Richard Gray, Daily Mail, February 13, 2015

They are largely thought to have roamed the freezing landscapes of Europe during the last ice age, but it seems Neanderthals may have spread far further east and lived alongside modern humans there for longer than was previously thought.

Two new pieces of research have suggested that the ancestors of modern East Asians may have interbred with the now extinct Neanderthals far more than they did in Europe.

Analysis of the traces of Neanderthal DNA found in the genomes of modern humans has shown that people in East Asia carry between 15 to 30 per cent more of their DNA than Europeans.

Scientists now say there appears to be two distinct occasions when Neanderthal mixed with modern humans in East Asia compared to just one occasion in Europe.

This suggests that Neanderthals were able to spread further towards East Asia than was previously thought.

Almost all of the remains of Neanderthals have been found in southern Europe and western Asia.

They were not thought to have gone much further east than the Altai Mountains in central Asia, on the borders of what are now Russia, Mongolia and Kazakhstan.

But the new findings have raised the prospect that Neanderthals lived in the east of the continent and may have clung on there for longer than their European relatives, who died out around 30,000 years ago–we have just yet to find the archaeological evidence.

Professor Joshua Akey, a geneticist at the University of Washington who led one of two new studies, said: ‘The history of admixture between modern humans and Neanderthals is most likely more complex than previously thought.’

The research was conducted by two separate teams working at the University of Washington and the University of California, Los Angeles.

Professor Akey and his colleague Benjamin Vernot analysed distinctive patterns in the DNA of 379 modern Europeans and 286 modern East Asians from China and Japan.

Using computer models they attempted to simulate how the mixtures of Neanderthal DNA seen in the European and East Asian genomes could have occurred

They concluded that one theory–that modern Europeans interbred more with populations from Africa to water down the Neanderthal DNA they carried–was unlikely.

Instead they found it was more likely that ancestors of the East Asian populations had bred with Neanderthals more than once.

Mr Vernot said: ‘One thing that complicates these analyses is the fact that humans have been constantly migrating throughout their history–this makes it hard to say exactly where interactions with Neanderthals occurred.

‘It’s possible, for example, that all of the interbreeding with Neanderthals occurred in the Middle East, before the ancestors of modern non-Africans spread out across Eurasia.

‘In the model from the paper, the ancestors of all non-Africans interbred with Neanderthals, and then split up into multiple groups that would later become Europeans, East Asians.

‘Shortly after they split up, the ancestors of East Asians interbred with Neanderthals just a little bit more.

‘The important thing is that we show that we didn’t just meet Neanderthals once in our history–it looks like we met them multiple times.

‘But as we are able to look at individuals from more and more populations, we’ll hopefully get a better idea of where our ancestors have been, and where they may have interacted with Neanderthals.’

Previous research has led to theories that modern humans first interbred with Neanderthals as they migrated through the Middle East 55,000 years ago before they then moved further into Europe and Asia.

The evidence that a second mixing between the two species took place among East Asian populations implies that this occurred sometime later and further East than the first interbreeding event.

Previous research has led to theories that modern humans first interbred with Neantherthals as they migrated through the Middle East 55,000 years ago before they then moved further into Europe and Asia.

The evidence that a second mixing between the two species took place among East Asian populations implies that this occurred sometime later and further East than the first interbreeding event.

Professor Akey says it is also possible that European ancestors bred with another as yet undiscovered species of ancient human that led to the Neanderthal DNA being watered down.

However the second study conducted by Dr Kirk Lohmueller, an evolutionary geneticist at the UCLA, used similar computer models and found that the most likely explanation was that Neanderthals interbred with humans multiple times in Asia.

Dr Lohmueller said: ‘It’s very hard to put these findings into spatial context.

‘The key idea is that there would have to have been some additional interbreeding events involving East Asians, but not Europeans.

‘These interbreeding events could have been directly between Neanderthals and East Asians, maybe in some other indirect way.’

Dr Simon Underdown, an athropologist at Oxford Brookes University, said the findings should profoundly change our view of what Neanderthals were like.

He said: ‘It strongly suggests that rather than a one off interbreeding event between humans and Neanderthals around 60,000 years ago there must have been multiple occurrences of humans and Neanderthals having sex and producing offspring.

‘This in turn suggests that the boundaries between humans and Neanderthals as different species are increasingly becoming blurred almost to the point of being non-existent.

‘This of course has huge significant for those who wrongly claim the neanderthals were less intelligent, didn’t have symbolism and couldn’t speak.

‘We can no longer think of Homo sapiens as the ‘top dog’ who replaced the more primitive hominin species it encountered on the long trip out of Africa.

‘Rather we should think of our direct ancestors as one member of a diverse genus that interbred with other members of Homo multiple times and in multiple locations.’

Professor Chris Stringer, one of the world’s leading anthropologists at the Natural History Museum in London, added that our view of Neanderthals had perhaps wrongly become too ‘Eurocentric’.

He said: ‘The common view is that Neanderthals were ‘European’, because that is where the original and the most famous remains of this species have been discovered.

‘But we have known since the 1930s that they were in Asia too, and we now have their fossils from sites in countries like Israel, Syria, Iraq and Uzbekistan.

‘More fragmentary remains have recently been studied in Siberia, and the highest quality Neanderthal genome is from Denisova Cave in the Altai.

‘While there have been claims that Neanderthals lingered longest in places like Gibraltar, we only have a poor fix on the dating of their disappearance further East.

‘So it is certainly quite possible that there was further interbreeding with late Neanderthals as modern humans traversed Asia, although we still lack decent fossil evidence from many regions, particularly in southern Asia.’