September 14, 2011
Humans Didn’t Often Mate With Neanderthals
Modern humans do show some traces of DNA from Neanderthals, but a new study from Swiss researchers suggests that any breeding between the two was a relatively rare event.
The new model, based on DNA samples from modern humans in France and China, shows that successful breeding between the two species occurred at a rate of less than 2 percent, according to researchers at the University of Geneva and the University of Berne in Switzerland.
The research, published Monday in the Proceedings of the National Academy of Sciences, suggests that either inter-species sex was quite forbidden, or that hybrid offspring had trouble surviving.
The research team said there may have been “extremely strong barriers to gene flow between the two species because of a very low fitness of human-Neanderthal hybrids, a very strong avoidance of interspecific mating, or a combination.”
Roughly 2 to 4 percent of the human genome can be linked to the ancient Neanderthal species and their caveman relatives, who died out about 40,000 years ago, their last known refuge being Gibraltar.
Why they died out has been a source of debate, because they co-existed alongside modern humans, which have continued to thrive.
Research by French authors published findings in the journal Science last month suggesting that modern humans gleaned a competitive immune advantage from their sexual interactions with early cavemen.
However, there is no real evidence that suggests the nature of those encounters, whether violent or consensual.
Some other studies have also suggested that modern humans crowded out the primitive Neanderthals, and that the species may have also not been able to handle a wave of harsh, wintry weather conditions.
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