Interbreeding between archaic and modern humans been shown that Neanderthal ancestry has been selected against in conserved biological pathways, such as RNA processing. Consistent with the hypothesis that purifying selection has reduced Neanderthal contribution in present-day modern human genomes, Upper Paleolithic Eurasian modern humans (such as the Tianyuan modern human) carry more Neanderthal DNA (about 4–5%) than present-day Eurasians modern humans (about 1–2%). Genes affecting keratin were found to have been introgressed from Neanderthals into modern humans (shown in East Asians and Europeans), suggesting that these genes gave a morphological adaptation in skin and hair to modern humans to cope with non-African environments. This is likewise
Flora and fauna of the Outer Hebrides there occasionally, but are more common off the West Beach. The grey seal now breeds on Hirta but did not do so before the 1930 evacuation. The beach at Village Bay in St Kilda is unusual in that its short stretch of summer sand recedes in winter, exposing the large boulders on which it rests. A survey of the beach in 1953 found only a single resident species, the crustacean isopod "Eurydice pulchra". Amongst the more exotic species found off the Outer Hebrides, is the giant squid ("Architeuthis") - specimens are occasionally washed up on the islands. There are only