A New Understanding of Why Females Outlive Males

It is commonly known that women tend to outlive men, but do we know why? This is the question that Patricia Wright of Stony Brook University set out to find the answer to. In 1986, Wright and her team ventured out to Madagascar to study a whopping 70 individual Milne-Edwards' sifaka lemurs inhabiting Ranomafana National Park. The team recorded births, deaths, and behavior of the lemurs. These lemurs are especially unique in that both sexes are essentially the same in terms of habits and patterns. With the Milne-Edwards' sifaka, both males and females have the same amount of testosterone and grow to be the same height and weight. Both sexes are equally likely to pick a fight, and are equally aggressive. Their coloring- orange eyes and dark brown fur- is the same. And, above all, both sexes routinely leave their original group and venture out on their own. However, despite all these similarities, males on average only live until their late teens, while females live until their early thirties.
So, what's going on? Why do males meet their ends dramatically sooner than females? Wright and her team analyzed their data, searching and searching for the answer. Finally, they noticed an odd pattern in the dispersal data. Their data says that males and females venture out equally frequently and go just as far, but there was one major difference that could be the answer to it all. While females stopped dispersing after reaching age 11, males dispersed their entire lives. Due to this risky behavior, males often die earlier than females. "'When you're a social animal and you go off on your own into unfamiliar territory, finding food can be more of a challenge. Plus you don't have the extra protection of other group members who can help look out for predators. Even when you find a new group to join, you may have to fight your way in and there's a chance of getting injured in a fight,' said co-author Jennifer Verdolin of the National Evolutionary Synthesis Center in Durham, North Carolina."

Of course, this doesnt explain this phenomenon in humans. However, it might just give a clue. In humans, risk-taking behavior is typically done at different ages, as with the Milne-Edwards' sifaka. This "reveals age-specific mortality risk factors" that have not been considered as of yet.
I think this article is exteremely interesting. As a female, I've always noticed that males are much more prone to risk-taking behaviors, such as dirtbiking and crazy stunts. That's not to say that all females stay away from behavior like that, but there is no denying that males participate much more often, even into their adulthood. Many injuries can occur, often leading to an untimely death, thus the average early male deaths compared to women.