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Basic instincts

本能

英文部分选自经济学人191123science and technology版块

Sexual orientation of animals

动物的性取向

Basic instincts

本能

A new hypothesis argues that same-sex sexual behaviour is an evolutionary norm, not an aberration

新的假设认为，同性性行为属于远古祖先的行为特征，而非畸变（非之前认为的从异性性行为演化而来）。

When it comes to sexual behaviour, the animal kingdom is a broad church. Its members indulge in a wide variety of activities, including with creatures of the same sex. Flying foxes gather in all-male clusters to lick each other’s erect penises. Male Humboldt squid have been found with sperm-containing sacs implanted in and around their sexual organs in similar quantities to female squid. Female snow macaques often pair off to form temporary sexual relationships that includes mounting and pelvic thrusting. Same-sex sexual behaviour has been recorded in some 1,500 animal species.

谈到性行为，动物王国可谓是包罗万象。动物们沉浸于各种活动，包括和同性之间的活动。比如，雄性狐蝠会聚在一起相互口X；美洲大赤鱿被发现在其性器官内部及周围有被植入的精荚，数量和雌性的差不多；雌性雪猴经常结对形成临时的性关系，尝试各种体位（你懂的）。目前已发现的具有同性性行为的物种达1500种左右。

注：

1.broad church：a group, organization, or set of beliefs which includes a wide range of different opinions or ideas 

2.Flying fox：狐蝠，雄狐蝠选择聚在一起相互口，详细链接

https://www.weibo.com/ttarticle/p/show?id=2309404263248651223248&mod=zwenzhang?comment=1  

3.Humboldt squid美洲大赤鱿

http://m.49363.com/tansuo/4/201503/16696_5.html

美洲大赤鱿美洲大赤鱿又被成为洪堡鱿鱼、Pota或Diablo Rojo（西班牙语中“红魔鬼”的意思）。它们不仅有武装，而且武装到了牙齿——确切说是触手上也有牙齿。这些长在吸盘里的小钩还会弯曲，就像尖利的钳子，使它们在捕猎的时候威力大增。

4. 雪猴：即日本猕猴，每到冬天来临时，日本猕猴的身上就经常会披满白雪，因此这种猴子被人们称为“雪猴”。雌猕猴之间容易结成紧密的关系，而且实行的是临时“一夫一妻”制，一只雌猕猴只在固定时间里与另一只雌猕猴成为性伴侣，但在一个繁殖期里，一只雌猕猴可以先后与数只雌猕猴搭上关系。雌猕猴之间的性行为多为模拟雄性生殖器，以及在亢奋时发出类似雄性的咯咯声。雄猕猴之间也存在同性性行为，只不过雄性之间的性游戏结束后，它们会立即离开对方。雌性猕猴和自己的孩子关系密切，这种关系可以延续终生。 

The mainstream explanations in evolutionary biology for these behaviours are many and varied. Yet they all contain a common assumption: that sexual behaviours involving members of the same sex are a paradox that does indeed need explaining. Reproduction requires mating with a creature of the opposite sex, so why does same-sex mating happen at all?

进化生物学中对这一现象的主流解释五花八门。但是，所有的解释中都包含一个共同的假设：同性性行为确实是一个需要解释的悖论。繁殖需要与异性交配才能完成，那么为什么还会发生同性交配呢？

A paper just published in Nature Ecology and Evolution offers a different approach. Instead of regarding same-sex behaviour as an evolutionary oddity emerging from a normal baseline of different-sex behaviour, the authors suggest that it has been a norm since the first animals came into being. The common ancestor of all animals alive today, humans included, did not, they posit, have the biological equipment needed to discern the sex of others of its species. Rather, it would have exhibited indiscriminate sexual behaviour—and this would have been good enough to transmit its genes to the next generation.

《自然生态与进化》杂志上的一篇论文提出了一种新的说法。研究人员认为，同性性行为并非之前认为的从异性性行为演化而来，事实上是属于远古祖先的行为特征（可能是动物原始祖先状况的一部分，并得以持续存在）。现存所有动物（包括人类）的共同祖先并不具备去识别其他同类的性别生物器官，因此便不分青红皂白地对所有性别同类发生性行为，从而尽可能地将其基因传给下一代。

The group of young researchers from institutions across America who wrote the paper, led by Julia Monk, a graduate student at Yale, argue that conventional models of sexual behaviour’s evolution take two things for granted that they should not. The first is that the cost of same-sex behaviour is high because energy and time spent engaged in it do not contribute to reproductive success. If that were true it would indeed mean that maintenance of same-sex behaviour over the generations requires some exotic explanation whereby such activity confers benefits that outweigh the disadvantage. The second assumption is that same-sex activity evolved separately in every species that exhibits it, from an ancestral population that engaged exclusively in different-sex behaviour.

这篇论文是由耶鲁大学研究生朱莉娅·蒙克（Julia Monk）与来自美国各个研究机构的研究人员一起完成的。他们认为，传统模式中的性行为进化理论基于两个假设。第一，同性行为代价太高，因为它耗费了大量时间和精力却又不能繁衍后代。如果这一说法是对的，那么若要解释同性性行为世代相传生生不息的现象，就需要别出心裁，证明同性性行为带来的好处大于缺点。第二，同性性行为是由只进行异性性行为的祖先物种向现代物种进化的过程中，各个物种独立演化而成的。

Do you come here often?

