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 some 9 million years ago, 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.
The study was published online in 2006 by the journal Nature.
Researchers at the Broad Institute are currently working on sequencing gorilla and other primate genomes and searching for similar patterns of evolution to help better tell the whole story of how modern humans came about.