Both the Neanderthals – who emerged around 400,000 years ago and lived in Europe and western Asia until 35,000 years ago – and the enigmatic Denisovans contributed DNA to present-day people.
The Denisovans are known only from DNA extracted from the finger bone of a girl unearthed at a cave in central Siberia. This 40,000-50,000-year-old bone fragment, as well as a rather large tooth from another individual, are all that is known of this species.
The tiny “pinky” bone yielded an entire genome sequence, allowing scientists to compare it to the DNA of modern people in order to better understand the legacy of ancient interbreeding.
Denisova Cave, where the Denisovan girl’s fingerbone was found.
Now, researchers have linked an unusual variant of the EPAS1 gene, which is involved in regulating the body’s production of haemoglobin – the molecule that carries oxygen in the blood – to the Denisovans.
When the body is exposed to the low oxygen levels encountered at high elevations, EPAS1 tells other genes in the body to become active, stimulating a response that includes the production of extra red blood cells.
“After the Denisovan DNA came into modern humans, it lingered in different Asian populations at low frequencies for a long time”, Prof Nielsen said.
“Then, when the ancestors of Tibetans moved to high altitudes, it favoured this genetic variant which then spread to the point where most Tibetans carry it today”.
The full family tree is even more complicated, as Denisovans interbred with Neanderthals directly, as well as a yet-unknown and very ancient hominid.
Very cool stuff. I keep hoping 23andme adds a Denisovan DNA analysis to accompany the Neanderthal analysis it already provides.
Via BBC News.