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  (Source: BBC)
New study offers strong genetic evidence in support of the hypothesis that humans and their close kin hooked up

With the sequencing of the Neanderthals (Homo neanderthalensis) genome, we discovered that 1 to 4 percent of genes of humans (Homo sapiens) matched those found in Neanderthals.  Notably, matching genes suggested Neanderthals likely were fair skinned with blond/red hair, while humans at the time appeared to mostly have dark skin and black/brown hair.
 
The hot question in the aftermath of that sequencing was whether these similarities occurred spontaneously or whether they were the result of our ancestors getting it on, technically speaking, with Neanderthals.
 
The interbreeding hypothesis is attractive due to geography if nothing else.  Namely, the locations with the last surviving Neanderthal populations (Scandinavia, the English isles) also happen to have the most prevalent rate of Neanderthal appearance genes (fair skin, blond/red hair) of anywhere in the world.
 
We felt this particular hypothesis to be quite compelling.  That Neanderthal glancing at you across the campfire might look a little odd at first, what with her fair skin, auburn hair, and angular cheekbones.  But get a couple of Stone Age beers in you and she starts to look like a perfect 10.

Stone Age beer
Stone Age beer likely played a key role in human and Neanderthal hook ups.
[Image Source: Asle Rønning]

Now evolutionary geneticists with the University of Edinburgh and the Wageningen University (Netherlands) have published an impressive study in the peer-reviewed journal Genetics that indicates that's indeed how the genetic similarity likely arose.
 
The new study comes in response to a 2012 study in the Proceedings of the National Academy of Sciences by Anders Eriksson and Andrea Manica of the University of Cambridge.  That study acknowledged the interbreeding possibility, but argued in favor of an alternative -- sustained substructure.  According to that theory, certain subpopulation of each group retained traits, or evolved traits in parallel, via random mutations.
 
But Professor Laurent Frantz of Wageningen University calls that idea "unparsimonious" (too theoretically complex/violating Occam's razor).  He and his UK colleague did a more thorough analysis of known human mutation rates and genetic variance, plus looked at population distribution and other factors.  The results, he states, show a resounding win for the interbreeding hypothesis, while leaving the door open to the possibility that some common genes did come from sustained substructure.

Neanderthal chuck norris
Likely not a coincidence: apparently Neanderthals looked a lot like Chuck Norris.
[Image Source: BBC]

Professor Frantz was the study's senior author, UK Professor Konrad Lohse was the first author.  Professor Frantz comments to The Verge:

We did a bunch of math to compute the likelihood of two different scenarios.  We were able to do that by dividing the genome in small blocks of equal lengths from which we inferred genealogy.

Our analysis shows that a model that involves interbreeding is much more likely than a model where there was sustained substructure in Africa.  [Substained substructure might have contributed to genetic commonality] but it cannot be used to explain the genetic similarities [alone].

There seemed to be something that has gone wrong [in that study] because it seems unparsimonious... When we tested two hypotheses, we got a high support for a scenario where humans and Neanderthals interbred.

There have been a lot of arguments about what happened to these species.  Some think that we outcompeted [other hominins] or that they were killed by humans, but now we can see that it's not that simple.  Human evolution is much more complex than we previously thought.

In other words, why would early man, struggling to survive against nature and competing tribes, waste resources on killing and driving out Neanderthals? They could instead ally with them, recruiting the close relative to join the tribe.

neanderthal skull
Geneticist Svante Pääbo, one of the men who helped sequence the Neanderthal genome peers at the fossilized remains of his possible ancestor. [Image Source: Frank Vinken]

It's a compelling notion indeed.  So crack open a cold beer; chances are your ancestors were doing the same on one fateful night some 500,000 years ago.  Thanks to them, now that Neanderthal isn't just your close phylogenetic kin, it's also your direct ancestor.

Sources: Genetics, The Verge



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RE: is anybody surprised?
By mepinion on 4/12/2014 4:07:14 AM , Rating: 2
IMO, intra-species competition was hugely important!

Especially the taking of the environmentally presented procreation promoting evolutionary and selective pressure of opportunity type that specifically consisted of the opportunity to raid and usurp (murder) neighboring troops or tribes. That is, the usurped types of troops that those that were less coordinated, less 'focused'=lacking in capacity to not respond with pain to injury or with fear while attacking or being attacked, and less motivated because of not carrying the pleiotropic FOXP2 mutation (that occurred roughly ~6~ million years ago in a single common ancestor of ours and that endowed this ancestors and its descendants with strongly ambiadvantageous adaptive traits).

Another mutation in the same gene region is estimated to have occurred not long before last important exodus from the African cradle of humankind.

Mother Nature rocked this cradle of our evolution significantly more rapidly with the event of the last two major FOXP2 mutations.

I seemed to me that everything else you wrote was muddled or missed conveying any other point (if you had one to make?).


RE: is anybody surprised?
By Jeffk464 on 4/14/2014 12:15:19 PM , Rating: 2
So your saying their reason for extinction is that they were peaceful? Of course to this point they are a more successful species than modern humans as they were around much longer than we have been around. Time will only tell if we make it as long as they did.


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