-1524) rounded the southern tip of Africa, sailed along the Cape of Good Hope, and found the sea route from Europe to India.

The gradual discovery of the flora and fauna of the New World put an end to the fantastic stories that previous explorers had told. The observations of chronicler Gonzalo Fernandez de Oviedo y Valdes (1478-1557), those of Jesuit missionary Jose de Acosta (1539-1600), and those of physician Francisco Hernandez (1517-1587) made no references to the unicorns or headless men that appeared in the 1513 world map of the Turkish admiral Muhyi al-Din Piri Rais (1470-1554). In fact, the fascinating differences they observed between the New World's flora and fauna and those of the Old World also showed how similar they were, even if they remained hard to explain. The discovery of the New World revealed that the world was a single entity and that the laws of nature were the same all over Earth.

Polish astronomer Nicolaus Copernicus (1473-1543) and, later, Italian scientist Galileo Galilei (1564-1642) gave the final touch to this revolution in the way people thought about the universe by showing that Earth was not at the center of the universe but rotated around the Sun, as Aristarchus of Samos had correctly proposed more than 1,800 years earlier. The sky, and space itself, can be understood in terms of geometry, and objects and their motion can be analyzed using vectors. This disposed of the idea of a cosmos where every object is in its place, or should be, in accordance with an unchanging order. "Heavy bodies" no longer had a "natural" place, and their fall no longer indicated that they had been displaced by a "violent" movement that upset the order and harmony of the world, as Aristotle had thought.

The idea that the world "above" (supralunar) was perfect and unchanging was gradually replaced by the view that it possessed the same characteristics as world "below" (sublunar). Galileo's invention, the Galilean telescope, provided abundant confirmations: the phases of Venus were comparable to those of the Moon (see pp. 40-41), Jupiter has several satellites, and there are spots on the Sun ("sunspots"). Galileo also observed that Saturn was a strange shape, though his instrument's resolution was not high enough to discern the rings.

The new view of the engineers

A new type of science was thus taking shape, and it was accompanied by new ideas. A new approach was also taking shape in Western societies--that of the engineers, who manipulated, transformed, dissected, directed, and imitated nature. Florentine architect and engineer Filippo Brunelleschi (1377-1446), for example, was a goldsmith, mathematician, and sculptor. When he was in charge of construction of the dome of Santa Maria del Fiore in Florence, he not only drew up the plans but also resolved all the technical problems that arose during construction; thus, he can be considered a pioneer of Renaissance architecture. Leon Battista Alberti (14061472), another architect and engineer, was a philosopher, poet, writer, musician, painter, and archaeologist. Francesco di Giorgio Martini (1439-1502) was a painter and sculptor (therefore capable of working metal) who became a military engineer; his interest in city planning marked the beginning of interest in the organization of space. Albrecht Durer (1471-1528), an engraver, botanist, and military engineer, changed from the art of fortifying cities to city planning as such, as well as studying the proportions of the human body.

The most famous of all these multi-talented engineers, Leonardo da Vinci (1452-1519), was a goldsmith, a painter, and an anatomist. He studied geometry under Florentine painter and mosaicist Paolo di Dono (also known as Paolo Uccello; 1397-1475) and learned the rules of perspective from Alberti. In 1485 Leonardo drew up highly geometric plans for an ideal city on two levels: he took into account the need to disperse smoke and the inherent restrictions derived from reliance on natural light. His manuscripts, which were only published in the late eighteenth century, show he thought marine fossils were the remains of living things, repeating the ideas of Avicenna and Albert the Great on this subject. French potter and paleontologist Bernard Palissy (c. 1510-1590), like Leonardo, thought that fossil seashells were deposited by the seas when the waters covered what is now dry land. In 1492 Leonardo invented a flying machine that imitated the flapping wings of bats. Might imitating nature not be a way of understanding her mysteries and mastering them? Two years later, he began dissecting human corpses. Might not even the secrets of life be accessible to the scalpel?

A world stripped of enchantment

Over the course of the sixteenth century, the view of nature as something that could be understood only through myths was replaced by an increasingly mechanistic view, and nature came to be seen as something that could be dominated. The world became something to conquer--and not just the New World, whose discovery showed the European societies that the "new" is to be found everywhere. A planetary conception of the world and of nature was thus arising. People looked at the globe with hope. They discovered remarkable faunas and floras, which they acclimatized. In time, they exploited this new wealth in the form of trade in coffee, cocoa, tobacco, sugar cane ... and slavery. The ancient correlation between the exploitation of nature and the exploitation of humans became even closer, as it has remained to the present day.

In parallel, the persecution of the Protestants and the wars of religion encouraged the breakdown of religious certainty. Many people thought there was no heaven in the sky and wondered if human beings were the only ones in the universe. This led some to speculate about the origin of order in nature and how it is maintained, questions of great importance for the development, much later, of the idea of the biosphere. Such an approach led thinkers to ask if this natural order could be threatened--and, if so, what should be done? The tremendous cultural change that took place in the Renaissance, thus, has to be understood as a complex and contradictory process. The flourishing of the arts and letters, new scientific knowledge, the new conception of the world--all of these events were accompanied by deep concerns, not that far removed from the concern about the biosphere that has developed in contemporary society since the 1970s.

1.4 The Enlightenment: ideas about Earth and the economy of nature

Over the course of the seventeenth and eighteenth centuries, new approaches were adopted to questions like the origin of order in nature. It was becoming clearer and clearer that the text of the Bible was contradicted by facts. All the theories proposed to reconcile these contradictions considered that the presence of living things on the planet's surface was the result of divine providence and that the great natural balances were also divinely inspired.

The Earth in transformation: Neptunism and Plutonism

The presence of marine fossils on mountain ridges had caused great controversy since antiquity. Once it was accepted that they had been deposited at the bottom of the sea, the problem was to explain their presence high up on mountains, since some geological theory was required to explain the rising of mountains. Avicenna had pointed out that mountains might have formed either by the rising of Earth's crust or by erosion by water. Erosion by water was initially more widely accepted: at the moment of creation, the sea would have covered the entire surface of the planet; as its level fell, the dry land was uncovered and exposed to weathering. This could not be explained by invoking the biblical Flood, as the Bible mentions the existence of landscapes prior to the Flood.

This theory proposing a central role for water action in the development of Earth's features is known as Neptunism, a name derived from Neptune, the Roman god of the sea. Neptunism was initially advanced by the German philosopher and mathematician Wilhelm Leibniz (1646-1716) in his work Protogaea, Sive de Prima Facies Telluris (Protogaea, or the First Appearance of the Earth) which was published in 1749 but written in the late seventeenth century. The most important eighteenth-century representative of Neptunism was Abraham Gottlob Werner (1749-1817). Neptunism was replaced by the philosophy of Scottish geologist James Hutton (1726-1797) in the late eighteenth century. His ideas, known collectively as Plutonism (from Pluto, the Roman god of the underworld), trace the existence of Earth's crust to the rising of molten materials from within Earth.

Neptunism was developed and radically extended by a French diplomat named Benoit de Maillet (1656-1738), who served as French consul general in Egypt (1692-1708). De Maillet's frequently exaggerated ideas were partly inspired by the theories of Danish geologist and anatomist Niels Steensen (1638-1686; better known by his Latin name, Nicolaus Steno) and by those of the ancient Muslim philosophers such as Omar Khayyam (c. 1048-1123). De Maillet's views were expressed in a work known as Telliamed, presented as the name of an Indian philosopher but in fact the name "de Maillet" spelled backwards. According to his ideas, the level of the sea was always falling. Terrestrial species, including humans, he said, were descended from marine ancestors that had lived in shallow waters and had undergone a process of transformation. Is it not true, asked de Maillet, that on the banks of rivers, "mermen" and "mermaids" were regularly found in the stomachs of large fish and in fishermen's nets, and that these beings were clearly halfway between fish and human beings? De Maillet further concluded that there were no fossils on so-called Aprimitive mountains because, when they started to rise, the sea level was too high for life. De Maillet's conception of time was cyclic (see fig. 13), in opposition to biblical teachings.

The fact that marine fossils are found on mountains has thus played an important role in the integration of scientific thought. Over the centuries, their study has brought together the initially distant sciences now known as biology and geology, showing how closely linked life is to Earth itself. This process represents another important factor in the formation and development of the idea of the biosphere.

The economy of nature

Linnaeus [Carl von Linne (1707-1778)] is one of the most important figures in the history of biology. He is especially remembered for the introduction of the "binomial system of classification," known as the Linnaean system, in which every species is assigned a Latin generic name followed by a specific name. Every species belongs to a genus, every genus belongs to a family, every family to an order, and so on in an hierarchical progression of taxonomical units. Yet, in the context of this particular text, a different aspect of Linnaeus's work is of greater interest, namely his idea that providence regulates all the aspects of what he called the "economy of nature."

Linnaeus held the chair of botany at Uppsala University (Sweden) and is considered the author of publications like Amoenitates Academicae (Academic Discussions, 1749-1769), which are in fact rewritten versions of the dissertations of the students he supervised. Some of them, including Oratio de Telluris Habitabilis Incremento (Discourse on the Increase of Habitable Land), refer to aspects of the "economy of nature." Linnaeus's starting position is in agreement with Neptunist ideas, and he affirms that all the land was under the waters in the "infancy of the world." A single island paradise emerged, where all the animals lived and where conditions were favorable for them. By relating the biblical paragraph in which all the animals are presented to Adam for naming to the necessarily limited size of the paradise/Eden island ("otherwise it would have been very difficult for Adam ... to find all the animals"), Linnaeus concluded that the "father of beings" had only placed a single pair of each plant and animal species, even insects, in the Garden of Eden, and that since then "the area of dry land has continuously increased, and the species have continued to grow and multiply."

This raised the problem of predation, that is, that these animals would have eaten one another. A dilemma such as this was hard for these naturalists to resolve because they had to reconcile observation of nature with the Bible. This is essentially the same as the frequently raised problem of how all the different species managed to live together within Noah's ark. Linnaeus answered this with the idea of the "economy of nature": "the wise arrangement by the Creator of the natural things, in accordance with which they are apt to accomplish their common ends and their reciprocal uses," as "it has pleased the Creator's hands to add this proportion which we find between herbivores and carnivores, birds, fish, insects and between the animal and plant kingdoms."

Once again, geology is related to the author's ideas about the increase of habitable land and the science of living things. Linnaeus also made great contributions to the knowledge of the interrelationships between species, and his teleological approach (as opposed to a mechanistic one) was not an obstacle to the development of a deeper science of the mechanisms of equilibriums between populations. This notion was later examined from a nonreligious perspective by British geologist Charles Lyell (1797-1875), the founder of modern geology. Nevertheless, humans came to be viewed over the centuries as increasingly powerful agents in the changes taking place on the face of their planet. It was during the eighteenth century, as we shall see later, that the human species entered on the scene as an important, if not essential, factor in the transformation of the world.

2. Humans' place in nature

2.1 Humans, the conscious fraction of the biosphere

Humanity's place in nature was considered by two of the most important naturalists of the eighteenth century. The Frenchman Georges-Louis Leclerc, Comte de Buffon (1707-1788), thought human beings "the vassals of heaven" but "the kings of the Earth," who ruled over all the creatures and embellished, cultivated, populated, and enriched the surface of the planet. He believed that humans were primates and that they remained subject to the laws of nature and bound to respect its harmonies because humankind was the "external throne of divine magnificence." Linnaeus, a contemporary of Buffon, also assigned humans a central place in nature; everything had been created for their happiness, and the creator had given them dominion "over the entire world." Like Buffon, Linnaeus thought that humans were the "ultimate and greatest servants" of the divine plan and thus subject to the same laws as other organisms.

Dualist conceptions of human nature

The problem of humanity's place in nature has confounded scholars throughout the ages. The human species appears to us as a duality (Homo duplex, as Buffon wrote in 1753), consisting of a "spiritual principle," the soul, and an "animal principle" that precedes it. In fact, the question of human identity cannot be dissociated from that of the place of the human species in nature, and thus, the legitimacy of the reasons underlying human actions transforming the environment. Since their origins, one of the crucial questions facing science and philosophy has been the essence of human identity--and thus human nature. Once it was accepted that human beings were animals, the problem was to distinguish them from the other animals in order to explain their remarkable intellectual and social abilities. Discovering human nature helped answer another equally crucial question: what is the nature of nature?

If one follows the classical definition of nature as "that from which man is absent," nature is something intangible. In this case, human action would then be illegitimate because it is a corrupting influence and a source of many imbalances. If, however, humans form part of nature, their actions are legitimate to the extent that they do not threaten natural balances and thus the survival of the human species. These two approaches are almost mirror images of each other.

For many years, the builders of philosophical systems proceeded in the Aristotelian manner, including the object to be defined within a class (man is an animal) and then specifying some distinguishing feature ("... an animal that buries its dead, or prays, or which the Creator has given a soul"). Usually, however, the factor that they thought distinguished humans from other animals was nonmaterial, a metaphysical entity, the soul. They thought the soul was immortal, immaterial, and what allowed access to an eternal and ideal world. In the words of the French scientist, mathematician, and philosopher Rene Descartes (1596- 1650), the soul is "what makes me what I am."

These examples give us an outline of the scholarly view of nature as everything that was not the human soul. To use the language of the philosophers, the soul was what defined man, that is to say, his essence. But, in keeping with this line of thought, the body--with all its desires--formed part of nature and therefore should be dominated or at least fought. As we shall see later, these dualist conceptions are still influential in the representation of nature found in Western societies.

The retreat of dualism

The question of the relation of human society to nature was raised in a new way as a result of the retreat of religious certainty after the Renaissance, the progress of materialist (or at least nondualist) philosophy (such as that of Georg Wilhelm Friedrich Hegel [1770-1831]), the triumph of the Newtonian paradigm, and the secular tendencies promoted by the French Revolution. The problem was how to define the features distinguishing humans without resorting to metaphysical entities.

The implications of the above questions, became more and more important during the development of industrial society in the nineteenth century, since the answers are (as always in philosophy) responses to social practices, which in this case were mutually opposed. If nature is "that from which man is absent," then nature should be actively protected and conserved. But if humans are part of nature and their transformation of nature by their labor is natural, then it is assumed that rational management practices should be drawn up and implemented.

In 1845-1846 German philosophers Karl Heinrich Marx (1818-1883) and Friedrich Engels (1820-1895) proposed a solution to the problem of human nature in the first part of Die Deutsche Ideologie (The German Ideology) and in Elf Thesen uber Feuerbach (Eleven Theses on Feuerbach). On the one hand, they considered that the factor distinguishing humans is not an abstract metaphysical entity "inherent to each individual." What is distinctive about humans lies outside the individual, in the "set of social relationships." When a child is born, the authors noted, it is only a candidate to become a person, as the individual only becomes fully human by acquiring the cultural heritage of his or her society.

This attitude underlies the theoretical reflections of most contemporary anthropologists and paleoanthropologists, though it is frequently present implicitly or in derived forms. On the other hand, Marx and Engels considered that nature, defined as "that from which man is absent," does not exist "except, perhaps, for a few recently formed Australian atoll reef islands." Nature is never virgin, it is not an object external to humans. It is, in fact, "human action." All this makes it possible to discern what might have developed into a Marxist school to ecology, at least in the philosophical sense, if the idea and practice of ecology had existed in 1846. For Marx and Engels, the way nature was transformed and managed was closely connected to the way society operated. In other words, if people exploit each other, they will also exploit nature. But if people treat each other respectfully and with equality, their relations with nature will be different.

There was a second, quite different, approach to the question of what factors make humans special. This approach was based on transformism, the theory that one species is changed into another and that species change over time in response to the environment. The transformation of species was first proposed by French naturalist Jean-Baptiste de Lamarck (1744-1829), the father of transformism (Lamarckian evolutionary theory).

This theory was later replaced by the theory of evolution by natural selection, proposed by English scientist Charles Darwin (1809-1882). Darwinian adaptation is a process in which selection pressure exerted by "circumstances," as was said at the time, selects between the small hereditary variations that appear in an organism's offspring. The "fittest" individuals will survive to reproduce. The ideas of transformism and evolution have several philosophical consequences, including the scandalous (for its times) idea that humans share a common ancestor with the great apes. Once evolution was accepted, the problem was not where to classify humans among the higher apes but to recognize the factors distinguishing them and to understand how they have evolved.

Darwin also thought direct adaptation was very important. Darwin's own ideas in his 1871 work The Descent of Man and Selection in Relation to Sex had room for the evolution of "social virtues" (see pp. 60-61) and differed greatly from the image portrayed by nineteenth-century English poet Alfred, Lord Tennyson's phrase "nature red in tooth and claw" or by the phrase "the survival of the fittest," in which "fittest" is taken to mean "competitive and brutal." Darwin thought some types of mutual aid were advantageous for the individuals in the populations practicing them and were thus transmitted to their offspring. Natural selection, he theorized, might have effects quite different from those that would be expected if evolution were merely competition, among them patterns of social behavior such as solidarity, mutual aid, and charity. Marx and Engels had suggested that the exploitation of nature was related to social exploitation, and Darwin realized that human nature was the result of the mechanisms of evolution--two ideas that are still present in modern reflections on the biosphere.

