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