The Himba People of northern Namibia, one of the world's last surviving nomadic populations, have very different ideas about marriage and fidelity to most of the world. Not only is sex outside marriage accepted, but Himba men have no problems with raising children who are not biologically their own. The findings challenge the perception of a biological basis for monogamy as a social norm.
Most societies for which we have records prize monogamy, at least for women. Evolutionary psychologists generally ascribe this to the imperative for men to pass on their genes. They point to animal examples where it is common for dominant males to not only punish females they catch having sex with others, but kill offspring that are not their own. Indeed, there are abundant commentators who use these theories to justify domestic violence, either implicitly or explicitly.
An alternative view, most prominently promoted in the book Sex at Dawn, holds that ancestral humans were far less hung up about such matters, and monogamy only became seen as so important after the development of agriculture. A single study can't settle such a debate, but a combination of biological and sociological research among the Himba certainly favors those who doubt the universal status of currently dominant norms.
Despite the widespread belief that children of adulterous affairs are common, studies have found only 1-2 percent of children born into long-term relationships are the result of liaisons outside the pair. All but one of these studies have been done in the West, however. In Science Advances, UCLA's Dr Brooke Scelza reports that among the Himba the figure is 48 percent.
In most other societies such a figure would be seen as representing widespread trickery, with the mothers deceiving long-term partners into raising children of men they preferred for casual sex. However, Scelza found most Himba fathers are aware when children are not biologically theirs, and don't consider this important.
"Himba have strong beliefs about the importance of social fatherhood, that a child is yours if it is born to your wife, regardless of paternity," Scelza said in a statement. "Both the stigma that typically surrounds women having multiple partners and the bias that might lead to children being mistreated are markedly lower among Himba than they are in much of the rest of the world." Many Himba fathers raise children who are biologically their own alongside those who are not without apparent favoritism.
One nomadic society is not necessarily indicative of how all humanity operated prior to the adoption of agriculture. Indeed as pastoralists who move with their herds in search of the best grass, rather than hunter-gatherers, the Himba lifestyle is different from most of human prehistory.
Nevertheless, the addition of modern genetic techniques allows new light to be shed on an old debate. Margaret Mead, for example, became a superstar in anthropology partly for her claims that Samoan culture accepted casual sex before marriage, but subsequent visitors to the same islands have disputed these claims and tarnished her reputation.
Scelza is not claiming jealousy is unknown among the Himba, and witnessed it occurring, but has previously reported: “Many [Himba] people would be uninterested in having a spouse who could not attract other partners.”
As the paper notes, studies like this raise “a host of logistical and ethical challenges that are not present when assessing paternity in other species.” Scelza spent seven years consulting with the Himba themselves and Namibian institutions to design a unique double-blind process to avoid community disruption. The results of individual genetic tests were not revealed either to the Himba, or to anthropologists working on the ground.