Two other interesting examples of localized 'evoluation' of the human genome.   Another took place in the Middle Ages when those who could process alcohol survived at much higher rates than those who could only hydrate with the germ ridden water of the day (http://www.washingtonpost.com/wp-dyn/content/article/2008/07/09/AR2008070901934.html).

The Paleolithic Model of nutrition is based on the idea that our genome has not significantly changed in the last 10,000 years.  We evolved to eat a non-grain, therefore largely low carbohydrate diet.  Even within that paradigm, however, there's evidence that some evolutionary effect has taken place - which is to say, some of those with grain intolerance diet out faster and younger and with fewer offspring.  That's why the Paleo paradigm is a model, to guide inquiry.  Ultimately, when the model collides with what we find through experience or science, we defer to 'what works.'

"Ten thousand years ago, people in southern China began to cultivate rice and quickly made an all-too-tempting discovery — the cereal could be fermented into alcoholic liquors. Carousing and drunkenness must have started to pose a serious threat to survival because a variant gene that protects against alcohol became almost universal among southern Chinese and spread throughout the rest of China in the wake of rice cultivation.

Multimedia

Genetic Changes

RSS Feed

 Get Science News From The New York Times »

The variant gene rapidly degrades alcohol to a chemical that is not intoxicating but makes people flush, leaving many people of Asian descent a legacy of turning red in the face when they drink alcohol.

The spread of the new gene, described in January by Bing Su of the Chinese Academy of Sciences, is just one instance of recent human evolution and in particular of a specific population’s changing genetically in response to local conditions.

Scientists from the Beijing Genomics Institute last month discovered another striking instance of human genetic change. Among Tibetans, they found, a set of genes evolved to cope with low oxygen levelsas recently as 3,000 years ago. This, if confirmed, would be the most recent known instance of human evolution."

http://www.nytimes.com/2010/07/20/science/20adapt.html?_r=3&ref=science