Ancient humans interbred – again

Abstract

Our ancestors mated with a species of ancient hominin called the Denisovans at least twice. The discovery suggests our extinct cousins were widely spread across Asia, and may have coexisted happily with modern humans. The Denisovans were unknown until 2010, when a fragment of bone was found in Denisova cave in Siberia. When a team sequenced its surviving DNA, they found it didn't belong to known hominins, such as Neanderthals. What's more, comparisons of this genome with those of living people found that around 5 per cent of the DNA of some Australasians--particularly people from Papua New Guinea--is Denisovan. From this researchers calculated that humans mated with Denisovans 50,000 or more years ago. The species presumably died out fairly soon after. Now Sharon Browning at the University of Washington in Seattle and her colleagues have found evidence of a second case of interbreeding with Denisovans--this time on the Asian mainland. Browning's team trawled for hominin DNA in the genomes of 5600 living humans from Europe, Asia, the Americas and Oceania. Because other species of hominin were present for longer, their DNA stands out because it is rich in mutations, which built up in their genomes overtime. This abundance of mutations isn't present in the younger human lineage. When humans and other hominins mated, their children inherited these mutation-rich regions of DNA.