How Breeding with an Ancient Human Species gave Tibetans their Head for Heights

A recent study of the DNA of Tibetans has looked at the gene underlying their ability to live in the low-oxygen conditions at high altitudes. It found that this gene has come from an unexpected source – the mysterious group of ancient humans called the Denisovans. This work, a collaboration between Chinese, Danish and American scientists, has been published in the journal Nature.

In the 1990s, a consensus existed about the origin of our human species, Homo sapiens. Our species is young, evolving in Africa around 200,000 years ago, and spreading throughout the world, reaching Europe perhaps only 60,000 years ago.

But we are not the first species of the genus Homo to live in Europe. Fossils from 300,000 to 30,000 years ago reveal the Neanderthal people, Homo neanderthalensis. Many viewed the process where modern Europeans and Asians left Africa and supplanted the Neanderthals as a complete replacement, with no interbreeding. This is what the fossils seemed to say, and seemed confirmed when the sequence of one small part of the Neanderthals’ DNA – that found in the cell’s mitochondria, revealed the Neanderthals to be quite distinct from all modern humans.

More than just us

But, in 2010, studies refuted this simple picture. The Neanderthal genome project found that Modern Europeans and Asians, but not Africans, had somewhere between 1% and 4% of their DNA that came from the Neanderthals. There had been interbreeding between the groups after all.