You might think that
suicide flies in the face of evolutionary theory. If the goal is to spread one's seed as much as possible then why on earth would anyone "defy nature" by intentionally removing themselves from the
competition? One way for evolutionary scholars to handle the problem of human suicide is to treat it as a psychopathological breakdown in the adaptive system, a fluke that doesn't really require evolutionary explanation at all. Yet in fact some biologists, drawing from
inclusive fitness principles, theorise that even such an extreme behaviour as suicide may be genetically adaptive in context. In several controversial studies, McMaster University biologist
Denys deCatanzaro reported a negative correlation between the frequency of suicidal thoughts and reproductive value; that is to say, the more suicidal a person is, the less likely they are to have children in the future or to assist their biological kin in some meaningful way. Depressed suicidal people often see themselves as a burden to others - the proverbial "you'd be better off without me" refrain a case in point. (Suicide bombers and the like operate very differently, I should say.)
Whatever you may think of it, deCatanzaro's theory does help to explain why suicides are concentrated so heavily among the "undesirables" in our societies: the sick and infirm, the elderly, homosexuals and gender disordered, the financially troubled, and the fallen from grace. It's a hard one to get your head around. But the brains of suicidal people may be unconsciously crunching the numbers, and in some cases, remaining alive may actually compromise one's own net genetic value by interfering with the reproductive success of one's biological relatives. The "cost" of staying alive may be as little as being an extra mouth to feed without contributing to the household, especially when times are hard. Or, in the case of those who kill themselves out of shame for committing a major social faux pas, the cost may be as great as placing family members at risk by angry in-group members seeking vengeance for your wrongdoing. Many people exposed publically for committing crimes, for example (especially those crimes that really stir up moral outrage among in-group members) report that their first instinct is to commit suicide, and some of course do.
We may not want the biology of suicide to work this way, and surely any good and humane person would do everything possible to prevent a desperate person from committing suicide (except perhaps in extraordinary cases of suffering), but nature turns a deaf ear to suggestions for becoming more in tune with our own moral emotions.
