In modern societies, extramarital affairs are unacceptable. However, in many Amazonian cultures it was not only common for a woman to have multiple sexual partners , but also the indigenous people considered that, when the woman became pregnant, each man with whom she had had relations was a partial biological father of her child , according to reveals a study published in the journal PNAS .
This model of multiple fatherhood had several advantages, since different men participated in the maintenance of the child, reducing the risk of infant mortality . Furthermore, since wars were so common in ancient Amazonian societies, if the mother was left a widow there would always be other father figures for the child. At the same time, for men, sharing a woman was a way of creating or reinforcing alliances between them.
"This custom began about five thousand years ago and was maintained in most societies in the region until a couple of generations ago; it is probably still maintained in 20 or 30 communities that have little contact with the outside," explained Robert Walker, researcher at the University of Missouri (USA) and co-author of the study.
