Humans Still Evolving, Research Finds

Human evolution shows signs of having sped up in the past 10,000 years, thanks in part to growing populations and the dietary changes brought about by agriculture, according to new research from the University of Utah.

Henry Harpending, a professor of anthropology, led a research team that analyzed DNA from 270 people from four population groups: Han Chinese, Japanese, the Yoruba of Africa and northern Europeans, most of whom were Utah Mormons. They looked for genetic variations known as "single nucleotide polymorphisms" (SNPs) that indicate a recent mutation that benefits humans in some way, allowing them to survive longer and reproduce more.

"If a favorable mutation appears, then the number of copies of that chromosome will increase rapidly (in the human population)," Harpending said. "And if it increases rapidly, it becomes common in the population in a short time.

The team's findings indicate that "humans are evolving rapidly, and that the pace of change has accelerated a lot in the last 40,000 years, especially since the end of the Ice Age roughly 10,000 years ago," Harpending said.

The research also suggests that different population groups around the world are becoming more different rather than homogenized.

"Human races are evolving away from each other," Harpending said. "Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity."

However, Harpending cautioned against anyone using the team's findings to justify racism or discrimination. Genetic differences between different groups "cannot be used to justify discrimination," he said. "Rights in the Constitution aren't predicated on utter equality. People have rights and should have opportunities whatever their group."

One of the team's key findings was that 7 percent of human genes have evolved rapidly in recent history. The introduction of agriculture about 12,000 years ago contributed greatly to that, as has the human species' rapid population growth since then, Harpending said.

"Rapid population growth has been coupled with vast changes in cultures and ecology, creating new opportunities for adaptation," the researchers wrote in their study. "The past 10,000 years have seen rapid skeletal and dental evolution in human populations, as well as the appearance of many new genetic responses to diet and disease."

"History looks more and more like a science fiction novel in which mutants repeatedly arose and displaced normal humans -- sometimes quietly, by surviving starvation and disease better, sometimes as a conquering horde," said study co-author Gregory M. Cochran, also an anthropologist at the University of Utah. "And we are those mutants."

Other members of the research team, whose findings are published this week in the online version of the Proceedings of the National Academy of Sciences, include John Hawks, a former Utah postdoctoral researcher who's now an anthropologist at the University of Wisconsin, Madison; Eric Wang, a geneticist with Affymetrix Inc. in Santa Clara, California; and Robert Moyzis, a biochemist at the University of California, Irvine.

University of Utah, "Are Humans Evolving Faster?" URL: (http://unews.utah.edu/p/?r=120607-1)