Amazonian Cultures Found Social Benefits in Multiple Fathers

Up to 70 percent of Amazonian cultures practiced multiple paternity–more than one man fathering and taking responsibility for a child–according to research announced today by the University of Missouri (MU).

“In modern culture, it is not considered socially acceptable for married people to have extramarital sexual partners. However, in some Amazonian cultures, extramarital sexual affairs were common, and people believed that when a woman became pregnant, each of her sexual partners would be considered part-biological father,” MU said about a study published in the journal Proceedings of the National Academy of Science that found that nearly three out of four Amazonian cultures may have believed in the principle of multiple paternity.

“In these cultures, if the mother had sexual relations with multiple men, people believed that each of the men was, in part, the child’s biological father,” said Robert Walker, assistant professor of Anthropology in MU’s College of Arts and Science. “It was socially acceptable for children to have multiple fathers, and secondary fathers often contributed to their children’s upbringing.”

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The Yanomami are among the Amazonian cultures who have beliefs in partible paternity.

NGS stock photo by Robert Madden.

Sexual promiscuity was normal and acceptable in many traditional South American societies, Walked explained.

“Married couples typically lived with the wife’s family, which increased their sexual freedom,” Walker said.

“In some Amazonian cultures, it was bad manners for a husband to be jealous of his wife’s extramarital partners. It was also considered strange if you did not have multiple sexual partners. Cousins were often preferred partners, so it was especially rude to shun their advances.”

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Approximate distribution of the six major language families discussed in this study.

Data provided by World Language Mapping System. Map by Robert Walker, University of Missouri.

Previous research had uncovered the existence of multiple paternity in some Amazonian cultures, MU said in a news release about the research. “However, anthropologists did not realize how many societies held the belief. Walker’s team analyzed ethnographies (the branch of anthropology that deals descriptively with cultures) of 128 societies across lowland South America, which includes Brazil and many of the surrounding countries. Multiple paternity is reported to appear in 53 societies, and singular paternity is mentioned in 23 societies. Ethnographies for 52 societies do not mention conception beliefs,” the university explained.

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Walker’s team has several hypotheses on the benefits of multiple paternity, according to MU.

“Women believed that by having multiple sexual partners they gained the benefit of larger gene pools for their children. [Walker] says women benefited from the system because secondary fathers gave gifts and helped support the child, which has been shown to increase child survival rates. In addition, brutal warfare was common in ancient Amazonia, and should the mother become a widow, her child would still have a father figure.”

Photo: Robert Walker, assistant professor of Anthropology in the College of Arts and Science. Photo courtesy of MU.

“Men benefitted from the multiple paternity system because they were able to formalize alliances with other men by sharing wives,” MU said. “Walker hypothesizes that multiple paternity also strengthened family bonds, as brothers often shared wives in some cultures.”

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Village men in a Yanomami settlement. In the majority of Amazonian cultures, it was socially acceptable for children to have multiple fathers, and secondary fathers often contributed to their children’s upbringing.

NGS stock photo by Robert Madden.

Walker collaborated with Mark Flinn, professor in the MU Department of Anthropology, and Kim Hill, professor in Arizona State University’s School of Human Evolution and Social Change.

Read the paper: Evolutionary history of partible paternity in lowland South America.

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