It appears that old guys hooking up with younger women may be a key to increasing human lifespan:

Women often lose their reproductive capacity around age 50, but if men can still reproduce into their 70s, Darwin would say it's advantageous for males to live longer lives providing they can hook up with a woman capable of reproducing. Natural selection should favor longevity-boosting genes, which would get passed down from fathers to both sons and daughters. So women would benefit as well in future generations, the scientists say.

Result: Over time, the older-guy-with-younger-gal lifestyle would lift the lifespan ceiling for both men and women in the next generations and so on.

"By increasing the survival of men you have a spillover effect on women because men pass their genes to children of both sexes," said Cedric Puleston, a doctoral candidate at Stanford University.

At a mere 12 years older than my bride, I'm apparently not doing that much to help. It turns out that a 5-15 year age difference within married couples has been the norm in traditional societies throughout history, so Suraya and I are just normal (or perhaps old school).

Anyhow, this probably isn't going to prove a very effective means of extending human lifespan going forward -- seeing as we have more direct methods available -- but it might explain how we got here.