A new study has revealed that 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.
The study by University of Missouri found that up to 70 percent of Amazonian cultures might have believed in the principle of multiple paternities.
"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 the College of Arts and Science.
Walker said sexual promiscuity was normal and acceptable in many traditional South American societies. He said married couples typically lived with the wife's family, which he says increased their sexual freedom.
"In some Amazonian cultures, it was bad manners for a husband to be jealous of his wife's extramarital partners," Walker said.
"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."
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.
The team has several theories. 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.
Men benefitted from the multiple paternity system because they were able to formalize alliances with other men by sharing wives. Walker hypothesizes that multiple paternity also strengthened family bonds, as brothers often shared wives in some cultures.
The study has been published in the journal Proceedings of the National Academy of Science. (ANI)