From the Max Planck Institute: "Marriage is more beneficial for men than for women - at least for those who want a long life. Previous studies have shown that men with younger wives live longer. While it had long been assumed that women with younger husbands also live longer, [a new study] has shown that this is not the case. Instead, the greater the age difference from the husband, the lower the wife's life expectancy. This is the case irrespective of whether the woman is younger or older than her spouse. ... The mortality risk of a husband who is seven to nine years older than his wife is reduced by eleven percent compared to couples where both partners are the same age. Conversely, a man dies earlier when he is younger than his spouse. For years, researchers have thought that this data holds true for both sexes. They assumed an effect called 'health selection' was in play; those who select younger partners are able to do so because they are healthier and thus already have a higher life expectancy. ... These theories now have to be reconsidered. It appears that the reasons for mortality differences due to the age gap of the spouses remain unclear."