A remarkable finding could answer the question whether our human ancestors and the Neanderthals interbred some time after both species left Africa many thousands of years ago. Only 10 years after scientists triumphantly decoded the human genome, an international research team has mapped the genes of the long-extinct Neanderthal people and report there’s a pinch of Neanderthal in all of us.
The report, published today in the journal Science, capped more than five years of intensive work by a group of 56 international scientists led by German paleogeneticist Svante Pääbo and Richard E. Green of UC Santa Cruz.
The project’s scientists used tiny specks of powdered bone retrieved from three Neanderthal females who died in a Croatian cave more than 40,000 years ago to complete the draft of the Neanderthal genome. They then compared the genes to those of modern humans living today in five different regions of the world: France, Papua New Guinea, China, and southern and northern Africa.
The research concluded that humans living today carry between 1 and 4 percent of Neanderthal genes that carry the code for proteins in our bodies. Those genes must have entered our lineage sometime during a 50,000-year period when the Neanderthals and humans left Africa through the Middle East and spread throughout Europe and Asia. The Neanderthals became extinct about 30,000 years ago.
The complete genomes of the Neanderthals and modern humans, whose lineages separated from some unknown common ancestor at least 400,000 years ago, are 99.5 percent identical. They are, in fact, our closest evolutionary relatives. By comparison, humans and chimpanzees share 98 percent of their genes.
The scientists analyzed 4 billion units of Neanderthal DNA, called nucleotides – at least 60 percent of the Neanderthal’s entire genome. While incomplete, Pääbo told reporters during a teleconference this week that 60 percent “is a very good statistical sample of the entire genome.”
Finding the Neanderthal genes in people living today provides “compelling” evidence that thousands of years ago some interbreeding occurred between the two species, Green said.
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