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Middle aged heterosexual, WASP male. Semi retired, semi-sane and semi-serious. And endangered species and I'm not going quietly!!!!

Tuesday, June 26, 2007

One more Kick at the Evolution/Creation Cat!

Forget about the people who don't believe in Evolution at all.

We also have to address the people who believe in evolution but just aren't sure of the exact process.

Historians often assume that they need pay no attention to human evolution because the process ground to a halt in the distant past.

That assumption is looking less and less secure in light of new findings based on decoding human DNA.

Guest Post by NICHOLAS WADE of the New York Times:

Genetic differentiation in modern humans has continued to evolve since our leaving the ancestral homeland in northeastern Africa some 50,000 years ago.

This both through the random process known as genetic drift and through natural selection.

The genome bears many fingerprints in places where natural selection has recently remolded the human clay, researchers have found, as people in the various continents adapted to new diseases, climates, diets and, perhaps, behavioral demands.

A striking feature of many of these changes is that they are local.

The genes under selective pressure found in one continent-based population or race are mostly different from those that occur in the others.

These genes so far make up a small fraction of all human genes.

A notable instance of recent natural selection is the emergence of lactose tolerance — the ability to digest lactose in adulthood — among the cattle-herding people of northern Europe some 5,000 years ago.

Lactose, the enzyme that digests the principal sugar of milk, is usually switched off after weaning. But because of the great nutritional benefit for cattle herders of being able to digest lactose in adulthood, a genetic change that keeps the lactose gene switched on spread through the population.

Lactose tolerance is not confined to Europeans.

Last year, Sarah Tishkoff of the University of Maryland and colleagues tested 43 ethnic groups in East Africa and found three separate mutations, all different from the European one, that keep the lactose gene switched on in adulthood.

One of the mutations, found in peoples of Kenya and Tanzania, may have arisen as recently as 3,000 years ago.

That lactose tolerance has evolved independently four times is an instance of convergent evolution. Natural selection has used the different mutations available in European and East African populations to make each develop lactose tolerance.

In Africa, those who carried the mutation were able to leave 10 times more progeny, creating a strong selective advantage.

So there you have it! Being able to drink milk has such an evolutionary advantage that people who have acquired this trait can expect to live long enough to have 10 times as many kids.

This give them a much greater chance of their progeny continuing in future generations.

In other words, the long and the short of it is that we are STILL evolving, and will continue to do so!

Allan

(Remind me sometime to tell you about Genghis Khan, who is related to about 30 to 40 percent of all Mongolians!)

Allan W Janssen is the author of The Plain Truth About God-101 (what the church doesn't want you to know!) www.God-101.com

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