为了完成人类繁衍的伟大使命，男男女女在进化过程中英勇献身，以减寿、衰老为代价换得生育成功，还利用各种感官系统加速这一过程（尤其是嗅觉）。真可谓相爱相杀，永无止境。
不得闻香识女人
作者：Michael Segal
译者：
唐 萧
校对：
倪凌晖
策划：唐 萧
本文选自 Nautilus | 取经号原创翻译
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Why Smelling the Opposite Sex Can Age You
为什么异性身上的气味会让你老得更快
The evolutionary tradeoff between longevity and reproduction changes with gender.
长寿和繁殖在进化方面此消彼长的关系存在性别差异
There’s the usual advice. If you want to live longer, exercise. Eat green vegetables. Avoid stress.
人们通常会这么建议：如果你想长寿，那就锻炼身体，吃绿色蔬菜，给自己减压。
Oh—and be careful about smelling the opposite sex.
哦还有——当心异性身上的气味。
Scientists have known for some time that exposing flies and mice to pheromones of the opposite sex can change the pace at which the animals age. The question is, why does this happen?
科学家早已发现，把苍蝇和老鼠放在异性的信息素之下，可以改变它们衰老的速度。但问题是，为什么？
Evolutionary biology provides one framework for understanding the effect, by positing a tradeoff between investing in reproduction on the one hand, and in repair and maintenance on the other. The framework also suggests an explanation for gender differences in aging: Since males and females have very different relationships to reproduction, the ideal tradeoff between reproduction and repair looks different for each of them.
进化生物学为解释上述现象提供了一个理论体系，即假定繁殖与修复之间存在此消彼长的关系。它还解释了两性的衰老差异：由于雄性和雌性同繁殖的关系有很大不同，繁殖和修复之间此消彼长的情况也有性别上的差异。
Michael Garratt*, a professor genetics and aging at the University of Michigan, is a recent recipient of a grant from the American Federation for Aging Research (AFAR) to study how olfaction（嗅觉） can transmit social signals that regulate aging. Nautilus caught up with him earlier this month.
密歇根大学从事遗传与衰老研究的迈克尔·盖瑞特（Michael Garratt*）教授最近收到了美国衰老研究基金会（AFAR）的一笔拨款，用以研究嗅觉是如何传递可调控衰老速度的社会信号的。本报在本月早些时候对他进行了采访。
What is the connection between reproduction and aging?
繁殖和衰老之间有什么联系？
Evolutionary biology predicts that investing in reproduction causes aging indirectly. Imagine that your body has protective mechanisms which can let you live longer, but that they’re energetically costly. Evolutionary theories of aging would say that there’s a trade-off between investing energy into those mechanisms, or into reproduction. Animals in the wild suffer high levels of mortality from things like predators and accidents, so are unlikely to live to late ages. So it makes sense for them to invest heavily in reproduction, even if that accelerates the aging process, because they will usually be dead by the time aging occurs anyway.
进化生物学推测，生育会间接导致衰老。想象一下，你的身体有一个可以让你活得更久的保护机制，但它们很费精力。有关衰老的进化理论认为，用于修复这些机制的精力越多，用于繁殖的精力就越少。野生动物因受到天敌和意外等的威胁，死亡率很高，所以它们不可能活得很长。如此，野生动物要拼命繁衍，即使这会加快衰老速度。因为它们通常在衰老来临之前，就已经死了。
Why do males and females age differently?
为什么雄性和雌性的衰老过程不同？
Because males and females reproduce differently, you also expect them to age differently. Males can potentially father lots of offspring quickly, and produce millions of sperm. Their reproductive rate is not as constrained as females, which produce relatively few eggs, and in mammals need to deal with pregnancy and lactation. Males may be selected to invest heavily in reproduction because they can maximize their reproduction success relatively quickly, as opposed to females who might take a more conservative reproductive strategy. That could make males age faster.
