Tattersall is curator emeritus of the Spitzer Hall of Human Origins at the American Museum of Natural History and an authoritative voice on the subject of human origins. His book offers anyone a chance to catch up on the current state of the art. One thing we learn is that the comparison with apes is misleading. None of our ancestors were much like apes. Hominid forebears have been evolving rapidly and dramatically away from apes for more than two million years. Hunting is another red herring. We did not evolve to be hunters, or under conditions where success at hunting was crucial to survival. Technology, moreover, does not drive our evolution. New stone technologies never emerge with new species. In each case, old kinds of hominids begin to do new things with stone and other material. What most differentiates early hominids from chimpanzees, and disqualifies emphasis on hunting, is that coming down from the trees to walk on two legs made hominids opportunistic generalists. As Tattersall tells it, the acquisition of modern human qualities was not a gradual, progressive accumulation of adaptations. Nor is the emergence of our species a predictable development from earlier trends or a threshold effect of gradually rising brain size. The emergence of Homo sapiens was an abrupt and recent event, primarily in response to deteriorating (increasingly dry and cold) climate. We did not adapt genetically to the changed conditions but accommodated to them through culture, creating a way of life that had a new level of freedom from the environment, which then could change without leaving us unable to cope. That accommodation may be why many today remain indifferent to the threat of climate change. We are accustomed not to worry about such things. We have always pulled through. Such optimism is bred in the bone. But it was only right in the past, and this comfortable habit may be our doom.
Barry Allen’s books include Truth in Philosophy; Knowledge and Civilization; and Artifice and Design: Art and Technology in Human Experience. He teaches philosophy at McMaster University and is associate editor of Common Knowledge for philosophy and politics. His monograph-length article “The Cloud of Knowing: Blurring the Difference with China” appeared in the Fall 2011 issue.