Why modern life left polygamy at the altar

UC DAVIS (US) — Compared to monogamous societies, polygamous cultures see more rape, kidnapping, murder, child abuse, and other crimes, a new study suggests.

When men take multiple wives, the competition for fewer available women results in greater levels of strife, the researchers hypothesize.

The findings may explain the global rise of monogamy as the dominant marriage institution in recent centuries, replacing polygamy, which was once practiced by 85 percent of the world’s societies, says Peter Richerson, environmental science professor at University of California, Davis..

“We wanted to understand both why monogamous societies have been economically more successful in the last few centuries and why monogamy has spread to many formerly polygamous societies in the course of modernization,” adds Richerson.

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Criminological data suggest unmarried men, particularly unmarried men of lower social status with lesser prospects of attracting wives, are disproportionately responsible for violent and other seriously disruptive behavior, he says.

Polygamy continues to be practiced in parts of Africa, Asia, the Middle East, and North America.

“The emergence of monogamous marriage is also puzzling because multiple marriage is mostly practiced by the economic and political elite who should be in a position to defend the practice,” Richerson says. “South African President Jacob Zuma, for example, is proud of having several wives.”

But, Richerson points out, what seems good for the man who has many wives does not work out as well for the rest of society.

“Our findings suggest that institutionalized monogamous marriage provides greater net benefits for society at large by reducing social problems that are inherent in polygamous societies.”

Published in the journal Philosophical Transactions of the Royal Society, the study says that by shifting male efforts from seeking wives to paternal investment, institutionalized monogamy increases long-term planning, economic productivity, financial savings, and child investment.

Monogamous marriage also results in significant improvements in child welfare, including lower rates of child neglect, abuse, accidental death, homicide, and intra-household conflict. These benefits result from greater levels of parental investment, smaller households, and increased direct “blood relatedness” in monogamous family households, the researchers say.

Joseph Henrich, a cultural anthropologist at the University of British Columbia, led the study, working with Richerson and Robert Boyd, a UCLA anthropology professor.

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