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For Hadza, build and brawn don't matter for choosing mates

Study of hunter-gatherer community in Tanzania shows that, across human groups, mating criteria vary

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3:23pm, November 13, 2009
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Unlike most Western guys and gals looking for love, Africa’s Hadza foragers pair up without regard to each other’s size and strength, a new study finds. And that stature-may-care approach underscores the often unappreciated variety of human mating strategies, the researchers say.

Hadza marriages don’t tend to consist of individuals with similar heights, weights, body mass indexes, body-fat percentages or grip strengths, say behavioral ecologist Rebecca Sear of the London School of Economics and anthropologist Frank Marlowe of Florida State University in Tallahassee. Neither do Hadza couples feature a disproportionate percentage of husbands taller than their wives, as has been documented in some Western nations, the researchers report in the Oct. 23 Biology Letters.

Almost no Hadza individuals mention height or size when asked to explain what makes for an attractive mate, Sear and Marlowe add.

People everywhere seek healthy, fertile marriage partners, Sear proposes. “But I suspect there may not be a preference for one particular signal of health in mates across every population,” she says.

Among the roughly 1,000 Hadza scraping out a living in rural Tanzania, knowledge of a potential mate’s health history may render that person’s height and weight irrelevant, the researchers suggest. Also, any health benefits of being big may get nullified by the difficulty of maintaining a large body during periodic food shortages endured by the Hadza.

Sear and Marlowe criticize evolutionary psychologists who have argued that physical size influences mating decisions in all societies. That argument rests largely on self-reports of Western college students and analyses of personal advertisements in U.S. newspapers for dating partners, they say.

Other researchers suspect that cultural evolution over the past 50,000 years, not genetic evolution during the Stone Age, has allowed human mating strategies to become increasingly diverse (SN: 5/23/09, p. 5).

“Cross-cultural data are hard to come by, and this is a valuable contribution,” comments psychologist Robert Kurzban of the University of Pennsylvania in Philadelphia. But he argues that the Hadza findings do fit with evolutionary psychologists’ proposal that genetically ingrained, universal mating strategies get triggered in different ways depending on social and ecological conditions.

In large societies, where people know little about one another’s health history and food is plentiful, height and weight may be reasonable initial indicators of a healthy mate, he suggests.

But increasing familiarity with a romantic partner breeds a more discriminating eye, remarks anthropologist Boguslaw Pawlowski of the Polish Academy of Sciences in Wroclaw.

Sear and Marlowe analyzed evidence for mating based on size and strength in 185 to 236 Hadza couples, the number of couples depending on the particular measure. A team led by Marlowe gathered this evidence from 2001 to 2006. Nearly all couples who were married during that period participated in the study.

Among the Hadza, women marry at around age 18 and men at age 20. After a sexual liaison, a couple will begin sleeping at the same hearth and is considered married. Only a small minority of men have more than one wife. Divorce is common, though, and most people get married many times.

In 8.2 percent of Hadza marriages, the wife was taller than the husband. That’s no different than the frequency of female-taller marriages expected to occur by chance, Sear says. In a 2006 investigation, she also found a random-chance level of female-taller marriages in an African farming community.

In contrast, the proportion of female-taller marriages in England is substantially lower than expected by chance, signaling a male-taller preference, she says.

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