Malthusian pessimism

The question of the relation between the increase in the world's resources and the growth of the human population--a question of great contemporary relevance--was first discussed in rigorously mathematical terms by English economist Thomas Robert Malthus (1766-1834) at the end of the eighteenth and the beginning of the nineteenth centuries.

The first known observations on the growth of a population (a population of mice) date back to Aristotle. In his History of Animals, Aristotle writes: "On one occasion a she-mouse in a state of pregnancy was shut up by accident in a jar containing millet-seed, and after a little while the lid of the jar was removed and upwards of one hundred and twenty mice were found inside it." Aristotle considered this rapid rate of increase was due to the abundance of food. Many centuries later Linnaeus commented on the difference between a population's potential rate of increase and its real growth, pointing out that some flies reproduce so fast they would quickly occupy the entire universe unless their numbers were kept in check by predators. Linnaeus considered this yet another example of divine providence maintaining the appropriate proportions between and among species. But his correct analysis merely followed in the footsteps of the true founder of animal demography as an experimental science, the Dutch microscopist Antony van Leeuwenhoek (1632-1723), who even bred lice in his own tights and wore them for six consecutive days to measure their rate of increase.

According to Malthus, population growth is geometric, while growth in resources is arithmetic (see pp. 62-63). His work "An Essay on the Principle of Populations ..." (1798), written in a cold, pessimistic, and inhumane style, caused great controversy. Malthus justified the misery of the working classes and defended the cruel idea that it is useless for the state to assist the poor. (He claimed that assistance would cause the numbers of the poor to increase, and then they would die.) Malthus later published a second version of his essay, in which he promoted late marriage as a way of reducing population growth. His idea was that population growth, precisely because it is geometric (that is, exponential), will inevitably outstrip the growth of resources. In general, though, any idea stressing the risks of overpopulation is considered Malthusian. As we shall see later, this position was criticized when it was used as a basis for the economic policies that, since the 1970s, have proposed the transfer of many productive activities from developed countries to regions where labor is cheaper. Many present-day economists believe: 1) that the world's population and its overall production could increase substantially; and 2) that hunger in the Third World results not from insufficient total food production but from the unfair distribution of the food produced. This inequity is due to the way in which wealth is distributed and to the inhumane effect of the liberal, or more accurately, neo-liberal globalization of the economy. Even so, the mathematical point raised by Malthus is still considered valid. The idea that it is essential for the world population to stabilize and for the systems of production and exchange to be reorganized is now held in intellectual circles that are usually considered far removed from ecology.

2.2 The romantic vision of nature

The rationalist attitudes toward human nature, human evolution, and population growth took root over the course of the nineteenth century. From the end of the eighteenth century onward, however, an opposing point of view arose. This view became known as romanticism; it was associated in Germany with Johann Wolfgang von Goethe (1749-1832) and Friedrich Holderlin (1770-1843) and in Great Britain with William Wordsworth (1770-1850). The romantic movement was linked to the political and social changes of the time and to the emergence of cultural nationalism in the countries of Europe. Later, in the 1820s, romanticism spread to France, Italy, Spain, and then the rest of Europe and the Americas.

The clash between feelings and reason

The literary school that gave birth to German romanticism is known as Sturm und Drang (German for "Storm and Stress"), the name of a tragedy by Friedrich Maximilian von Klinger (1752-1831) that was first performed in 1777. For the members of the romantic movement, the storm of the sentiments, the impulses of the heart and the entire being had to prevail over classical rationality.

Romanticism opposed the rationalism of the Enlightenment, the Newtonian paradigm, the intellectual and cultural influence following the French Revolution (1789), classicism and neoclassicism, and the excesses of modern science, which it considered too analytical and mechanistic. Romanticists attached more importance to feelings--subjective feelings--than to the tyranny of an exclusively rational approach because they believed that rationalism fragmented knowledge, thus impoverishing it. The richness of the imagination, dreams, and escapism were all favored over the rigors of analysis.


The rupture represented by the romantic vision of the world gave rise to a new philosophical approach, a phenomenon that occurs every time it becomes necessary to understand deep feelings that shake a society to its foundations. Goethe and Friedrich von Schiller (1759-1803) were greatly influenced by Johann Gottfried Herder (1744-1803), one of the figureheads of the Sturm und Drang movement and an important link between the new aesthetics and the new philosophy. His unfinished work Ideen zur Philosophie der Geschichte der Menschheit (1784-91; Ideas on the Philosophy of the History of Man) strongly opposes the Enlightenment and argues that humanity is performing a divine project of which it is unaware.

In his writings on the philosophy of nature, Friedrich Wilhelm von Schelling (1775-1854) considered that nature shows itself as a system whose foundations are of the spiritual order. Schelling rejected the traditional opposition of matter and spirit, body and soul, subject and object, humans and nature, visible and invisible, arguing that reductionist science wrongly separates these things--entities that, in human experience, are inseparably joined. His was another philosophical system that credited a divine order with guiding the development of humans and the world. As a consequence, neither this plan nor human beings could be understood by considering humanity in opposition to nature. To the contrary, Schelling considered that human beings were part of nature, participating in the life of the world, in harmony with its vital rhythms.

Thus, naturphilosophie plays an important role in any consideration of how the idea of the biosphere arose. Reacting against dualist ideas that established impenetrable obstacles between the things mentioned above, Herder and Schelling adopted a unifying and monist view of the world. In this philosophical system, humans are animated by the same immanent design that governs the entire world; their relations with nature have to be very different from those prevailing in the dualist conception of the world, where the classic antagonisms (for example, between mind and body) take the form of relationships of domination (the mind dominates the body, spirit dominates matter, and humans dominate nature). To the contrary, naturphilosophie is based on harmony and communion with nature. This conception still has some valid aspects, in the sense that it is based on consideration of a complex and gigantic whole; it is possible to discern a system. The idea of the interdependence of the components of the system, which characterizes the gigantic object that would later be known as the biosphere, is not that far off. As we shall see later, this idea was already taking shape in a series of founding works that would now be considered ecological in their approach.

The leading romantic

Johann Wolfgang von Goethe is perhaps the most representative figure of German romanticism, though after 1775 he distanced himself from the movement, returned to a form of classicism, and later definitively broke with romanticism. Works like Die Leiden des jungen Werthers (The Sorrows of Young Werther, 1774), Faust, and Aus meinem Leben: Dichtung und Wahrheit (Poetry and Truth: From My Own Life, 1811) are known to the general public, at least by name. Goethe's scientific work is far less well known and includes Metamorphose der Pflanzen (Attempt to Explain the Metamorphosis of Plants, 1790), Farbenlehre (Theory of Color, 18101823), and the even less well-known Memorandum on the Geological Composition of Marienbad (1821), Essay on Doctrine on Atmospheric States (1825), and several others. Goethe's interest in the organism as a whole led him to recognize that the parts of the flower are in fact modified leaves. He introduced the word morphology, trying to promote a more qualitative understanding of nature.

Goethe was interested in science throughout his life. One of his most important scientific discoveries was his demonstration of the existence of the human os intermaxillare (that is, the premaxilla of modern anatomists). This bone is present in mammals and great apes, but its existence had been denied by the Renaissance anatomist Andries van Wesel, better known as Andreas Vesalius (1514-1564), and by Goethe's contemporary, German scientist Johann Friedrich Blumenbach (1752-1840). Goethe's discovery--almost a half-century before Darwin's theory of evolution was published--was a landmark in the development of comparative anatomy, which is based on analysis of morphological similarities. Goethe greatly influenced people's attitudes toward science, its objectives, and the intellectual and experimental procedures it uses. One might say that Goethe had his own philosophy of science, or epistemology. His thoughts on all these points were in agreement with the Sturm und Drang school; reducing reality to its purely quantitative aspects was a reductionist artifice that impoverished the object being studied and "rips the guts out of it."

In Goethe's view, classical science was excessively analytical and fragmented reality beyond recognition. The mechanistic Newtonian paradigm only distorted reality, recreating an artificial and impoverished image of it. Overemphasizing dissection, the purpose of which is to understand living organisms, would be absurd, since it is only possible to study a dead organism by dissection.

As opposed to trying to understand things only by quantified abstractions, Goethe, the poet, wanted to experience the changing world rather than contemplate a reality from which it is detached. Goethe sought to grasp the immanent spiritual energy that goes beyond nature and humans. He rejected a mechanistic approach to science based on analysis (since he considered the sole use of analysis as "criminal"). Thus, he predicted a physical, chemical physiology within the idea of morphology. To sum up, Goethe thought science should try to take everything into consideration or, at least, should try to understand the whole. This is a theme that occurs again and again in the consolidation and development of the idea of the biosphere. As we shall see later, this overall approach has played an important role in the formation of ecology, the scientific discipline that has taken in and structured works relating to the biosphere. Ecology is the scientific study of the interrelationships among and between organisms and between them and all aspects--living and nonliving--of their environment. Thus, the term ecology has a very clear holistic and integrating implication.

Humboldt's attitude to science and the origins of ecology

The science of ecology originates from many different ideas and approaches, among them: 1) the realization that divine providence was not responsible for maintaining natural balances (as Linnaeus had considered); 2) the growth of plant physiology and the use of chemical fertilizers in agriculture; 3) Lamarck's idea that species changed and adapted; 4) the study of fossil plants and their environment; and 5) the development of physical geography (i.e., the study of the form, structure, and changes of the surface of the Earth). Before the concept of ecology was defined, these different disciplines had come together under the name plant geography, the study of the distribution of plants and the reasons for this distribution. Plant geography, as we know it, was founded by the great Prussian scholar Baron Friedrich Wilhelm Karl Heinrich Alexander von Humboldt (1769-1859).

Alexander von Humboldt was a paradoxical romantic, who, unlike other German scientists of the time, can be considered a rationalist. He was highly influenced by the German romantic movement and knew many of its leading figures. Humboldt met Goethe and Schiller in the east-central German city of Jena in 1797. He was a good friend of Goethe (whom he had met previously) and visited him several times in Weimar. Humboldt did not get on very well with Schiller, even though he initially contributed to the newspaper that Schiller edited. Schiller is said to have detested Humboldt, and the dislike was mutual. Humboldt criticized Schiller for his "sentimental disorder" and his "lack of scientific rigor."

Humboldt dedicated the first German edition of his Essai sur la Geographie des Plantes (Essay on the Geography of Plants) to Goethe. This work was first published in 1805 in Paris in French. Humboldt's mother was French, and he lived in Paris for more than 20 years, forming part of the French scientific milieu of the first quarter of the nineteenth century. He was trained as an engineer, became a geologist and an expert on mining, and had a lively interest in physics, chemistry, botany, and various other subjects. Humboldt was prodigiously erudite and physically strong. Together with Aime-Jacques-Alexandre Bonpland (1773-1858), a surgeon in the French Navy and a keen botanist, he undertook a five-year-long voyage (1799-1804) through tropical America, from Cuba through Mexico and to Peru.

Humboldt's observations on this expedition influenced his ideas on plant geography. For example, the two men tried to climb to the peak of Mount Chimborazo in Ecuador, then thought by some to be the highest mountain in the world. Humboldt observed the distinct zones of vegetation at different altitudes on the sides of the mountain. He realized that the zones of vegetation on a mountainside, which vary with altitude, are in some ways comparable to the zonal bands of vegetation on Earth's face, which vary with latitude. Humboldt paid special attention to the fact that vegetation with similar overall appearance but of very different species-composition occurs in widely separated areas, where physical conditions (such as climate) are similar. He was more interested in these morphological aspects of plant geography than in the distribution of plant species. Ecology took off as a science when plant geography developed into plant ecology- -the study of plant communities and their environments--in the late nineteenth century. The plant ecology approach considered plant communities (such as tropical rainforests) and their adaptations as a whole rather than restricting itself to a study of the distribution of the species that make up the community.

Those who followed the romantic approach (or epistemology) to science, and also many conventional naturalists of the time, thought it was crucial to take nature as a whole into account--to see the big picture. Humboldt's interest in landscapes corresponds with his romantic leanings and his desire as a naturalist to understand nature as a whole. Landscapes and plant communities could not be understood by the typical floristic analysis, as this was little more than drawing up a list of the plant species present. Humboldt made great efforts to collect specimens, but he did not perform the tricky and time- consuming work of classifying them. The plant specimens he and his fellow voyager Bonpland brought from the Americas alone seem to have increased by 5-6% the total number of plant species known to science at the time. Humboldt, whom some have called the "modern Aristotle," understood thoroughly that analysis and synthesis are equally necessary, and his work Cosmos, represents a landmark in the development of this approach. In Cosmos, Humboldt tried to bring together everything that had then been discovered about "the celestial spaces, the surface of the world and, to the limited extent it has been possible, the depths." The planet Earth as a whole is thus clearly the work's main theme.

Cosmos does not deal with the actions of humans on the world, because, according to Humboldt's decision, "a physical description of nature finishes where the sphere of intelligence begins. It must reach this limit but not pass it." This is where we reencounter the idea, common at the time, that nature is "that from which man is absent." It is also worth commenting that in the phrase "sphere of intelligence," he uses the word sphere in a way that has nothing to do with geometry; rather, it is a metaphoric use of the idea of the sphere to refer to ideas far removed from the geometry of solids (and it reappears later in the twentieth century in several forms). Humboldt was not unaware of the importance of the action of humans on the world; he noted that the human species is a "participant in the life that animates our whole world." However, this represents an intuition rather than a reasoned consideration on the importance of the human factor in the changes occurring on Earth. The reason for this attitude is very simple: the effects of the Industrial Revolution were still not destructive enough for Humboldt and most other naturalists of his time to take them into account. But after the 1860s, these changes became noticeable enough for the most lucid minds to perceive them.

2.3 The Industrial Revolution and the transformation of the world

It is difficult to assign a precise date to what is usually known as the Industrial Revolution. Many historians and economists consider that it has developed continuously since the early eighteenth century to the present day. Others, stressing the period when the rate of change was fastest, would center it in the 1950s to the 1970s. Over the twentieth century, industrial production increased 50-fold, and four-fifths of this increase took place after 1950, while air transport increased 30-fold after 1950. Even so, it is preferable to remain within the dominant historical tradition, which considers that there was a major social and economic change in some western European countries and in the United States between 1760 and the 1870s (see vol. 7, pp. 308-309). Especially in its earliest forms in Great Britain, the Industrial Revolution brought together contributions from many different sources, among them the developing mercantile capitalist banking system, major changes in technology, the spread of transport systems, the relative stagnation of agricultural production, and political change in response to the growing awareness of the differences between unmet needs and the possibility of meeting them. This text seeks not to try to summarize the history of the Industrial Revolution but simply to examine its main characteristics from the double point of view of its environmental repercussions on the planet and its effects on ideas about nature.

Coal and the steam engine

In the late seventeenth century, demand for iron was not very high. Cast iron was produced by a reducing process that involved heating the iron with charcoal. The cast iron could then be refined by remelting and hammering (water-powered hammering) it to produce wrought iron. But the shortage of wood caused by deforestation became worrying: 25 steres of wood (a stere is a unit of measure of fuelwood equivalent to the branches or logs occupying about 1 m3) was needed to produce 110 lb (50 kg) of iron. It has been calculated that in 40 days, a charcoal maker could completely deforest a radius of 0.6 mi (1 km). The increasing shortage of wood and firewood first became clear in Great Britain (see vol. 7, p. 307) and led to a change from the use of charcoal to the use of coal (especially as coke, obtained by distilling soft coal in a confined space). During the eighteenth century, the percentage of cast iron produced using coke rose from 5% (in 1750) to 77% (in 1785).

Growing demand for iron led to the popularity of the steam engine, which was initially developed by the Scottish instrument maker James Watt (1736-1819) in order to power the pumps used to extract water from mines. This new and reliable source of energy replaced water mills (a substandard energy production method) to power bellows in foundries and hammers in ironworks. Steam engines soon became commonplace in ironworks throughout the industrializing countries. In the 1780s the rapid introduction of mechanization in spinning mills was constrained by relying on water as a source of power, and steam-powered machinery was soon developed for the mills, following James Watt's example. By the 1850s machine-produced textiles dominated the markets. Steam engines were initially built and controlled by engineers on the basis of empirical know-how, and this made it necessary to develop a new physical framework to explain their workings. Such a framework was developed by the young French engineer Nicolas-Leonard-Sadi Carnot (1796-1832) in his small work Reflexions sur la puissance motrice du feu et sur les machines propres a developper cette puissance (Reflections on the Motive Power of Fire and on the Machines Fit to Develop This Power), considered a forerunner to the study of thermodynamics (the physical properties of heat). Carnot realized that the energy that can be obtained from a steam engine is not unlimited but is "limited by the temperatures of the bodies between which, in the final analysis, the heat is transported."

