Our ancestors mated with another species of ancient hominins, the Denisovans, on at least two occasions. The discovery suggests that Denisovans were widely across Asia, and apparently co-existed happily with modern humans, to the point of having children with them in two different parts of the ancient world.This is another nail in the coffin of the Out Of Africa theory, which held that a wave of African migrants completely displaced all other hominins about 50k years ago.
The Denisovans were unknown until 2010, when researchers described a fragment of a girl’s finger bone found in Denisova cave in Siberia. Soon afterwards, researchers sequenced its genome from the surviving DNA. The DNA did not belong to any known hominins, such as Neanderthals, so it had to be something new.
What’s more, around 5 per cent of the DNA of some Australasians – particularly people from Papua New Guinea – is Denisovan. Humans evidently mated with Denisovans 50,000 or more years ago. ...
The upshot is that Denisovans bred with modern humans in at least two places: in east Asia, and further south-east in Indonesia or Australasia. “Our research demonstrates that there were at least two distinct populations of Denisovans living in Asia, probably somewhat geographically distant,” says Browning.
Even more interbreeding
“The fact that two episodes of interbreeding occurred suggests that at least in some instances, Denisovans and modern humans were willing to live in proximity and interact,” says Browning.
As well as mating with Denisovans, there is strong evidence that humans interbred with Neanderthals, which were a sister species to the Denisovans.
“This new work is important because for the first time it unambiguously demonstrates a third interbreeding [of modern with ancient hominins],” says David Reich of Harvard Medical School in Boston. “Up to this point, we only had data for two.” There have been claims of a second, earlier instance of interbreeding with Neanderthals, but not everyone is convinced.
Tantalisingly, breeding with Neanderthals and Denisovans may not be the end of our ancestors’ promiscuity. A quarter of the chunks of ancient DNA that Browning found in living humans didn’t match either Neanderthal or Denisovan DNA. So we may have also had children with other, unidentified hominins.
Our school textbooks all say that the human race evolved in Africa. It is not really true, as European and Asian humans evolved mostly outside of Africa.