Lemurs chat only with their best friends

When you get a phone call or a text from a friend or acquaintance, how fast you respond — or whether you even bother to pick up your phone — often depends on the quality of the relationship you have with that person. If it’s your best friend or mom, you probably pick up right away. If it’s that annoying coworker contacting you on Sunday morning, you might ignore it.

Ring-tailed lemurs, it seems, are even pickier in who they choose to respond to. They only respond to calls from close buddies, a new study finds.

These aren’t phone calls but contact calls. Ring-tailed lemurs live in female-dominated groups of 11 to 16, and up to 25, animals, and when the group is on the move, it’s common for one member to yell out a “meow!” and for other members to “meow!” back. A lemur may also make the call if it gets lost. The calls serve to keep the group together.

The main way ring-tailed lemurs (and many other primates) build friendships, though, is through grooming. Grooming helps maintain health and hygiene and, more importantly, bonds between members. It’s a time-consuming endeavor, and animals have to be picky about who they bother to groom.

Ipek Kulahci and colleagues at Princeton University wanted to see if there was a link between relationships built through grooming and vocal exchanges among ring-tailed lemurs. Contact calls don’t require nearly as much time or effort as grooming sessions, so it is possible that animals could be less discriminating when they respond to calls. But, the researchers reasoned, if the vocalizations were a way of maintaining the relationships built through painstaking grooming sessions, then the lemurs would be as picky in their responses as in their grooming partners.

So they watched four free-ranging lemur colonies — two at the Duke Lemur Center in North Carolina and two on St. Catherine’s Island in Georgia — and mapped out who groomed whom and which lemurs responded to which calls from other lemurs. The researchers also played back recorded lemur calls to see who responded. The team reports their findings in the December Animal Behaviour.

Not all lemurs were alike. Some were extremely social, grooming lots of other animals and calling back to plenty of their brethren. Others were loners, hardly grooming anyone and rarely responding to contact calls. But regardless of how social an animal was, the lemurs tended to respond vocally only to lemurs that they groomed most frequently and probably have the strongest social bonds, the researchers say. In other words, they may have groomed their friends, but they only responded to the contact calls of their besties.

The contact calls may allow the lemurs to “groom-at-a-distance” and maintain their social bonds, the team concludes.

And maintaining those bonds is important. If I were dependent on others to pick dead skin, insects and other bits and pieces off my body, I’d probably answer the phone when they called.