The big science news yesterday and this morning is the announcement by researchers that modern humans have Neanderthal genes – maybe up to 4% of our genes from them.
The theory had been that the split between our ancestors and Neanderthals occurred about 400,000 years ago, with the Neanderthals going extinct about 30,000 years ago, and with anthropologists believing it was very unlikely that there was interbreeding.
The Wall Steet Journal had the best coverage of this today, but there's no sense linking to that article since only paid subscribers can access it.
Here's the Washington Post –
Ancient DNA shows interbreeding between Homo sapiens and Neanderthal
The new data answer a few of the many questions about modern human beings' relationship with their last big hominin competitors, who died out about 30,000 years ago. The data also hint at what Homo sapiens had — but Homo neanderthalensis didn't — that may have made the difference between survival and extinction.
"What this means is that Neanderthals are not totally extinct. In some of us, they live on," said Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Germany, who led the genome reconstruction described in Friday's issue of the journal Science.
The findings show that modern humans and Neanderthals interbred, probably in the Middle East, between about 100,000 and 80,000 years ago, soon after modern humans migrated out of Africa and before they diversified, through chance and natural selection, into the ethnic groups that exist today. That's why northern Europeans, the Chinese and Papua New Guineans carry traces of Neanderthal ancestry, but Africans do not.
And additiional interesting stuff – some of it a bit speculative –
On a genetic level, Neanderthals and modern humans are almost as closely related as today's ethnic groups are to each other.
But the differences may be important.
The researchers identified 73 genes for which all modern people have the same molecular version but for which Neanderthals have the more ancient, chimpanzee version. Five of the genes have two molecular differences between the human and Neanderthal-and-chimpanzee versions, suggesting there might be something especially distinct about the human version.
One of those genes encodes a protein that helps the sperm cell's flagellum beat. Another is for a protein that seems to be involved in the healing of wounds. A third is for a protein abundant in skin, sweat glands and hair roots. Successful reproduction, survival after injury and the ability to interact optimally with the environment: All are crucial to survival and obvious "targets" for natural selection.
If all of the data is correct, and independent geneticists not involved in the project are quoted as being confident the "data is bona fide" (WSJ), then the old idea that Neanderthal and modern Homo Sapiens are different species will have to be re-examined. One of the definitions of a species is the ability to mate successfully, and produce offspring themselves capable of reproduction. Obviously, that'sthe case here.
Yup. I always knew I was a caveman.
Here's a link to the NY Times coverage of this – Signs of Neanderthals Mating With Humans
Leave a Reply