Did chimp and human ancestors interbreed? - LiveScience - MSNBC.com

"The earliest known ancestors of modern humans might have reproduced with early chimpanzees to create a hybrid species, a new genetic analysis suggests.



Based on the study of human and chimp genomes, the scientists believe the split between the human and chimpanzee lines occurred much more recently than previously thought — no more than 6.3 million years ago and perhaps as recently as 5.4 million years ago.

Human and chimpanzee ancestors began branching apart on the primate evolutionary tree about 9 million years ago, scientists say, but there are significant gaps in the fossil record. The new analysis suggests that a full split, which scientists call speciation, wasn't achieved for nearly 4 million years and might have occurred twice."