Thursday, March 09, 2006


A story by Nicholas Wade in the New York Times on March 7, 2006, says: "Proving 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.
Looking at the time period, we realize that these instances of selection reflect what happened as people abandoned their hunting and gathering way of life for settlement and agriculture.

Three populations were studied, Africans, East Asians and Europeans. In each, a mostly different set of genes had been favored by natural selction that affect skin color, hair texture and bone structure. Now, we have a better answer for young people when they ask, why do people have different skin colors!

According to Jonathan Pritchard, a population geneticist from the Univresity of Chicago who headed the study, selection has been a major driving point in our evolution during the last 10,000 years. There's no reason to suppose that it has stopped!

Dr. Richard G. Klein, a paleoathropologist at Stanford added it was hard to correlate the specific gene changes in the three poupulation with events in the archaeological record but that the timing and nature of the changes in the East Asians and Euopeans seemed compatible with the shift to agriculture. Rice farming became widespread in China 6,000 to 7,000 years ago and agriculture reached Europe from the Near East about the same time.