Thus, in an energetically isolated container, temperatures tend spontaneously to uniformity (the second law of thermodynamics), leading to an increase in entropy (a measure of this tendency to uniformity). In the long term, no energy exchange is possible within the container due to the total uniformity of temperatures; this marks the "heat (or thermal) death" of the system. The massive use of fossil energy in the form of coal, and later, petroleum, had contradictory ecological consequences. It favored the reforestation of European countries, especially in the second half of the eighteenth century, but it greatly accelerated the emission of carbon into the atmosphere in the form of carbon dioxide. French mining engineer Francois Joseph Ebelmen (1814-1852) began studying this point in 1845. He considered that the variations in the levels of carbon dioxide in the atmosphere could be the cause of global climatic changes on the scale of geological time, a hypothesis he formulated long before Irish physicist John Tyndall (1820-1893) first formulated the idea of the greenhouse effect in 1861. Ebelmen also thought "the variations in the nature of the air must have been constantly related with the living things that lived in each of these epochs." Ebelmen and the German chemist and mineralogist Karl Gustav Cristoph (1792-1870), who worked independently, may well have been the first to study biogeochemical cycles on a global scale.

Migration to the cities and urban growth in the early stages of the Industrial Revolution

Industrialization was accompanied by slow but large-scale migration from rural areas, a trend that resulted more from the creation of jobs in industry than from a shortage of jobs in agriculture. In fact, in France, though agricultural workers became poorer and poorer, the number of jobs in agriculture grew throughout the nineteenth century. The rural labor force performing proto-industrial activities (on a domestic scale) became the source of the workers for large industries, as many of them migrated to the city to find work in commerce or construction. Seasonal migration related to construction, for example, gradually turned into permanent settlement. It is estimated that from 1830-1850, in the 46 most-affected French departments, the average index of emigration was greater than 36%.

The urban phenomenon in nineteenth century Europe had contradictory characteristics: the city represented the promise of wealth, but poverty was harsher and more widespread in urban areas than it is today (1998). Dwellings and factories were very unhealthy and hygiene was deplorable. Pollution due to the burning of coal and wood greatly affected the quality of the air and the water. Bacterial contamination also affected confined waters and environments.

The result was a profound change in attitudes. The harsh working conditions (including those of working children) and the absence, or inadequacy, of social legislation introduced a deep division between the lifestyle of people living in the city and those living in the country (see also vol. 7, pp. 354-356). From the 1830s on, a concentrated and combative working class arose in all the industrialized countries, and this class was prepared to question the established order. Yet they never questioned the dominant idea that held that the progress of humanity was related to the development of the science and technology, and with the increasing rate of industrial and agricultural growth, the idea that production was essential and that more and more and more had to be produced. The industrial model and its ideology of growth reached the rural world and eventually took the form of capital-intensive agriculture (relying on large inputs of artificial fertilizers, especially ones containing nitrogen and phosphorus). In northern France and the south of the Paris Basin, for example, farms were merged into larger units; the same trend occurred in the United States slightly later (see vol. 7, pp. 348-351).

The development of transportation, increasing pollution, and the proliferation of calamities

The development of transportation in the eighteenth century continued over the course of the nineteenth century, with the exception of interruptions due to the Napoleonic Wars (1800-1815). Between 1800-1840 the network of canals in Great Britain increased from 2,690 mi to 3,470 mi (from 4,329 km to 5,584 km). In France at roughly the same time, the network of waterways tripled; the network of roads spread almost as fast as the canals.

Furthermore, nineteenth-century transportation methods were revolutionized by the appearance and spread of railways and steamships (see vol. 1, pp. 312-313). Railways spread rapidly, mainly because of lower prices--railway transport cost only a third or a quarter of road transport. Railroads were more expensive than transport by canals but had two distinct advantages: they were easier to build and they were not immobilized by droughts or frosts. At the same time, progress in steamship design led to the decline of the elegant clipper sailing ships and the fragile paddle wheel steamers of the nineteenth century (see vol. 10, pp. 226-230). The size of the ships increased and the cost of sea transport fell sharply.

Increasing sea trade had important repercussions on European agriculture, which suddenly found itself subject to severe competition from North American exports. European farmers found that they had to use chemical fertilizers to increase their yields. This economic pressure is now known to have had serious ecological consequences, most importantly the eutrophication of lakes and watercourses due to the runoff of water containing phosphate and nitrate fertilizers.

Another consequence of greater international trade was the accidental introduction of weeds and pests, which proliferated in the absence of the natural enemies that kept them under control in their region of origin. Phylloxera (Viteus vitifolii) is a small insect from the Mississippi Valley that belongs to the aphid (plant lice) family, order Homoptera. It sucks the sap from the roots of vines and kills them. In 1869 phylloxera reached Europe, accidentally introduced through the French ports of Roquemaure and Floirac in the estuary of the Gironde. Within 30 years phylloxera had devastated almost all the vineyards in Europe and spread as far as Turkey (see vol. 5, pp. 268-271). This inadvertent introduction had catastrophic effects, as did many later accidental introductions, including that of the cottony-cushion scale insect (Icerya purchasi, order Homoptera, originally from Australia), which reached the United States in 1890. This pest was controlled by the introduction of ladybird beetles (or ladybugs) from Australia, a process that gave a boost to biological control techniques, which are based on controlling a pest species by introducing a species that is its natural predator. The discovery of DDT's insecticidal properties during World War II (1939-1945) slowed research into these nonaggressive pest control techniques.

Population shifts during the Industrial Revolution

Over the course of the seventeenth century, the population of France, Germany, and northern Italy declined, a trend that is generally attributed to the ravages of the Thirty Years' War (1618-1648). Yet between 1750 and 1850, the population of Europe increased from 162 million to 265 million (an increase of nearly 65%). The end of the major famines [the last major famine in Europe was the Irish Potato Famine, 1845-1849 (see vol. 9, pp. 278-281)], an improved diet, and advances in food hygiene, together with the medical advances made in the late nineteenth century, all contributed to population growth and a sharp decline in infant mortality rates. For example, in France, mortality per 100 live births decreased from around 30 in 1750 to 18 in the 1820s and continued falling from 1850 to 1900. By 1998 there was less than one death per 100 live births.

But it is hard to assess how much of the population growth between 1750 and 1850 was due to the Industrial Revolution and how much would have happened anyway, especially when considering human population growth from a long-term perspective. Demographic historians agree that (broadly speaking) about 500,000 years ago there were roughly one million human beings on Earth, and that at the end of the last glaciation, roughly 12,000 years ago, this number had increased to about five million people. The Neolithic Revolution led to an increase to roughly 150 million about 5,000 years ago; by the year 1000 a.d., the human population had reached about 250 million, then quadrupled around 1840. Since then, population growth has been spectacularly fast, reaching two billion by 1930, four billion by 1975, and five billion in 1987. The United Nations (UN) stated officially that the world's population reached six billion in 2000. Current estimates suggest that the world's population will top eight billion by the year 2025.

Reasoning on the basis of a birth rate for the planet as a whole is a rather dubious abstraction, and the planet is far from reaching its maximum potential production, but this exponential growth of the human population makes reducing the birth rate a question of great importance (though it is no longer considered from the dismal perspective of Malthus). Reducing the birth rate is important, even if one takes into account the opinions of experts who consider that the misery in developing countries is not the result of their overpopulation, but that their overpopulation is the result of their misery. Apart from the growth of the human population, several other ecological alarms are going off.

The human species: is it threatened with extinction?

Human population growth, like many other ecological phenomena, shows great inertia on the planetary scale.

According to the long-term predictions of the United Nations Population Fund (UNPF), if a birth rate of slightly more than two children per couple were reached in 2010, the planet's population would stabilize at 7.7 billion in 2060. If this rate were not attained until 2065, the population would not stabilize until the end of the twenty-first century at a figure of 14 billion!

The problem of the greenhouse effect shows similar inertia. Because the concentration of carbon dioxide in the atmosphere increased due to the tenfold increase in carbon dioxide emissions over the course of the twentieth century, many experts consider that industrial activity is responsible for global warming. Estimates suggest that even if appropriate measures were taken right now, it would take 50-100 years for our planet's temperature to stabilize. It will no doubt be a long time until these measures are implemented. Some people still reject the scientific evidence for the greenhouse effect and, as the Kyoto Conference showed, politicians are unwilling to stand up to the large industrial powers and make decisions whose results would not be seen for a century.

Another major problem is the ozone hole over Antarctica, which is due to the catalytic breakdown of ozone by CFCs (chlorofluorocarbons). CFCs are estimated to survive 50-100 years in the atmosphere. Together with the fact that phosphorus is being lost from dry land and deposited at the bottom of the seas (because the phosphorus cycle is not closed), this might lead to the conclusion that, on the scale of the biosphere as a whole, the very survival of the human population is at risk. This frightening possibility has fast become a crucial and dramatic issue in scientific circles.

3. The development of the ecological sciences and the idea of the biosphere

3.1 Nature has a history: species change over long periods of time

The idea that the world had been created and that nature was immutable still prevailed in the early eighteenth century, but this philosophy was repeatedly contradicted as new knowledge and information came to light. The notion that species could change was gradually adopted as a result of the work of the naturalists Charles Bonnet (1720-1793), Jean Baptiste Robinet (1735-1820), Benoit de Maillet, Pierre Moreau de Maupertius (1698-1759), Denis Diderot (1713-1784), George-Louis Leclerc, Comte de Buffon, and Erasmus Darwin (1731-1802), among others.

The realization that nature has a history

The Linnaean system was useful for classifying plants into a genus and species, but was totally artificial at higher levels. Michel Adanson (1727-1806), Bernard de Jussieu (1699-1777), and Augustin Pyrame de Candolle (1778-1841, who introduced the idea of taxonomy) all produced "natural" classifications that grouped plants into families on the basis of more "natural" features, including their general anatomy and embryonic development. Grouping genera into families made it possible to see them as morphological series and thus suggested they had changed over time. Lamarck, as already mentioned, was the first to propose the theory that species can undergo transformation, that is, change over a very long period of time, "due to the influence of circumstances," to use the language of the time.

Lamarck's idea of transformation is based on three principles. First, at the most basic level, life can appear by spontaneous generation. Second, living things possess an innate tendency to increase in complexity. Third, this tendency is constantly subject to disturbances caused by external conditions. Without these disturbances, the course of evolution would be regular, but observation shows morphological series are discontinuous. Moreover, without disturbances, the course of evolution would also be linear, rather than branching. Note that Lamarck used the word "transformation," not "evolution" (evolutio, unrolling, which was then used to refer to the development of preformed beings). Lamarck is now best remembered for his idea of "direct adaptation," implying that organs are improved with repeated use and weakened by disuse and that such environmentally determined acquisitions or losses of organs "are preserved by reproduction to the new individuals which arise." Thus, in a celebrated example, the forelegs and neck of giraffes have become lengthened through their habit of browsing the highest leaves of the trees of the savannah.

Charles Darwin's breakthrough was the idea of natural selection, a mechanism by which this change could have occurred. First published in On the Origin of Species in 1859, Darwin's theory can be summed up as the action of four processes: reproduction, limits to reproduction, variation, and natural selection. Natural selection is the effect of the environment acting on the differences between individuals of a species to select those best adapted to their environment. Returning to the example of the giraffe, individuals with favorable variations (being born with a relatively long neck) will have greater success, reproduce, and thus transmit the variation. If the variation does not favor the individual, the individual will be less successful at reproducing. Eventually, the species evolves in response to natural selection; in short, giraffes have long necks as the result of natural selection, not because they use their necks a lot.

Darwin and Lamarck made it clear that nature is the result of a long, long, process of change, an idea that completely overturned the former view of the world and one that stands as a landmark in the development of modern thought. The idea that species had changed gradually over very long periods of time was enough to demolish the dogma that life had been created and had remained unchanged. Historians prefer neat schemes with dates and usually consider that this change in attitude toward life and the history of the world occurred when Darwin published his theory of evolution, but Lamarck also made a very important contribution. The idea of transformation, and subsequently the theory of evolution, did not just cause a revolution in the life sciences. It also encouraged people to consider that there was a deeper process at work, beyond merely contemplating immutable objects in the apparently unchanging reality of day-to-day life, an approach that was very much in line with the philosophical ideas of Hegel and Marx. After Darwin and Lamarck, nature was seen as something extremely complex that has always been in a state of permanent change. This leap forward in understanding life and the world was soon followed by Haeckel's introduction of the term ecology and, later, by a global approach to ecological phenomena.

Natural balances are not the work of Creation

In the 1830s Charles Lyell, in his Principles of Geology (1831-1833), had removed the need for God to explain geology with the argument that small changes over long periods of time are enough to explain geological history and, thus, the present. The idea that the way things are could be explained without invoking a creator was brought home to the public in 1859, when Darwin published On the Origin of Species. Apart from its general implications for biology, Darwin's theory introduced a new materialist approach to the factors controlling distribution of plant species. Darwin explained that the number of cats indirectly affected the abundance of clover, as the cats destroy the nests of the bumblebees that fertilize their flowers.

Later, when an orchid was discovered on Madagascar with a nectar receptacle 8-10 in (20-25 cm) long, Darwin felt his theory allowed him to predict that an insect would be discovered that was capable of pollinating this orchid. About 40 years later a local race of the hawkmoth Xanthopan morganii was discovered that had a proboscis this long. Darwin felt he could stake his reputation on this prediction, precisely because it went beyond measuring the parts of flowers and sought to see the big picture, the evolutionary perspective. This marked a major step forward in understanding the factors controlling plant distribution. Such an interdependence among living things, and in particular between the plant and the animal kingdoms, is at the center of an important field of research, which represents an important stage in the history of thought on biogeochemical mechanisms.

The interdependence of living things

The German zoologist Karl August Mobius (1825-1908), the son of a wheelwright, studied first to be a schoolmaster but ended up becoming a trailblazer in the field of ecological research. An admirer of Alexander von Humboldt, Mobius entered the University of Berlin to study zoology under Johannes Peter Muller (1801-1858) and became a professor of zoology at Kiel University in 1868. A year later the Prussian government was worried by the decline in the oyster banks of Schleswig-Holstein and commissioned Mobius to study the growth of the mussels and oysters. He traveled to France and Great Britain to observe other oyster banks, and his studies led him to consider the banks as a whole, bearing in mind that these bivalve mollusks are filter feeders. His research led him to conclude that the growth of the railway network, a consequence of the Industrial Revolution, had increased the market for oysters and led to overexploitation, the immediate cause of the decline of the oyster banks. It was in this study that the idea of the biocenosis appeared for the first time, though the word is now mainly used in Eastern Europe and Russia. The biocenosis consists of the plants, animals, and microbes in a habitat and was studied during the first decades of the twentieth century as biocenology (known in English as ecology). This research field was greatly advanced by the work of Charles Elton (1900-1993), a zoologist at Oxford (see also p. 95).

Shortly after the concept of the biocenosis appeared in 1887, American naturalist Stephen Alfred Forbes (1844-1930) introduced the concept of the microcosm (see pp. 100-101), based on his observations of life in lakes. He used this word to apply to the living organisms (the biocenosis) in the lakes he studied. The complex food chains Forbes described were forerunners of the early descriptions of the food chains and food webs that would appear in many early twentieth-century works on ecology. Perhaps, for his time, the most important aspect of Forbes's work was that he worked on lakes, highly isolated systems that were relatively independent.

The birth and consolidation of the science of ecology

Nineteenth-century biogeographers studied the geographical distribution of different plant groupings on the basis of the program drawn up by Alexander von Humboldt in his Essay on the Geography of Plants. (See also p. 73.) The climatic and soil factors that govern the distribution of vegetation types were studied in increasing detail, as was their relation to the "plant associations," a term introduced by German botanist August Heinrich Rudolf Grisebach (1813-1879) in 1838. In 1840 German chemist Justus von Liebig (1803-1873) stated his law, Liebig's Law of the Minimum, according to which a plant's growth is limited by the nutrient that is in shortest supply. One metaphor that expresses this idea is that a chain is only as strong as its weakest link. Liebig's Law of the Minimum was basic to the development in the twentieth century of a form of agriculture that relied on large inputs of nutrients in the form of chemical fertilizers. As we shall see later, the fact that phosphorus is one of the main nutrients limiting plant production means that the loss of phosphorus from dry land to the sea is a serious long-term problem for the world. The studies of French botanist Gaston de Saporta (1823-1895) and Swiss botanist Alphonse de Candolle (1806-1893) on the Tertiary floras and the environmental conditions in which they lived, as well as their inquiries into an experimental line in ecology (starting with the work of Gaston Bonnier [1853- 1922]), placed the emphasis of plant geography once more on research into the conditions of life of the different types of vegetation, rather than on their respective geographical distribution. The work of the Danish botanist Eugenius Warming (1841-1924) marked the birth of an ecological approach to plant geography. His late nineteenth-century studies provided an ecological basis for classifying plant communities utilizing the habitat, density, phenology, etc., of the plants and their adaptation to physically or physiologically available soil moisture. Warming introduced the terms hydrophytes, xerophytes, mesophytes, and halophytes for the plants typical of wet, dry, temperate, and saline environments. European ecologists were creating a more statistical approach to ecology to explain the adaptations of the different plant associations to their surroundings, but their North American counterparts were creating a more dynamic view of ecology, which soon took the process of adaptation into account. The European approach was like analyzing a series of still photos; the American one was more cinematographic in that it sought to see long-term changes. It was realized that plant associations were undergoing major changes in space and time, but only very slowly. The association was thought to "invade" a given space or colonize it or "migrate" from it, and, thus, over the course of time one type of vegetation "succeeds" another (the idea of ecological succession) until the community stabilizes in a state of dynamic equilibrium known as the climax (from the Greek word klimax, meaning ladder).

