That’s similar to humans. But unlike humans, whose survival is linked in part to socioeconomic status, a higher place on the social pecking order didn’t help baboons. The most dominant males were 13 percent more likely to die at any given age than the least dominant ones.

The scientists believe this may be related to the big trade-offs male baboon bodies make for the traits that guarantee social status. Male baboons with high testosterone have a reproductive advantage, but the hormone suppresses their immune system. They age faster, too.

So do social ties actually cause longer lives, or is it just a correlation? “We still don’t know,” says Susan Alberts, chair of the Evolutionary Anthropology Department at Duke University, in a news release. The researchers say more work needs to be done to tease out the potential connection. “It’s one of the most wonderful black boxes in my life.”