Last week at the Royal Society in London, research was presented suggesting that Neandertals not only interbred with H. sapiens sapiens, but that their genes were helpful to modern people moving out of Africa.
This pioneering study was led by Peter Parham of Stanford University, and was only possible after the draft genome of H. neanderthalensis was published. The researchers looked at human leukocyte antigens (HLAs), genes important to the functioning of the immune system.
Different regions of the world are known to have unique HLAs, because different variations create specific disease resistances. It would have been advantageous for the earliest modern humans to breed with a species (or subspecies) already adapted to living in a different climate. Moderns could have picked up helpful genes that were already in existence from Neandertal populations, which would have possibly allowed their populations to expand more rapidly. Why wait for random mutation when you can interbreed with a people already successfully adapted to an area?
While only approximately 6% of the modern European genome was contributed from earlier hominins, around half of specific HLAs can be attributed to these earlier forms of people. As a form of further substantiation, Europeans have HLA variations present within the Neandertal genome not found in Africans. Interestingly, Asian populations today also have a variation not present anywhere else, which could indicate Denisovan (mystery Siberian hominin) admixture.
As if the draft sequence showing interbreeding was not enough last year– this study has raised the bar on the type of information we can hope to glean from looking at ancient DNA. There was a time when archaeology and anatomy were the only windows we had into our ancestral relatives. It will be exciting to see what is uncovered next.
By Matthew Magnani