Anthropologists at University College in London, England have put together a possible explanation as to why humans became monogamous, when 97 percent of the Earth’s mammalian population is polygamous.
The team, led by Christopher Opie, had three possible explanations to start with.
The first explanation has to do with the demand of young children. When there are two parents around, the child can be better served. The second explanation is what is called “mate guarding,” which refers to males staying near their mates to protect them from rival males. Finally, the third explanation says that males serve to protect their babies from violent male rivals may try to kill the baby to make females fertile again.
To figure out which explanation was the right one, the team looked at the family tree of some 230 mammals and examined data on infanticide rates, paternal care and mating habits.
The team also ran a simulation that showed the rise and fall of monogamy over the course of 75 million years. After running the program millions of times, the team came to its conclusion: preventing infanticide is the main reason monogamy developed.
“Monogamy is only one strategy for dealing with infanticide. But it’s not the only one,” Opie said. “Chimps mate with all the males in their group to confuse paternity so males won’t attack. But in others, humans included, males stick with females to protect them.”
Another study on monogamy was also published this week, in the journal Science. Researchers on that study looked 2,500 species of mammals (excluding humans) and posited a different theory: the pairing of a male and a female allowed animals to travel farther away from their packs in search of food.
As well, there is some disagreement with the University College team’s findings.
“It would be premature to confidently claim that infanticide was the key factor in the evolution of social monogamy in primates,” Maren Huck, a primate researcher at the University of Derby, told CNN.
As well, some scientists aren’t completely convinced that humans are as monogamous as Opie’s research team suggests.
“I’m far from convinced that humans are really monogamous,” said Tim Clutton-Brock, a professor of ecology and evolutionary biology at the University of Cambridge. Clutton-Brock was also the lead author on the mentioned Science paper.
The findings of Opie’s team’s research was published in the journal Proceedings of the National Academy of Sciences.
