[Rury]

Yeah, I personally believe women's longer lifespan mostly stems from a lower caloric intake. Studies have long suggested that reducing caloric intake can be one of the best things you can do for health and extending lifespan. And this has been shown true across many species including: yeast, worms, flies, mice, monkeys, fish, and others.

We also observe that larger animals tend to live longer than smaller animals, but intra-species it tends to be the opposite (e.g. small dogs tend to live slightly longer than large dogs). It also makes some sense biologically speaking, as we now know that most genetic mutations and errors happen during cellular reproduction when DNA is copied, and cellular reproduction rates correlate with nutrient uptake, alongside mutations with age.

Of course too much caloric restriction can be detrimental, but seems to me this could explain much of the difference in life expectancy between men and women. That and perhaps the genetic advantages from having two X chromosomes.