More Monkey See, Monkey Do.

[jamesq]

Quasi-related to the previous post, I read a study about a year ago on altruism in animal populations. I don't have a cite for it now (I read it in a magazine) so this is mostly from memory.

Chimps cooperate with each other and also do each other favours. This is not surprising when you consider that they're our closest living relative and very similar as far as social primates go. What surprised the researchers was that favour-trading was almost exactly like humans. Basically, you can divide favour-trading behavior into three categories:

1. Screw you: Chimp-A isn't going to do a favour for Chimp-B, even if it means losing out personally. For example, cooperation gives a reward of some kind. This seems to be reserved for when Chimp-A has a personal grudge against Chimp-B.
   
2. Tit-for-tat: Chimp-A keeps a mental tally of favours to Chimp-B and will stop doing them if Chimp-B doesn't reciprocate. Note that the favours will start up again if Chimp-B cleans up his act. Also note that new chimps tend to fall into this category, albeit with a fairly narrow leeway.
   
3. Mi Casa Su Casa: Chimp-A is always willing to help out Chimp-B (and vice-versa), but they don't keep a mental tally. The chimps are friends basically.

This is classic game theory, so the researchers weren't terribly surprised by the findings. It was when they looked at chimps that jumped from one category to another that they found it to be especially human-like.

It takes a lot of effort to move between categories. The level of effort also changes depending on past behavior. Going up a level (tit-for-tat to mi casa su casa for example is relatively simple the first time you do, but becomes a lot harder if you've dropped and are trying to return. A large enough betrayal and you can't return at all.

Love and loyalty. Hatred and betrayal. There was a time when I thought animals couldn't have the same level of emotion that we do, but I'm coming around on that. Partially because I read this study and it felt very right to me.

Comments

[wee-megan.livejournal.com]

I just wrote my primate behaviour final so I'll add my 2 cents ;)

The third type of altruism you mentioned (Mi Casa Su Casa) is thought to have evolved through Kin Selection as these interactions are almost ALWAYS between two closely related chimps (or other primates for that matter...many of them do this). Kin Selection is related to natural selection except for that it explains how altruistic behaviours likely evolved.

An altruistic behaviour is hard to understand in terms of natural selection as it is a behaviour that actually LOWERS the fitness of the actor. If one monkey makes an alarm call for example to warn the others of a predator, it has just exposed itself and is more likely to be the one caught and eaten. Kin selection looks at something called "inclusive fitness". It's like adding your own reproductive success (# of your alleles passed on to future generations) and the reproductive success of your relatives (but weighted by how closely related they are to you). So if by acting altruistically the chimp decrease its own direct fitness but increase its inclusive fitness more than what was lost of direct fitness then it will act in an altruistic manner.

The "tit for tat" type of altruism are referred to as reciprocal altruism and is exactly that. "I'll groom you for 45 minutes if you back me up in a fight later." etc. These don't have to be between kin because they're getting something back for their effort.

The first type of altruism "screw you" is usually a ranking issue. A higher ranking chimp can receive altruistic actions from others with no need to return the favor becauase they've "earned" their position and help do things like defend the territory etc and "deserve" these rewards.

Anyway, I'm probably just rambling at this point and I have no idea if you're even interested in what I'm writing so I'm going to stop now...super tired...