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There's a fascinating New York Times article that unfortunately I can't link to which has stuff about this. I'll post a few key bits:
Most animals struggle to survive in a harsh environment, beset by accidents and predators. Humans got that problem largely under control long ago but live in a fiercer jungle — that of a human society. Indeed, social intelligence — the ability to keep track of a society's hierarchy and what chits an individual owed to others or had due — may have been a factor in the increase of human brain size. As the prevalence of Caesareans suggests, the circumference of babies' brains seems to have gotten as large as circumstances permit. Will requirements for extra neural circuitry make our descendants into coneheads? Doubtless, sexual selection will maintain a decorative swatch of hair on top.
Society, and the knowledge needed to survive in it, seems to get ever more complex, suggesting that human social behavior will continue to evolve. Unfortunately, evolution has no concept of progress, so behavioral change is not always for the better. "I suspect that our social behavior evolves rapidly but that much of it changes direction over time," said Dr. Henry C. Harpending, an evolutionary anthropologist at the University of Utah.
Warrior societies like the Yanomamo of South America give reproductive success to the man who is "violent, scary and effective at male-male conflict," whereas among peasant farmers, the successful male would be one who feeds his children and passes on an estate to them, Dr. Harpending said.
A dramatic instance of the former process came to light earlier this year with the discovery that no less than 8 percent of men who live today in the former domains of the Mongol empire carry the Y chromosome of Genghis Khan and the Mongol royal house. It is hard to see a Genghis having much reproductive success in modern societies. Perhaps another Panglossian prediction is called for: in a more ordered society, evolution will favor the fostering type of male over the Yanomamo-style brutes.
Not everything is roses in evolution's garden. Ronald Fisher, the British biologist, pointed out in 1930 that the genes for mental ability tend to move upward through the social classes but that fertility is higher in the lower social classes. He concluded that selection constantly opposes genes that favor creativity and intelligence.
Fisher's idea has not been proven wrong in theory, although many biologists, besides detesting it for the support it gave to eugenic policies, believe it has proven false in practice. "It hasn't been formally refuted in the sense that we could never test it," Dr. Pagel said. Though people with fewer resources tend to have more children, that may be for lack of education, not intelligence. "Education is the best contraceptive. If you brought these people up in the middle class they would have fewer children," Dr. Pagel said. "Fisher's empirical observation is correct, that the lower orders have more babies, but that doesn't mean their genotypes are inferior."
Given all the possibilities for human evolutionary change, it is hard to know which path our distant descendants will be constrained to tread. From a New York perspective, however, it is hard to ignore a certain foreboding: that under the joint power of sexual selection and Fisher's gloomy prognosis we will become ever more beautiful and less acute. The future, in a word, is Californian. |
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