In 1968 Catalan ecologist Ramon Margalef (b. 1919) proposed in his Perspectives in Ecological Theory an interesting hypothesis to explain these divergences in style between the different schools of ecology: "All the schools of ecology have been influenced by a genius loci that derives from the local landscape.... The mosaic of vegetation in the Mediterranean countries, subject to thousands of years of human interference, contributed to the birth of the Zurich-Montpellier school of plant sociology.... Scandinavia, with a poor flora, produced ecologists that count every shoot and bud.... And it is highly natural that the large spaces and smooth transitions of North America and Russia have inspired a dynamic focus and the theory of the climax in ecology." The ecology of plant succession, and succession in general, developed from 1898 on, thanks largely to the work of Henry Chandler Cowles (1869-1939) and Frederic Edward Clements (1874-1945) and, later, of the animal ecologist Victor Elmer Shelford (1877-1968). This approach was very productive because it made it possible to explain, for example, why the North American vegetation is richer in species than the European vegetation. The vegetation in North America could move southward during the Quaternary glaciations and recolonize the ground lost during the interglacial periods, while the European vegetation was obstructed by the Pyrenees, the Mediterranean, the Alps, and other mountains of southern Europe and was impoverished by the loss of nonresistant species.

The birth of mathematical analysis of population fluctuations

The question of population growth was first raised rigorously by Malthus (see p. 59) and was hotly debated among many nineteenth-century economists. All populations have the potential for exponential growth, but in practice their growth is never truly exponential; in practice, there are always factors slowing down population growth, as food resources cannot grow indefinitely. In response to this social concern about population growth, some mathematicians tried to describe more precisely the action of the factors slowing down population growth. The S- shaped growth curve (the logistic equation) describes the theoretical growth of a population with limited resources--a population whose growth is initially exponential but gradually slows down as it reaches its carrying capacity. This equation was discovered by the Belgian mathematician Pierre-Francois Verhulst (1804-1849), who collaborated with his compatriot, the astronomer and statistician Adolphe Quetelet (1796-1874). Verhulst calculated that the upper potential limit for the population of Belgium was 9.4 million, which was passed by the end of the 1960s.

The predictive capacities of the logistic equation are thus limited, at least in its application to human societies. English-born American ecologist George Evelyn Hutchinson (1903-1991) demonstrated that this equation becomes less reliable when the potential value of the carrying capacity increases. In 1920 the logistic equation was rediscovered by U.S. demographers Raymond Pearl (1879-1940) and Lowell J. Reed (1886-1966). Pearl, who in 1921 recognized Verhulst's priority in the discovery of this equation, thought that he had discovered a law of growth valid for all populations, including human ones. The controversies provoked by this discovery led to the birth of modern population ecology, with the work of U.S. physicist and demographer Alfred James Lotka (1880-1949), who proposed a system of differential equations to describe the periodic fluctuations in the populations of a prey species and its predator.

These equations later became known as the Volterra-Lotka (or Lotka-Volterra) equations, as they were independently discovered by Vito Volterra (1860-1940), an Italian mathematician. Volterra became interested in these matters at the urging of his daughter Luisa, a marine biologist who was married to zoologist Umberto d'Ancona (1896-1964), both of whom worked on statistical problems related to fisheries in the Adriatic Sea. These equations gave ecology a more mathematical basis, marking the birth of mathematical modeling as a research tool in ecology. Great effort then went into constructing mathematical models of ecological phenomena, and then into global models for ecological phenomena, which also contributed to the rise of the modern concepts of the biosphere and ecosystems.

3.2 The idea of the biosphere and the concept of ecosystem

During the first decades of the twentieth century, one of the main questions facing ecologists was why climax communities remained stable indefinitely unless they were disturbed (see also page 109). In 1880, the German zoologist Carl Gottfried Semper (1832-1893) pointed out the theoretical reason why herbivores are common but carnivorous predators are rare, justifying the pyramidal structure of communities. He noted," ... only 100 units ... of herbivorous animals can live on 1,000 units of plant food, and the amount of food provided by 100 herbivores only permits the existence of at most 10 carnivores." In the 1920s Charles Elton extended this idea of a pyramidal structure, but based it on real figures (see p. 106). Returning to Semper's work, he described the transfer of matter within the communities of living things and explained how this matter was transferred along the food chain. It had been known for a long time that photosynthetic organisms are the basis of food chains, and in the nineteenth century it was discovered that part of the decomposed material (ejection and excretion products and dead organisms) is recycled within the community.

The importance of the science of the lakes: limnology

The difficult question of why communities were stable remained unresolved, and it took several decades to find an answer. A Swiss naturalist and physician, Francois-Alphonse Forel (1841-1912), laid the basis for understanding this aspect of ecological systems years before the term ecosystem was coined. Forel was the founder of limnology, which he described as "the oceanography of lakes." Limnologists have played an important role in the history of the development of the concept of ecosystem; lakes are very clearly defined entities, and their relative independence makes them very suitable for ecological studies.

Forel had studied zoology, geophysics, physiology, and archaeology. As nobody had previously investigated lakes, he had to invent new instruments for this unprecedented type of study. Forel invented the xanthometer to measure differences in the color of the water of lakes and the limnograph, which measures rhythmic oscillations in levels (rises and falls) of just a few millimeters. He also discovered the fauna living on the bottom of the lake. It is worth pointing out that his broad interests and multidisciplinary training led him to postulate a position based on synthesis in order to understand the interactions between the physical factors that characterize the lake and the living things that dwell within it (or, like birds, that simply frequent it).

When Forel discussed the flow of organic matter from one set of organisms to another, he was describing what we now call an "ecosystem." Plants are the basis of the system, and they are consumed by herbivores, which are eaten by carnivores, which eventually decompose. This is an extension of the ideas of Semper and Elton. Finally, and this is the important point, the complex structure of the community of organisms in the lake is, at least partly, a closed system: "The circulation is complete; the circle is closed." This approach was thus stated for the first time in precise and comprehensive terms and prepared the way for an answer to the question concerning the mysterious durability of ecological systems.

The organicist ideology

Analogies have long been made between the organization of the individual organism (understood as a being in which the parts form an organic whole) and the organization of some systems (in which the parts form a single whole). Comparisons had long been made between a swarm of bees or a nest of ants and an individual animal, with the individual bees and ants as its organs. Organicist metaphors have often been applied to human society, and reference is made to "the social body." Hegel, for example, considered in his Propodeutica philosophica that "the science of the State is that which describes the organization of a people in the measure that it constitutes of itself a living organic whole." British sociologist and philosopher Herbert Spencer (1820-1903), the founder of social Darwinism, gave this line of thought its most extreme expression by establishing an analogy between animal organisms and human societies.

The idea of the superorganism appeared in ecology in 1901 in a lecture given by Frederic Edward Clements to the Botanical Society of America. In his talk he said he saw vegetation "as an entity in which the modifications and structures are ruled by certain basic principles, in exactly the same way as the functions and structures of individual plants respond to defined laws." The controversy generated by these affirmations contributed to the origins of the formulation in 1935 of the concept of the ecosystem.

Controversial though it was, the idea of the superorganism brought with it the idea that the plant community (and later the animal community and the entire biotic community) could be considered as an entity in its own right. Ecologists soon accepted that these communities showed some degree of autonomy, which probably favored the extension of this idea to the planet as a whole. This eventually led to the development of the concept of the biosphere as a global entity, consisting of relatively autonomous communities inseparably linked by the great biogeochemical cycles.

The sphere of life

The term biosphere was first used in 1875 by the Austrian geologist Eduard Suess (1831-1914) in a small book on the origin of the Alps. He wanted to distinguish between the lithosphere, the upper layer of Earth's crust, and Earth's thin film of living things. In a surprisingly modern approach, Suess argued that this distinction only applies the notion of biosphere to the space of life upon Earth's crust and the temperature and chemical conditions that this implies, totally excluding all speculation about the processes of life that may occur on other planets. From his perspective, the biosphere is thus unique in space and in time.

Russian mineralogist Vladimir Ivanovich Vernadsky (1863-1945), usually regarded as the father of the theory of the biosphere, was the first to investigate the theory scientifically. Vernadsky studied under another mineralogist, Vasily Vasilyevich Dokuchayev (1846-1903), the founder of soil science. A student at schools in both France and Russia, Vernadsky attended Saint Petersburg University at a time when the teaching staff included major scientists like Dmitry Ivanovich Mendeleyev (1834-1907). Vernadsky became a professor at the University of Moscow but resigned in 1910 in protest against the brutal measures used against the students. Between 1922 and 1925 he returned to France, where he frequented the laboratory of Marie Curie (1867-1934).

In 1924 Vernadsky published a work called La Geochimie (Geochemistry), which brought together a series of lectures he had given at the Sorbonne in 1922-1923. The Jesuit priest, philosopher, and paleontologist Pierre Teilhard de Chardin (1881-1955), the philosopher Henri Bergson (1859-1941), and the mathematician and philosopher Edouard Le Roy (1789- 1954) attended these conferences. These four thinkers greatly influenced one another. Teilhard de Chardin's idea of the noosphere (the "sphere of human spirit") is derived from the idea of the biosphere. Vernadsky adopted the term noosphere in 1945. La Geochimie contains arguments that recall Teilhard de Chardin's, as well as the use of the term Homo faber, which is also found in the work of Bergson. La Geochimie was the first work in which Vernadsky used the term biosphere. While mineralogy studies the elements at a given moment in a given site, geochemistry deals with the history of the chemical elements that make up Earth and, thus, the changes they have undergone. Once again, a new approach arises when people start to understand things as the result of a long process of change (transformism), within the perspective that nature has a history, an echo of Lamarck. Trying to understand the history of the elements that formed Earth led Vernadsky to take an interest in the biogeochemical cycles, especially the carbon cycle, and to study "the geochemical activity of mankind."

The Biosphere (published in Russian in 1926, in French in 1929, and in German in 1930) is Vernadsky's best-known work. It defines the concept of the biosphere from a biogeochemical perspective and from a thermodynamic perspective (as in La Geochimie). Vernadsky stresses the importance of the fact that the degradation of energy and its dissipation in the form of heat will lead, eventually, to an even distribution of the heat (that is, entropy increases to a maximum), which thus cannot be used to produce work, in agreement with the second law of thermodynamics (see also p. 76). This irreversible equalization of energy, leading inevitably to the heat death of the universe, is to some extent retarded on Earth by the growth of photosynthetic green plants and autotrophic bacteria and protists. As was shown by the physicist Erwin Schrodinger (1887-1961) in his 1945 book What Is Life?, living systems delay their moment of maximum entropy (or death) by their metabolic activity. Thus, everything that lives can be said to counteract entropy, to produce negative entropy.

Vernadsky's idea of the biosphere is surprisingly modern. "All life, all living matter, can be considered as an invisible whole within the mechanism of the biosphere." For Jacques Grinevald (b. 1946), a Swiss historian of the concept of the biosphere, the central idea of Vernadsky's book is that life on Earth is not an accidental phenomenon but a geological phenomenon requiring a multidisciplinary and quantitative approach. Though these "cosmic" ideas were largely ignored when they were first proposed, recent developments in ecology mean they are once more of great interest. As we shall see later, the birth and development of the theory of ecosystems has returned Vernadsky's ideas to the forefront of contemporary ecology.

The theory of ecosystems

"Comparing organisms with cosmic systems, and cosmic systems with organisms is an ancient custom. Once again ... it is worth comparing the biome (biotic formation) with an amoeboid organism, a unit consisting of parts, that grows, that moves and shows internal processes that can be compared with the metabolism, locomotion, etc., of an organism." This statement, which in retrospect may seem strange, was published in 1931 by American ecologist Victor E. Shelford in an article in the academic journal Ecology. His words clearly express the situation of crisis ruling in biocenology in the 1930s.

In 1905 F. E. Clements published the first university textbook of ecology, Research Methods in Ecology, in which he confidently repeated the ideas he had stated in his historic talk at the Botanical Society of America. Insisting on the dynamic nature of vegetation, he claimed that each plant community was part of a succession toward a climax and that plant communities were comparable to a superorganism. British botanist Arthur George Tansley (1871-1955) responded by stating that, although it may be easy or fruitful to make an analogy between living organisms and plant communities, this does not mean that the communities are living organisms. A professor of botany at Oxford, Tansley was noted for his broad intellectual endeavors and this is presumably why he rejected this idea for epistemological reasons (that is, based on the philosophy of science).

Comparing the large biomes with amoebas was unreasonable, but it was useful insofar as it made it possible to consider them as gigantic entities with some degree of autonomy. In 1935 Tansley proposed the word ecosystem for the sum of the living components (the biocenosis and its biotopes) and nonliving components that interact to form a system. Thus, living things and their environment form a whole, a system, whose workings show some analogies with the functioning of a living organism. This new way of looking at things led to a great deal of research into why a biotic formation that has reached its climax remains in this state of dynamic equilibrium indefinitely (as long as conditions do not change)--a question that is clearly related to Vernadsky's thermodynamic concerns.

Much of the ensuing progress was due to the work of North American specialists in limnology, a discipline of great importance in the development of the concept of the ecosystem. Work in limnology at the time aimed to analyze things in energetic terms, using a single unit, the calorie, to measure these quantities.

In the year 1928, after teaching for two years in South Africa, Cambridge- educated British ecologist George E. Hutchinson arrived at Yale University. In 1941 a student of Hutchinson's, Raymond Laurel Lindeman (1916-1942), proposed a description of the circulation of matter within a lake ecosystem. His approach differed from Forel's in two main ways: the circulation of matter in the food chains was quantified in energetic terms, and the autotrophic photosynthetic organisms were recognized as the base of the food webs.

In 1942, at just 27 years of age, Lindeman died tragically of leukemia. Lindeman's generalization of his theory to all ecosystems marked the birth of the modern idea of ecology. As happens so often in science, at almost the same time as Lindeman published his ideas, Russian ecologist Vladimir Nikolayevich Sukachev (1880-1967) proposed the concept of biogeocenosis, which is very similar to the idea of the ecosystem. By definition, the biogeocenosis is a combination, in a specific area, of homogeneous phenomena, with a specific type of interaction and a definite type of exchange of matter and energy. It is now known that Lindeman's historic article was only published because of the determination of Hutchinson, his tutor. In fact, two important limnologists opposed publication because they considered the author's ideas excessively abstract and an unjustifiable generalization. These two scientists--Chancey Juday (1871-1944) and Paul S. Welch (1882-1955)--rejected Lindeman's article on the basis of Forel's theory that all lakes were individual, but they were wrong, as Lindeman did not reject this idea.

The Hutchinsonian synthesis

It is not hard to discover numerous similarities between Vernadsky's ideas about the planet Earth and the trophic-dynamic approach to ecosystems (or theory of ecosystems) proposed by Lindeman. As we shall see later, both approaches are present in today's concepts of the global model, especially in the framework program of global change. This point of view is due largely to Hutchinson, a researcher who dominated the field of ecology from his arrival at Yale University until his death more than 50 years later.

At Yale, Hutchinson started to take a serious interest in biogeochemical cycles. One of his colleagues, Alexander Petrunkevitch (1875-1964), was a Ukrainian expert on the classification of arachnids who had been a student of Vernadsky at the University of Moscow. Hutchinson was thus familiar with Vernadsky's thoughts (as author of The Biosphere) very early in his career. Vernadsky's son, Georges Vladimirovitch Vernadsky (1887-1953), taught history at Yale and translated his father's works into English. Hutchinson was especially interested in human impact on the carbon and phosphorus cycles. These initially ignored studies brought Vernadsky's work into Western ecological theory and helped to bring together Vernadsky's holistic conceptions, the theory of ecosystems, ecology, and the ecology of global change.

Hutchinson had some very prestigious students, including Lindeman and the brothers Eugene P. Odum (b. 1913) and Howard T. Odum (b. 1924), authors of the famous textbook Fundamentals of Ecology, published in 1953 with new editions in 1959 and 1971. This book has been translated into many languages and has greatly influenced contemporary ecology by spreading and developing Lindeman's ideas.

