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Scientists decode the mystery of monogamy

Let’s stay together for the kids.

Scientists studying the evolution of human monogamy have found it’s more about lineage than love.

According to new research published in the Proceedings of the National Academy of Sciences, men evolved to stick by their female partner to make sure that rivals didn’t kill off their kin.

“Humans have ended up monogamous to some extent, it’s the predominant way we live,” head researcher Christopher Opie, an anthropologist at University College London, told The Guardian.

“What we have now is an evolutionary pathway for the emergence of monogamy.”

Opie and his team found the evolutionary path to monogamy by first examining the three commonly held theories for why any species evolves to monogamy.

The first theory holds that raising babies is hard, therefore it is better to have two parents instead of one. In the second theory, known as “mate guarding,” males stick by their mates in order to protect them from rivals. And finally, in the third theory, males stick around to make sure that rivals don’t kill off their offspring.

With the three theories in mind, Opie examined the family trees of 230 animals — including a number of primates and modern humans — to figure out rates of infanticide, mating behavior and paternal care.

They then repeatedly ran a simulation of evolution from 75 million years ago until modern day to find out how monogamy ebbed and flowed through time.

The scientists found out that infanticide by males was the only thing that preceded monogamy for primates.

“You do not get monogamy unless you already have infanticide, and you do not get a switch to paternal care if you don’t already have monogamy,” said Opie.

“Monogamy is only one strategy for dealing with infanticide. But it’s not the only one,” continued Opie. “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.”

While Opie’s findings seem reliable, Dr. Maren Huck, who studies animal behavior at the University of Derby, said that the conclusions should be taken with a grain of salt.

Huck’s biggest points of contention are that the authors of the study made false assumptions about infanticide and that the definition of monogamy that they used produced unusually high rates of monogamy.

“Very few old world monkeys, for example, are monogamous,” Huck said.