Science Stuff

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Evidence of Neanderthal/Human interbreeding
From DailyGalaxy:

Ealy modern humans left Africa about 80,000 to 50,000 years ago. The question has long been whether the physically stronger Neanderthals, who possessed the gene for language and may have played the flute, were a separate species or could have interbred with modern humans. The answer is yes, the two lived in close association.

In July 2011, an international team of researchers led by Damian Labuda of the Department of Pediatrics at the University of Montreal and the CHU Sainte-Justine Research Center announced that the human X chromosome originated from Neanderthals and is found exclusively in people outside Africa, which confirmed recent findings suggesting that the two populations interbred," said Labuda. His team places the timing of such intimate contacts and/or family ties early on, probably at the crossroads of the Middle East.

Neanderthals, whose ancestors left Africa about 400,000 to 800,000 years ago, evolved in what is now mainly France, Spain, Germany and Russia, and are thought to have lived until about 30,000 years ago. 
"In addition, because our methods were totally independent of Neanderthal material, we can also conclude that previous results were not influenced by contaminating artifacts," added Labuda.

Labuda and his team almost a decade ago had identified a piece of DNA (called a haplotype) in the human X chromosome that seemed different and whose origins they questioned. When the Neanderthal genome was sequenced in 2010, they quickly compared 6000 chromosomes from all parts of the world to the Neanderthal haplotype. The Neanderthal sequence was present in peoples across all continents, except for sub-Saharan Africa, and including Australia.

"There is little doubt that this haplotype is present because of mating with our ancestors and Neanderthals," said Dr. Nick Patterson, of the Broad Institute of MIT and Harvard University, a major researcher in human ancestry who was not involved in this study.

"Dr. Labuda and his colleagues were the first to identify a genetic variation in non-Africans that was likely to have come from an archaic population. This was done entirely without the Neanderthal genome sequence, but in light of the Neanderthal sequence, it is now clear that they were absolutely right!" adds Dr. David Reich, a Harvard Medical School geneticist, one of the principal researchers in the Neanderthal genome project.

"Variability is very important for long-term survival of a species," concluded Labuda. "Every addition to the genome can be enriching." 

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Chimpanzees have Greater Genetic Diversity than Humans
From I09

Genetic diversity among chimpanzees reveals just how closely related humans really are

There are four genetically distinct chimpanzee populations, all found in two relatively small regions of Africa. And yet these populations, which are sometimes less than a mile apart, are more genetically diverse than humans that live on different continents.

Three of the common chimpanzee groups are found in very close quarters. While the distinct bonobo subspecies on the southern side of the Congo River, the Eastern, Central, and Cameroonian subspecies form a nearly contiguous region in Central Africa, with only the Western population isolated from the others by any considerable geographic distance.

That's why the results of a new genomic study conducted by an international team of researchers is so surprising. Based on the DNA from 54 chimps taken from across these four populations, these chimps really are genetically distinct from each other despite often being so close together. What's more, the genetic diversity of these different chimp populations, even those who are practically right on top of each other, is significantly greater than that found in humans separated by entire continents. Oxford professor Peter Donnelly explains:

"Relatively small numbers of humans left Africa 50,000-100,000 years ago. All non-African populations descended from them, and are reasonably similar genetically. That chimpanzees from habitats in the same country, separated only by a river, are more distinct than humans from different continents is really interesting. It speaks to the great genetic similarities between human populations, and to much more stability, and less interbreeding, over hundreds of thousands of years, in the chimpanzee groups."

The high level of diversity also adds another wrinkle to ongoing chimp conservation efforts. Until now, it wasn't clear just how distinct the different sub-species really were - in particular, there was considerable debate whether the Cameroonian chimps really represented a separate group or not - and now we know that these really are very different groups of chimps, and we probably need to adjust our conservation plans according, as study leader Dr. Rory Bowden explains:

"These findings have important consequences for conservation. All great ape populations face unparalleled challenges from habitat loss, hunting and emerging infections, and conservation strategies need to be based on sound understanding of the underlying population structure. The fact that all four recognized populations of chimpanzees are genetically distinct emphasizes the value of conserving them independently. Genomics can also provide tools for use in chimpanzee conservation. Genetic tests could cheaply and easily identify the population of origin of an individual chimpanzee or even a sample of bush meat."