October 8, 2012 8:30 am
When Did Human-Neanderthal Hook Ups End?
Photo: Stefan Scheer
DNA analysis shows that Neanderthals and humans once interbred, but when did the romance come to an end? A new study reveals that Upper Paleolithic humans coming out of Africa lost interest in Neanderthals about 47,000 years ago.
As i09 explains, when scientists first sequenced the Neanderthal genome back in 2010, they found that Neanderthal DNA comprises between 1 to 4 percent of modern Eurasian genomes. Africans, however, inherited no such genetic relics. From this discovery emerged two theories. One had it that modern humans and Neanderthals started interbreeding in Europe about 100,000 years ago; the other, that African populations remained subdivided but eventually started breeding with Neanderthals as they made their way into Europe during the Upper Paleolithic era.
The latest piece of the puzzle—teased out by comparing the length of DNA pieces in European and Neanderthal genomes—indicates that Neanderthals and modern humans last got it on probably around 47,000 years ago, well after modern humans appeared outside of Africa, but probably before they made their way to Asia. Why the flame between humans and Neanderthals burned out, however, remains a mystery.
More from Smithsonian.com:
The Rock of Gibraltar: Neanderthal’s Last Refuge
Modern Humans Once Mated with Other Species
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There is one rather obvious explanation – that humans interbred with a Neanderthal-human hybrid that existed in the overlap of the Neanderthal and early human ranges in the Middle East from about 200,000 years ago before the two species diverged too much. If European Neanderthals had diverged from humans for 500,000 years as estimated, then it may be the case that humans could not produce viable and fertile offspring with European Neanderthals.
This is the only plausible explanation for why humans should have stopped interbreeding 47,000 years ago, and why the distibution of Neanderthal genes is not more prevalent in modern Europeans than Asians, which is what would be expected since Neanderthals lived mainly in Europe.
Comment by SMP — October 19, 2012 @ 6:01 pm