First, there are species of jellyfish and lobster (among others) that do not age. The mechanism of chromosomal deterioration isn't there. There are even plankton varieties that revert to a larval state after adulthood. Additionally, there are many life forms that, whether or not they actually age, are thousands of years old.
http://en.wikipedia.org/wiki/List_of_longest-living_organism...
In other words, aging is far more elastic and non-linear than first meets the eye.
And it's easy to understand why we evolved to age and die: Clearing out older populations leaves more resources for newer, fitter ones (in the evolutionary sense). Death became advantageous, but it's not, from a biological perspective, necessary.
So if you combine these two ideas together -- things don't really need to die but it just so happens that humans do -- does anyone really believe that technology won't find a way to beat the aging process, either by genetic modification or maybe nano-level chromosome reconstruction? At some point it'll be as "correctable" as laser eye surgery.
The implications of halting aging are staggering, earthshattering... there is not enough hyperbole in the English language to do it justice. I just know I don't want to be here when it happens.