NYT: Humans still evolve (HAPMAP)

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here is the HapMap homepage:

here is the NYT article by science-writer Nicholas Wade (7 March 2006)

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Still Evolving, Human Genes Tell New Story

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. Richard G. Klein, a paleoanthropologist at Stanford, said that it was hard to correlate the specific gene changes in the three populations with events in the archaeological record, but that the timing and nature of the changes in the East Asians and Europeans 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 around the same time.

Skeletons similar in form to modern Chinese are hard to find before that period, Dr. Klein said, and there are few European skeletons older than 10,000 years that look like modern Europeans.

That suggests that a change in bone structure occurred in the two populations, perhaps in connection with the shift to agriculture. Dr. Pritchard's team found that several genes associated with embryonic development of the bones had been under selection in East Asians and Europeans, and these could be another sign of the forager-to-farmer transition, Dr. Klein said.

Dr. Wells, of the National Geographic Society, said Dr. Pritchard's results were fascinating and would help anthropologists explain the immense diversity of human populations even though their genes are generally similar. The relative handful of selected genes that Dr. Pritchard's study has pinpointed may hold the answer, he said, adding, "Each gene has a story of some pressure we adapted to."

Dr. Wells is gathering DNA from across the globe to map in finer detail the genetic variation brought to light by the HapMap project...

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lots more, this is just more or less random exerpts

kind of a seachange in anthropology, I'd say, driven by advances in human genetics

Answers and Replies

  • #2
Evolution is defined, very basically, to be the change in allele frequency from one generation to the next. There doesn't have to be any noticeable change in phenotype, though there very often is one.
  • #3
A species will stop evolving if its environment stops changing and becomes permanent forever, and if the species is perfectly adapted to it. In other words, there will be no end to evolution.

I'm not surprised by the study, but glad to see some evidence, both for my own edification and as another argument against creationism.
  • #4
Just to clarify for everyone else, the above is known as the http://en.wikipedia.org/wiki/Hardy_weinberg" [Broken] and states (basically) that evolution of a population will not occur if:
1. there is no natural selection
2. there is only random mating
3. there is no genetic mutation
4. no migration, no contact with other populations

There are other rules cited too, listed on wikipedia or http://anthro.palomar.edu/synthetic/synth_2.htm" [Broken]

Suffice it to say, no population will ever stop evolving, probably not even if you tried to enforce these limits.
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