Eugene Odum explained that the decision to publish the book was a response to the way his ideas were misunderstood by his colleagues in the Biology Department at the University of Georgia. In addition, he wanted to point out the remarkable principles that emerged when studying levels of organization higher than that of the individual organism. This approach sees ecology as a discipline in which the whole is more than the sum of the parts, at all scales from the smallest ecosystems to the entire biosphere. But the Odum brothers did not emphasize these emergent properties; instead, they presented a simpler conception of the ecosystem that considered it as a heat machine capable of maintaining itself in a steady state, a "reductionist" approach that opposed the idea of "emergence" stated above. It can thus be said that this epistemological tension between reductionist and emergent conceptions has marked the development of contemporary ecology since its origins. Hutchinson's students also included Lawrence Basil Slobodkin (b. 1928), Robert H. MacArthur (1930-1972), one of the founders of island biogeography, and Rachel L. Carson (1907-1964), author of the 1962 book Silent Spring, which triggered the explosive growth of environmental concern in the United States in the 1960s (see also vol. 7, p. 351).

The way Hutchinson tried to integrate different approaches can perhaps be understood by looking at his analysis of the loss of phosphorus from terrestrial ecosystems. Phosphorus in the form of phosphates is the nutrient limiting production in many ecosystems; if availability of phosphorus is low, the ecosystem's production is low. Inorganic phosphorus is present in the lithosphere and becomes available to ecosystems as a result of weathering and when it dissolves in rainwater, groundwater, etc. Phosphorus enters the food webs when herbivores consume plants or when dead plant matter is recycled by microbial decomposition of animal wastes and of dead organisms.

Runoff water washes phosphorus from the soil and into lake and river ecosystems. It thus fertilizes the water masses on dry land (lakes and rivers), which in turn fertilize the oceans. It is known that the use of phosphates and nitrates as fertilizers may lead to eutrophication of lakes (and sometimes rivers) due to excess levels of phosphates and nitrates. The water is covered by a green scum. The concentration of dissolved oxygen increases at the surface because of the higher rate of photosynthesis but declines at depth due to the decomposition of plant remains that accumulate. As a result, the lake "chokes" in its own primary production, eventually filling in and turning into a wetland.

If the phosphorus cycle were limited to relatively small basins, it would be in relative balance (see vol. 1, pp. 165-166). Yet it has been estimated that the quantity of phosphorus discharged by rivers into the world's oceans is about 22 million short tons (20 million tonnes), which acts to fertilize it. A small part of the phosphorus is returned to dry land as a result of upwelling, predation by marine birds, deposition of guano, and industrial fisheries. But the rest, about 14.3 million short tons (13 million tonnes) per year, is lost when deposited on the seabed in dead organisms. In the very long term, tectonic movements restore this phosphorus from the seabed to terrestrial ecosystems, but only on a geological time scale.

3.3 The planetary ecosystem

On the basis of the phosphorus cycle, Hutchinson pointed out in his 1948 article "On Living in the Biosphere" that, in the long term, human beings will have to do something about the serious loss of phosphorus (close the phosphorus cycle) or face extinction. This biogeochemical approach thus relates the primary production of local ecosystems to the long- distance vectors along which phosphorus circulates on its path to the world's oceans. Hutchinson's analysis casts doubt on the future of the human species and marks the entrance of ecological thought into the debate on the role of human beings in the biosphere on a global scale.

Global ecology

Since the end of the World War II (1939-1945), studies of the phosphorus cycle, together with the pioneering work of Vernadsky and Hutchinson, have led to the development of a new approach to ecology--global ecology--dealing with the flow of materials and energy on the planetary scale. This extends the idea of the ecosystem from the local habitat to the global ecosystem, but extends it to consider the processes that occur on a planetary scale. Global ecology pays special attention to the main vectors in these processes (atmosphere, rivers, and oceans) because they play such an important role in joining together local ecosystems to form the biosphere as a whole.

The main concerns of this new approach are related to 1) the amount of incoming solar radiation; 2) the energy balance of the biosphere and the climate; 3) climate change; 4) the biogeochemical cycles; 5) the organic matter cycle; and 6) the water cycle--that is, the activity of autotrophic organisms and of consumers and decomposers. In the course of the last few decades, the study of human impacts on global processes has acquired increasing importance. The implications of research into these areas are of great significance, as decisions vital for the future survival of our species may have to be taken in the twenty-first century.

The Gaia theory

Gaia, or Gea, was the name of the Mother Earth of ancient Greeks. She was considered the original divinity who bore the first gods and many other monstrous divinities such as the Titans, her sons and daughters with Uranus (the god of the heavens). The Titans included Oceanus, Hyperon--father of Helios (the Sun) and Selena (the Moon)--and Chronos (the god of time).

Gaia also bore the giants (also the children of Uranus) and the Cyclops (who created the lightning bolt in honor of Zeus). Roughly 2,800 years ago, the Greek poet Hesiod (eighth century b.c.) praised Gaia, the "broad-bosomed Earth" that also engendered the human species. This brief, incomplete genealogy shows how suitable it was to give the name Gaia to the controversial hypothesis according to which Earth is a living system (see also vol. 1, pp. 100-103).

During the 1960s British chemist and engineer James E. Lovelock (b. 1919) was working for the U.S. National Aeronautics and Space Administration (NASA) as a scientific advisor. He had already invented the electron capture detector, which was capable of measuring extremely small quantities of substances by gas chromatography. This detector also found traces of chemical pollutants in the environment, even in the most unexpected places, providing much of the evidence used in Rachel Carson's groundbreaking book Silent Spring (see p. 121).

At NASA, Lovelock participated in the development of methods to detect life on Mars, research that led him to reflect on the nature of life. He considered, as had Vernadsky and Schrodinger, that a reduction or inversion of entropy in a planet would reveal the presence of life. The presence of life on Earth can thus be "deduced" from the chemical composition of Earth's atmosphere, in which the proportion of gases is unstable and far removed from chemical equilibrium. This is, therefore, a sign of the production of negative entropy and thus of life.

On this basis, Lovelock suggested in 1967 that Earth's atmosphere was the result of the metabolic activity of life as a whole, not simply the result of inorganic processes. Though it was not alive itself, he noted, the atmosphere could be considered an extension of life (like the fur of a cat or a bird's feathers) that acted to maintain a given environment.

On the advice of the British novelist William Golding (1911-1993), author of the novel The Lord of the Flies (1954) and a 1983 Nobel laureate, Lovelock finally dared, as the result of a discussion at Princeton University (New Jersey), to name this living system Gaia. Gaia was later described as an entity that included terrestrial life, the atmosphere, the oceans, and Earth (namely, the biosphere, the atmosphere, the hydrosphere, and the lithosphere). This ensemble formed a system that "seeks" an optimum environment for the expansion of life on the planet. Since 1970 American biologist Lynn Margulis (b. 1938) has supported the Gaia hypothesis and has developed its microbiological aspects, especially those referring to the role of bacteria in the initial stages of the evolution of life on the planet and the evolution of biogeochemical cycles.

The notion of Earth as a living "being" was severely criticized in scientific circles. A living "system" would be more appropriate, but strictly speaking, Earth shows only very weak analogies with a living system. Earth cannot, for example, reproduce, nor is it subject to selective pressure from the environment, and its metabolism (anabolism, or metabolic synthesis, and catabolism, the breakdown of large molecules for energy) can only be considered a metaphor. If, in light of current ideas on living organisms, the theory that Earth is alive becomes totally indefensible, the idea that Earth is comparable to a living system requires some modifications.

Some of the enthusiasts for the Gaia theory have inadvertently served as its worst enemies. For example, in 1990 French philosopher Michel Serres (b. 1930) was so enthusiastic in his book Le Contrat Naturel that he wrote of "humanity, the astronaut," floating in space "like a fetus within the amniotic fluid, joined to the placenta of Mother Earth by the nutrient pathways." He wondered about humanity's relations to Earth: "Shall I recognize her as mother, as daughter and as lover all at once?" thus adopting a perspective closer to psychoanalysis than thermodynamics. All other opinions and controversy aside, Lovelock's idea, like Vernadsky's, draws attention to the basic unity of the planet and also shows its fragility (though Lovelock has been criticized for overestimating Gaia's resilience capacity). His efforts have contributed to the growing public awareness about the threats facing the planet.

Lovelock correctly considers that the Apollo missions' photos of Earth have created a new mental image of our planet (such as the one on p. 123), while satellites have provided new information about Earth's atmosphere and its surface, thus revolutionizing our understanding of the interactions between the "living parts and the inorganic parts of our planet." It seems difficult even for the most convinced opponents of the idea to continue thinking and acting as if the Gaia theory had never existed. This shows that efforts to refute an idea can, paradoxically, make it stronger.

Major international programs

The problems relating to the environment were raised for the first time by the United Nations (UN) at the Intergovernmental Conference of Experts on the Scientific Bases of the Rational Use and Conservation of the Resources of the Biosphere. Held in Paris in 1968, this conference was organized by the United Nations Educational, Scientific and Cultural Organization (UNESCO), together with the World Health Organization (WHO), the Food and Agriculture Organization (FAO), the International Union for the Conservation of Nature (IUCN), and the International Council of Scientific Unions (ICSU). The ideas of the biosphere and the world ecosystem were strongly present at the conference, and the expression "Spaceship Earth," which later became widespread, was used, apparently for the first time, in official documents. This conference also laid the foundations for an international program, the Man and Biosphere (MAB) Programme, created in 1971 for the development of a rational basis for the use and safeguarding of the resources of the biosphere. The work you are reading, the Encyclopedia of the Biosphere, is based on the principles of the UNESCO-MAB Programme and has been supported by UNESCO.

In September 1986, during its general assembly, ICSU launched a new cross- disciplinary program, the International Geosphere-Biosphere Program (IGBP), also known as the Global Change Program, as it was established to "describe and understand the interactive, physical and chemical and biological processes that regulate the global system of the Earth, the special environment it provides for life, the changes that are occurring and the way in which human activity is affecting them."

Programs of this size imply the synergy of many forces and many projects. The idea is to ensure the greatest collaboration possible among physicists, chemists, biologists, ecologists, climatologists, geophysicists, oceanographers, and other scientific experts. But international research programs on the environment are problematic. Can they really act independently of the large powers that provide the funding they need but are, at the same time, accused of damaging the mechanisms capable of restoring balance of the biosphere? "Harmonizing" international research programs with national ones also gives rise to problems: international research programs play a role in the buildup of scientific knowledge. And does this not all raise the risk of reducing the diversity of these different approaches through uniformity? In other words, the question raised by these programs is that of the possible financial, scientific, conceptual, and methodological domination that could be imposed by one or another set of powers.

Yet problems of this nature arise in any international undertaking. The Global Change Program has already made progress possible in many fields, among them the depletion of the ozone layer, the disturbances derived from the greenhouse effect, and the subject of hydrosphere- atmosphere and vegetation-atmosphere interactions. There has also been great progress made in the fundamental field of creating dynamic global models of the climate. It is equally clear that scientific progress solves nothing unless it is accompanied by the political will--on an international scale--to deal with the environmental problems facing humanity. This political will can only be created by raising individual awareness of the problems and by increasing people's ability to organize themselves.

4. The biosphere of Encyclopedia of the Biosphere

4.1 A neo-romantic perspective for the postindustrial period

Consider, for a moment, the following statement: The science of ecology has its roots in the romantic movement. Most ecologists would disagree with it, and some epistemologists would definitely reject it. The majority of academic ecologists would, at best, accept it with indifference or simply ignore it. At the risk of being ignored, those responsible for drafting the text (and some of the authors) of the Encyclopedia of the Biosphere see things this way. We feel that much of the current crisis of creativity shown by academic ecology throughout the world is precisely because the academics have forgotten or seek to deny the romantic roots of ecology and have not adopted the multidisciplinary approach this implies.

Ecology's roots in the romantic movement

First, we should define what we mean by romanticism, which is a problem to begin with, because there is no satisfactory definition that encompasses the field of science. In a review of romanticism and the sciences, editors Andrew Cunningham and Nicholas Jardine avoid giving a definition of romanticism and simply describe some characteristics relevant to the relationship between romanticism and scientific activity. These characteristics include: hostility toward a mechanistic conception of nature and the descriptive natural history typical of the Enlightenment; a preference for dynamic and synthetic approaches rather than static and analytical approaches; and the defense of an intuitive--and nonrational--aspect of knowledge, which gives great importance to direct observation in contact with nature.

Perhaps the best definition of romanticism is the one produced by two sociologists, the Brazilian of Austrian origin Michael Lowy (b. 1938) and the American Robert Sayre (b. 1943), in their 1992 book Revolte et Melancolie: Le Romantisme a Contrecourant de la Modernite (Revolt and Melancholy: Romanticism against the Tide of Modernity). These authors suggest that romanticism represents "a critique of modernity, that is to say, of modern capitalist civilization ... created by the industrial revolution and the generalization of the market economy ... in the name of the values and ideals of the past." This critique is, however, made from within the modern perspective, not from some intellectual space excluded from modernity. The romantic perspective criticizes modernity but does so in modern terms and can thus be seen as a self-criticism. The romantic perspective, for example, shares the modern approach to individualism. The full development of individual self-awareness is linked to the emergence of modernity.

Yet the individualism of the romantics is not the same as that of modern liberalism. The romantic ideal of the individual is not the same as the liberal "numerical" concept of individualism, in which each individual, considered as an agent of a defined social and economic function, can be replaced by any other individual who plays the same role. In the modern concept of the individual, the development of the inner world of the person--imagination, subjectivity and emotions, and social deviations of socially accepted behavioral pattern--is distrusted, if not repressed. The romantic view of individualism is a "qualitative individualism" that stresses the unique and unrepeatable nature of the individual personality, leading to an uprising of repressed subjective feelings and emotions, which have been channeled and deformed by modern society.

To the extent that its critique is from within modernity, romanticism does not reject modernity as a whole but only some points particularly unattractive to the romantic view of the world. To begin with, romanticism does not accept the disenchantment of the world, the rejection of what is marvelous--something that seems to have been expelled from nature by the determinist approach of modern science (from Newton to Lavoisier). Furthermore, technology reduces this nature to a mere source of raw materials for industry. Secondly, romanticism clashes with the mechanization of the world and of society, shown in the destruction of the links between human beings and nature and in the disappearance of all traditional activities within society. Political systems are becoming increasingly mechanical, dominated by the "machinery of the state" or the "party apparatus," which hinder the direct participation of the individual and of social groups, and so these traditional activities are displaced one after another by the domination of machines. Thirdly, romanticism opposes the abstract rationalism inherent in a capitalist economy, which is based on abstractions like jobs (unrelated to any specific work), gross domestic product, and money. And, finally, romanticism rejects the breakdown of social links, the loneliness within human societies that are deprived of human relationships by the destruction of the ancient forms of sociability, by the lack of solidarity, by rejection of "the other," and by marginalization.

Another problem is how to link this to the roots of ecology. This is difficult if we accept the Catalan Ramon Margalef's definition of ecology in his 1974 textbook as the "biology of ecosystems." He defines ecosystems as "systems consisting of individuals of many species in an environment defined by a given set of characteristics and involved in a dynamic and unceasing process of interaction, adjustment and regulation, that can either be expressed as exchange of matter and energy, or as a sequence of births and deaths, and the results of which are: the evolution at the level of organization of the species and the succession of the whole system." Margalef points out that many strategies have been used to study these systems, even before they received the name of ecosystems or were recognized as levels of organization. He also points out that the history of ecology is "unlike that of other sciences, because other sciences tend to analysis, to circumscribe and then divide the field they are working on, but ecology is a science based on synthesis, combining material from different disciplines with their own perspective." Many approaches have participated in this synthesis, but four are especially important. These are: 1) the description and classification of the geographical landscape; 2) practical questions related to agriculture and stockraising; 3) physiology and ethology; and 4) demography, the latter the field in which mathematical points of view were introduced.

For Margalef, these different approaches all flowed together and fused in the last third of the nineteenth century, 20-30 years after Ernst Haeckel defined the term ecology. This point of view is rejected by some historians of ecology, who feel that the scientific practice of ecology dates from long before it was named. These authors recognize the fact that ecology has many roots but tend to arrange them in a hierarchy of importance or use one or two lines of thought as guidelines for their historical narrative, in which they successively integrate the contributions of the other roots. This is the approach we have adopted, considering that the axis structuring what would later be called ecology has its roots in Humboldt's ideas on science.

Humboldt's lifelong ambition was "to bring together in a single volume the entire material universe, all that is known of the phenomena of the heavens and the Earth, from the nebulous stars to the geography of mosses and granitic rocks," and "in a vigorous style, to excite and capture sensitivity." He called his great work Kosmos (Cosmos), subtitled Outline of a Physical Description of the World (see pp. 73-74). In fact, from the time of his youth, Humboldt thought of all the works he published as fragments or approximations of this final work, the culmination of his career, which had great influence on many fields of study. It is in this sense that it is possible to talk of a Humboldtian science, a science that, starting from the typically romantic aim of "exploring the unity of nature" and discovering the interaction of natural forces and the influences of the geographic environment on plant and animal life, has established an innovative scientific practice. The most outstanding features of this Humboldtian science would be, among others, the explicit aim of studying the large systems or wholes and interrelating all the phenomena they show. These phenomena would also include the phenomena derived from human action, trying to relate them to each other as well as to observations relating to plant and animal life. Humboldtian science would make systematic use of measures of all types, introduce observation networks as a means of studying, and introduce isolines (starting with isotherms) as a means of globally expressing phenomena that show gradual and continuous variations in the area under investigation.

