Personally I don't think suicide evolved or was selected for in humans in the same way that it may have been in social insects. I think what has been selected for is misery and unhappiness as the basic human condition. Look at the number of great thinkers who were also depressed, alcoholic or suicidal. The mere fact of unhappiness makes one want to change his environment. Unhappiness can act as a force or gradient to try to improve oneself or one's station, or, by extension, the condition of society via inventing, improving and innovating. The difference between the strident man and the suicidal is hope versus despair. Unhappiness plus hope is a recipe for positive change and success, and something that absolutely could be selected for, because every woman wants to score a winner. Unhappiness plus despair apparently can be disastrous. It seems, then, that perhaps despair is a disease of civilization, as they say, much like cancer and hypertension.