2001 : WHAT QUESTIONS HAVE DISAPPEARED?

Darwinism is alive and well in academic discussions and in pop thinking. Natural selection is a key element in explaining just about everything we encounter today, from the origin and spread of AIDS to the realization that our parents didn't "make us do it," our ancestors did. Ironically, though, Darwinism has disappeared from the area where it was first and most firmly seated the evolution of life, and especially the evolution of humanity. Human evolution was once pictured as a series of responses to changing environments coordinated by differences in reproduction and survivorship, as opportunistic changes taking advantage of the new possibilities opened up by the cultural inheritance of social information, as the triumph of technology over brute force, as the organization of intelligence by language. Evolutionary psychologists and other behavioralists still view it this way, but this is no longer presented as the mainstream view of human paleontologists and geneticists who address paleodemographic problems.

Human evolution is now commonly depicted as the consequence of species replacements, where there are a series of species emanating from different, but usually African homelands, each sooner or later replacing the earlier ones. It is not the selection process that provides the source of human superiority in each successive replacement, but the random accidents that take place when new species are formed from small populations of old ones. The process is seen as being driven by random extinctions, opening up unexpected opportunities for those fortunate new species lucky to be at the right time and place.

The origin and evolution of human species are now also addressed by geneticists studying the variation and distribution of human genes today (and in a few cases ancient genes from Neandertals). They use this information to estimate the history of human population size and the related questions of when the human population might have been small, where it might have originated, and when it might have been expanding. It is possible to do this if one can assume that mutation and genetic drift are the only driving forces of genetic change, because the effect of drift depends on population size. But this assumption means that Darwinian selection did not play any significant role in genetic evolution. Similarly, interpreting the distribution of ancient DNA as reflecting population history (rather than the history of the genes studied the histories are not necessarily the same) also assumes that selection on the DNA studied did not play a role in its evolution. In fact, the absence of Darwinian selection is the underlying assumption for these types of genetic studies.

Human paleontology has taken a giant step away from Darwin will it have the courage to follow the lead of evolutionary behavior and step back?

MILFORD H. WOLPOFF is Professor of Anthropology and Adjunct Associate Research Scientist, Museum of Anthropology at the University of Michigan. His work and theories on a "multiregional" model of human development challenge the popular "Eve" theory. His work has been covered in The New York Times,New Scientist, Discover, and Newsweek, among other publications. He is the author (with Rachel Caspari) of Race and Human Evolution: A Fatal Attraction