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Saturday Stub: Maybe Humans and Neanderthals Didn’t…you know…

Posted by Ethan Clow on August 18, 2012

So I’m doing Saturday Stub’s again. For a refresher, this is where I take a small item and write a bit about, not too much since it’s Saturday, but enough to get you thinking.

A while back there was an interesting news story that hinted that perhaps, long ago, our human ancestors interbreed with Neanderthals.

It was not something completely out of the question. Early humans were living areas where there were lots of Neanderthals. The question of course is how much interbreeding and what was the outcome? Not just in biological terms either. What did this mean when it came to human-Neanderthal diplomacy (if I can use that word) Because early humans were sharing space with these folk, it’s likely they were also competing for resources, shelter, and everything else. Did humans and Neanderthals try setting aside their tribalism and interbreeding was the result? Or was this the result of widespread contact that was not always consenting?

But here’s a news story suggesting that the initial idea might not even be true. Quote from The Guardian:

“When scientists discovered a few years ago that modern humans shared swaths of DNA with long-extinct Neanderthals, their best explanation was that at some point the two species must have interbred.

Now a study by scientists at the University of Cambridge has questioned this conclusion, hypothesising instead that the DNA overlap is a remnant of a common ancestor of both Neanderthals and modern humans.”

Basically it comes down to 4% of our genetic link to Neanderthals. One explanation for this connection that most people who lived outside of Africa had, was that their ancestors who left Africa in the past, interbreed with Neanderthals and the native African population, descended from people who didn’t leave the continent never interbreed and thus don’t that that shared 4% of DNA.

Scientists Andrea Manica and Anders Eriksson are suggesting that the so-called 4% is an over-estimation. Further, they suggest that it can be explained as an indicator of a common ancestor that humans and Neanderthals shared about 500,000 years ago.

So what about the fact that Africans don’t share the 4 (or less) percentage of DNA? Manica and Eriksson say that we need to take into account “substructuring” which is the variation of genetics among populations that are not homogeneous or well mixed, as Manica and Eriksson claim African populations were like during the time period in question.

A link to the actual study can be found here.

The folks championing the interbreeding hypothesis, aren’t taking this laying down either (no pun intended) Professor Svante Pääbo, who sequenced the Neanderthal genome, is quoted as saying that Manica and Eriksson’s hypothesis was viewed as “a less parsimonious explanation.”

Pääbo has a paper awaiting peer review that he believes will further support his conclusions.

I eagerly await more human-Neanderthal intrigue.


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