In Cell this week, a team led by the University of Pennsylvania's Sarah Tishkoff discusses evolutionary history and adaptations of different African hunter-gatherer populations. The team sequenced the whole genomes of 15 African men — five each from the Western Pygmy, Hadza, and Sadawe populations — which the team then compared to previously published data from a San individual as well as from other diverse African populations.
As our sister publication GenomeWeb Daily News reports, Tishkoff's team found signals of interbreeding of all three populations with an unknown archaic hominin as well as population-specific adaptations. For example, the team found variants specific to the Pygmy population located near pituitary gland-related genes that may contribute to height in Pygmy populations.
In The New York Times, Nicholas Wade says that this report of interbreeding between these hunter-gatherer populations and an unknown archaic hominin, as well as previous (and an upcoming) reports of interbreeding of populations outside of Africa with Neandertals, conflicts slightly with paleoanthropological findings. Human fossils uncovered in Africa from the last 100,000 years or so have all been of modern humans, and there is no evidence of the unknown archaic hominin, Wade says. Paleoanthropologists caution that genetic data should be considered in conjunction with fossil and archaeological findings, he adds.
At his Gene Expression blog, Razib Khan says the Times' account is misleading. "Some paleoanthropologists are unhappy. This is not a debate between all paleoanthropologists and all geneticists," he writes, [emphasis original]. "In fact, some [geneticists] are moderately skeptical of admixture because they think it might be due to population structure in the ancient African H. sapiens sapiens."