Male gorillas who babysit have five times more babies

When it comes to gorillas, the males who help females out with their infants get benefits. The benefits? More babies. A new study of male gorillas in the wild in Rwanda has found that those who spend the most time grooming infants and resting with them—others’ offspring as well as their own—have about five times more offspring than males who don’t help out with the little ones.

This is surprising, scientists say, because male caretaking isn’t usually considered a smart reproductive strategy in primate species where access to females is intensely competitive. Instead, researchers thought the most successful strategy for males would be to put more time and energy into outcompeting other males for a mate, as chimps do.

That strategy still works for many male gorillas, who dominate small harems of females. But in 40% of the groups of mountain gorillas studied at the Dian Fossey Gorilla Fund’s Karisoke Research Center in Volcanoes National Park in Rwanda there is more than one male in a group, sometimes as many as nine. And those males need to be resourceful to get a female’s attention.