When I got my new driver’s license last week, I was asked if I still wanted to be an organ donor (that stipulation is put on the license). I said, “Of course.” There’s no reason not to be a donor: it doesn’t cost you anything since you’re dead and don’t need the organs (unless you’re the kind of Christian who thinks he needs a heart and corneas to meet Jesus), and it gives you some satisfaction that even after death you can help someone else.
People call that an “altruistic” gesture, but it isn’t, really—it isn’t “cultural”altruism” and it isn’t “biological altruism”. “Cultural altruism” is simply sacrificing something you want to help someone else, without getting anything of equal value in return for your sacrifice. Examples are people like volunteer firemen—women are included here, I just don’t know if “firepersons” is a word)—who risk their lives for no pay, and soldiers who fall on grenades to save their fellows. In such cases it’s hard to make an argument that what you get back is equal to losing your life. Another example is Lennie Skutnik, who risked his life in 1982 diving into the Potomac to save the life of a passenger in the water after the Air Florida Flight 90 crash.
But things get a bit dicier with lesser acts of “heroism”. If you tutor illiterate adults to help them learn, as I once did, was that altruistic? After all, I got a great deal of satisfaction from watching people learn to read as adults, so was what I reaped less than what I sowed? How do you know? After all, I get bragging rights (I just bragged), and even if others didn’t know about it, there’s still an internal sense of satisfaction. Those who donate big sums of money to colleges to build buildings with the donor’s name on them are in the same position: they have lots of dosh and don’t lose much—but they get to see their name on a building, and have everybody refer to that building as “Cowles Hall”. Gestures of generosity are often publicized, so they’re less “unselfish” than you think.
It’s hard to judge most acts as “altruistic” since the currency of action versus personal satisfaction aren’t comparable. One could claim, for instance, that “everyone does what they want, which is more or less a claim that you always reap at least as much as you sow. Nevertheless, you have to admire those who risk their lives, like Skutnik, to help others, for he could have died doing that, and would reap no reward. It is for these reasons that I don’t like to use the word “altruism” as shorthand for “doing something costly”.
Biological altruism is very different, and has to do with genes rather than emotional satisfaction. (People are always mixing up biological and cultural evolution, and mixing up both with kin selection, as I note below.) Biological altruism is a genetically coded behaviors for actions that lower your lifetime reproductive success while enhancing the reproductive success of some other member of your species (or even of another species). If fighting fires had a genetic component, volunteer firemen would be an example of biological altruism, for they lower (on average) their net reproductive success while enhancing that of the people whose lives they save. I doubt, though, whether there’s a genetic component to fighting fires, though there may be for risk-taking.
A better example would be a baboon risking its own life to save the life of a baboon from another troop. Or an individual warning other unrelated individuals that a predator is near, and risking its life by so doing (perhaps giving an “alarm call” focuses the predator’s attention on you). There are alarm calls, but they may incur no reproductive cost (after all, you’ve already seen the predator), or they may help save your relatives more than others, in which case their evolution could be understood by kin selection (see below).
Biologically altruistic behaviors are not expected to evolve under Darwinian natural selection, because the genes promoting them would be eliminated by selection from populations. The only way they can evolve is by group selection—groups with higher proportion of genetic altruists may do better than groups having a lower proportion. And although within each group altruists are selected against, that might be outweighed by the higher proliferation and longer persistence of groups that contain more altruists. If the “group-persistence-and-reproduction” effect is strong enough, it could outweigh selection within groups and increase the proportion of altruists in a species.
But that kind of group selection would have to be strong, and even if it did work, after the altruists come to dominate a species the genes for altruism will continue to be selected out of the species. Altruism is genetically unstable under group selection.
Because of this, we don’t expect to see much true biological altruism in animals. And we don’t: I’m not aware of any examples in which an individual reduces its lifetime reproductive success (“fitness”) to help another individual without gaining a genetic benefit. Even in cases that look like altruism (creches in which mothers suckle young of other individuals), there’s always a potential individual-selection explanation (reciprocity is one: someone may suckle your cubs if you suckle theirs). The altruism that we see in humans is almost certainly the result of social and moral conditioning rather than of genes encoding “altruistic behaviors.”
What about helping your kids at the expense of what you want to do? Well, that’s not altruism at all, but the result of a form of Darwinian selection: kin selection. Genes for behaviors that help your kids (nursing, parental care, etc.), so long as they’re not too detrimental to your own future reproduction, will spread in populations through the offspring that are helped. That’s why many animals show parental care, which isn’t a sacrifice in reproduction (though it is in energy!), but an adaptively favored trait.
The take-home lesson: “altruism” in humans isn’t the same thing as biological altruism.