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To pass their genes along to the next generation,most animals need to partner.So in one sense,mating is cooperative, with each partner contributing half their DNA to the offspring.But mating also involves plenty of competition between the sexes.That's because both males and femals are hard wired to try to make babies that can survive and reproduce,but they do this in totally different ways ,ways that actually threaten the other sex's genetic legacy.
为了将基因遗传给下一代，大多数动物都需要配偶。所以在某种意义上交配是种合作行为，参与的伴侣每人可以将一半的DNA遗传给下一代。但交配同时还涉及两性间激烈的竞争。因为雌性都会本能地尝试，让后代得以存活并繁衍后代，但两性实现目的的方法全然不同，事实上有些方法会对异性的遗传物质产生危害。
For males,it's all about quantity.Sperm are easy to mass produce,and most males spend little time or energy parenting,so their best mating strategy is to bread in bulk:the more offspring they have,the better the odds that some will thrive.For most females,this strategy doesn't work,because they have a limited supply of eggs and spend lots of time and energy caring for their young.
对雄性而言就是数量问题。精子易于批量生产，大多数雄性在育儿方面花费的时间和精力较少。因此它们的最佳交配策略就是大量繁殖：繁殖出的后代越多，部分后代繁荣的可能性就越大。对大部分雄性而言这种策略就不管用了，因为卵子的数量往往有限，而且她们需要花较多的时间和精力照顾后代。
Instead,females want to make sure they get the best dad for every one of their offspring.Some choose only to mate with the biggest,flashiest or best-behaved males.Others mate with multiple males,then choose a winner;chickens,for instance can selectively squirt out sperm from subpar suitors.But the pickier females are,the tougher it is for the average male to make babies.
取而代之雌性希望可以确保她的每个娃都有个最棒的爹。有些雄性选择只跟最大只，最华丽或表现最佳的雄性交配。有些雌性则选择跟无数雄性交配，然后从中择优;例如 母鸡可以选择将次等精子喷射出体外，但是雌性越挑剔，那么普通水平的雄性就越难繁育出后代。
So males have evolved ways to limit females' discretion:In some species,males take their mates through brute force,whild males in other species take the slightly less unsavory approach of obsessively following their mates around to keep other suitors away.Male squirrels try to ensure fidelity by plugging females'reproductive tracts with a fluid that hardens after sex,creating a sort of biological chastity belt.
因此雄性进化出了限制性选择权的方式。有些物种雄性会用蛮力完成交配，其他一些物质的雄性则选择稍微不那么令人讨厌的方式，他们会紧紧跟在雌性身边赶走其他竞争者。雄松鼠为了确保配偶忠诚在交配后使用会固化的液体堵住雌性的生殖器，形成类似生物贞操带的东西。
雄性果蝇更过火，它们会随精液释放一种化学混合物令其他精子失效刺激排卵，并且用性欲抑制剂从此扼杀配偶的性冲动。作为应对雌性进化出了反反攻战略重夺优势。例如 一些雌松鼠，想出了排出贞操塞的方法。另一些动物
And male fruit flies go even further:along with their sperm,they release a chemical cocktail that deactivates other sperm,stimulates ovulation,and kills their partner's future sex drive with an anti-aphrodisiac.In response,females develop counter-counter-strategies to regain the upper hand ...wing...or paw.
例如雌鸭子和雄鬛狗，她们进化出了迷宫般的生殖系统，只有在她们通力合作的情况下方能通行。雄性的回应是再次进化 性别战越加激烈，这解释了为何有些鸭子的阴经会是这个样子的。
Some female squirrels,for instance,have figured out how to pluck out their chastity plugs.And in other species,like ducks and hyenas,females have evolved maze-like reproductive tracts that require their full cooperation to navigate.Males evolve in response,and the sexual arms race keeps escalating,which explains why some ducks have penises that look like this.
一般而言一个物种的雄性水平越参差不齐，雌则越挑剔两性进化战则越激烈。另一方面倾向与发展长期伴侣关系，并且共同抚养后代的物种。例如人类 ，一方的繁殖成功对另一方而言也是成功，所以这种后代养成策略，会令两性更加亲密。
In general,the more promiscuous a species' males are,too choosier the females,and the more intense the sexual arms race.On the other hand,in species in which partners tend to have longer-term relationships and raise offspring together-like homo sapiens-reproductive success for one partner also means success for the other,so the two sexes' baby-making strategies line up more closely.
但一夫一妻的可行性，依然能引发一些微妙的托词。虽然看似浪漫，但婚戒实际上只是个圈住配偶的镀金圈圈罢了。
But even the possibility of non-monogamy is enough to spark some subtle subterfuge,although seemingly romantic,a wedding ring is really just a gilded form of guarding our mate.
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