Neanderthal genome picture
May 5, 2010 - Researchers have sequenced the genetic blueprint of Neanderthals from bones found in Croatia and compared the genome with those of five present-day humans. The results reveal that 1-4% of human genes were derived from Neanderthals and the two species most likely interbred.
An international research team has sequenced the Neanderthal genome, using pill-sized samples of bone powder from three Neanderthal bones found in a cave in Croatia.
The researchers, led by Svante Pääbo of the Max-Planck Institute for Evolutionary Anthropology in Leipzig, Germany, compared the Neanderthal genome with the genomes of five present-day humans from different parts of the world. The results reveal a variety of genes that are unique to humans, including a handful that spread rapidly among our species after humans and Neanderthals split from a common ancestor.
These findings, published in the May 7 issue of the journal Science, thus offer a shortlist of genomic regions and genes that may be key to our human identity. The scientists also found that modern humans and Neanderthals most likely interbred to a small extent.
“Having a first version of the Neanderthal genome fulfills a long-standing dream. For the first time we can now identify genetic features that sets us apart from all other organisms, including our closest evolutionary relatives,” said Pääbo.
Neanderthals first appeared around 400,000 years ago, ranged across Europe and western Asia, and became extinct approximately 30,000 years ago.
The draft Neanderthal genome sequence being reported in Science represents about 60 percent of the entire genome. The genetic material that was sequenced came from single bones from three individual Neanderthals.
Most of what we know about genetic variation among humans today is based on European populations. Seeking a broader picture, Pääbo and his colleagues sequenced the genomes of five present-day humans from southern Africa, West Africa, Papua New Guinea, China and France, and compared the Neanderthal genome to the genomes of these individuals.
The Neanderthal genome sequence proved to be slightly more similar to those of the non-African individuals than to the African ones. Approximately 1 to 4 percent of the modern human genome seems to be from Neanderthals, the authors estimate.
Though other explanations are possible, one of the simplest scenarios is that early modern humans interbred with Neanderthals in the Middle East, after leaving Africa and before spreading into Eurasia.
The researchers also used the Neanderthal genome to produce the first version of a catalogue of genetic features that exist in all humans today but are not found in Neanderthals or apes. This catalogue will be valuable for scientists who study what sets humans apart from other organisms.
“It’s cool to think that some of us have a little Neanderthal DNA in us, but, for me, the opportunity to search for evidence of positive selection that happened shortly after the two species separated is probably the most fascinating aspect of this project,” Pääbo said.