[lkrubner]

I think aging, in vertebrates, is mostly driven by the need to preserve what data has been encoded in the nervous system.

Ask yourself these questions. Would you rather have old bones or young bones? Would you rather have an old cardio-vascular system or a young cardio-vascular system? Would you rather have old muscles or young muscles?

In every case, the answer is "young".

But would you rather have an old nervous system or a young nervous system? The old nervous system is trained, the young one lacks all skills (skills range from the basics, like control of urination and defecation, to knowing how to hunt down an antelope).

Creatures that do not have a trainable nervous system (trees, coral, insects) experience a very different aging process.

Among vertebrates, those creatures that demonstrate negligible senescence (tortoises) also demonstrate a lack of learning. The price of immortality is perpetual immaturity of one's nervous system.