Thurg, above, speculated on genetic programming as an explanation of why young men don't like to show emotion. His explanation makes sense, as far as it goes, but if you try to invoke genetics and evolution to explain suicide, you get involved in a lot of paradoxes.

Humans are the only animals I know of that commit suicide. (I'm not sure about whales that beach themselves. I don't think anyone has figured that out yet.) Maybe it takes a big brain to invent the kind of convoluted logic that makes suicide seem like a good idea.

From an evolutionary standpoint, suicide seems like the worst, most counterproductive (literally) thing you can do. Even things like murder and cannibalism make more sense genetically. That is, you can easily think of scenarios (not in our current civilized world, but among our primitive ancestors) where committing murder and cannibalism might enable an individual to pass more of his genes on to the next generation. Therefore, it's likely a few members of our species will always be willing to commit murder and/or cannibalism, especially when they are under great stress. We're genetically programmed for it.

Depression, too, might have some survival value. Depressed people don't move around very much, and don't require as many calories to survive. So, while some individuals are out getting themselves killed trying to bring down a mastodon for supper, others might be home in the cave, curled up in a fetal position, feeling miserable, but surviving.

But suicide? Suicide makes sense genetically only if the suicide of one individual makes other closely related individuals more likely to survive. That would mean extreme hardship for the entire band—famine, say, so severe that some members would have to die. Genetically, it would make sense for some individuals to take themselves out of the competition for food. Logically, those should be the least productive members of the band, the old people, the sick, and those already severely depressed.

But suicide isn't the only way to take oneself out of the competition. One could just get up and leave, take one's chances somewhere else.

It baffles me, trying to explain within an evolutionary framework, why suicide would ever be a better solution than just leaving.

I remember, back when I was young, depressed, and thinking of suicide, one thought would frequently come to me and help me make it through the night: I could always just leave. It might not work. I might become just as miserable in a new place as I am now. But it was something I could try. As long as I hadn't tried it yet, I knew I wasn't totally out of options, and knowing that helped keep me alive.

I don't know if that would make sense for everyone.

(Zoloft works for me now.)