Did early humans go ape for chimps?. 18/05/2006. ABC News Online:
"Did early humans go ape for chimps?
Humans' ancestors interbred with chimpanzees after the two species drew apart millions of years ago, a paper suggests.
The provocative idea is sketched by US genome experts, who have discovered that hominids and chimps diverged far more recently - and over a much longer time scale - than anyone had thought.
During this time, the authors theorise, the two primates were rather more than kissing cousins: they had sex, swapping genes before making a final separation.
'The ... analysis revealed big surprises, with major implications for human evolution,' co-author Professor Eric Lander, the director of the Broad Institute of Harvard and the Massachusetts Institute of Technology (MIT), said.
Until now, the belief was that humans and chimpanzees shared a common ancestor but went their separate ways around 6.5 - 7.4 million years ago.
The basis for this is a carbon-dated fossil called Toumai, whose supporters say is the oldest known human.
Its critics, though, dismiss Toumai as an ape."