I have been thinking about this recently, and I think it is a pretty interesting concept. From my understanding, biological evolution seems to be a process that is strongly in the favor of the individual being, what with the whole ďsurvival of the fittestĒ tag being a good descriptor of its general theme. Determinists and reductionists can tell you that lifeís sole biological purpose is to pass on your genetic material as often and as much as you can: biological systems are generally built for this. The question then arises, if ďsurvival of the fittestĒ is the general way to go, why doesnít evolution support a being that will never die a natural death. I think about this, and would think that a being that can pass on genetic information indefinitely until killed by something would be favored, rather than organisms that have biological mechanisms that force them to die, or force them to be not as able to stave off a natural death.
I will use humans as an example, but you can see this in almost every complex organism. What is the evolutionary, biological advantage to the chemicals released that begin the aging process? Why donít our bodies try to maintain our physical and sexual peak? I donít really buy the argument that it simply costs too much energy to do so. Why, after a specified time, does our body begin to weaken itself and allow for death? I canít really think of a biological explanation that preserves evolutionís individual preference for one being succeeding over many lesser specimen.
I can think of philosophical or psychological reasons as to why death is something incorporated into life in general, however none that are biological [although Iím sure some would argue psychological is biological in terms of neuroscience]. Iíd rather get otherís opinions on the topic, but to set us in a direction, a psychological reason as to why death exists may be because a consciousness may not be able to handle the concept of never dying. Think of how death is such a part of our lives, if that makes sense. Could a conscious being be able to handle the fact that they will never die of old age. That if they are healthy and take their flu shots and look both ways all the time, they will not die. They will exist forever. Maybe evolution has already tried this approach, and the organisms couldnít handle it, because they were never afraid of death enough to resist it.
All opinions and reasons are welcome, even the spiritual, all viewpoints should be considered. Iíd just rather not this devolve into God vs Science. Also, I'm fully prepared for somebody to completely prove me wrong, but I couldn't find anything in my reading to answer this question.