Probably the first work in which Humboldt expressed unambiguously his scientific project was his Essay on the Geography of Plants (see also p. 73), which can be considered the foundation of ecology. Humboldt justified his selection of the geography of vegetation because he considered it a primary expression of the physical environment, as well as a factor conditioning human life, both in material and spiritual aspects. For Humboldt "the geography of plants, a science that has until now only existed in name ... is an essential part of general physics," which, in turn, is "one of the most beautiful fields of human knowledge," the main aim of which would be the study of nature as a whole.

This holism, that is to say, Humboldt's desire to build global units of study, where all phenomena are interrelated, is precisely one of the most significant features of the emerging ecology. In addition, it is one of the aspects of the permanent tension between the two main trends in contemporary ecology: the holism of its roots and the reductionism required by the academic world in order to be accepted as a "normal" science, like all the other sciences. This does not imply that ecology should abandon reductionism, the interpretation of complex phenomena through their most simple components. The implicit criticism of organicism (that is, the notion of the superorganism) and of the idealistic components present in many holistic positions has been healthy, and this criticism certainly relies upon the accumulation, at a relatively modest scale, of data and facts referring to the species or individual organisms that make up ecosystems. Yet, any reductionist approach to the problems studied by ecology is more likely to be successful if it integrates its results by taking into account how the different parts of the ecosystem combine on a larger scale. Nor is holism the panacea, especially if it restricts itself to cliched affirmations that the whole is greater than the sum of the parts. It is a fact that ecosystems, as the object of study of ecology, have properties that are not explained by their parts, but by the way they interact (and in fact this happens in all the sciences that seek to deal with living matter, whether at the scale of the cell, the organism, or the biosphere as a whole).

The holistic view of the biosphere

Yet when the biosphere as a whole is the object to be considered, it is difficult to apply a perspective that is not holistic, though for purposes of expression, it is necessary to treat different aspects of this single ecosystem. This is the approach that this series has followed from the very beginning. We have sought to explain the biosphere as an indivisible whole, describing, in accordance with a pre-established scheme, each of the biomes, considered as spaces in which life has 1) characteristic expressions that correspond to environmental conditions, which may be homogeneous to a greater or lesser extent, and 2) an evolutionary history determined partly by the distribution of land, seas, and ice over the course of geological time and partly by the results of the intervention of the human species in the more recent past. This series has sought to be an updated version centered on the living matter of Humboldt's Cosmos.

And, like Humboldt's Cosmos, the human species has not been excluded from this conception of the living world but is treated instead with great attention. This is because it is hard to understand some phenomena on a global scale without entering into evaluations of the role of humans as active agents of change in the biosphere, for good or bad. How can global warming be explained without considering the high consumption of fossil fuels in the last two or three centuries, especially the twentieth century? How can the hole in the ozone layer be explained except by the consumption of CFCs? How can the almost total transformation of the prairie biome be understood without reference to human action? As Margalef has pointed out, the inclusion of human beings in the field of the study of ecology not only sheds light on the ecological problems of the human species but also provides a more detailed view of ecology in general. Problems like these or others related to horizontal transport, flows, or succession are more clearly shown in systems that either have not been highly modified by human action or have been modified only slightly.

Even if this view has its roots in Humboldt's approach, opposed to the positivism that dominated science in the nineteenth century, it has had some revivals in the twentieth century, almost always at the same time or in relation to revivals of the romantic movement in art and culture. The first development of ecology (before the term was established)--lasting until almost the end of the nineteenth century--took the form of studies of plant geography, with contributions from naturalist travelers (especially Charles Darwin and Alfred Russell Wallace [1823-1913]) or studies of the waters of the seas or lakes. In accordance with the outline of romanticism given above (and according to the more conventional histories of the period), throughout this period discordant attitudes persisted with the dominant social and economic system and with its aesthetic tendencies, though from the mid-nineteenth century their presence was reduced, eclipsed by positivism in thought and science, by the different versions of the official arts in the field of architecture and art, and by realism in literature. Instead, toward the end of the century, the self- recognition of ecology and the appearance of the first books that used the word "ecology" in their titles with its modern meaning coincided with the first proposals of intuitionist thought, that proposed by Henri Bergson, with pictorial and literary symbolism and with the romantic revival of decorative craftsmanship associated with what is known as modernisme in Catalonia, jugendstil in Germany, art nouveau in Belgium, France, and the United Kingdom, and as the estil liberty in Italy.

The 1920s, a new period of cultural and artistic effervescence, saw the emergence of concepts of the ecosystem and the biosphere. The same period saw the growth in art of expressionism, surrealism, and all the artistic vanguards. This was the time when the vitalist ideas of Bergson were most widespread, which later had an influence on Vernadsky's thought. These were also the years of the rise of fascism and national socialism--the "dark side" of a certain romanticism The 1960s were without a doubt the most romantic period of the twentieth century and also saw the most spectacular advances in the field of ecology, ranging from the contributions made by the International Biological Programme to the first formulations of the Gaia theory, as well as the rise of the environmental movements (social movements that base their political ideas and actions on the understanding of nature provided by ecology). These advances continued until the early 1970s but withered away after the oil crisis and coincided with the changes undertaken by the political, financial, and industrial powers in the developed world and with the growing influence of Karl Popper's Logical (neo-) Positivism. According to Popper, a proposition or theory is metaphysical (and thus not scientific) if it does not show falsifiability--that is, if it simply cannot be shown to be true or false--because it cannot be denied or confirmed by comparing it against facts that might contradict it.

The 1960s also saw the introduction of computers and integrated circuits (chips), which led to huge leaps forward in the human ability to manipulate and exchange information. This seems to have opened up a route to go beyond the industrial society of the nineteenth and twentieth centuries toward a new society that envisages a new technological revolution for the future. The Neolithic Revolution was based on the control of production and using the biomass of domesticated plants and animals, and the Industrial Revolution was based on increasing control of the flows of energy, but this new technological revolution will be based on the increasing flow of information. In the face of the challenges raised by the new postindustrial conditions, spreading the available knowledge about the unity and complexity of the planetary ecosystem becomes a moral imperative. Is this a neo-romantic attitude? Perhaps, but critical awareness is needed as a contrast to conformity, as was shown in their time by Dickens and Marx, Darwin and Mobius, Ruskin and Kropotkin, Vernadsky and Teilhard de Chardin, and thousands of other less well-known figures. This is the attitude adopted by the Encyclopedia of the Biosphere.

4.2 An effort to be transdisciplinary

As the popular saying goes, "The road to hell is paved with good intentions." The moral imperative to spread the knowledge available, and the desire to do so, is not enough. One has to do it, and do it as effectively as possible. They are many obstacles that vary greatly in their nature, from those inherent in the prevailing scientific practice to those inherent in the language and the economic viability of the product.

Reductionism and the compartmentalization of academic knowledge

Contemporary scientific disciplines not only tend to be separated, but they are also jealous of their identity and independence and tend to be incestuous if not totally closed to all outside influences. The multidisciplinary approach is frequently mentioned, but very few works are published that truly cross disciplines. Specialization or specialism, it is said, is a precondition for quality research, and there is no time to waste in working together with people from another branch of knowledge, possible competitors in obtaining resources that will allow them to consolidate their own tiny specialized group. There are more and more "scholars" who know almost everything about nothing, while the number of those who know a little about everything is declining.

This process of specialization has been taking place for a long time--since the beginning of the nineteenth century--but it accelerated over the course of the twentieth century. Increasing specialization initially had beneficial effects, but in the long run its general adoption and the consolidation of a model of research in sealed compartments is being shown to be negative and difficult to reconcile. This process of compartmentalization has also led most disciplines to adopt some form of reductionism, mainly methodological, according to which all systems can be completely explained by the properties of their parts. This form of reductionism should not be confused with ontological reductionism, which argues that there is nothing that is not, in the final analysis, explainable by physical causes.

Without resorting to vitalist or organicistic (the idea of the superorganism) interpretations, which belong to the past, and without invoking any sort of vital principle or animism, the fact is that living matter shows special features that cannot be reduced readily to their physical components. These special features can be attributed to their more or less ordered arrangement and to the ways in which they participate in the construction of something more complex, that is, a higher-level system of organization. Both its aims and its historical evolution make ecology difficult to fit in among the other academic disciplines.

Ecosystems, the object of the study of ecology (according to Margalef as seen above), can be described as physical systems. However, beyond the components that make them up and their relations and interactions, they have a history and structure, as do the subsystems of which they are formed and which are the result of a long process of evolution. The biosphere is not a uniform layer of living matter surrounding the planet, but space inhabited by discontinuous units of living matter of different types--organisms that associate and interact in different ways over the course of time. Every exchange of energy, as in every physical system, represents an increase in entropy, but in the case of living systems, a significant portion of this increase is recovered very effectively in a form that is denominated (called complexity or information), as if the energy exchange left a mark or sign on matter (see also vol. 1, p. 210).

It is therefore understood that, while recognizing the methodological legitimacy of some degree of reductionism, a purely reductionist methodology cannot be accepted as the only approach to gathering knowledge on ecology (just as an exclusively holistic approach cannot be considered the only answer). In the present practice of ecology, especially in Catalonia and despite the influence of Margalef, the prevailing approach is dominated by reductionist casuistry. Ecological practice is isolated and often decontextualized, and it lacks an interest in studying the complexity of complete living systems by going beyond the simplest analysis of the flows of materials and energies. This is largely due to the dominant attitude among the practitioners of other scientific disciplines, and among those who administer the resources, always scarce, for research. Being out of line with those who administer research funds is particularly dangerous to a scientific career, and this means that ecologists usually find themselves at a disadvantage when compared with their colleagues in more "rigorous" disciplines--the ones that adopt a more reductionist methodology. As a result, ecologists strive to reduce methodological distances with the disciplines seen "more favorably" by the managers of scientific policy. The myopia of these managers (together, perhaps, with some degree of timidity by the ecologists) is the cause of a certain degree of stagnation in the production of scientific knowledge in the field of ecology. Ironically, this trend contrasts sharply with the vitality of the social movements related to the defense of environment--movements that were inspired by ecological thinking.

Yet it is true that the study of systems as complex as ecosystems requires the joint work of scientists from many different fields, including experts on physical science and social sciences. This is an extremely complicated task due to the current structure of universities and research centers around the world. Every individual researcher, every laboratory, every center, struggles to affirm its identity and tries to distance itself as much as possible from any other. Working together, except in a few instances, cannot even be considered or is only suggested to satisfy outside specifications when responding to requirements for funding. In this sense, one of the fundamental features of the Encyclopedia of the Biosphere has been to impose a multidisciplinary approach on the work of more than 200 specialists from a very wide range of disciplines. Except in a few cases, they have not worked together; they have been willing to work individually and accept a common discipline, subject to a general organization to fit in with a position that had been explained to them beforehand. They have almost all been willing to lose part of the identity of their personal work, their special jargon, to benefit comprehension by the reader and greater dissemination throughout society.

Creative transgression

Only through creative transgression, which includes such illustrious names as Humboldt, Darwin, Mobius, Dokuchayev, Warming, Clements, Vernadsky, Tansley, Lindeman, Hutchinson, the Odum brothers, Margalef, and Lovelock, is it possible to advance in the knowledge of the biosphere of which humans are part and upon which their life depends. But it is not easy in these times to find platforms where this promiscuity of knowledge can be exercised without criticism. Nor has the Encyclopedia of the Biosphere escaped this criticism. Some people have criticized its oblique, mixed, anecdotal nature, the rapid jumps from botany to stockraising, from zoology to bioclimatology, from anthropology to ecology, from epidemiology to agriculture, from the past to the present. Others have said it is "not very scientific."

We welcome this criticism; it is the best praise we could ask for the Encyclopedia of the Biosphere, one of the basic aims of which was to innovate in the dissemination of knowledge. It has done this by showing the connections between questions that are disconnected in normal learning--that are rarely considered as a whole. There are few works that discuss topics as far-reaching as the influence of the Industrial Revolution on the growth of slavery in the southern United States (caused by the growing demand for cotton by industry in the early nineteenth century), or the impact of the exemplary conservation of forests and landscapes in Japan on the tropical rainforests of Indonesia or the temperate forests of Australia or Chile (i.e., destruction of these Indonesian, Australian or Chilean forests by the Japanese logging industry). It is also uncommon to find in a single work parallelisms such as the survival of the different forms of the cult of the bear throughout Eurasia and the floras of North America and Europe. Nor is it usual to find ecological data on the most important woods used in cabinet making, or on the fish that produce the best types of caviar. Yet all these things are part of the biosphere. People and bears, trees and fish, memory (that is to say, information) and the present. And only by realizing this and by realizing that human history--with all its miseries and all its glories, with its triumphs and its frustrations--forms part of the history of the biosphere, is it possible to hope that humans will assume responsibility for the maintenance, for many more centuries, of this common history.

1 Every human group has had its own perception of nature, both on the cosmic scale, to explain the unreachable heavenly bodies, and at the more immediate level, to explain the objects and living things of the daily environment. These perceptions, marked by ambivalence between respect for the unknown and the desire to dominate it to meet immediate needs or desires, is one of the oldest bases of human cultures. The representation of a woman in the photo, from the Sanctuary of Sahure (Sah-U-Ra) at Abu Sir (Egypt), personifies the fertility of the Earth. Hanging from her arm are three ankhs, the symbol of life, and she is carrying a sort of tray with an offering of bread, symbolizing the food provided by the Earth. Sahure (Sah-U-Ra) reigned in the twenty-fifth century b.c., and was the second pharaoh of the fifth dynasty, a dynasty that worshipped Ra, the Sun God. All the members of this dynasty were called the sons of the Sun, and they built large temples in his honor, some of which contain (like the funeral temples of the dead pharaohs) splendid examples of ancient Egyptian relief carvings.

[Photo: National Museum, Cairo / Werner Forman Archive]

2 Calendars are social constructions that try to reconcile linear and cyclic conceptions of time, a way of thinking of time that is present to a greater or lesser extent in all societies. On the one hand, there is the irreversible inevitability of the future ("time's arrow"), imposed by the laws of thermodynamics and confirmed by individual and social awareness and accumulated memories; on the other hand, there is the repeated confirmation of cyclic changes in the environment, correlated with observations of the apparent movement of the heavenly bodies. Aztec and Mayan astronomers had observed and recorded the movements of the heavenly bodies more precisely than their counterparts in the Old World. At the time of the Spanish conquest of Mesoamerica (i.e. Middle America), the length of the solar year calculated by Mayan astronomers (365.2420 days) was closer to the true figure than the figure that was then accepted in Europe. The center of this Aztec calendar carved in relief on a basalt monolith weighing 27.5 short tons (25 metric tons) and 12.1 ft (3.7 m) across is known as the "Piedra del Sol" (the Calendar Stone or Sun Stone), and represents the god Tomatiuh, the Aztec sun god. It is a visual representation of the Aztec's cyclic conception of time. They thought that time had a beginning and an end, that is, the beginning and the end of Tomatiuh's power over the world, and they also believed in the cyclic occurrence of major natural catastrophes. These catastrophes happened every 52 years, when their ritual calendar and civil calendars returned to the same positions relative to each other (the Binding Up of the Years). The ritual cycle was 260 days long (13 x 20), while the civil calendar was 365 days long, a solar year (to the nearest day). At the end of this cycle of 52 years, it was feared that the Sun would never shine again, and the altars and the images in houses and temples were replaced; a human sacrifice was made at the New Fire Ceremony so Tomatiuh would make the Sun disc reappear.

[Photo: Museo Nacional de Antropologia, Mexico City (D.F.) / Werner Forman / Archiv fur Kunst und Geschichte, Berlin]

3 Many cultures share a belief in a non-material dimension of the person, which leaves the body on death. Some cultures practice ancestor-worship. This belief largely explains why many humans consider themselves and their cultures as something outside nature, whether to "protect nature" or "dominate nature," and only consider themselves subject to the laws of physics in their material dimension. This terracotta Etruscan sarcophagus is an expression of this aspiration to transcendence that seems inherent to the human condition, at least in cultures with a dualist conception (i.e., a person is composed of two parts--a body and a soul). Other cultures believe in a spiritual dimension that is not limited to humans but which extends to all living things, such as Hinduism and Buddhism, or do not recognize any transcendent dimension, such as the many different forms of materialism.

