Study: Humans and Neanderthals Didn’t Interbreed As Much As We Feared/Hoped

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REUTERS/Nikola Solic

Here we go again. It’s been barely two years since a breakthrough study found that people living outside Africa shared up to 4% of their DNA with Neanderthals, prompting speculation that there had been quite a bit of, shall we say, interspecies intimacy during the 15,000-year period when the two species co-existed in Europe. Now, scientists at the University of Cambridge have proposed that these genetic similarities might instead stem from both species sharing a common ancestor.

In the latest study, evolutionary biologist Andrea Manica and Anders Eriksson used computer simulations to examine the case for inter-species mating, otherwise known as hybridization. They published their sensational findings in on Monday in the journal Proceedings of the National Academy of Sciences.

(MORE: CSI Stone Age: Did Humans Hunt Neanderthals?)

In a statement reported by the Daily Telegraph, Dr Manica said: “To me the interbreeding question is not whether there was hybridization but whether there was any hybridization that affected the subsequent evolution of humans. I think this is very, very unlikely.”

“Our work shows clearly the patterns currently seen in the Neanderthal genome are not exceptional, and are in line with our expectations of what we would see without hybridization,” he added.  “So, if any hybridization happened then it would have been minimal and much less than what people are claiming now.”

(MORE: Be (Sorta) Jealous: Chimps Have Better Sex than Humans)

In short, our Homo sapiens ancestors probably got it on with their Neanderthal cousins, but not to any great degree — and certainly not enough to so strongly affect our genetic makeup.

The story, according to Manica and Eriksson, actually began half a million years ago, during the existence of a common ancestor to the Neanderthals and Homo sapiens. Roughly 300,000-350,000 years ago, the species diverged between those who migrated North, ultimately evolving into the Neanderthals, and those who moved south, from whom modern humans emerged. It was not until 60,000-70,000 years ago that we humans began to expand from Africa.

(MORE: Evidence Proves that Humans and Neanderthals Mated)

As for why some humans more closely resemble Neanderthals than do others, Dr Manica, stressed “common ancestry” and “geographical differences” over hybridization. “The idea is that our African ancestors would not have been a homogeneous, well-mixed population but made of several populations in Africa with some level of differentiation, in the way right now you can tell a northern and southern European from their looks,” he explained.

“Hopefully, everyone will become more cautious before invoking hybridization, and start taking into account that ancient populations differed from each other probably as much as modern populations do.”

(MORE: Fossils Reveal New Missing Link on Humans’ Family Tree)

Within the academic community, not everyone’s convinced just yet. Professor Svante Pääbo of the the Max Planck Institute for Evolutionary Anthropology, who led the 2010 research, admitted to the Guardian that he was surprised that the study refuting his work had been published and has himself co-authored a new paper, currently awaiting peer review, that adds credence to his original thesis. Meanwhile, Harvard University’s Professor David Reich, a key proponent  of the hybridization explanation, told the BBC, “the patterns observed [in our analyses] are exactly what one would expect from recent gene flow.”

It looks like we’ll be talking about human-Neanderthal love for some time.

COVER STORY: How Man Began

4 comments
Ninio Calle
Ninio Calle

Still in denial stage? Better to accept interbreeding. Just look at the facts on the ground.  Europeans are the only ones that have blonds and distinct Euro features while the rest of those coming out of African don't.  Why should Europeans be different when all of us are exposed to the same environmental factors.  The Asians, the native American Indians and the rest of us don't have blond and other European features.  Maybe a reverse computer program to investigate this would finally seal this.

Albin
Albin

Canadian Broadcasting Corp radio did a piece on the original claim that there must have been interbreeding.  The takeaway was that, since these were not "multicultural" societies, any successful interbreeding resulted from violent triumphal rapine following conflicts between sapiens and neanderthal tribes.   If the claim is true, we are all, you and me, the progeny of stone age rape victims.

LoudRambler
LoudRambler

 I increasingly like the hypothesis that the melting of glacial analog off current Arabian peninsula, and that we may have a flooded craddle of humanity out of which there were waves of migration.

 And, definitely, we should study Middle East a lot better.

Nishal Wadhwani
Nishal Wadhwani

 There are black people with naturally blonde hair that live in Micronesia. Plenty of Central Asians (e.g. Kazakhstan, Afghanistan) have hair and eye colours running the full 'European' spectrum. I myself am Indian, but I have green eyes (but no Caucasian ancestry whatsoever); so do other family members of mine. Many East Asians have natural light-brown hair. Plus, you're assuming that Neanderthals had blonde hair and blue eyes.