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Neanderthals and Denisovans, two archaic hominid species, have been shown by genetic tests to have interbred with human migrants in Europe and Asia.  (Source: Corbis)

Researchers speculate that such sexual attractions between the species were rare, but that the children were much more genetically fit, so came to dominate the population.  (Source: Google Images)

The highest rates of Denisovan DNA occurrence were found in the DNA of natives of Papua New Guinea.  (Source: Flickr)

The immune proteins our hominid relatives gave to us during interbreeding made us hardier and more resist to potentially deadly infections.  (Source: Paul de Bakker)
Turns out Europeans and Asians may be the least "genetically pure" homo-sapiens

It turns out that European DNA, like that of Asians and Africans, has traces of archaic hominids mixed in with the familiar Homo sapien-specific stretches.

The sequencing of the Neanderthal genome
 has led to some incredible discoveries -- among them, that humans were having sex with Neanderthals.  A pair of new studies has shown that Neanderthal genes aren't evenly distributed throughout the entire human population -- rather some populations have more or less of them.

A new study, whose senior author is 
Peter Parham, a professor of cell biology, microbiology and immunology at the Stanford University School of Medicine, examines how interbreeding with our closely related hominids led to a superior human immune system.

Svante Pääbo, director of the Department of Genetics at the Max Planck Institute for Evolutionary Anthropology and senior author on the paper [abstract] detailing the original Neanderthal genome draft, suggests that one of two possibilities occurred.  Either migrants to Asian and Europe broadly had sex with Neanderthals or just a few did, but whose progeny survived in greater numbers, passing on the early hominids' genetic material.  Researchers believe the latter explanation is more likely the case.

Humans are thought to have migrated from Africa around 67,500 years ago, spreading to Asia and Europe.  In these regions they encountered Neanderthals and Denisovans -- another archaic hominid, who they at least occasionally engaged in sexual intercourse with.  Interbreeding is thought to have occurred starting around 50,000 years ago.

Those hairy charmers passed something valuable along to the migrants -- improved immunity.  Many of Eurasians'  HLA genes -- fast evolving human immune system components -- are thought to have been "borrowed" from the Neanderthal and Denisovan genome.

It found that one Denisovan-derived gene -- HLA-A  -- was 95 percent likely to occur in residents of Papua New Guinea, 70 percent in residents of China, 50 percent in Europe, and virtually non-present in Africa.

The genes are thought to have conferred improved survival rates on the migrants, as they gained defenses against local diseases, which took their archaic hominid co-inhabitants millennia to develop.

Africans, who never personally interbred with the Denisovans and Neanderthals did receive a bit of these genes second hand, from migrants who returned to the region around 10,000 years ago.  And they are thought to have an even stronger and more diverse immune system, as they bred with other species of archaic hominids
, which were native to Africa.

Previous studies have shown that non-Africans have around 4 percent Neanderthal genes, while Melanesians -- natives of Indonesia and the surrounding islands -- also have 4 to 6 percent of their genes derived from the Denisovans.

The study on the project is published
 [abstract] in the prestigious peer-reviewed journal Science.

The new work could offer some additional explanation of why Native Americans may have been so susceptible to diseases brought to the New World by Europeans and Africans.  Native Americans may have missed much of the interbreeding opportunities.  Thus while they may be the most "pure" examples of Homo sapiens DNA, that may have proved fatal to many of them.

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RE: Hmm...
By wordsworm on 8/30/2011 6:13:42 AM , Rating: 1
When you've got a white and a black parent, you're black. Hence, all the headlines that came out declaring Obama as America's first black president.

My half sister, for example, has a black father and a white mother, and everyone says she's black. Donald Brashear, my cousin, is also half black. His dad is black, his mom is white. But everyone says he's black.

I also would wager that a smart slave is an awful lot better than a dumb one.

I'm curious, Skywalker, why do you have a hard time with anti-white rhetoric but have no problem with anti-Asian rhetoric? Both my father and mother are white. I work in Korea and am married to an Asian. A good 1/3 of my relatives are black. My family is as multi-racial as they come.

Most of the folks who have replied to my reaction to the 'ha ha, Japanese have small penises' have been offended that I said that African Americans are superior to Caucasian Americans, or that I said that the reason why Asian men have smaller penises is because their women are loyal (for which there is a fair amount of evidence if you look at other species).

RE: Hmm...
By mindless1 on 8/31/2011 9:51:06 PM , Rating: 2
Actually there isn't a fair amount of evidence, these things you claim as proofs would have had to happen long before recorded history to have had any significant impact on evolution, so what you claim as proof is either only someone's guess, propaganda from a hate group, or invalid due to being a time period too recent.

What you've done is classic pseudo-learning. You hear someone propose an idea and state a fact, nevermind if the fact is relevant, or proof, if you have all the facts, or if other contradictory facts are more significant.

I can claim "outer space" is blue because when I look up the sky is blue. In ancient times, before we had more knowledge than we do now, most people would believe I was right. Once they form their opinion they are reluctant to weigh further evidence equally.

This is a terrible human fault, the insistence that we "know" things for certain when the evidence is essentially built like a house of cards.

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