Male Guinea baboons have a curious habit. They will walk—or sometimes run—to another male baboon and say a quick hello in a very enthusiastic way: with a “mutual penis diddle”. Or sometimes it’s a quick mount from behind. Other times, they do a short dance-like “polonaise,” facing the same way, on their hind legs, hand on the other’s hip, and a few steps forward.
Clearly, this behavior needs an explanation. In some ways, it’s not all that much of a mystery: ritual greeting is actually fairly widespread among many primate species and takes many colorful forms. It's a behavior that's “common among males living in multi-male groups,” write the authors of a new paper exploring Guinea baboons’ greeting behavior.
So it’s no surprise that the Guinea baboons greet each other. But the intimacy of their behavior stands out. Unlike other species, where ritual greetings serve to cool down a tense or aggressive moment, for Guinea baboons, it seems to be more about keeping their social bonds strong.