Why do we age the way we do?

These days, that's a question I ask more and more. :-)

And why, for example, do humans live to around 80 years, but chimpanzees only make it to 40? How do some whales make it to 200?

The prevailing theory about aging is that it results from wear and tear of our cells, which eventually lose the ability to repair themselves. But how does that explain the wide disparity in different species' lifespans?

A new study led by Stuart Kim at Stanford suggests an alternative: that changes in the expression of certain genes results in aging. In essense, each species is pre-programmed to live for a certain length of time before beginning to fall apart. (A more detailed article here.)

Interesting stuff. But I'm not sure I'd want to live any longer than that 80 years...