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Why Human-Neanderthal Sex Is Tricky to Prove

Science & Tech  (tags: ancient, concept, discovery, environment, habitat, health, history, humans, investigation, medicine, research, science, scientists, society, study, world )

- 1989 days ago -
A bundle of recent genetic studies have suggested modern humans had sex with Neanderthals thousands of years ago when the two populations roamed the planet alongside each other.

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Kit B (276)
Tuesday December 11, 2012, 10:57 am
(Photo Credit: Milagros González)
A female mantled howler monkey in Tabasco, Mexico.

A bundle of recent genetic studies have suggested modern humans had sex with Neanderthals thousands of years ago when the two populations roamed the planet alongside each other. However, the bones left behind by the two species don't bear any obvious traces of interbreeding, and a new study of monkeys in Mexico shows why we shouldn't expect them to.

Researchers examined blood samples, hair samples and measurements collected from mantled howler monkeys and black howler monkeys that were live-captured and released in Mexico and Guatemala between 1998 and 2008. The two monkey species splintered off from a common ancestor about 3 million years ago; today they live in mostly separate habitats, except for a "hybrid zone" in the state of Tabasco in southeastern Mexico, where they coexist and interbreed.

Through an analysis of genetic markers, from both mitochondrial DNA (the DNA in the cells' energy-making structures that gets passed down by mothers) and nuclear DNA, the researchers identified 128 hybrid individuals that were likely the product of several generations of interbreeding. Even so, these hybrids shared most of their genome with either one of the two species and were physically indistinguishable from the pure individuals of that species, the team found.

"The implications of these results are that physical features are not always reliable for identifying individuals of hybrid ancestry," Liliana Cortés-Ortiz, an evolutionary biologist and primatologist at the University of Michigan, said in a statement. "Therefore, it is possible that hybridization has been underestimated in the human fossil record."

The work on howler monkeys was part of the doctoral dissertation of Mary Kelaita, now a postdoctoral fellow at the University of Texas at San Antonio. Kelaita added that the study "suggests that the lack of strong evidence for hybridization in the fossil record does not negate the role it could have played in shaping early human lineage diversity."

When scientists finally finished sequencing the Neanderthal genome in 2010, they revealed that between 1 percent and 4 percent of some modern humans' DNA came from the stocky hominids. This suggested humans had sex with Neanderthals, picking up some genes, and possibly even an immunity boost, from Neanderthals before the population disappeared about 30,000 years ago. But not all scientists are convinced the genetic evidence alone proves ancient interbreeding and a study last year found that even if humans and Neanderthals did have sex, those encounters would have rarely produced offspring.

The scientists of the new study say more work is needed to learn about interbreeding and the factors governing the expression of physical characteristics in hybrid individuals.

The research was detailed online Friday (Dec. 7) in the American Journal of Physical Anthropology.

By: Megan Gannon, News Editor | Live Science |


Terrie Williams (798)
Tuesday December 11, 2012, 1:04 pm
...."But not all scientists are convinced the genetic evidence alone proves ancient interbreeding and a study last year found that even if humans and Neanderthals did have sex, those encounters would have rarely produced offspring.".....

Oh, Gee, is this the 'proof' that female bodies have ways of shutting these things down? (yes, I am being sarcastic as hell today,.....) :) How the hell would they know if there would be or wouldn't be pregnancies or lack thereof.....were they frikken there? Well......maybe, but they wouldn't remember it would they.......

Personally, I think they did interbreed and there were offspring and there is evidence in the genetic makeup of modern humans. Duh. It's called evolution and selective breeding. We still do it today and will probably continue to do it until we as a species goes the way of the dinosaurs.....or some of our ancestors. :)

Thanks for the article, Kit.

Roger G (154)
Tuesday December 11, 2012, 1:35 pm
noted, thanks !

Kit B (276)
Tuesday December 11, 2012, 1:41 pm

I tend to think there was inter-species cross breeding, though I hadn't thought of Jim's answer and that just a ring of hilarity if not exact fact.

It's kind of a shame we have to comment on our own use of sarcasm, not to worry Terrie, this naturally sarcastic eye caught that.

