Marcus recently came across this BBC article, discussing some of the suggested reasons women live longer than men. Across any country, and across any period of time, women have tended to outlast their male counterparts by an average of 3 years.
The reasons listed below and in this podcast are not our views, they are simply a summary of the BBC article. In this episode, we discuss the merits of each reason, the ones we like and agree with, and the ones we don’t (like being taller).
Some excerpts from the BBC article appear below.
Idea #1 – Men work harder
Men work harder (physically) – the view is that the gap may begin to change with both men and women largely doing sedentary work.
In fact, the difference in lifespan has remained stable even throughout monumental shifts in society. Consider Sweden, which offers the most reliable historic records. In 1800, life expectancy at birth was 33 years for women and 31 years for men; today it is 83.5 years and 79.5 years, respectively. In both cases, women live about 5% longer than men.
Idea #2 – Men respect their bodies less
Nor has it been easy to prove that men are more abusive of their bodies. Factors such as smoking, drinking, and overeating may partly explain why size of the gender gap varies so widely between countries. Russian men are likely to die 13 years earlier than Russian women, for instance, partly because they drink and smoke more heavily. But the fact is that female chimpanzees, gorillas, orangutans, and gibbons also consistently outlive the males of the group, and you do not see apes – male or female – with cigarettes hanging out of their mouths and beer glasses in their hands.
Idea #3 – The chromosome insurance plan
There are many potential mechanisms – starting with the bundles of DNA known as chromosomes within each cell. Chromosomes come in pairs, and whereas women have two X chromosomes, men have an X and a Y chromosome.
That difference may subtly alter the way that cells age. Having two X chromosomes, women keep double copies of every gene, meaning they have a spare if one is faulty. Men don’t have that back-up. The result is that more cells may begin to malfunction with time, putting men at greater risk of disease.
Idea #4 – Women exercise without moving
Among the other alternatives is the “jogging female heart” hypothesis – the idea that a woman’s heart rate increases during the second half of the menstrual cycle, offering the same benefits as moderate exercise. The result is delayed risk of cardiovascular disease later in life.
Idea #5 – Men are taller
Or it could also be a simple matter of size. Taller people have more cells in their bodies, meaning they are more likely to develop harmful mutations; bigger bodies also burn more energy, which could add to wear and tear within the tissues themselves. Since men tend to be taller than women, they should therefore face more long-term damage.
Idea #6 – Testosterone
But perhaps the true reason lies in the testosterone that drives most other male characteristics, from deeper voices and hairier chests to balding crowns. Evidence comes from an unexpected place: the Imperial Court of the Chosun Dynasty in Korea. Korean scientist Han-Nam Park recently analysed the detailed records of court life from the 19th Century, including information about 81 eunuchs whose testicles had been removed before puberty. His analyses revealed that the eunuchs lived for around 70 years – compared to an average of just 50 years among the other men in the court. Overall, they were 130 times more likely to celebrate their hundredth birthday than the average man living in Korea at the time. Even the kings – who were the most pampered people in the palace – did not come close.
Although not all studies of other types of eunuch have shown such pronounced differences, overall it seems that people (and animals) without testicles do live longer.
Not only do women escape the risks of testosterone – they may also benefit from their own “elixir of youth” that helps heal some of the ravages of time. The female sex hormone oestrogen is an “antioxidant”, meaning that it mops up poisonous chemicals that cause cells stress. In animal experiments, females lacking oestrogen tend not to live so long as those who have not been operated on – the exact opposite of the male eunuch’s fate. “If you remove a rodents’ ovaries, then the cells don’t repair against molecular damage quite as well,” says Kirkwood.
Idea #7 – Children need their mothers more than their fathers
Kirkwood and Gem both think of this as a kind of evolutionary pay-off that gave both men and women the best chances of passing on their genes. During mating, women would be more likely to go for alpha males, pumped up on testosterone. But once the children are born, the men are more disposable, says Kirkwood. “The welfare of offspring is intimately connected with welfare of the maternal body. The bottom line is that it matters more for the children that the mother’s body should be in good shape, rather than the father’s.”