The Time Before History: Five Million Years of Human Impact.

The notion that the Egyptians and Greeks were ancient, writes Colin Tudge in this inviting new book, "was applied by 18th century historians who thought that the world itself was new and that the people they called ancient had lived near its beginning." Current research places, instead, the age of the Earth at around four billion years, the phase of mammal life at around 600 million years and counting, the period of human forebears at somewhere around three to five million years, and the period of "civilization"--agriculture and towns--at perhaps 10,000 years. Understanding the true human influence on the Earth won't be possible, Tudge believes, until we begin to grasp the extended time-scale of existence.

The Time Before History attempts to do just that, with mixed results. Tudge, an able British science writer, sets an impossible goal when he declares, "I want to tell the true history of human beings from the beginning." No one has more than an educated guess about the true history of humankind, and it's not clear if anyone ever will, as all information predating the Egyptian and Sumerian writing systems is inferential. The regularity with which "knowledge" about human antecedents is over-turned--seemingly on an annual basis, some widely accepted premise about the far human past gets voided by a new scientific finding--forecloses much beyond speculation. Still, Tudge has written a valuable work that offers a long-term perspective generally missing from debates about the environment or the course of society.

The Time Before History has its predictable elements, including too much on Charles Darwin. British writers just can't seem to get enough of Darwin, perhaps because of his role in shaking the foundations of the English establishment. But the book offers a number of original ideas and engaging segments on, for instance, why farming societies inevitably triumph over hunter groups (the ranchers didn't just beat the cowboys in the West, says Tudge--it's been happening throughout history); or how the vast floods that probably accompanied the close of the last ice age may have influenced the beginnings of organized culture, to say nothing of the book of Genesis. And it's great fun to read Tudge squirming around the question of whether present-day human beings are "superior" to their forebears.