Just before Christmas, an important study came out by Robert Moyzis, Eric Wang, et al. entitled "Global landscape of recent inferred Darwinian selection for Homo sapiens" [PDF]. It lists 1,800 genes that have been under varying selection pressure in Africa, Europe, or East Asia over no more than the last 50,000 years. It was based on the revolutionary HapMap study of genetic differences among Yoruban Nigerians, Utah whites, and Japanese & Chinese East Asians. I wrote it up on my blog and in VDARE.com, but because the indispensable Nicholas Wade didn't cover it in the NY Times (I'm guessing he was on Christmas vacation), almost nobody else in the American media paid it much attention, other than a small number of bloggers in my Links list.
Fortunately, Wade is now splashing in the NYT a new study by a different team using HapMap data:
Still Evolving, Human Genes Tell New Story
By NICHOLAS WADE
Providing the strongest evidence yet that humans are still evolving, researchers have detected some 700 regions of the human genome where genes appear to have been reshaped by natural selection, a principal force of evolution, within the last 5,000 to 15,000 years.
The genes that show this evolutionary change include some responsible for the senses of taste and smell, digestion, bone structure, skin color and brain function.
Many of these instances of selection may reflect the pressures that came to bear as people abandoned their hunting and gathering way of life for settlement and agriculture, a transition well under way in Europe and East Asia some 5,000 years ago.
Under natural selection, beneficial genes become more common in a population as their owners have more progeny.
Three populations were studied, Africans, East Asians and Europeans. In each, a mostly different set of genes had been favored by natural selection. The selected genes, which affect skin color, hair texture and bone structure, may underlie the present-day differences in racial appearance.
The study of selected genes may help reconstruct many crucial events in the human past. It may also help physical anthropologists explain why people over the world have such a variety of distinctive appearances, even though their genes are on the whole similar, said Dr. Spencer Wells, director of the Genographic Project of the National Geographic Society.
The finding adds substantially to the evidence that human evolution did not grind to a halt in the distant past, as is tacitly assumed by many social scientists. Even evolutionary psychologists, who interpret human behavior in terms of what the brain evolved to do, hold that the work of natural selection in shaping the human mind was completed in the pre-agricultural past, more than 10,000 years ago.
"There is ample evidence that selection has been a major driving point in our evolution during the last 10,000 years, and there is no reason to suppose that it has stopped," said Jonathan Pritchard, a population geneticist at the University of Chicago who headed the study.
Dr. Pritchard and his colleagues, Benjamin Voight, Sridhar Kudaravalli and Xiaoquan Wen, report their findings in today's issue of PLOS-Biology.
Their data is based on DNA changes in three populations gathered by the HapMap project, which built on the decoding of the human genome in 2003. The data, though collected to help identify variant genes that contribute to disease, also give evidence of evolutionary change.
The fingerprints of natural selection in DNA are hard to recognize. Just a handful of recently selected genes have previously been identified, like those that confer resistance to malaria or the ability to digest lactose in adulthood, an adaptation common in Northern Europeans whose ancestors thrived on cattle milk.
But the authors of the HapMap study released last October found many other regions where selection seemed to have occurred, as did an analysis published in December by Robert K. Moysis of the University of California, Irvine. [More]
My published articles are archived at iSteve.com -- Steve Sailer
Posts
No comments:
Post a Comment