Not sure it matters that much if we prove it with gene sequencing or not, some have an understanding of evolution and others (by choice?) do not.

Theodore Shayne (56)
Tuesday December 11, 2012, 3:59 pm
There sure are a lot of homo sapiens sapiens that act like they're only one or two steps removed from the common ancestor. A lot of them wear suits too.

Past Member (0)
Tuesday December 11, 2012, 4:06 pm

Susanne R (235)
Tuesday December 11, 2012, 10:35 pm
Interesting article, Kit, and even more interesting comments! Thanks for posting this!

Tanya W (65)
Wednesday December 12, 2012, 3:55 am
Interesting - thanks.

Daniel Partlow (179)
Wednesday December 12, 2012, 6:49 am
Noted. An interesting post, thanks.

Past Member (0)
Wednesday December 12, 2012, 1:42 pm
Isn't Rush Limbaugh proof positive?

Madeleine watt (243)
Wednesday December 12, 2012, 5:46 pm
enjoyed immensely. thx

Lynda G (122)
Wednesday December 12, 2012, 6:14 pm
I believe the Neanderthal species were only just adaptive enough to survive for as long as they did. They lacked ‘ambition’, or ‘inventiveness’, if you like. While one person will be content to do what they always do with what they have, another person will stop and think, “how can I make this easier/more efficient/faster?” One will want to see what’s on the other side of the mountain, another will remain in their own village all their life. This does not necessarily reflect intelligence, but intelligent people will invent more and adapt better to their environment and adversity. I believe this is why the Neanderthal species eventually faded out as a ‘pure’ species.

Interesting article - thank you Kit.

Debra Van Way (12)
Wednesday December 12, 2012, 6:37 pm
Gee, does this mean Adam and Eve didn't ride dinosaurs? Sorry, I just couldn't resist. MJ M, how can you slander innocent Neanderthals like that? They would never produce such a creature on their worst day. If by chance it did happen-they would have taken one look and killed it knowing it was a freak of nature that would spread ignorance and stupidity any time it spoke. lol

Excellent article. Thanks for sharing.

Past Member (0)
Wednesday December 12, 2012, 8:21 pm
I think you’re right Debra. I have a feeling that Limbaugh must have a closer genetic connection with primordial slime.

Debra Van Way (12)
Wednesday December 12, 2012, 8:55 pm
MJ M-you know, I think you hit the nail on the head. Slime certainly comes to mind any time I read about Limbaugh. Truthfully though, I believe primordial slime needs to hire a good lawyer and sue Limbaugh for defamation of its character. I don't think it ever in its worst days ever sank as low or as dirty as Limbaugh. I would certainly believe good ole primordial slime before I would Limbaugh, wouldn't you?

Past Member (0)
Wednesday December 12, 2012, 11:04 pm
Come to think of it, yes, I would.

Parvez Zuberi (7)
Thursday December 13, 2012, 2:21 am
Interesting article thanks

Lloyd H (46)
Thursday December 13, 2012, 5:13 am
Some times interesting is just another term for stupid. First off the fact that 'physical characteristics' are not valid proof of interbreeding also means that they are one way or the other not valid proof against interbreeding. Second, assuming for the sake of discussion that New World Monkey interbreeding in a totally different environment by animals with out cultures is a valid comparison for humans with cultures, the fact that the offspring of said interbreeding is not distinguishable would indicate that the offspring of two human subspecies would also be indistinguishable both to scientists and the species involved.
Actually I feel the entire thing is some what moot as there is still no tdefinitive proof as to whether Neanderthals are a subspecies or separate species. Fact is genetics aside, every year Neanderthals are being proven to be more Human like mentally and culturally/socially that any one ever imagined even 10 years ago. And then there is the fact that 'humans' will have sex with anything that can not get away, cultural barriers, language barriers and physical differences are meaninless. If the Neanderthals and Human lived in the same areas at the same time you can bet the farm that they interbred and at least some of the genetic evidence supports this.
And I have to agree with Jim that the in amny respects Repug/Tea Baggers lend some proof of recessive genetic retrogression to a subspecies that is not capable of adapting to new environments for survival.
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