Are humans the only species with members who knowingly end their own lives? I imagine the whole consciousness thing (which animals are self-aware etc) would factor in here, but irregardless, how can this be explained by the theory of evolution, which says we are born to live?
Whales beach themselves. Knowingly? Who knows.
Theory of Evolution doesn’t apply to individuals, only groups. Commit suicide before breeding? Well, then you’re a cull.
Evolution says nothing of the sort. Evolutuion is simply the change in groups of organisms over time. That’s all. The theory of evolution attempts to explain how evolution works. Said theory gives no meaning to life, it merely attempts to explain the mechanisms by which evolution occurs.
I think that some people would argue that humans are the only species that “knowingly” does anything.
Salmon swim up river to spawn, and some species die immediately after. Do they know what is going to happen beforehand? Probably not.
The irony of Darwinian discussions is that his statements can always be invoked on behalf of both sides of the question.
If a person has already procreated and then commits suicide, he is leaving more food for the next generation, and is promoting the species. If the person hasn’t reproduced then he is a waste of genetic material and the quicker he exits the more food is left for the rest of the species.
First, the staff report:
http://www.straightdope.com/mailbag/mbugsuicide.html
??!??!!!??
The “theory of evolution” doesn’t say that. The theory, insofar as it is just one theory, basically states that changes in gene frequency in populations will result in populations with different genetic frequencies. Nicely tautological really. There are a lot of other caveats, addenda and bits and pieces added that go on to say that those genotypes that are most successful at replicating themselves will dominate and so forth. The important point is that nowhere does evolutionary theory say that any organism is born to live. You might just get away with saying they are born to reproduce, but even that is debatable.
There are many creatures, from cabbages to kangaroo rats, that shorten their life spans dramatically by the act of reproduction. Living is not the name of the game. Replication of one’s genes is.
With ‘deliberately’ suicidal animals the dieing creatures are usually sterile drones.
However many otherwise fertile animals will seriously reduce their chances of living and breeding in order to ensure the survival of closely related individuals. This works simply because it is the multiplication of individual genes that marks evolutionary success, not multiplication of individuals. Provided at least two individuals I lay down my life for carry the same gene for self-sacrifice as I do, then the gene has multiplied itself. In fact it has done so faster than if I had had two children of my own who carried the gene.
In short, suicide, or at least altruistic sacrifice, in no way conflicts with evolutionary theory.
I’ve read about cases where monkeys will commit suicide. IIRC from a Jane Goodall movie, a young male monkey got rejected from his group. But instead of going off and living on his own he simply layed down and died.
Elephants are well known too go off die on their own when they’re old, then lay down and die. So there are two non-human cases. I’m sure if you looked hard enough you’ll find a lot of ‘higher animals’ can suffer from depression and lose the will to live.
And as everyone else has posted, the Theory of Evolution has nothing to do with living, its all about having grandchildren.
Blake: That was a very thorough answer, and excellent quickie-summary of TOE too, thank you!
emack: poor monkeys 
lemmings!
Human being’s evolutionary advantage is our adaptive minds. Take a gander at all the different cultural beleifs that have developed as a response to the environment. On an individual and social (sociologists see suicide as a form social deviance) it works against the evolutionary benefits of mankind.
Not always, surely?
“I am just going outside and may be some time”
I realize that what I’m about to say will sound callous, but here it is:
Sucicde is usually a result of either a mental disorder (such as depression), or as an escape when the victim either cannot deal with life in general, or some specific social situation. Thus, suicide tends to cull out those who are either prone to specific types of mental illness, or who are ill equipped to handle stress. Thus, suicide can be seen as a positive evolutionary force.
Well, there are a few species of insect where mating is immediately followed by the male’s death at the hands of his female partner. On the other hand, by definition, the male in question has a very high chance of havinq passed on his genetic traits. From a Darwinian perspective (or rather from a modern Darwin-Watson-Crick-Gould-Dawkins-ian perspective, but that’s harder to say), that’s the only thing that’s required for such sacrificial traits to prosper. Likewise, plenty of animals go through a maternal period where they’ll defend their young to the death - again, this promotes survival of the genetic line to a much greater degree than if mom ran off to let her kids die, and then maybe has more if she’s lucky. It’s not always pretty, but it’s successful by definition, since you’re still seeing species withthat behavior around despite the higher mortality rate.
By the by, here’s a link to Jane Goodall’s site, detailing the death of the chimpanzee Flint, in 1972.
Actually, evolution operates on individuals, not groups. In other words, characteristics are selected for because of their positive impact on the individuals inclusive fitness, not on the groups. However, I’ll give you the benefit of the doubt, as I suspect you were trying to get accross the fact that individuals do not ‘evolve’ over the course of their lives (a la Lamarck), but that species evolve over many generations.
Surely evolution, by its nature, can only affect those traits that are controlled by genes? I’d be surprised if there’s a “suicide gene”. For the same reason, evolution “allows” myopia because it’s not a genetic phenomenon (right?)
Paging Darwin’s Finch…
The jury’s still out on that one. Some researchers think that myopia is genetic, and others think it is environmental.
As for suicide not being genetic, you’re right. However, some factors that tend to lead to suicide are genetic. For instance, the predisposition to depression is genetic.
OK, so turning the argument around - if myopia were genetic, why wouldn’t evolution have de-selected it? Being myopic would seem like a major disadvantage for survival.
Why are people born deaf or blind? There are quite a few genetic abnormalities out there that are detrimental.
My guess would be that genetic disabilities are either recessive side effects of otherwise beneficial genes, or relatively new mutations (evolutionarily speaking) that continue to exist because humans are able to survive with disibilities that would be a death sentence to wild animals.