One thought I had was that species evolved to maximize the survival of the species, not the individual organism. Once an organism is too old to reproduce or contribute to the survival of the species, it's probably better to die than becoming a burden to the rest of the members of your species. It sounds cold hearted and brutal but that's just how nature works. Maybe it is possible for an individual organism to reproduce and live forever someday but that would be very hard to achieve and we're probably stuck in a local maxima.
antognini|8 years ago