There’s an amazing story in the NYT this morning about new evidence in molecular biology supporting the idea that there was a hybrid species that rose after the split between chimp and human lineages. The idea is that females of this hybrid species (which eventually led to humans) mated with males from the chimp world since all the hybrid-style males were sterile.
Hybrid populations often go extinct because the males are sterile, Dr. Reich pointed out, so hybrid females may have mated with male chimps to produce viable offspring. The human lineage finally re-emerged from this hybrid population, Dr. Reich suggests, explaining the younger genetic dates, while the very early fossils with humanlike features may come from the earlier period before the hybridization.
David Page, a human geneticist at the Whitehead Institute in Cambridge, said the design of the new analysis was "really beautiful, with all the pieces of the puzzle laid out." Whether the hybridization will turn out to be the right solution to the puzzle remains to be seen, "but for the moment I can’t think of a better explanation," he said.
These crucial events in early human evolution are hard to judge dispassionately, Dr. Page noted. "We’d like to have a more Victorian view of our genome," he said, "and this reminds us that we are really animals and gives us a glimpse of our past and of a story that we might like to have told in a different way."
Just wait til the neurological psychiatrists get a hold of this. It seems useful in explaining all sorts of irrational male fear.