Birds of a feather flock together.
These are two proverbs we are all familiar with. When it comes to friendship, we are keen on the former, but when it comes to love, it is the latter we hold dear. This got me thinking: Do animals make a similar distinction depending on whether they are looking for a best friend or for that special someone?
The answers tell us a lot about how we make these judgments as well.
First, let’s establish that animals do form friendships with each other. Like humans, sometimes these friendships are fleeting, and other times they are stable over many years. Although there are many benefits to having friends, it takes time and energy to maintain these relationships. If you are human, that may involve late-night phone calls comforting a friend after a breakup. If you are a chimpanzee, you may spend time digging bugs and dirt out of your pal’s hair.
But, human or chimp, how does one actually decide who to be friends with? How alike you are may be the key, whether it is age, gender, social status (high school, anyone?), or even personality. A recent study looking at what factors predicted friendships between pairs of chimpanzees revealed that individuals with similar personalities were more likely to be friends. Massen and colleagues report (in Evolution and Human Behaviour) that outgoing chimpanzees were buddies with each other, while shyer types also stuck together. For chacma baboons, touchy-feely types tended to pair up while the more aloof become friends—without all the touching and feeling, of course.