New Study May Explain Evolution of Monogamy in Humans
"Breaking up is hard to do": it's a saying that many have heard or said, because of the emotional effects that break-ups can carry. However, it may also well be the lesson learned from studies on primates. Researchers from the University of Pennsylvania in the United States and from the University of Derby in the United Kingdom have found that, among owl monkeys, monogamous couples have 25 percent more children than monkeys who have two or more partners.
Owl monkeys are a species that had been known to be socially monogamous. Typically, their families consist of a nuclear family similar to many of those found in the human world: two parents and their offspring, who typically leave the nest at around the age of 3 or 4. However, over the course of a 16-year study in Argentina, researchers discovered a surprising phenomenon: floaters, who would attack one of the mates and wrest control of the nest. The attack would often end fatally for the original partner who was attacked. Over the course of their study, 27 female floaters and 23 male floaters replaced partners in the brood.
Researchers found that monogamous monkeys had more reproductive success than those who were forced to change partners. They have several theories for this phenomenon. Female owl monkeys are typically only fertile between the months of March and May. Because monogamous couples have already taken the time to assess one another before reproducing, there is no need for a delay during that window.
Another theory with wider implications is simply that monogamy promotes reproductive fitness. Because the males know that the offspring is theirs, they are more likely to share parental duties with the females, easing the burden of pregnancy and lactation. This may be particularly true among owl monkeys, where males invest significantly in the care of their offspring.
While even today not all human cultures are monogamous, "there's some consensus among anthropologists that pairs-bonds must have played an important role in the origin of human societies," study author Eduardo Fernandez-Duque said in a statement. "Call it love, call it friendship, call it marriage, there is something in our biology that leads to this enduring, emotional bond between two individuals that is widespread among human societies."
The study was published in the journal PLoS One.