[Photo: Musee du Louvre, Paris / Erich Lessing / Archiv fur Kunst und Geschichte, Berlin]

4 Aristotle's work on nature is still surprisingly relevant. He was considered the supreme authority on biology as late as the Middle Ages and the Renaissance. His works were transmitted as copies of copies and as translations of translations. They were not published until centuries after his death, and were to some extent forgotten, but he was and is recognized as one of the leading thinkers of antiquity, for both the Roman Catholic and Orthodox churches of Christianity, and the entire Muslim world. Even at the beginning of the nineteenth century, Aristotle's books History of Animals greatly impressed the Baron de Cuvier (1769-1832), a leading French zoologist. This fourteenth century Flemish miniature, taken from the work Der Naturen Bloeme, by Jacob van Maerlant (1235-1291), represents Aristotle (wearing a philosopher's cap) at the apex of the pyramid of knowledge.

[Photo: Bibliotheque Royal Albert Ier, Brussels]

5 De Materia Medica, by Pedanius Dioscorides (first century a.d.) is the great summary of the pharmacological knowledge of antiquity. After the expansion of Islam, this work was translated into Arabic, and spread throughout much of Asia, North Africa and Al-Andalus (Islamic southern Iberian Peninsula, Andalusia). In the Christian West of Europe it only became known in the tenth century, after it was translated from an Arabic version of a Greek codex. This codex was taken to Cordoba around the middle of the tenth century by a Byzantine monk who, together with a group of Andalus doctors, identified the plants and other remedies that appeared in the codex by their names in Classical Arabic, Andalusi Arabic, Berber, Latin, and Romance. Giving the name in several languages, unlike the eastern tradition of merely transliterating into Arabic the Greek names given by Dioscorides, was continued in most Andalus texts on medicine, and made it much easier to transmit Greek and Arabic learning to the Christian West. Thanks to successive translations, Dioscorides's Materia Medica, became the common source of knowledge on pharmacology in Christian Europe and in the Arabic world. The illustration shows a page from a Persian manuscript of the work, written in the thirteenth century in Arabic.

[Photo: Metropolitan Museum, New York / Werner Forman Archive]

6 The Book of the Hunt and Falconry, by Gaston III of Foix (1331-1391), also known as Gaston Phoebus, is one of the few medieval works to make an original contribution to the knowledge of nature inherited from Aristotle and Pliny the Elder, probably because of its practical approach. Many of these works are treatises on hunting or falconry that were written or commissioned by lords, kings and emperors. Though none of them treated the subject in a way that can be called scientific, they contain many first hand empirical observations that were both precise and far from the scholasticism that dominated thinking at the time. Gaston Phoebus was a typical example of the Occitan aristocracy of the fourteenth century. He took advantage of the conflicts between the kings of France and England (the Hundred Years War) to strengthen his independence from them and to create a splendid court. The illustration is taken from a fifteenth century copy at the Musee Conde, Chantilly, in Ile de France, and is taken from the section dealing with how to treat dogs.

[Photo: Musee Conde, Chantilly / AISA]

7 Every human society has had a system of ideas about the basic elements of nature and how they are related. Many pre-Socratic philosophers thought one or another of the four primordial elements recognized by the Greeks (earth, air, fire and water) was the origin of all the other elements and of nature as a whole. Belief in the four elements persisted in western thought until the Industrial Revolution, as can be seen in the medieval diagram of the Universe (upper illustration), in which the Earth is shown surrounded by spheres of water, air and fire (and then the spheres of the Sun, the Moon, the planets and the fixed stars). The Taoists, however, recognized five elements (water, fire, wood, metal and earth), all of them fruit of the interaction of the two basic principles or forces, yin and yang (lower illustration). This idea is still very influential in Chinese thought. Yin, the feminine force, is associated with darkness, cold, and passivity, and the Moon. Yang is the male counterpart, and is associated with brightness, warmth, and activity, and the Sun. Together they form the qi, the energy-matter of which all things are made. Yin predominates in water, and to a lesser extent, in wood. Yang is present in fire, and to a lesser extent in metal, while in earth the two principles are in balance. In Taoism, the idea of the functional unity of nature is implicit, as nothing can be considered unless in the framework of the whole. The Tao (the way), is a process in which everything is interrelated and which gives rise to the natural order, in which the two opposites complement each other. The symbols for yin and yang complement each other to form a circle, as in the centre of the wooden carving in the lower image.

[Photos: Ancient Art and Architecture Collection and Private Collection / Werner Forman Archive]

8 The introduction and the rigorous application of perspective in landscape painting was one of the most outstanding achievements of the Renaissance in Italy. Unlike other schools that have excelled in painting landscapes (such as the Chinese school, and even the Flemish school, which treat landscape on the basis of feeling, playing with their outlines or with the light, without having to be geometrically precise), the Florentine school and other Italian schools in the early Renaissance (early and mid-fifteenth century) typically used a linear perspective from a single point of view, identified with the supposed position of the painter with respect to the scene painted. The illustration shows a fragment of Saint Peter by Francesco del Cossa (1436-1478), who was born in Ferrara (Italy), and is a good example of the Ferrarese school of landscape painting in the mid-fifteenth century. The author renders the landscape with a rigorous sense of space, though he uses tricks like viewing the landscape by integrating it in an architectural setting (here, for example, the landscape is seen through an arch opening in some ruins). This allows him to treat the landscape in this composition as partly independent from the painting as a whole, but maintains the unity of a single point of view. At the same time, the treatment of the saint's bare foot (which is anatomically correct) and the play of light and shadow to accentuate the folds of the drapery, show he was a highly skilled painter.

[Photo: Pinacoteca di Brera, Milan / Giraudon]

9 Leonardo da Vinci was one of the greatest engineers of all time, as well as a major figure in European art. He designed all sorts of machines, especially water-powered machines and war engines, and even designed a flying machine, as can be seen in the drawings in the illustration, which are taken from a codex. Leonardo had a distinctive style of writing; he was left-handed, but he wrote his codices back-to-front in mirror-like writing, so they had to be read with a mirror.

[Photo: Bibliotheque de l'Institut de France, Paris / Lauros / Giraudon]

10 Measuring the true size of the world was achieved with the work of the great Flemish Renaissance cartographers Gerhard de Kremer (1512-1594) and Joost de Hondt (1563-1611), who are better known by their Latinized names as Gerardus Mercator and Jodocus Hondius. Mercator was an engraver and cartographer who devised the Mercator projection, which represents the Earth's surface on a flat sheet, with parallels and meridians rendered as straight lines spaced so as to produce an accurate ratio of latitude to longitude at any point. This projection was first proposed in Mercator's 1569 map of the world, which completed the geometric analysis of the Earth begun by Renaissance astronomers and physicists like Copernicus and Galileo. This projection enabled mariners to steer a course over long distances by plotting straight lines. Mercator was also the first to apply the term "atlas" to a set of maps, though a complete edition of his atlas was not produced until a year after his death (by his son). Hondius was also a remarkable engraver and cartographer. He opened a workshop in Amsterdam in 1595 that produced some of the major cartographic works of the time, including Mercator's map of the world and atlas. Hondius's son Hendrick continued his father's business, and in 1619 he published a new edition of Mercator's atlas with this frontispiece on the cover showing his father and Mercator.

[Photo: British Library, London / Bridgeman / Giraudon]

11 The great intellectual and material changes that occurred in the Renaissance provoked strong opposition. Like all free-thinkers, Galileo's ideas were considered subversive by the highest ranks of the Roman Catholic Church, but he was also condemned by many of the Aristotelian professors then dominant in the universities in Italy. Galileo defended Copernicus's heliocentric theory (i.e., the Earth moves around the Sun, not the other way round), and he was condemned by the Inquisition in the trial shown in this painting by an anonymous Italian artist. He also defended atomism (the philosophical theory of atoms), which the Church considered incompatible with the dogma of the transubstantiation of the Eucharist, and he favored experimental physics over the Aristotelian physics of the scholastic school. Galileo can be said to have started modern science and what has been called the Scientific Revolution.

[Photo: Private Collection / Bridgeman / Giraudon]

12 In the late seventeenth century there was no scientific theory to explain the Earth's formation, internal structure and history. The first geological systems date from this period, and among the first were those of the German Jesuit priest Athanasius Kircher (1601-1680). In his book Mundus Subterraneus (Underground World, 1665), from which the accompanying illustration is taken, he proposed that there was a fire at the center of the Earth and large deposits of water (hydrophilaceous deposits), fire (pyrophilaceous deposits) and air (aerophilaceous deposits). The hydrophilaceous deposits supplied the seas, rivers and springs by underground canals, while the pyrophilaceous deposits were connected to the fire at the center of the Earth, and also gave rise to volcanic eruptions. Water was favored as the formative element in Neptunist systems (such as Maillet's proposed system, which postulated that the level of the sea had fallen and that the face of the Earth had been shaped by part of the circulating waters), while the action of fire was favored by the later Plutonists (who started from the theory of the internal fire advanced by Descartes, and whose ideas solidified in Hutton's theory of the Earth), and this was debated until the nineteenth century.

[Photo: AISA]

13 The biblical idea of the Flood was a major obstacle for all ideas about the Earth developed by early geologists. Some, such as Thomas Burnet (1635-1715), calculated the volume of rain that would have had to fall to make the sea rise enough to flood all dry land. When he realized that it was quite impossible for this much rain to fall in 40 days, he attributed the rise in water levels to the release of the water contained under the Earth's crust, which would have sunk. Others, such as Linnaeus, sought explanations for the difficult coexistence of animals with antagonistic ways of life in Noah's ark. The anonymous modern Tunisian artist who created this painting on glass entitled Mr. Noah's Voyage avoided these problems by showing the humans and animals living in perfect harmony.

[Photo: Collection C. Campderros / Jordi Vidal / ECSA]

14 Hindu cosmology is totally different from the Christian Bible, and humans are not considered the lords and masters of creation as in Christianity. Time is cyclic and the Universe is undergoing a process interrupted by large rises and falls. The basic cosmic cycle, the kalpa or "day of Brahma" is a period of 4,320 million years, at the beginning of which the god Vishnu sleeps on the cobra Ananta, symbol of eternity, who is floating on the cosmic ocean of primeval chaos within which are the remains of a previous universe. This is represented in the lower part of the image, a seventeenth century painting from Rajasthan. In the Hindu triad of the three great gods, Brahma, Vishnu and Shiva, Brahma is the creator, Vishnu is the protector and Shiva is the destroyer. From Vishnu's navel a lotus flower grows, and Brahma emerges from the flower bud. Brahma creates the Universe for the enjoyment of Vishnu, who awakes and takes control of the Universe for the entire "day." At the end of this "day," Shiva destroys the world and Vishnu reabsorbs it into his body, and goes back to sleep for a period of several kalpa, known as the "night of Brahma." After this "night," the process is repeated an indefinite number of times, until Vishnu eventually founds his personality in the "Absolute Spirit of the World," which is the only reality in existence for an even longer period, until Vishnu appears again and the cycle begins anew. In Hinduism, the "Cosmic Order" affects all living things (which are essentially the same) in the same way, and souls transmigrate among all these living things. The social order, in this point of view, is also part of the cosmic order.

[Photo: Narodni Galerie v Praze, Prague / Werner Forman Archive]

15 Viracocha (or Huiracocha) was worshipped in the Andes area before the Incas as the creation god of the Earth, heavens and humans. He was also worshipped by the Incas, and was considered to have brought the arts of civilization, technological knowledge and social institutions to humankind. He was also the father of the Sun God, the supreme divinity of the Inca civilization. This stele from the Tiahuanaco culture (500-1200 a.d.), is from the La Paz region of Bolivia, and shows the god holding a scepter (now broken) in each hand. The Incas attributed the monoliths in the ruins at Tiahuanaco, which were already old when the Spanish conquistadors (conquerors) reached the Bolivian highlands, to a punishment by Viracocha, who had turned the human sinners into stone.

[Photo: Museum fur Volkerkunde, Berlin / Werner Forman Archive]

16 The genius Michelangelo (1475-1564) sums up the Biblical version of the creation of Adam, the first man. This painting is on the roof of the Sistine Chapel, in the Vatican (Rome). God transmits life to the man he made in his own image with the clay of the Earth, and thus adds the final touch to his creation. In the monotheistic Judeo-Christian tradition, creation is linked to the word of the creator, not to a struggle between chaos and the creative force, as in other traditions. Man is crowned king of creation, as he alone is able to hear and understand the word of God and to obey God's order, including filling the Earth and dominating it (see pp. 26-27).

[Photo: Scala]

17 Goethe considered himself influenced by the classics, and he detested the romantics during the last years of his life. Despite this, he was undeniably one of the leading figure in the changes in attitudes that were linked to the romantic movement. The painter Heinrich Cristoph Kolbe (1771-1836) painted this portrait in 1826, when Goethe was 77. Kolbe accentuated Goethe's romantic aspects by conventionally locating him against the background of the Gulf of Naples, which Goethe had only visited once, about 40 years before. Goethe is portrayed next to the ruins of a classical temple, with slightly ruffled hair, pencil and notebook in hand, his hat and walking stick left on the base of a ruined column and in a rather negligent attitude. As a whole, these elements are all very typical of the romantic style of portrait, which sought to express the freedom of the person portrayed (and to an even greater extent if the person represented was an artist) rather than an exclusively formal image. The person was often represented in a relaxed pose in an unusual setting, and was elegantly but nonchalantly dressed. Kolbe thus portrays Goethe as a typical romantic.

[Photo: Universitatsbibliothek, Jena / Archiv fur Kunst und Geschichte, Berlin]

18 Classicism and romanticism were not considered contradictory in Germany at the time of the French Revolution. On the contrary, they both rejected the model of progress of the Enlightenment and favored instead models from the past that were closer to the development of a distinctively German culture different from the Enlightenment, which was of French origin. Between 1794 and 1805, Goethe and Schiller both lived in Weimar, where they collaborated in the intimate fusion of classicism and romanticism. This is what the painter Otto Knille (1832-1898) sought to capture in his painting Weimar 1803 (painted in 1884), as his homage to one of the most brilliant moments of German culture. Some of those portrayed are survivors of the Enlightenment but most of those present were the great figures of classicism, led by Goethe (standing in the center, at the base of the central bust). It also shows the romantics of the Sturm und Drang movement, such as Schiller and Klinger (at the far right of the painting) and younger romantics, such as the brothers Wilhelm and Alexander von Humboldt (side by side and behind Goethe).

[Photo: Universitatsbibliothek, Berlin / Archiv fur Kunst und Geschichte, Berlin]

19 Johann Friedrich Blumenbach was one of the most remarkable German scientists of the romantic period. He was one of the first naturalists to think of nature as something that was undergoing change. He also believed that plants and animals have become extinct and that they are characteristic of defined geological strata, an idea that formed the basis of the later development of Lamarck's ideas of change over long periods of time and Darwin's theory of evolution. He was also an excellent anatomist, and together with Cuvier he created comparative anatomy. He is, however, best known for having been the first to study humans as part of nature (as "the most perfect of the domestic animals"), and human variability. Blumenbach considered that differences in the size and shape of the skull could be used to classify the different branches of humanity, however he rejected any racist interpretation of the superiority or inferiority of any one shape of skull and of one human over another. A dozen editions of his Handbuch der Naturge-schichte (Manual of Natural History) were printed bet-ween 1779 and 1830, and his Beytrage zur Naturge-schichte (Contributions to Natural History), which was published for the first time in 1790, was also reprinted several times. Both helped to spread his idea about human natural history, the historical basis of nature, and of comparative anatomy.

[Photo: Staatsbibliothek zu Berlin, Preussischer Kulturbesitz, Berlin]

20 Alexander von Humboldt and Aime Bonpland brought more than 60,000 herbarium specimens back from their voyage to the Americas. The specimens represented about 6,000 different species, more than half of them previously undescribed. Studying this huge volume of material was a major undertaking that took many years. The initial idea was that Bonpland would publish it all, but Bonpland had only finished his monograph on the Melastomataceae and two volumes of Plantes Equinocciales (Tropical Plants) before he returned to the Americas, where he remained until his death in 1858. The remaining material was studied by the German botanist Carl Sigismund Kuhn (1788-1850) and he produced the seven volumes of Nova Genera et Species Plantarum (New Genera and Species of Plants). Kuhn and Humboldt were co-authors, and the seven volumes were printed between 1816 and 1825, with about 700 splendid engravings of the new species being described, produced by the French botanists Pierre Turpin (17751840) and Antoine Poiteau (1766-1850). The illustration shows one of Turpin's engravings, featuring a species of Salvia from the pine and oak forests of the mountains of Mexico. This species was named Salvia cardinalis by Humboldt and Kuhn, but they did not know that this species had already been described as S. fulgens by Antoni Josep Cavanilles (1745-1804), a name that thus takes priority.

