be sure to floss
In the fossil record, Neanderthals don't grade smoothly into Homo sapiens. In fact, anatomically modern humans existed at least 160,000 years ago, and Neanderthals became extinct only 30,000 years ago. It's more likely that they were two distinct species. Meanwhile, paleoanthropologists found species that seemed distinct from Lucy some 3 million years ago. Even at the very earliest stages of hominid evolution, five to six million years ago, at least three highly distinct species seemed to coexist. Hominid evolution was looking less like a straight line and more like a bush, with branches shooting off throughout hominid evolution. Because our branch happens to be the one still left on Earth, we fooled ourselves into thinking that we were the product of linear progress.
Tim White has never bought this line. White, a paleoanthropologist at the University of California at Berkeley, has carried some of the greatest work on human evolution. (Among other things, he found those 160,000 year old Homo sapiens.) White has argued that simply finding some differences between hominids that lived at the same time doesn't always indicate a vast diversity of hominids. He has maintained that with so few fossils of really old hominids, we simply don't have a big enough sample to draw any hard conclusions. We don't know which traits in a given fossil were new features in their evolution and which were hold-overs from primitive ancestors. The hominid family tree could be bushy, or it could be more like a Charlie Brown Christmas tree, with a few scant branches. No one could say.
Carl Zimmer/The Loom/Corante Mar.05.04
