More than a million years ago, ancestral hominids were present across most of Europe and Asia. Perhaps they had spread from Africa but that is not certain. They gave rise to Neanderthals, Denisovans, at least one unknown hominin species and also to homo sapiens. New research reported in Nature now shows that interbreeding took place – and probably were not just isolated events – between the various hominin species.
The genome of the offspring of a Neanderthal mother and a Denisovan father
Neanderthals and Denisovans are extinct groups of hominins that separated from each other more than 390,000 years ago1,2. Here we present the genome of ‘Denisova 11’, a bone fragment from Denisova Cave (Russia)3 and show that it comes from an individual who had a Neanderthal mother and a Denisovan father. The father, whose genome bears traces of Neanderthal ancestry, came from a population related to a later Denisovan found in the cave4,5,6. The mother came from a population more closely related to Neanderthals who lived later in Europe2,7 than to an earlier Neanderthal found in Denisova Cave8, suggesting that migrations of Neanderthals between eastern and western Eurasia occurred sometime after 120,000 years ago. The finding of a first-generation Neanderthal–Denisovan offspring among the small number of archaic specimens sequenced to date suggests that mixing between Late Pleistocene hominin groups was common when they met.
A female who died around 90,000 years ago was half Neanderthal and half Denisovan, according to genome analysis of a bone discovered in a Siberian cave. This is the first time scientists have identified an ancient individual whose parents belonged to distinct human groups. The findings were published on 22 August in Nature.
Given the patterns of genetic variation in ancient and modern humans, scientists already knew that Denisovans and Neanderthals must have bred with each other — and with Homo sapiens. ……… Before the discovery of the Neanderthal–Denisovan individual, whom the team has affectionately named Denny, the best evidence for so close an association was found in the DNA of a Homo sapiens specimen who had a Neanderthal ancestor within the previous 4–6 generations.
A single Out-of-Africa source for all homo sapiens is looking less and less likely. There were probably multiple waves out of Africa and many of the subsequent expansions probably came out of AfricArabia. It is very likely that as these “modern humans” spread, they met and interbred with their distant Neanderthal, Denisovan and other cousins. Possibly the Denisovans were mainly in what is now Central and east Asia and even eastern Siberia. Possibly the Neanderthals were spread from Central Asia to points west across Europe.
The human genetic story now goes back to times from which there is little or no archaeological record. It seems that some Neanderthals may well have had speech even if not any well developed language. The control of fire goes back some 400,000+ years ago. Stone tools were around from around 1.8 million years ago. Perhaps the beginnings of modern humans does not have to start so far back, but it does look like the story of homo sapiens now needs to be pushed backwards into time to at least the common hominin ancestor from around a million years ago.