It’s a fact, today women live longer than men by at least 4.2 years in average, even 6 to 8 years in some developed countries, because men are more intimately linked to Alcoholism , smoking and give less attention to their health than women do, but that’s not really the main reason, In fact women live longer than men because there is a hormonal implication in the issue, the estrogens are women’s closest allies in the battle against death , for several reasons the first is that they favor the elimination of hostile fat diminishing the risk of having cardio-vascular diseases for instance, In France only one fifths of persons having cardio-vascular diseases are women(take a look at French Science et Vie Magazine, August 2007).
Another utility for the estrogen is that it stimulates the liberation of Nitric oxide through blood-vessels which may cause vessels to dilate decreasing the risk of blood-clotting inside the vessels.
Other than estrogens, the women’s second X contribute to proper maintenance for the chromosomes (it contains 900 to 1200 genes against less than 80 genes for men’s Y) and so it permits to create more anti oxidizing agents which helps preserve cellular “youth” more effectively than men’s mechanism .
However living longer doesn’t mean living healthier, actually in many developed countries women at the same period of age as men (older than 75 years)and even if they are less exposed to cardio-vascular diseases, they suffer more often from diseases like Alzheimer, have more troubles with eyesight ,walking and spend more hours in Hospitals than men , a French statistics shows that from 18% of those who are older than 75 years and who suffer from diseases or are handicapped two thirds are females. So there is some sort of balance between both sexes.