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Bottoms Up

Recent evidence of convergent evolution in humans1 in the form of a gene which enables adult humans to digest lactose

shows that the mutations conferred an enormous selective advantage on their owners, enabling them to leave almost 10 times as many descendants as people without them. The mutations have created “one of the strongest genetic signatures of natural selection yet reported in humans,” the researchers write.

It’s stunning to think of how technē, biology, and environment come together to manifest “selective pressure” on living organisms and their descendants. Pastoralism among African populations provides an evolutionary incentive for genes which preserve lactose digestion into adulthood and confers reproductive advantage to people who inherit those genes.

However, when it comes to humans, the force of “natural” selection is subject to deformation by human agency. In this case, “natural” selection of lactose-tolerant humans who live in pastoral cultures presumes (for example) that the historical abundance of lactose-rich foods did not come at the expense of grain (to feed milk-producing cattle). It is entirely possible (nearly to the point of certainty) that those in a position to trade for lactose-rich foods and those who bred dairy cattle (read wealthy people in pastoral cultures) not only possessed the mutation which enabled them to digest milk into adulthood, but these people also may have had a deciding influence on the economies of their regions.

Excuse me while I finish my latté. end of article

1 Should the link to the New York Times article expire, an archived copy may be consulted.