Today, most of us carry modest amounts of the Neaderthal genome. This is because modern humans interbred with Neaderthals between 50,000 and 28,000 years (after which the Neaderthal subline became extinct). In genetic terms, this is an example of admixture. Now we’re finding out that this modest amount of Neadertal genome has a substantial role in our health (and disease risk) today.
On average, Europeans and Asians have inherited ~1.5% of their genomes from Neanderthals. On the other hand, Oceanians (Island Melanesians) carry an additional 2% to 3% of DNA inherited from another extinct group, the Denisovans. Most Africans lack this archaic DNA because the interbreeding happened after migration from Africa. The attached article and editorial describe a method for scanning electronic health records of 28,000 Americans to show that some Neanderthal gene variants today can raise one’s risk of depression, addiction to alcohol, precancerous skin lesions, blood clots, and urinary tract disorders.
There is also an upside: as I shared with you a few weeks back, two studies published in the Jan Am J Hum Genet identified three archaic genes that boost the innate immune response, which helps us defend against fungi and parasites––as well as bacteria. All three genes have been strongly selected for in Europeans and Asians. These three genes work together in subtle ways to regulate the expression of TOLL-Like receptors on the surface of white blood cells, presumably boosting the innate response.
Science 12 Feb 2o16; 351: 737–741 and 648–649