Modern Humans and Neanderthals Share Common Ancestry

In the last two years, a number of studies have suggested that modern humans and Neanderthals had at some point interbred. Genetic evidence shows that on average Eurasians and Neanderthals share 1 to 4 percent of their DNA.

In contrast, Africans have almost none of the Neanderthal genome. The previous studies concluded that these differences could be explained by hybridization which occurred as modern humans exited Africa and bred with the Neanderthals, already inhabitants of Europe.

A new study that is being published in the Proceedings of the National Academy of Science raises question about the concept of hybridization. 

The findings of a study by researchers at the University of Cambridge suggest that common ancestry, not hybridization, better explains the average 1-4 per cent DNA that those of European and Asian descent (Eurasians) share with Neanderthals.

According to the lead author Dr Andrea Manica, from the University of Cambridge, "Our work shows clearly that the patterns currently seen in the Neanderthal genome are not exceptional, and are in line with our expectations of what we would see without hybridization. So, if any hybridization happened -- it's difficult to conclusively prove it never happened -- then it would have been minimal and much less than what people are claiming now."

On the basis of the study done, the scientists feel that modern humans expanded out of Africa 60-70K years ago, would have brought out that additional genetic similarity with them, making Europeans and Asians more similar to Neanderthals than Africans.

Manica concluded saying, "Thus, based on common ancestry and geographic differences among populations within each continent, we would predict out of Africa populations to be more similar to Neanderthals than their African counterparts -- exactly the patterns that were observed when the Neanderthal genome was sequenced; but this pattern was attributed to hybridization. Hopefully, everyone will become more cautious before invoking hybridization, and start taking into account that ancient populations differed from each other probably as much as modern populations do."