mondaymonkey

Well we must look at this from an evolutionary perspective. Why would humans...or any other animal for that matter, evolve the capacity to live past reproduction stages?

Remeber that the sole mechanism of evotion lies in reproductive fitness... not parent surivival... (unless it somehow gives advantages to the child).

Remember that in a ecological niche, resources are always finite in some respect, and killing older animals naturally makes sense, as more young can use those resources. Remember that the offspring will often times be more reproductively fit than their parents, due to evolutionary forces.

IntelligenceQuotient

I understand your point and it is a valid one. My counter would be that why can't the old live to further benefit the young. A young mind knows very little about the world, and it is the old who must teach. The longer we live the more we can learn ourselves and therefore teach. Thus by living longer we already start the next generation out a step ahead. With this kind of intelligence transfer and intellectual accleration all resource issues and human problems could be resolved... incredibly quickly.
Excuse me if this ounds a little utopianistic.

nornerator

You are quite educated on the topic of natural selection, this makes me very happy. Not many people I know actually understand natural selection.

There have been several reasons postulated for why humans live past reproductive age. The most popular is because grandparents increase the survival of their grandchildren. Humans require such a long developmental period that it is likely a parent or even both parents may die within the first 10 years of birth. Someone 10 and under without any parental care would surely die. Having a longer lifespan allows for extra security in raising the young. There are other benefits of having grandparents as well.