so it's not just because they're men

This was kind of interesting. It might go into explaining why women tend to live longer than men:

Men's cells break down quicker than women's apparently.

A short (hopefully lay) summary:

For those who don't remember their basic biology course, teleomeres are proteins that are at the end of the chromosome. With each cell division, the amount of teleomere is less than the previous generation. So as we age, the DNA will eventually be unprotected and break down more. It has been shown in children with progeria (early aging), their amounts of teleomere proteins are less than other children their age. The amount of teleomere protein is regulated by genetics, but a therapy to extend the life of progeria children has yet to be tested.

Maybe our hormones help protect the teleomere better than in men.