你有没有想到过这个层面？

Ms Monk and her co-authors question the first assumption by pointing out that many animals seem to mate at a frequency far higher than looks necessary merely to reproduce—meaning that the proportional costs of any instance of sexual activity which does not produce offspring must be low. If this is true, it reverses the burden of proof. The cost of the sensory and neurological mechanisms needed to identify another’s sex, and thus permit sex-discriminating mating behaviour, is high. Sometimes, that will be a price worth paying, especially if a long-term relationship is involved in reproduction, as it is in most birds and some mammals. But it is the evolution of sex-discrimination for which special-case exemptions must be sought, not the evolution of same-sex behaviour.

蒙克女士以及合著者对第一种假设（贴心备注：第一，同性行为代价太高，因为它耗费了大量时间和精力却又不能繁衍后代）提出疑问。他们指明，很多动物交配的频率远远高于繁衍所必需--意味着每次不能产生后代的性行为代价一定很低（无论同性还是异性的比例）。如果这一假设成立，就推翻了举证责任。不仅如此，识别另一种性别，从而允许划分性别的交配行为所需的感知和神经系统所消耗的代价很高。有时候这个代价是值得付出的，特别是在大多数的鸟类和哺乳动物中，当涉及到一段长期的、关乎到繁衍的关系时便是如此。此句留给大家一起探讨，欢迎留言。

The second assumption is even easier to challenge. Typically, evolutionary biologists assume that traits shared widely across a related group are likely to have evolved in an ancestral population, not repeatedly and separately in each lineage. Ms Monk and her colleagues argue that cognitive biases in the subject’s practitioners have pushed them to look for fantastic explanations for the evolution of same-sex behaviours in a range of animals, rather than considering the perhaps more reasonable explanation for its persistence, that it is a low-cost ancestral trait that has little evolutionary reason to disappear.

第二种假设（贴心备注：第二种假设是同性性行为是由只进行异性性行为的祖先物种向现代物种进化的过程中，各个物种独立演化而成的）更容易被推翻。通常情况下，进化生物学家认为，在一个互相具有相关性的生物群体中广泛表现出的特性可能由同一个祖先群体中进化而来，而不是在每个谱系中重复独立演变而成。蒙克女士和她的同事认为，这一主题的研究者内在的认知偏差促使他们为一系列动物的同性性行为的演变寻找完美的解释，而不为同性性行为延续下来寻找可能的更合理的解释，即这是一种低成本的祖先特征，从进化的角度上看没有理由消失。

Although the idea that same-sex behaviour has always been a norm is scientifically intriguing, the paper’s authors are also making a broader point about human beings’ pursuit of knowledge. Ms Monk says that the paper’s authors met through a Twitter account which promotes the work of lgbtscientists. This was a serendipitous encounter which gave them space to explore an idea that might have been dismissed at first sight in a more conventional setting. The group includes people with a range of sexual orientations, so naturally they had an incentive to ask whether mainstream evolutionary biology’s view of sexual orientation is correct. 

尽管把同性性行为当正常现象的观点在科学界令人兴致盎然，但这篇论文的作者们也对于人类对知识的追求提出了更广泛的思考角度。蒙克女士说，该论文的作者是通过推特账户认识的，该账户推广同性恋、双性恋和变性人科学家们的工作。这是一次偶然的相遇，这次相遇给了他们去探索在相对传统的环境中可能会被立刻忽略的想法的空间。这个群体中人性取向各异，所以他们自然而然地就有动机去探寻主流进化生物学对性取向的观点是否是正确的。

Their hypothesis still needs testing. That will mean zoologists gathering more observational data on sexual behaviour of animals in the wild—and doing so with an open mind. The authors themselves are also mulling approaches involving computer modelling, which might show that a group of organisms behaving according to their theory is capable of reaching the distribution of sexual behaviours seen in the wild today. If their hypothesis is confirmed, it raises the question of which other facets of scientific knowledge might be being obscured because the backgrounds of practitioners in those fields do not lead them to ask unconventional questions. Ms Monk’s and her colleagues’ theory may yet turn notions of the evolution of animal sexual behaviour on their head. With a broader array of minds focused on other problems, other fields might follow, too.  

他们的假设仍然需要检验。这将意味着动物学家们会收集更多关于野生动物性行为的观察数据——并且以开放的心态做这件事情。作者们自己也在考虑涉及计算机建模的方法，以期证明按照他们的理论行动的动物会最终呈现出今天在野外看到的性行为分布情况。如果他们的假设得到证实，就会引出这样一个问题：科学知识的哪些其他方面可能会因为这些领域从业者的背景，造成他们不会提出非常规的问题，进而被忽略呢？蒙克女士和她的同事的理论可能会颠覆动物性行为进化的观念。也许紧随其后的，便是更多领域的科学研究者对其他问题的更加广阔的审视。

翻译组：

Cindy ，女，未来外贸工，TE粉

Frank，男，小硕，经济学人的死侍

Helga，女，笔译民工，经济学人爱好者

校核组：

Lee ，爱骑行的妇女之友，Timberland粉

Nikolai，子承父业，蛋糕厂员工，AKB49

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