Consilience: The Unity of Knowledge.

by Edward O. Wilson, New York: Alfred A. Knopf, 332 pages, $26.00

This is a book about everything, in a sense, and it contains something to provoke, disturb, or irritate just about everybody. Edward O. Wilson argues that all fields of knowledge and inquiry - ranging from physics and chemistry to art criticism and moral reasoning, with the social sciences somewhere in between - can and should be knit together into a comprehensive worldview. His case for "consilience," literally a "jumping together" of disciplines, encompasses, among other things, an attack on postmodernism, a brief for environmentalism, a critique of religion, a dismissal of Freudianism, a couple of swipes at the economics profession, and a protracted defense of biological explanations for human consciousness and behavior.

Wilson, a biologist who taught at Harvard for over four decades before his semiretirement in 1997, has carved out an influential career in several intellectual niches: as one of the world's leading authorities on ants and other social insects; as an exponent of the concepts of bio-diversity and "biophilia" (the latter being a deep, inborn human affinity for nature); and as a founder and popularizer of human sociobiology (also known by the roughly synonymous term "evolutionary psychology"), a school of thought that emphasizes genetic and Darwinian influences on culture and society.

Sociobiology, following its advent in the 1970s, sparked sharp criticism from thinkers in various disciplines who were committed to conceptions of human nature as highly flexible, nonexistent, or socially constructed. (Nonthinkers entered the debate as well; in one much-reported incident, leftist protesters at a conference dumped a pitcher of ice water over Wilson's head.)

These varied elements of Wilson's career all are evident in Consilience. While the book's sweeping thesis may seem to have little to do with insects, the tiny critters enter the narrative at several points. (In one of the book's best and most amusing passages, Wilson speculates about what sort of political speeches would be heard in a world where termites had evolved a high level of intelligence.) Wilson's concerns regarding biodiversity and biophilia are manifest in his discussion of the environment.

Most central to the book's argument, however, is sociobiology, which emerges as a crucial strand in the seamless web of knowledge that Wilson seeks to construct. For if human minds and societies are shaped by genes - segments of DNA, which in turn are shaped by the laws of physics and chemistry - then the outlines of a comprehensive worldview begin to appear.

There is much of value in Consilience. Wilson provides a cogent overview of neuroscience, population genetics, and other areas of biology. He presents a largely convincing picture of confusion and stagnation in the social sciences and humanities; it becomes easy to believe that these fields would benefit from some form of linkage to the natural sciences, or at least from a greater awareness among social scientists and humanities experts as to what's actually going on in the natural sciences.

Yet Wilson's overall argument is so far-reaching and ambitious that it begins to buckle under its own weight. Precisely because he asserts that everything is connected, the weakness of any of his claims brings the entire thesis into question. Ultimately, the consilient worldview seems more a dream for the distant future than a program for the present; and one wonders whether the real thing, if and when it emerges, will bear more than a passing resemblance to Wilson's vision.

Sociobiology, the linchpin of that vision, is a bold but rather speculative school of thought. Its view of the human condition lends itself readily to caricature. If people are driven by their genes - and in particular by the imperative to replicate their genetic material - then why, ask skeptics, would so few men be delighted to learn that they had fathered an extra child by a prostitute? Furthermore, given that humanity evolved to thrive in the African savanna, why do most people seem to prefer vacations in the mountains or on the beach? (High plane fares to Africa?)

Wilson, however, does not argue that genes determine exactly how people behave, or that every decision has an immediate Darwinian explanation. Rather, he propounds the more subtle notion of "epigenetic rules," hereditary regularities in brain structure and cognitive development that make certain types of learning and behavior more likely than others. These hereditary regularities tend to have some adaptive value, enhancing the ability of those who possess them to survive and reproduce in a given environment, but their precise manifestation will vary with time and place.

Such innate propensities, in Wilson's view, underlie certain widespread or universal features of human societies. The incest taboo is a prime example; Wilson argues persuasively for the existence and hereditary nature of the "Westermarck effect," a revulsion against sexual contact not only with relatives but with any person one lived with during early childhood. Bolstering his argument are data showing the high failure rate of Taiwan's once-common arranged marriages among unrelated people raised in the same household.

In defending the Westermarck effect, Wilson pokes a significant hole in Freudian psychology's doctrine that the incest taboo was formed to restrain powerful and widespread incestuous desires. Yet when Wilson addresses another question that has Freudian implications - Why do people dream about snakes? - the limitations of both sociobiology and his larger consilience program become clearer. Images of snakes in dreams or drug-induced hallucinations are experienced by numerous people all over the world, Wilson asserts, and such "dream serpents" often are invested with cultural significance, for example in shamanistic rituals. Seeking a consilient explanation for all this, he begins with an analysis of brain chemistry and the pharmacology of plants used by shamans; eventually, he winds up in a discussion of one Pablo Amaringo, a Peruvian artist who often paints pictures of snakes.

