Why do women live longer than men?
为什么女性比男性长寿？

As soon as I was born, I was already destined to die earlier than half the babies in my maternity ward – a curse that I can do little to avoid. The reason? My sex. Simply due to the fact that I am male, I can be expected to die around three years earlier than a woman born on the same day.

一出生，命运就已注定我会比那个产科病房里一半的婴儿短命。什么原因呢？我的性别。仅仅因为我是男性这一事实，预计我就会比同一天出生的女性寿命短三年左右。

What is it about being a man that means I am likely to die younger than the women around me? And is it possible for me to break the curse of my gender? Although this puzzling divide has been known for decades, it is only recently that we have started coming close to some answers.

作为男性，我可能就要比周围的女性早死，这是为什么？我是否能够打破这个性别魔咒？虽然这一令人费解的区别几十年前就为人所知，但我们也是最近才开始对其所以然有了一些答案。

One early idea was that men work themselves into an early grave. Whether working in a mine or ploughing the land, they put extra stress on their bodies and amassed injuries that caught up with them later in life. Yet if that were the case, you might expect the gap to be closing, as both men and women converge on the same, sedentary jobs.

早期的一种观点是：男人们自己把自己早早送入坟墓。无论是在矿场工作还是在田间耕作，男人们在自己身上施加了过多的压力，累积了生命晚期困扰他们的累累伤痕。果真如此，您就有望缩小寿命差距，因为男性和女性同样可以从事久坐不动的工作。

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. As one recent article put it: “This remarkably consistent survival advantage of women compared with men in early life, in late life, and in total life is seen in every country in every year for which reliable birth and death records exist. There may be no more robust pattern in human biology.”

事实上，即使经过巨大的社会变革，寿命差异依然存在。瑞典提供了最可靠的历史数据。19世纪，人们的平均寿命女性为33岁，男性为31岁；如今，女性和男性的平均寿命分别为83.5岁和79.5岁。在这两种情况下，女性比男性寿命长大约5%。正如最近的一篇文章所述：“在有可靠的出生和死亡记录可循的每个国家的每一年，与男性相比，早年、晚年甚至整个一生，女性的生存优势始终显而易见。人体生物学中可能没有比这更稳固的模式了。”

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.

证明男性更加虐待自己的身体也并非易事。抽烟、喝酒以及暴饮暴食等因素可在一定程度上解释为何各国之间不同性别的人寿命差异如此之大。例如，俄罗斯男性可能比女性寿命短13年， 部分原因是由于男性比女性喝酒和抽烟更严重。但事实上在黑猩猩、大猩猩、猩猩和长臂猿中，雌性也比同类雄性寿命长，而且你也看不到猿类，无论雌雄，嘴里叼着香烟、手里持啤酒瓶。

Instead, it would seem like the answer lies in our evolution. “Of course, social and lifestyle factors do have a bearing, but there does appear to be something deeper engrained in our biology,” says Tom Kirkwood, who studies the biological basis for ageing at Newcastle University in the UK.

答案似乎在于人类进化过程。“当然，社会因素和生活方式确实会有影响，但我们的生物机理的深层似乎有某种东西，”英国纽卡斯尔大学研究老化的生物原理的汤姆·科克伍德(Tom Kirkwood)说。

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.

这里有很多潜在的机制 — 从每个细胞内被称为染色体的DNA开始。染色体成对出现，但女性有两个X染色体，男性有一个X染色体和一个Y染色体。

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.

这种差异可能会使细胞老化方式产生微妙的变化。有了两个X染色体，女性的每个基因都有一个备份，如果其中一个出现问题，另一个可以发挥作用。男性就没有这种备用基因，。随着时间的推移，越来越多的细胞机能开始失常，使男性面临更大的患病风险。

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. 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.

另一个观点是“做慢跑运动的女性心脏”。这个观点是说在生理周期后半期女性心跳加速，带来的好处堪比适度运动，这就延迟了生命后期患心血管疾病的风险。或者，也可能只是体格大小的问题。个子高的人体内有更多的细胞，发生有害突变的可能性更大；较大的身躯也会消耗更多的能量，从而加大组织自身的损耗。由于男性往往比女性高，所以，他们面临更多的长期损害。

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.

但或许真正的原因在于睾丸素，它主宰者大多数男性特征，从低沉的嗓音、多毛的胸部到秃顶。证据往往来自让人意想不到的地方：朝鲜王朝时代的宫廷。韩国科学家朴汉南(Han-Nam Park) 最近分析了19世纪以来宫廷生活的详细记录，包括81位在青春期以前被割去睾丸的太监的资料。分析显示，这些太监活了大约70岁，而朝廷中其他男人的平均寿命只有50岁。总之，与当时生活在朝鲜的普通人相比，他们庆祝百岁生日的可能性要大130倍。即使国王，宫中最娇贵的人，也无法与之相比。

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.

虽然并非对于太监的其他研究都显示出如此明显的差异，但总体来看，没有睾丸的人 (和动物)活得更长。

The exact reasons are elusive, but David Gems at University College London speculates that the damage may be done by the end of puberty. For speculative evidence, he points to the sad cases of mental health patients, institutionalised in the USA in the early 20th Century. A few were forcibly castrated as part of their “treatment”. Like the Korean eunuchs, they too lived for longer than the average inmate – but only if they had been sterilised before the age of 15. Testosterone might make our bodies stronger in the short-term, but the same changes also leave us open to heart disease, infections, and cancer later in life. “For example, testosterone might increase seminal fluid production but promote prostate cancer; or it might alter cardiovascular function in a way that improves performance early in life but leads to hypertension and atherosclerosis later,” says Gem.

尽管确切的原因捉摸不定，但伦敦大学学院的大卫·杰姆(David Gem)猜测：青春期结束之前，伤害可能已经形成。至于推测的依据，他举了一些20世纪初美国精神病患者的悲惨例子。作为对其“疗法”的一部分，一些人被强行阉割。同朝鲜王朝太监一样，他们也比同院的一般病人寿命更长 —— 但前提是他们在15岁之前就已绝育。虽然睾丸素短期内可使我们的身体更强壮，但这些变化同样会增加我们在生命后期患上心脏病、传染病和癌症的可能性。“例如，睾丸素会增加精液的产液量，引发前列腺癌；或者在生命早期提高性功能但晚期导致高血压和动脉粥样硬化，以这样的方式改变心血管机能，”杰姆说道。

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.

女性不仅避开了睾丸素的风险，还可能得益于自身的“青春灵药”，这可以帮助她们愈合一些时间创伤。女性体内的雌性激素是一种“抗氧化剂”，可以清除导致细胞应激的有毒化学物质。在试验中，缺乏雌激素的雌性动物往往没有比未做过手术的动物长寿 ——与被阉雄性的命运正好相反。“如果切除啮齿动物的卵巢，细胞就无法很好地修复分子损伤，”科克伍德说。

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.”

科克伍德和杰姆都认为这是一种进化中的补偿机制，是男性和女性传递基因的最好机会。交配期间，雌性更愿意找睾丸素满满的雄性领袖，但孩子出生后， 雄性就变得可有可无，柯科伍德说。“子孙后代的幸福与母体密切相关。对孩子来说，母亲而不是父亲的身体处于良好状态，这一点更为重要，这是底线。”

That’s cold comfort for men today. As it is, the scientists admit that we need to keep on looking for a definitive answer. “We really have to retain an open mind as to how much the difference can be explained by hormonal differences and other factors,” says Kirkwood. But the hope is that eventually, the knowledge may provide some hints to help us all live a little longer.