quote:
Why do bodies grow old and die? Would it not be evolutionarily 'stable' to live longer and have more children and look after them and have more children and so on and so on?
You should read about r/K selection theory as it deals directly with this question. An r strategist live hard and die young (much like a rockstar). They will use up all the energy they have acquired to produce as many offspring in the shortest perioud of time. Think about annual flower plants. They grow, flower, produce seeds, and die. Then the next year it is the same t hing.
A K strategist lives long and conservatively. They spend more time producing quality young and nurturing their young. They usually inhabit much more stable environments.
Here is a link to the wikipedia article on r/K strategies
r/K selection theory - Wikipedia
As for why we die of old age, it is the same reason why we have to buy new computers and cars eventually. The components wear out. I don't know if there was a study for this to see what strategy would be most beneficial, but from observations from life seems that what evolved was a mechanism for reproduction rather than repair. The 2nd law of thermodynamics is not going anywhere and the parts that make up our bodies are going to wear out.
As a side note, I always enjoyed though experiments of what would happen if we were not to die or live an extremely long life. I like to think in terms of morality rather than evolution because you would wonder what our thoughts of killing other non-mortal organisms would be like.
Edited by mobio, : added link