One may be the loneliest number for humans, but some mammals fare better when they are on their own. Take, for instance, the yellow-bellied marmot. As Douglas Quenqua reports for the New York Times, researchers in Colorado have tracked the interactions and lifespans of these hefty rodents. And they found that marmots that shirked social contact tended to live longer.
Yellow-bellied marmots are adaptable creatures that prefer to live on their own, but can get along with one another if their populations grow large and space becomes limited. To dig more into these social dynamics, a team of researchers, led by Daniel T. Blumstein, a biologist at the University of California, Los Angeles, spent 13 years tracking 11 marmot colonies in Colorado. These colonies were divided into social groups of different sizes, ranging from solitary females to those living in multi-female groups. (As Angela Chen of The Verge points out, the study focused on female relationships because adult males do not stay with colonies.)
Observing the critters from a distance using binoculars, scientists watched the marmots as they sat together, played, groomed one another and searched for food. The results of the team's study, published recently in the journal Proceedings of the Royal Society B, revealed that more socially active marmots lived, on average, two years less than the marmots that kept to themselves. That's a fairly significant discrepancy, since marmots' average lifespan is only 15 years.
These findings sets marmots apart from humans and other mammals whose longevity is increased by strong social bonds. Female baboons, for example, have been shown to live significantly longer when they have stable relationships. The same is true of female rhesus macaques. One study of humans found that a lack of social connections could increase the risk of premature death from all causes by 50 percent (something to keep in mind the next time you feel resentful about getting dragged to your second cousin’s wife’s baby shower).
But researchers aren’t entirely sure why marmots’ antisocial behavior leads to greater longevity. Blumstein tells Quenqua that social marmots might be transmitting diseases to one another, or waking each other up during hibernation, which can lead to starvation. It is also possible that hanging out with their buddies distracts marmots when they should be looking out for predators. “There are a variety of plausible explanations,” Blumstein says. “I just don’t know what they are yet.”