If they're vegetarians, they live longer (at least according to the description). Also, I'm under the impression that they live longer the higher lifetime points they have accumulated during their lives, although I could be wrong, but then some other person will come along here and tell us that, so we won't miss it if it's wrong.
Well, my record was a painter I had that, without life fruit or ambrosia, lived >105 days (normal aging in the options' menu).