17 October 2009

Human Beings Evolving at Unprecedented Rate

A team led by University of Wisconsin-Madison anthropologist John Hawks estimated that positive selection just in the past 5,000 years alone -dating back to the Stone Age - has occurred at a rate roughly 100 times higher than any other period of human evolution.

...The human population has grown from a few million people 10,000 years ago to about 200 million people at A.D. 0, to 600 million people in the year 1700, to more than 6.5 billion today. Prior to these times, the population was so small for so long that positive selection occurred at a glacial pace, Hawks says...

The Wisconsin study is published in the Dec. 10 issue of the Proceedings of the National Academy of Sciences __DailyGalaxy
Many of the recent adaptations relate to disease resistance, such as resistance to malaria, smallpox, and other plagues. Other adaptations no doubt relate to resistance to heat or cold, ability to digest particular foods, body size and shape, muscle mass and speed, and other relatively uncontroversial adaptations.

More controversial would be adaptations that influence brain size, complexity, plasticity, and reaction times. Anything that gives genetic advantage in terms of problem solving and / or goal orientation, would give significant advantage to populations possessing those positive 2nd order adapatations.

The study of Ashkenazi Jews by Harpending and Cochran ATTN: PDF provides a view focused upon a single population of loosely related individuals who underwent rapid evolutionary changes over the past few thousand years.

One of the greatest intellectual curses of modern day humans is "groupthink", which includes "political correctness" and excessive deference to authority. Mass incompetence provides groupthink with its power over populations. Mass incompetence is fed by poor childraising, perverse educational practises, a self-destructive popular culture, and the mass indoctrination into the groupthink cult by media and higher academia.

As scientists learn more about evolutionary adaptation to human culture, it will be fascinating to locate genes that provide resistance to groupthink.

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Blogger neil craig said...

I would have thought evolution would change more slowly in large populations & that Ashkenazi mutations have been able to become widespread & reinforced precisely because they were not diluted.

Sunday, 18 October, 2009  
Blogger al fin said...

An interesting question, Neil.

Selective pressures are different in large vs small population groups. Small isolated population groups can indeed "quickly" drift genetically away from a parent population -- due to selecting from a more limited choice of alleles.

A large population has a wider range of genetic potential, and can provide more adapted specimens for a larger number of niches.

Smaller breeding populations can evolve on their own, or in the middle of a much larger outside population -- as did the Ashkenazi.

In other words, the Ashkenazi were influenced by evolutionary pressures coming from outside the breeding community, and were provided survival niches by the outside, larger community.

It is not an either-or phenomenon when it comes to small populations immersed within -- but genetically semi-isolated from -- the larger population.

As for the adaptations providing disease resistance and a wider range of food tolerances, it should be obvious why larger populations provide more potential material for adaptation.

Sunday, 18 October, 2009  

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