Science Tuesday - Evolution

Adventures in Very Recent Evolution
By NICHOLAS WADE, The New York Times, July 19, 2010

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.

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.

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Tracking the Evolution of Malaria
By SINDYA N. BHANOO, The New York Times, July 19, 2010

Malaria is an ancient and persistent disease. It wasn’t eradicated in the United States until the 1950s, and it is still devastating in developing countries around the world. The latest estimate from the World Health Organization is that in 2008 the disease killed more than a million people and afflicted 247 million others.

Scientists have long speculated about just how ancient the disease is, and when the human malaria parasite originated, with wildly varying estimates from 10,000 years to several million years ago.

Now, using statistical modeling and DNA analysis, a group of researchers report in the journal Science that ancestors of humans first acquired the malaria parasite known as P. falciparum 2.5 million years ago. But, the researchers wrote, the parasite probably did not cause disease in humans until much more recently, perhaps 10,000 years ago at the beginning of agriculture.

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