由于雄雌两性繁殖方式不同，他们的衰老过程也不尽相同。雄性完全可能迅速繁衍出很多后代，并产生数百万精子。他们的繁殖速度不像雌性生物那样，受到很多限制。雌性产生的卵子数较少，而且哺乳类动物还要经历孕期和哺乳期。自然选择可能要求雄性把大量精力用于繁殖，因为相比于雌性，他们能够最大限度地提高繁衍后代的成功率。而雌性则采取了更加保守的生殖策略。这种生殖模式上的不同会让雄性衰老的更快。
How does smell tie into this process?
嗅觉在这一过程中扮演什么角色？
Males strategically change their investment in different components of reproduction when they perceive females in their environment. So it’s possible that sensing the presence of a female may effectively activate processes that are involved in reproduction, which might facilitate a male’s reproductive success if those females were around, but could increase aging as a consequence. There’s been a couple of studies in simpler organisms, like flies and worms, which have shown that sensory perception of the social environment can influence the aging process. If you expose male flies to female pheromones, then they age quicker. In mice, olfaction is also really important in controlling development and adult reproduction. Studies conducted in mice in the ‘60s and 70s’ showed that exposing both males and females to opposite sex pheromones during development made them sexually mature quicker. So we know that there are some priming effects of pheromones on reproduction, which could
conceivably
extend to influence aging.
当感知到雌性的存在时，雄性会有策略地改变他们对繁殖中不同要素的投入。因此，感知到周围雌性的存在可能会有效激活雄性的繁殖过程。如果那些雌性就在身边，则可能提高雄性的繁殖成功率，但这是以雄性的衰老加快为代价的。我们已经对较简单的生物，如苍蝇和蚯蚓，进行了研究。结果表明，对社会环境的感知能力会影响衰老过程。如果将雄性苍蝇置于雌性同类的信息素中，它们就会老得更快。对于老鼠来说，嗅觉也是会对发育和成年老鼠的繁殖过程产生重要影响。上世纪六、七十年代对老鼠进行的研究发现，将处在发育期的雌雄两性分别暴露在对方的信息素中，会促进二者的性成熟。我们可以依此判断，信息素在生物繁殖过程中起到了重要作用，也
从而
影响了衰老过程。
conceivable
/kənˈsiː.və.bļ/ adj. possible to imagine or to believe
What other aging-relevant social signals are there?
影响衰老的社交信号还有哪些？
If cues of the social environment do influence the aging process, then the sensory modality that regulates these effects could differ depending on the species. In some mammals, like mice, olfaction is a key sensory modality for social communication, so olfaction may be particularly important for this taxa. But in flies there is evidence that gustatory sensing is important for causing the aging effects of opposite pheromone exposure. Such effects could potentially occur with other modalities too: In squirrels, auditory cues of social competition have been shown to regulate offspring growth rates. If there is a trade-off between growth and aging, we might expect that these kinds of social auditory cues could also extend to influence aging.
如果对社会环境的感知确实影响了衰老过程，那么控制这些效果的感知特征也是随物种而异的。对于一些哺乳动物来说，嗅觉在社会交流中是一个重要的感知特征，因此，对于这一类物种来说，嗅觉可能特别重要。但对苍蝇来说，已有证据表明，味觉才是在异性信息素影响衰老的过程中的关键。这样的影响也可能由其他感知特征共同造成：松鼠在社会竞争中的听觉特质控制着后代的发育速度。如果发育和衰老之间存在此消彼长的关系，那么我们或许可以推测，这些社会听觉信息同样也影响着衰老过程。
Does the war of the sexes make itself felt through biological aging?
两性在衰老上存在此消彼长的关系吗？
The idea of sexual conflict in aging is an important one, and it has been researched in invertebrates. We do have evidence that males and females can influence each other’s aging rate, potentially to maximize their own reproductive success. Male fruit flies actually pass proteins in their seminal fluid to females when they mate, which can directly reduce female lifespan. The seminal fluid proteins initially get females to increase their egg laying, so the male effectively sires more of her offspring, but then it reduces female receptivity to reproduction later in life, and increases her aging rate. Seminal fluid proteins are diverse in both mammals and in flies, and sometimes these proteins will have evolved to facilitate reproduction in situations where males and females are in agreement over how much to reproduce. But there can also be this conflict.
