Tuesday, December 11, 2007

Are humans evolving faster?

 
The press release from the University of Utah [Are humans evolving faster?] describes the Hawks et al. (2007) paper I blogged about earlier [Accelerated Human Evolution].

One paragraph caught my attention ...
The new study comes from two of the same University of Utah scientists – Harpending and Cochran – who created a stir in 2005 when they published a study arguing that above-average intelligence in Ashkenazi Jews – those of northern European heritage – resulted from natural selection in medieval Europe, where they were pressured into jobs as financiers, traders, managers and tax collectors. Those who were smarter succeeded, grew wealthy and had bigger families to pass on their genes. Yet that intelligence also is linked to genetic diseases such as Tay-Sachs and Gaucher in Jews.
The idea that selection for intelligence among Askenazi Jews could be observable in only a few hundred years seem far-fetched, to say the least [Evolution in the Ashkenazi Jewish Population]. Natural selection just ain't that strong if all it has to work with is a few (male) money lenders.

The fact that these are the same authors as the Hawks et al. (2007) paper is disquieting.

Call me even more skeptical ....

The press release from the University of Wisconsin-Madison, where John Hawks is located, says [Genome study places modern humans in the evolutionary fast lane] ...
In a study published in the Dec. 10 issue of the Proceedings of the National Academy of Sciences (PNAS), a team led by University of Wisconsin-Madison anthropologist John Hawks estimates that positive selection just in the past 5,000 years alone — around the period of the Stone Age — has occurred at a rate roughly 100 times higher than any other period of human evolution. Many of the new genetic adjustments are occurring around changes in the human diet brought on by the advent of agriculture, and resistance to epidemic diseases that became major killers after the growth of human civilizations.

"In evolutionary terms, cultures that grow slowly are at a disadvantage, but the massive growth of human populations has led to far more genetic mutations," says Hawks. "And every mutation that is advantageous to people has a chance of being selected and driven toward fixation. What we are catching is an exceptional time."

The findings may lead to a very broad rethinking of human evolution, Hawks says, especially in the view that modern culture has essentially relaxed the need for physical genetic changes in humans to improve survival. Adds Hawks: "We are more different genetically from people living 5,000 years ago than they were different from Neanderthals."
Wow! We are more different genetically from people living at the time the pyramids were built that they are from the Neanderthals from whom they separated 100,000 years earlier.

This must be a really, really good paper if that's what it proves. I can hardly wait for it to show up on the PNAS website.


[Photo Credit: Al Pacino as Shylock in The Merchant of Venice]

3 comments :

  1. I guess evolution can be fast if there is appropriate and enough pressure. Delineating how important the pressure is and when and how it conferred selective advantage must be the tricky part.

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  2. I couldn't find the paper anywhere on the PNAS site yet either, but I think I did find it here. Haven't got a chance to look at it yet though.

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  3. Good article, you make some interesting points.

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