In “Breeding with Neanderthals helped humans go global,” ( New Scientist, 16 June 2011), Michael Marshall tells us,
When the first modern humans left Africa they were ill-equipped to cope with unfamiliar diseases. But by interbreeding with the local hominins, it seems they picked up genes that protected them and helped them eventually spread across the planet.
The publication of the Neanderthal genome last year offered proof that Homo sapiens bred with Neanderthals after leaving Africa. There is also evidence that suggests they enjoyed intimate relations with other hominins including the Denisovans, a species identified last year from a Siberian fossil.
The authors say that half of European HLA-A alleles come from other hominins, as do 72 per cent for people in China, and over 90 per cent for those in Papua New Guinea, suggesting that
they were increasingly selected for as H. sapiens moved east. That could be because humans migrating north would have faced fewer diseases than those heading towards the tropics of south-east Asia, says Chris Stringer of the Natural History Museum in London.
Interesting, but makes one wonder why the Neanderthals are still classified as separate species. News value?