In the ancient Amazon, children had many fathers - and women many lovers

Few cultures are as sexually liberated as those of the ancient Amazon rainforest. Nearly 70 percent of the tribes practiced multiple paternity, in which all of a woman's sexual partners were fathers to her children.

It was commonplace for people to be open about having multiple sexual partners in the ancient Amazon. Open sexual arrangements were socially accepted, even expected, according to anthropologist Robert Walker. And these multiple attachments were anything but casual. Men acted as father figures to the children of any and all of their partners. A woman could marry one man, making him the primary father to her children, but all the other men in her life would be considered vital secondary fathers.

In the ancient Amazon, children had many fathers - and women many lovers

As Walker explains, this was partly because of the ancient Amazonians' rather unique take on genetics:

"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. It was socially acceptable for children to have multiple fathers, and secondary fathers often contributed to their children's upbringing. In some Amazonian cultures, it was bad manners for a husband to be jealous of his wife's extramarital partner. 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."

For children, having as many fathers as possible had its advantages. More dads meant more gifts and support for the child, which is known to increase a youngster's odds of reaching adulthood. Besides, it was a rather pragmatic solution to a basic fact of life in a culture where warfare was all too common and brutal. If a child's primary father died, he or she would have other males around to step in and act as father figures, easing the newly widowed mother's burden.

Men also benefited from this system. Sharing paternity brought men together, cementing bonds and friendships (basically, just like Three Men and a Baby, just with less Steve Guttenberg). Indeed, one of the best ways for two men to cement an alliance was to share wives, often in a family - brothers were some of the most frequent wife-sharers.

According to Walker's new research, of 128 indigenous groups in lowland South America, 53 are known to practice multiple paternity, while only 23 are known to practice single paternity. The remaining 52 don't have clear conception beliefs, making it difficult to know whether they once possessed this custom. That means at least 40% and perhaps as much as 70% of these groups once practiced multiple paternity, which definitely means it was a common feature of Amazonian civilization.

[via Proceedings of the National Academy of Sciences]