For the past two weeks we've been discussion research related to altruism in non-human primates in my class on the evolution of primate cognition.

I hadn't really scrutinized the meaning of the word very much in the past, but repeated claims in the introductions to these papers along the line that "altruism has long been thought to be unique to humans" made me balk.

There are clear cases of animals either increasing the risk to themselves or sacrificing themselves in order to protect other members of their species. Bees basically gut themselves and die when they use their stingers, and yet they will engage in this behavior, killing themselves in order to protect the hive. Some birds will let out a warning cry when a predator is spotted, increasing the danger to themselves in order to warn others. Richard Dawkins cites many examples in The Selfish Gene. These are cases of kin selection, where closely-related individuals act at a cost to themselves in order to increase the fitness of others who share many of their genes.

One way to think about it is this: Even if you don't have children, but you sacrifice yourself to ensure the survival and reproduction of (let's say) 10 of your brothers and sisters, then the end result is that more of your genes will be passed on than if you had acted selfishly and let them die.

But what about unrelated individuals? Are humans the only species that acts selflessly without expectation of reward? Personally, I don't buy it. I think those who give confer psychological benefit due to empathy, but that the overwhelming majority of cases of "altruism" in humans have to do with the idea of reciprocation.

That is, most acts of giving or sacrificing for unrelated individuals are cases where we are expecting reciprocation in the future (not necessarily from the individual that we just helped, but from others in a position to reciprocate). Here's one example: Let's say you live in a community where most people (80-90%) tend to hold doors open for each other if someone is behind them. You tend to hold doors open for people too...but is this altruistic? What if everyone but you stopped holding doors open for anyone else? Would you continue to do it?

The cost for holding a door open is pretty low, so this is a mild example. But I think it still makes the point. If you continued to engage in altruistic behavior for the rest of your life, without anyone else in the community returning the favor, saying "thank you", or otherwise acknowledging your acts, I doubt many people would keep it up for long.

So I think the Golden Rule is essentially an implementation of tit-for-tat strategy. We engage in seemingly altruistic behaviors in anticipation of situations where we are the ones in need of help. We want to live in a highly reciprocal society because that kind of collective contract boosts our own well-being over a society in which everyone acts purely selfishly.

I don't think this makes us necessarily unique. Other species engage in this kind of mutual exchange all the time (which goes by the unfortunate name of reciprocal altruism, which seems like an oxymoron to me). What does make it different from other species is that our long memories and enhanced cognitive skills allow for a greater window of time in which to receive the reciprocation and link it with our own behavior. That is, most animals need immediate reinforcement for the behavior to persist. They might forget an individual's selfless behavior within a matter of minutes. But humans are able to track such acts over longer periods of time and fit them into larger contexts. So when we help someone today, we can still link that behavior with reciprocation many days, weeks, months, or even years later.

I don't think this makes us the angels of the animal kingdom. It just means that we're much more powerful, shrewder cooperators.