Breeding with Neanderthals helped humans go global
Breeding with Neanderthals helped humans go globalhttp://www.newscientist.com/article/mg21028174.000-breeding-with-neanderthals-helped-humans-go-global.htmlRecent investigations show that interbreeding with other hominins was critical to the globalization of Homo sapiens. Human leukocyte antigens (HLAs), a family of about 200 genes that essential to our immune system also contains some of the most variable human genes: hundreds of versions - or alleles - exist of each gene in the population, allowing our bodies to react to a huge number of disease-causing agents and adapt to new ones. One allele, HLA-C*0702, is common in modern Europeans and Asians but never seen in Africans; Peter Parham has found it in the Neanderthal genome, suggesting it made its way into H. sapiens of non-African descent through interbreeding. HLA-A*11 had a similar story: it is mostly found in Asians and never in Africans, and Parham found it in the Denisovan genome, again suggesting its source was interbreeding outside of Africa. This tallies with interbreeding giving H. sapiens pivotal resistance to non-African diseases. While only 6 per cent of the non-African modern human genome comes from other hominins, the share of HLAs acquired during interbreeding is much higher. Half of European HLA-A alleles come from other hominins, says Parham, and that figure rises to 72 per cent for people in China, and over 90 per cent for those in Papua New Guinea (Marshall M. 2011 Breeding with Neanderthals helped humans go global New Scientist 16 Jun).