Oh, I just can't resist:
McDonald, Kim A. "Shared Paternity in South American Tribes Confounds Biologists and Anthropologists," Chronicle of Higher Education, April 9, 1999, pp. A19-20:
"Recent studies of multiple fatherhood in indigenous societies in South America are forcing scientists to rethink their notions about the evolutionary roles of female fidelity and male provisioning...."
"'Throughout lowland South America, there is a belief in the partability of paternity... The belief, in essence, is that all of the men who have sex with a woman around the beginning of her pregnancy and all through her pregnancy share the biological paternity of her child. In this view, the fetus is considered to grow by repeated contributions of semen.'
"The pervasiveness of those beliefs among at least 18 widely separated and distinct cultures in South America, said Mr. Beckerman, suggests that social views about fatherhood are not universal and do not follow the standard picture of the evolution of human sexuality. In fact, he noted, examples of a belief in partible paternity are being discovered outside South America, in indigenous societies in New Guinea, Polynesia, and India.
... "What's more, the concept of multiple fatherhood may minimize sexual jealousy, a source of potentially lethal conflict between men. Mr. Beckerman said that one of the more fascinating findings in his work with the Bari, a lowland horticultural society, was that "we never got a man expressing jealousy over his wife taking a lover.
"[Beckerman says:] 'Presumably, it's because, when that happens, the husband, in effect, has purchased a life-insurance policy. If he dies, then there is some other male who has at least a residual obligation to those children, most of whom probably belong to the husband. So, it's to his benefit to have his wife take a lover or two.'" "'All of this calls into question this presumed evolutionary bargain between men and women in which, in effect, female fidelity and guaranteed paternity are the coin with which women pay for resources provided by their mates,' he said. (He is Stephen J. Beckerman, professor of Anthropology at Pennsylvania State University.)
..." Ms. Hawkes of Utah said that what was clear about all of those societies was that they do not fit the evolutionary paradigm—that, as humans evolved, males shifted their efforts away from competition with one another for mates to parental nurturing.
"Her own studies of the Aché of eastern Paraguay and the Hadza of northern Tanzania, she said, "don’t support the notion that men's work is about providing for their kids." Goes on to say hunting (and collecting honey) "do not provide more for a man’s own wife and children than they do for anybody else."
*** Jenny Brown