[Photo: Christie's Images]

21 The dogmatic positivism of the second third of the nineteenth century thought little of romanticism, and ignored its scientific manifestations. This was due to rejection of what the positivists saw as the irrational nature of Naturphilosophie. This negative perception of Naturphilosophie has lasted until the present day. Naturphilosophie, the basis of the romantic view of the world, represented a rupture in the history of knowledge that was decisive in the future development of a science like ecology (and others like thermodynamics and electromagnetism) and concepts like the ecosystem and the biosphere. In comparison with the "classical" sciences (such as geometry) and the modern sciences (such as physics), ecology can be considered a "romantic" science. Yet the romantic view of the world aims for an overall understanding that is not restricted to knowledge only through science. Art, like science, feeling, like reason, intuition like the senses, for the romantics, all lead to the experience of the whole. An experience that did not accept that there was an insuperable separation between matter and spirit, between the visible and the invisible, between the evident and the occult, the within and the without, and between the cosmic and the human. Nor did it accept the division of knowledge imposed by the illustration. Art and science, for example, are often found together in the work of scientists like Alexander von Humboldt for whom aesthetics were inseparable from science. This is shown by the illustration, a large format engraving published in Paris in 1807 to accompany Humboldt's Essai sur la geographie des plantes. His typically romantic objective was to "explore the unity of nature," and to discover the interaction of its forces and the influences of the geographic environment on plant and animal life. Humboldt took a decisive step towards the formation of ecology, by establishing an innovative scientific practice that makes it possible to talk of a "Humboldtian science."

[Photo: Archiv fur Kunst und Geschichte, Berlin]

22 The Industrial Revolution and the romantic movement were contemporary. James Watt produced the first steam engines when William Blake was starting to write poetry. The first iron-hulled stream ships were contemporary with the work of George Gordon (Lord Byron) and Sir Walter Scott. And the Le Creusot foundries were contemporary with the work of Francois Rene de Chateaubriand. Though they were contemporary, the idealization and "divinization" of nature characteristic of the romantics, conflicted with the pragmatism of the emerging capitalist classes who were interested mainly in maximizing production and profits and minimizing costs. The illustration shows an image of the drop hammer at the Le Creusot foundries, in 1867, in a xylograph made from a drawing by Ignace Francois Bonhomme.

[Photo: Archiv fur Kunst und Geschichte, Berlin]

23 The economic and social conditions surrounding the use and transformation of natural resources underwent an unprecedented change at the time of the Industrial Revolution, which took place first in Britain and later in other countries (see vol. 7, pp. 308-309). It was not, however, a well defined and sudden change (see vol. 1, pp. 300-302 and 312-13), nor did it occur simultaneously all over the world, but its consequences were felt around the world and are the basis of the development that has brought the planet to the current situation. Utilitarianism and Marxism are both products of the Industrial Revolution, however different their ideologies may be. Utilitarianism considers that the basis of all morality is to seek the greatest happiness for the greatest number of people. Marxism was founded on a historical interpretation of productive activities and the relations of production, which were always based on conflict between the different social classes ("class struggle"). Furthermore, Marxism considers the economic relations in capitalist society--the result of the Industrial Revolution--an appropriation of the labor of the working classes (in the form of the added value of the goods produced). The illustration shows a painting by the Catalan Art Nouveau painter Santiago Rusinol (1861-1931), who inherited a group of textile factories, and shows a group of women working in a Catalan textile factory around 1860.

[Photo: Ramon Manent]

24 The riches that accumulated in the European metropolises, as a result of their exploitation of their colonies, were one of the factors favoring the beginnings of the Industrial Revolution. This had two aspects--the exploitation of raw materials, which were processed to produce high value goods (using slave or very poorly paid labor), and the exclusive rights of access to the metropolitan market. This exploitation alone was not sufficient to trigger the Industrial Revolution, however; Spain and Portugal had the largest and wealthiest empires at the beginning of the Industrial Revolution, but neither underwent the early industrialization process that occurred in Great Britain and the Netherlands. The Creole artist Vicente Alban, who was active in Quito towards the end of the colonial period, in 1783 painted this image of a "Yumbo" Indian (the name given by the colonists to the Quechua Indians living on the banks of the Napo River), laden with the typical products that they transported from the Amazonian lowlands (to the east of Quito) to the city and the surrounding area.

[Photo: Museo de America, Madrid, Spain]

25 Railway stations are one of the most representative types of public building of the Industrial Revolution, where all the glories and miseries of contemporary society came together. The first railway lines were laid to connect sources of raw materials to major towns and cities and the ports from which goods were exported. Railways, thus, started to act as a unifying force for the developing national markets in both the metropolises and colonies. This painting, The Railway Station, by the British artist William Powell Frith (1819- 1909), is one of the most famous British paintings related to railways, and shows Paddington Station in London in 1862.

[Photo: Topham Picturepoint / Firo Foto]

26 The progressive distancing of the new rational science, associated with the Scientific Revolution of the sixteenth and seventeenth centuries, from all mythology is even reflected in the symbols associated with the most conventional mythical themes in the art of the time. This is clearly shown in this painting by Jan Bruegel the Elder (1568-1625), partly painted by another Flemish painter, Hendrik van Balen (1575-1632). It shows the recurring theme of the elements, in this case, air and fire, that were indispensable decorations in Baroque "curiosa" collections. The figure representing fire holds Zeus's thunderbolts in her hand, while the figure representing air is holding an armillary sphere, an instrument that had been known to Chinese astronomers since antiquity, but which was unknown in Europe until it was independently discovered by the Danish astronomer Tycho Brahe (1545-1601).

[Photo: Christie's Images]

27 The Cabinet du Roi in Paris developed greatly under Buffon, and was the predecessor of the collections of Museum National d'Histoire Naturelle created by the Convention in 1793. In general, during the seventeenth and eighteenth centuries curiosity cabinets ("curiosa" collections) developed into ordered collections of natural specimens, the forerunners of the natural history museums of the nineteenth and twentieth centuries. This development is perhaps most clearly seen in "Cabinet du Roi" in the Jardin des Plantes (Paris). Buffon was placed in charge of the collection in 1739 and in his Histoire naturelle generale et particuliere, avec la description du Cabinet du Roi (General Natural History with an Account of the 'Cabinet du Roi') he outlined his ideas about how natural history collections should be arranged and displayed.

[Photo: Biblioteca de Catalu-nya, Barcelona]

28 Until Lamarck occupied the chair of invertebrate zoology created in 1793 at the Museum National d'Histoire Naturelle in Paris, zoologists paid almost no attention to invertebrates. Lamarck started the process of cataloging and classifying the wide diversity of invertebrate groups. His role as a teacher led to the description of hundreds of new species within a few years, including this jellyfish (Cyanea lamarckii) from the North Atlantic, which was named after Lamarck by Francois Peron (1775-1810). It is shown here in an excellent painting by Charles Alexandre Le Sueur (1778-1846). After he occupied this chair, Lamarck devloped his theory of the transformation of species. Lamarck's ideas are very different from the impressions given by his detractors. He was the first to openly say that the diversity of species was not due to a single act of creation, and that there are natural mechanisms that can explain the diversity that now exists. He did not, however, correctly identify the way in which species change.

[Photo: Museum d'Histoire Naturelle, Le Havre]

29 Buffon considered that the current distribution of species can only be understood as the result of a historic process of migrations and adaptations, as he explained in his book Histoire naturelle, generale et particuliere (General and Particular Natural History). He did not postulate a theory of evolution as he only accepted limited modifications of fixed type species. He did not consider systematics to be very important, and his view that species did not exist, only individuals, also discouraged transformationist ideas. The publication of his work started in 1749 and continued till 1840, more than half a century after his death. Buffon's works were disseminated very widely due to his good literary style, the excellent engravings, and the fact that they were adapted and translated into many languages. The best engravings in Buffon's works are probably those in the Histoire des oiseaux (The [Natural] History of Birds), from which the illustration is taken. It shows a red kite (Milvus milvus) and a common buzzard (Buteo buteo), drawn and engraved by Francois Nicolas Martinet.

[Photo: Biblioteca de Catalu-nya, Barcelona]

30 Studies of the origin of cultivated plants began with Alphonse de Candolle and culminated in the work of Nikolay Ivanovich Vavilov (1887-1943), which reconstructed the origin of the plants from which modern crop species are descended. It thus raises questions about the environmental conditions in which domestication took place, the environmental limits of their cultivation, and the optimum environmental conditions for achieving the best yields. Vavilov made collections of most cultivated plants, and this was one of the first attempts to study and understand the intraspecific variability of these species, what we now call their biodiversity.

[Photos: Barcelona Botanical Garden / Jordi Vidal / ECSA]

31 In the title of this book, the word "ecology" (oecology) was used as a noun, a change from the 1895 Danish edition (Plantesamfund. Grundtraek af den rkologiske plantegeografi or Plant Communities--Fundamentals of Ecological Plant Geography), in which it is used as an adjective. This suggests that between the Danish edition and the 1909 English edition ecology became recognized as a scientific discipline. Barriers lasted for many years between ecologists trained in zoology or botany, and this led to the division into plant and animal ecology (which lasted until the 1970s). There are still barriers today between "terrestrial" ecologists, and oceanographers and limnologists.

[Photo: ECSA]

32 The German zoologist Karl Gottfried Semper was a forerunner of what would later be called "animal ecology" and studies of the special features of island faunas. As a young man, he travelled through the Philippines and the Palau Islands. Later, as director of the Institute of Zoology of the University of Wurzburg, at a time when zoologists still tended to morphological and taxonomic studies of dead animals, he insisted on the physiological and ethological (behavioral) study of the living animal, and introduced the concept of the food chain. His experiences in the Philippines led him to promote interest among his students in the special features of island faunas, especially those of the Mediterranean islands, such as the Balearic Islands, which had until then received little attention from zoologists. His main work Die Naturlichen Existenzbedingungen der Thiere (The Natural Conditions of the Existence of Animals) appeared in 1880 and was immediately translated into English. The work was, in fact, a compilation of the talks he gave in 1877 at Lowell Technological Institute in Boston, when he was on a visit to the United States. In this work, he insists on the influence of environmental factors on the physiology of animals, and draws conclusions that we would today consider "ecological."

[Photo: Staatsbibliothek zu Berlin / Preussischer Kulturbesitz, Berlin]

33 On the fiftieth anniversary of the publication of the book What is Life? by the Austrian physicist Erwin Schrodinger, the American biologist Lynn Margulis (b. 1938) and her son Dorion Sagan published a book with the same title. At the time when Schrodinger published his book, the double helix structure of the nucleic acids was unknown, as was their role in the storage and transmission of genetic information. Schrodinger sought explanations for the special properties of living matter, to explain them on the basis of the laws of physics and chemistry. In 1926, when he had already formulated the Schrodinger wave equation (which was the basis of the development of quantum mechanics), he became fascinated by the complexity of living things, though he recognized his inability to define life. Fifty years later, Margulis and Sagan have had to resort to a circular explanation in which, chapter by chapter, they present the attributes of living matter, ("a process that slithers and slides between matter like a tranquil and unknown wave; [...] a marvellously complex set of chemical reactions; [...] energy from the sun and matter that are transformed in the green fire of photosynthetic organisms") in the framework of their evolution. Thus, it is not a matter of giving a definition of life, but the elements or components of a definition.

[Photo: Jordi Vidal / ECSA]

34 The history of ecology is characterized by the convergence of knowledge and practices from many different disciplines, rather than the fragmentation and deepening of different parts of preexisting disciplines. This chronological scheme, based on that proposed by Ramon Margalef in his work Ecologia (1974), helps to locate some of the authors who have made important contributions to ecology in their historical setting. Especially in the case of the earliest authors, this does not reflect whether they were known as ecologists or not, or whether they have been considered as such by contemporary or later historians, and indicates when they lived and the tradition to which they belonged.

[Drawing: IDEM, from several sources]

35 Eugene Odum's book Fundamentals of Ecology was published in 1953, and spread to a wider public the concept of ecology based on the notion of ecosystems, on energy exchange between different trophic levels and on the biogeochemical cycling of nutrients. This was a conception of ecology based on the Hutchinsonian synthesis between the notion of the ecosystem as an organization of matter and Vernadsky's ideas on the biogeochemical cycles of the biosphere. In the years between the first edition (1953) and the third edition (1971), ecology ceased to be a little-known academic discipline and attained a high profile, especially in the United States, as ecology became the theoretical reference point of a political movement--the env- ironmental (ecological) mov-ement--which was small but already influential.

[Photo: Jordi Vidal / ECSA]

36 The Catalan painter Angels Santos i Torroella (b. 1912), halfway between expressionism and surrealism, has created some very original works. The one shown in this illustration was painted in 1929 and called Un mundo (One World). It depicts the disorder of a distorted planet, poorly planned and highly urbanized and technological, in the indefinite (but not according to her, distant) future. Until recently it was uncommon for artists to take the planet as a whole as the subject of their works. It is also worth pointing out that this picture was painted when the artist was only 17 years old, at almost the same time as the publication of Vernadsky's work on the biosphere.

[Photo: Museo Nacional Centro de Arte Reina Sofia, Madrid / Ramon Manent]

37 The first images of the Earth from space totally changed people's perception of the world. The planet as a whole ceases to be an abstraction or an object of the imagination and becomes something real that can be seen with one's own eyes. Its size and its limits could be grasped by the senses, despite coming from remote sensors that transmitted the information to Earth. At the time of the Cold War and the space race, it is not surprising that the planet was compared to a spaceship, Spaceship Earth, and the entire human population to the crew. The illustration shows the Earth in the background, partly obscured by a spacecraft, with two astronauts floating weightlessly in space.

[Photo: J. Novac / AISA]

38 The discovery of the hole in the ozone layer at the North and South Poles, between the end of winter and the beginning of spring in the northern and southern hemispheres, was confirmed in the 1980s (see also vol. 1, pp. 401-405), and it was shown that it is caused by chlorofluorocarbons (CFCs) and nitrogen oxides. Detecting these molecules in the upper atmosphere at very low concentrations is possible thanks to the electron capture detector, invented by James E. Lovelock in the 1960s. This detector had already been used to gather some of the information used by Rachel Carson in her book, Silent Spring, on the extent of the spread of toxic chemicals. The decrease in the ozone layer was the first global environmental problem against which action has been taken, namely the 1987 Montreal Protocol and its revision in 1990 in London.

[Photo: DRA / Still Pictures]

39 Knowledge of the global functioning of the biosphere is advancing very slowly. Yet programs like the IGBP have made possible advances in the knowledge of the processes that regulate Earth's global system, and the role of human activities in changing these processes. This knowledge has to be entertainingly and objectively transmitted to society as a whole, and to political leaders in particular, because many human social problems cannot be solved unless there are major changes in individual and social behavior. This composite image was obtained from images taken between September 4 and October 5, 1997 (by the Sea Wifs sensor on the U.S. Orbview satellite) and shows the density of chlorophyll in the land and sea over the planet; photos like this may help to change people's attitudes.

[Photo: NASA GSFC / Science Photo Library / AGE Fotostock]

40 The neo-romantic vision of ecology had its counterpart in many twentieth century artistic tendencies. Reinterpreting nature through art is as old as art itself. From cave art to abstract art, the motive of the creative gesture is almost always the reality surrounding the artist. Thus, different conceptions of space and of systems have their chronological artistic record in the work of sculptors and painters. The philosophical interpretation does the same, and it is reflected in texts. The confusing "ecosystem" in the image consists of trees, arthropods and birds, and forms part of this record as reflected in the work entitled The Chicken, by the Mexican artist Frida Kahlo (1907-1954), an artist who especially included natural elements from the New World tropics, where she lived.

[Photo: Fundacion Dolores Olimedo, Mexico City / Archiv fur Kunst und Geschichte, Berlin]

41 Exploitation pressures and environmental conflicts are expressed subjectively in this painting by Frida Kahlo (see previous photo), called The Wounded Deer (1946). The face on the deer is that of the artist herself. Kahlo represents her frustration with the progress of the bone disease that affected her, yet significantly the symbolism she used to represent this is the aggression of humans against the environment--a deer wounded by many arrows in a destroyed forest. Kahlo's paintings frequently reflect a rather dualist view of the world, a reflection of the Aztec conception in which Huitzilopochtli, the god of dawn, fire, day and summer, who was constructive and positive, confronts Tezcatlipoca, the god of twilight, water, night and winter, who is destructive and negative.

[Photo: Private Collection / Archiv fur Kunst und Ges-chichte, Berlin]

42 The integration within ecological systems of human objects shapes a new paradigm, which could be called social and ecological. This new paradigm is the contemporary stage of the development of knowledge about nature, and from the 1980s onward it broke definitively with the dichotomy that considers nature and humanity as two separate, independent and even as opposing entities. The rejection of exaggerated or deleterious artifice also took shape from this time onward. These tensely complementary notions, straddling acceptance and rejection, are expressed in Kahlo's (see preceding 2 photos) Self-Portrait on the Mexico-United States Border (1932). It reflects the opposition between a humanized world, that is, however, in harmony with the biosphere, and a world totally dominated by technology, with no space for anything but human objects.

[Photo: Manuel Royero Collection, New York (NY) / Christie's Images]
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Publication:Encyclopedia of the Biosphere
Geographic Code:1USA
Date:Nov 1, 2000
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