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Chimps and humans split 4 million years ago
mongabay.com
February 23, 2007

Chimp in Uganda, photo by R. Butler

New research using DNA analysis suggests that chimpanzees and humans split from a common ancestor just 4 million years ago -- much earlier than the 5-7 million years currently accepted by biologists. The study is published in Public Library of Science journal PLoS Genetics.

The researchers -- Asger Hobolth (North Carolina State University), Ole F. Christensen (University of Aarhus), Thomas Mailund (University of Aarhus / University of Oxford), Mikkel H. Schierup (University of Aarhus) -- compared the DNA of humans with three other species of great apes -- chimpanzees, humans, gorillas, and orangutans -- to develop a "molecular clock" estimate of when humans diverged.

"Primate evolution is a central topic in biology and much information can be obtained from DNA sequence data," the authors wrote. "Assuming orangutan divergence [18 million years] ago, speciation time of human and chimpanzee is consistently around 4 [million years ago]."

Sharing about 96 percent of their DNA, chimps are humans' closest living relatives. Gorillas and orangutans are less closely related.

The study comes the same day that a paper in the journal Current Biology reported the use of tools by chimpanzees in West Africa for hunting smaller primates.

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