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Neanderthals and humans interbred

New study leaves little room for doubt – Neanderthals and humans interbred

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In recent months, numerous DNA studies of ancient humans have all converged on one conclusion – Neanderthals and Homo sapiens interbred.  While for many this may seem unsurprising or even obvious, we must remember that until fairly recently the predominant scientific theory was that Neanderthals and Homo sapiens never came in contact with each other, let alone interbreed.  Science is also only just beginning to dispel the myth that Neanderthals were primitive cave men. But for some, the idea that up to 20% of Neanderthal genes are still present in the human race is still very hard to swallow. However, a new study , which utilised a more superior method of testing, leaves little room for doubt – many human beings alive today are the product of Neanderthal and Homo sapiens interbreeding.

The new research published in the April 2014 issue of the journal Genetics has utilised a technique that involves partitioning genomes into short blocks to calculate the statistical likelihood of distant or recent interbreeding and tracing back the biological ties that exist between humans and Neanderthals.  The method can more confidently detect the genetic signatures of interbreeding than previous approaches, and has further enabled the researchers to distinguish between two possible scenarios – the first is that Neanderthals occasionally interbred with modern humans after they migrated out of Africa, the second is that the humans who left Africa evolved from the same ancestral subpopulation that had previously given rise to Neanderthals.

“Although there has been mounting evidence for genetic exchange between modern humans and Neanderthals in Eurasia from a number of recent genetic studies, it has been difficult to rule out ancestral structure in Africa,” said study co-author Dr Konrad Lohse, a population geneticist at the University of Edinburgh. "Our approach can distinguish between two subtly different scenarios”.

The researchers found that evolution from the same ancestral population could be completely ruled out: “Our analysis allows us to conclusively reject a model of ancestral structure in Africa and instead reveals strong support for Neanderthal admixture in Eurasia at a higher rate (3.4% - 7.3%) than suggested previously,” wrote the study authors. Furthermore, the results demonstrate that “secondary admixture from Neanderthals into Eurasians took place after the expansion of modern humans out of Africa”.

The same method will be useful in other studies of interbreeding where limited samples are available. "Because the method makes maximum use of the information contained in individual genomes, it is particularly exciting for revealing the history of species that are rare or extinct," said Lohse.

"This work is important because it closes a hole in the argument about whether Neanderthals interbred with humans. And the method can be applied to understanding the evolutionary history of other organisms, including endangered species," said Mark Johnston, Editor-in-Chief of the journal Genetics.

By April Holloway

Comments

There is also new approach which suggests that applying human traits to neanderthal is wrong. Their skull is closer to a chimp than a man. They were also many times stronger and carnivorous. Most likely hunted homo sapiens for their tools, meat and sex. They probably kidnapped and raped women. Throughout ages, however, natural selection spared the most intelligent, agrressive homo sapiens tribes that took over and hunted down bulky, little sasquach to extinction. I can imagine that big organized groups hunted packs of neanderthals. They were 6 times stronger so they would never succumb to homo sapiens unless killed.

Humans tend to breed with any available mate. I think the Neanderthals would also exhibit this trait. As for the DNA, I would suggest that there were multiple lines of humanity that could have once been traced to the Neanderthals but the other lines died out over time.

NikiK's picture

Clan of the Cave Bear and the rest of the series was of course a fictional, but I can't help thinking about it when I see this.  Jean Auel did extensive research and presented a reasonable theory of ways that neanderthals and humans could have interbred, long before there was DNA evidence to back her up too. Fascinating really, I may just go back and read them again!

Fascinating I doubt our uptight sexual upbringing plays any roll in neanderthal and early man or women's thoughts in the day. My assumption would be that it was a matter of survival but then we all assume to much and put our feelings and thoughts into what may have happened. I can't even imagine what it took to survive then.....

And let’s face it we all know the myriad variations of human behavior, so no surprise that either male or female could have been the ‘originators’ of the contact – nature tends to look for mates with divergent dna, and maybe neanderthals were considered more beautiful by some humans, you cannot tell what the cultural beliefs were from skeletons after all ! Bones thru noses were a plus at one time !   I think that our attitudes are changing which allows us to consider ideas that would have been no-no in prior years. 

Veronica

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