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Robert Kurzban

The Evolutionary Psychology Blog

By Robert Kurzban

Robert Kurzban is an Associate Professor at the University of Pennsylvania and author of Why Everyone (Else) Is A Hypocrite. Follow him on Twitter: @rkurzban

Bottlenose Dolfriends

Published 10 November, 2010

Here’s one way that dolphins might choose their friends. They might have a look at the other dolphins and – assuming dolphins have a sense of what they look like – they might choose to befriend dolphins that look like them. You have a crooked dorsal fin? I have a crooked dorsal fin! We are made for each other. Kewl.

Another way that dolphins might choose their friends is pick the nearest other dolphin. Swim along, find a dolphin, whoever happens to be around and, hey, want to be friends? Let’s go tuna-tipping together!

Dolphin friendship decisions are important, I might mention. A report in Science last week discusses new findings reported in Biology Letters about bottlenose dolphins and the importance of their social networks. Male dolphins form alliances with one another and fight off other dolphin alliances in order to secure the favors of female dolphins, who are in estrus on average once every couple of months or so. So, of course, bad friendship choices can lead to serious effects on reproductive success. These fights can get really big, with up to about a couple of dozen dolphins involved, sort of like a football game.

The authors of the study, Richard Connor and his team, offer the following remarks about the relationship between what these mammals are up to and what we’re up to: “Only humans and Shark Bay bottlenose dolphins are known to have multiple-level male alliances within a social network. It is unlikely a coincidence that humans and dolphins also have in common the largest brains, relative to body size, among mammals. Our evidence for a third level of alliance formation in the dolphins should refocus attention on the potential cognitive burdens for individuals embedded in such a system, where decisions at one level may have impacts at other levels” (p. 4).

So, you know, they’re saying that alliances are complex things, requiring a lot of computation, subtlety, and that sort of thing.

Now, here’s my question. Two prevailing theories of friendship – arguably the leading theories – suggest that humans choose friends on the basis of similarity (homophily theory) or proximity (propinquity theory), along the lines of the way I began this post. (I’m not saying these are the only models; social exchange is a big one, too, and there are others.) The Connor work makes it sound like dolphins are very strategic, needing a big brain to maintain and navigate the complexities of multi-level alliances; in contrast, some theories of human friendship imply that our decision making in this respect is incredibly simplistic, relying on who’s around and who else has a crooked dorsal fin (or whatever). Does it seem right that dolphins are sophisticated social creatures while we’re the dullards?

Or could it be that theories of human friendship haven’t even scratched the surface of the subtlety and nuance of human friendship mechanisms?

That’s where my money is.

(Thanks to Peter DeScioli for bringing this work to my attention.)

  • Robert Kurzban

    Here’s a post by Jason Goldman drawing on this one.

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