I was looking at some global suicide statistics and I think it's an interesting question. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1489848/pdf/wpa010181.pdf Especially if you look at it what motivates suicide. There is nothing intrinsic that gives humans and most species, the desire to end life. It seems as if external factors are the main cause--mental disorders, personal troubles (ie financial, marital, problems). But there is nothing comparable to hunger, thirst, mating, sleep, etc.--in terms of ending life. According to the stats, On average, almost 3000 people commit suicide daily. For every person who completes a suicide, 20 or more may attempt to end their lives. Even one million people successfully committing suicide per year, is an incredibly small percentage. I guess from an evolutionary viewpoint, we do what we can to stay alive. It would be irrational for us to leave. Even solar nebulae, from an entropic viewpoint, don't have the option of not forming a solar system. But almost all species do have that choice and yet, choose no. There isn't that much data on animal suicide. But I have heard of scorpions stinging themselves when surrounded by fire. I thought this was an interesting question, anyone else agree?