Hairy Argument

For eight months, an erudite debate has roiled the letters column of the journal Science. At sober issue: How did man lose his body hair?

Geneticist Bentley Glass incited the fuss last winter when he suggested that human bodies began balding as soon as warm clothes ended the need for tufted torsos. Scoffing, one writer charged Glass with Lamarckianism, the discredited 1809 theory of French Naturalist Jean Baptiste Lamarck, who argued that giraffe necks grew long because the animals preferred eating treetop leaves and that such acquired characteristics could be passed on to offspring. In rebuttal, Glass argued that man's use of fire as well as clothing changed his environment enough "to make hairiness an inconsequential feature, except on the more exposed parts of his anatomy." Countered another scientist: What about "man's retention of abundant tufts in the axillae and pubic regions?"

Anthropologist C. Loring Brace waded in with the observation that humans who now wear the least clothing have the least hair on their bodies; those who wear the most have the greatest amount of hair. Brace believes that man lost his hair by hunting in the noon heat of tropical days; natural selection favored the relatively hairless hunters, whose bodies were best equipped to dissipate heat. This happened more than half a million years ago, says Brace, or roughly 400,000 years before man developed clothing.

Another debater suggests that ticks, fleas and lice living in the fur of hirsute early man carried epidemic diseases that destroyed whole populations, thus weeding out those carrying the hair gene. So far, no one really knows the answer. Perhaps the change was simply esthetic: bristly bachelors began preferring depilous dames.

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