“两性存在衰老上此消彼长的关系”是个很重要的观点。我们也已经就这一观点在无脊椎动物身上进行了研究。我们有理由相信，雌雄两性能够影响彼此的衰老速度，目的可能是为了尽可能提高各自繁殖的成功率。果蝇交配时，雄性会把精液中的蛋白质传给雌性，这一行为会直接折损雌性果蝇的寿命。起初，雄性精液中的蛋白质会促使雌性增加排卵量，好让雌性提高繁殖效率。但随后，这会削弱雌性未来对繁殖的接受能力，并加速其衰老。不同的哺乳动物和苍蝇，它们的精液蛋白质都是有差别的，而且有时还会变化。当雌雄双方就繁殖数量达成一致时，精液蛋白质会根据这一数量进行变化，从而提高生育率。但在衰老上，两性依然存在此消彼长的关系。
Does a stable relationship benefit lifespan?
稳定的两性关系能延长寿命吗？
If you’ve already got access to a female and you’re in a stable environment, then you may not need to invest a lot in attracting females. It may be less stressful because you don’t need to always be ready to attract females, to reproduce, or to compete with other males. A stable relationship might actually be beneficial for aging. There is some evidence in humans that men who are in a stable relationship have lower testosterone levels, and men who are married have less cardiovascular risk and lower rates of mortality. On the other hand, when you’re actively looking for mates, but you haven’t actually mated, that could be quite a stressful period. Work in flies shows that if you expose male flies to female pheromones, they have a much shorter lifespan, but if you then give them some females so that they’re allowed to mate, it actually alleviates these aging effects.
如果你已经有了一位女性伴侣，而且关系稳定，那么你也许就不必再费尽心思谋求他人青睐了。你也会压力更小，因为你不再需要总是随时准备“撩妹”、生殖，或者是和情敌竞争。一段稳定的两性关系或许真的能够延年益寿。有证据表明，恋爱关系稳定的男人睾酮水平更低，同时，已婚男人更不易患上心脑血管疾病，死亡率也更低。另一方面，当你积极寻找伴侣，却依然单身的时候，那是相当煎熬的。有关苍蝇的研究表明，如将雄性苍蝇置于雌性信息素当中，它们的寿命会减少；但如果再让它们同雌性苍蝇交配，则能够改善这种情况。
Are there any notable research programs looking at sexual effects on aging rates in humans? If so what are they examining?
在性别影响人类衰老速度方面，有没有引人瞩目的研究项目？如果有，它们研究的又是什么？
There have been several studies that have tested how a woman’s lifetime reproductive output influences her lifespan, both through historical datasets and in modern day. The results have been variable with both positive and negative relationships observed in some populations. One suggestion has been that high levels of reproduction may reduce female lifespan when environmental conditions are poor. In men, there have been several studies on historical datasets that have looked at effects of male castration on lifespan. Since testosterone is the hormone that controls many aspects of male sexual function, removing circulating gonadal testosterone could extend male lifespan if a trade-off between sexual function and lifespan exists. Again, results have been variable, but one study on Korean eunuchs living between the 1400-1900s suggested that these individuals lived much longer than comparable non-castrated individuals in the population. This suggests that male allocation to reproduction and sexual traits may trade-off against survival.
有些项目正在通过历史和当代数据，研究女性一生的生育数量对其寿命的影响。结果证明，人群不同，二者关系不同，有的呈正相关，有的呈负相关。一个结论是，如果环境条件较差，则女性生育率越高，寿命就越短。另外，也有些项目正在通过历史资料，研究阉割对男性寿命的影响。由于睾酮激素控制着男性性功能的许多方面。如果性功能和寿命之间真的存在此消彼长的关系，去除循环性腺睾酮可以延长男性寿命。针对男性的研究结果同女性一样，也是因人而异的。但在对15至20世纪朝鲜太监的一项研究中可以看到，这些宦官比同一时期未遭阉割的男性活得更久。这表明，男性在繁殖上的消耗和性特征可能损伤他们的寿命。
What is the specific research you intend to carry out using your new grant from the American Federation for Aging Research (AFAR)?