The connections between these topics are tenuous in any event, but sociobiology is a particularly weak link in the chain. Wilson argues that humans and their ancestors gained a survival advantage by reacting to snakes with fear and awe; fearsome dream serpents helped instill such reactions, and those cultures that reinforced the message through art and legend further enhanced their members' survival chances. But how certain will we ever be that these are the reasons why people dream about snakes?

As geneticist Steve Jones asks, why don't people dream about that other threat to our ancestors, rotten meat? Indeed, who knows how often people actually do dream about snakes in the first place, given that most dreams are forgotten and that worldwide polling on the subject is a formidable task? (I, for one, recall only a single snake dream in my life, and it occurred after I had owned a snake for months.)

Wilson's biological speculations extend to even the most ethereal of subjects. He likens religion to a mammalian "dominance hierarchy" in which the weaker members pay obeisance to the stronger (in this case the gods and their earthly representatives). He dismisses the poststructuralists' skepticism about knowledge and communication by noting that humans all have fundamentally similar brains with a common evolutionary heritage. Wilson's speculations on such matters are thought-provoking, but it is unlikely, to say the least, that religious believers or poststructuralists will find them compelling. And given the current sketchy state of biological knowledge about human brains and consciousness, there is little reason why they should.

Yet even if biological explanations can be taken too far, or applied prematurely, the social sciences often have erred in the opposite direction, by ignoring biology altogether. Wilson adeptly contrasts the meandering pace of the social sciences with the rapid progress occurring in the biomedical sciences; the latter, he notes, are more focused on seeking answers across multiple specialties and levels of explanation - in short, on consilience. Wilson rightly decries the dogmatic cultural relativism that has dominated anthropology during much of this century. He traces how a justified skepticism toward Social Darwinism evolved into a sweeping denial that human nature has anything to do with heredity. Sociology, as Wilson notes, is hindered by its own dogma that people are products of society. He likens the field, with its broad-brush approach, to what biology would be if biologists did not know or care that organisms are composed of cells.

By contrast, Wilson approves of economists' efforts to draw links between the "macro" and "micro" levels of economic activity, and between economic behavior and broader social phenomena. Nonetheless, Wilson's view of economics is mainly negative. Economic theories tend to be overly simplified and abstract, he argues, and they depend on a model of human behavior drawn largely from folk wisdom. These criticisms are questionable, however. Much economic theory, including the basic premise that humans are "rational utility maximizers," is counter-intuitive and therefore quite the opposite of folk wisdom. (Where, in all the world's folklore, does one find the principle of comparative advantage?)

Moreover, whether sociobiology's model of human behavior offers superior insights remains to be seen. Tellingly, one of Wilson's strongest points against conventional economics - that people often rely on "heuristics," or rules of thumb, rather than rational calculation - is derived from cognitive psychology, not sociobiology. Even so, he surely is correct to assert that integration between economics and biology is an avenue of research worth investigating.

The book's final chapter, titled "To What End?," is focused on environmental and social problems. Here, Wilson makes a number of assertions that seem to come from nowhere, or to jibe poorly with his main argument - not a good thing in a book about consilience. He argues that future generations should be "genetically conservative," or cautious in their use of genetic engineering; in an aside, he writes that such conservatism should not be confused with "the pietistic and selfish libertarianism into which much of the American conservative movement has lately descended." The book's final paragraph contains a sudden, ambiguous warning about "machine-aided ratiocination"; apparently, future generations should be cautious in using computers, too.

Wilson presents a grim picture of the global environment, emphasizing human population growth, the limits of arable land and potable water, and mass extinctions of plants and animals. Yet having argued that economics should be informed by biology, he now inadvertently demonstrates what biology and ecology look like when colored by a cursory and one-sided understanding of economics. Wilson complains about deforestation, for instance, while taking no notice of the government subsidies that often promote it. He worries that economic growth will increase humanity's environmental impact, and he calls, ominously, for governments to adopt unspecified "population policies"; he fails to note that in many nations rising prosperity has correlated with declining population growth. He avers that technological solutions to environmental problems are "prostheses" that make humanity more dependent and the environment more delicately balanced. And he wonders whether posterity will be angry at our era for presiding over the extinction of so many insect species. Bear in mind, though, that he is an entomologist.

Consilience, in the end, leaves us far from a convincing unification of knowledge. But it gives us a fascinating view of the world as seen by Edward O. Wilson, a bold, innovative, and idiosyncratic scientist.

Kenneth Silber ([e-mail]) writes about science, technology, and economics.