Becoming Human wasn’t so Clovis

Not “being so Clovis’ means human origins in America are not so straightforward as once the neocapitalistscientists arguing for the Clovis ‘origin’ of American descent claimed.

Ann Gibbons, October 14, 2011, in Science  wrote a cool summary of recent developments in becoming human. This issue is a most fascinating perhaps the most, for me, in our newer understanding of becoming human. The emergence of consciousness and language are the 2 most critical unsolved biological underpinnings of our nature:

“After sequencing the genome of Neandertals and that of mysterious hominins from Denisova Cave in Siberia, researchers concluded last year that our ancestors interbred with both Neandertals and Denisovans. One meeting may have been in western Asia with Neandertals, and a separate intermingling with Denisovans may have taken place in Asia (Science, 23 September, 1689).

Now, a team led by Hammer has found that some hunter-gatherers in Africa also carry unusual segments of DNA that the researchers propose are archaic, as reported last month in the Proceedings of the National Academy of Sciences (PNAS). The team screened 61 regions of DNA from three relatively isolated groups in sub-Saharan Africa, examining noncoding DNA that was less likely to be influenced by natural selection. They found three regions whose pattern of alleles varied widely among individuals—a sign of great antiquity. But the variants were linked to each other across extended regions of the chromosome, which suggested they were inherited recently, because such associations among chromosomal regions break down over time. So the overall pattern suggests that ancient segments of DNA recently entered the H. sapiens genome, as would be the case if the DNA was inherited from an archaic human.

The team screened for these three variants in an expanded sample of 500 Africans and found them in pygmy and nonpygmy populations from Zaire, Cameroon, and the Democratic Republic of the Congo. By using computational and statistical methods to simulate the distribution of the variants, Hammer’s team concluded that modern humans mated with archaic humans perhaps as recently as 35,000 years ago in central Africa. Hammer stresses that it was a small amount of interbreeding, “or we would have discovered this long ago.”

Just what archaic human did the ancestors of these Africans mate with? Geneticists can’t say because they have no ancient DNA from African fossils. And there are no fossils of Neandertals or Denisovans on the continent. But fossil hunters have long puzzled over a few strange African bones that carry both archaic and modern features. In a PLoS ONE paper published a week after Hammer’s, a team led by Stringer and Katerina Harvati of the Eberhard Karls University of Tübingen in Germany took a new look at the cranium of a modern human found in 1965 at Nigeria’s Iwo Eleru rock shelter.”


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