从进化角度看女性性高潮之谜

An eye is for seeing, a nose is for smelling. Many aspects of the human body have obvious purposes.

眼睛是用来看东西的，鼻子是用来闻气味的。人体的很多方面都有明显的用途。

But some defy easy explanation. For biologists, few phenomena are as mysterious as the female orgasm.

但有些地方令人费解。对生物学家来说，几乎没有什么现象能像女性性高潮那么神秘。

While orgasms have an important role in a woman’s intimate relationships, the evolutionary roots of the experience — a combination of muscle contractions, hormone release, and intense pleasure — have been difficult to uncover.

尽管性高潮在女性的亲密关系中发挥着重要作用，但这种经历——同时出现肌肉收缩、荷尔蒙分泌和强烈的快感——的进化根源却难觅踪迹。

For decades, researchers have put forward theories, but none are widely accepted. Now two evolutionary biologists have joined the fray, offering a new way of thinking about the female orgasm based on a reconstruction of its ancient history.

几十年来，研究人员提出了各种理论，但没有一种理论得到广泛的认可。现在，又有两名进化生物学家加入争论，提出了一种新的思考女性性高潮的方式，它的基础是再现其古老的历史。

On Monday, in The Journal of Experimental Zoology, the authors conclude that the response originated in mammals more than 150 million years ago as a way to release eggs to be fertilized after sex.

周一，两名作者在《实验动物学杂志》(The Journal of Experimental Zoology)上推断，女性性高潮这种反应起源于逾1.5亿年前的哺乳动物，当时是为了排出卵子，让其在性行为结束后受精。

Until now, few scientists have investigated the biology of distantly related animals for clues to the mystery.

此前，几乎没有科学家通过研究属于人类远亲的那些动物的生物学，来寻找解开这个谜团的线索。

“For orgasms, we kept it reserved for humans and primates,” said Mihaela Pavlicev, an evolutionary biologist at University of Cincinnati College of Medicine and an author of the new paper. “We didn’t look to other species to dig deeper and look for the origin.”

“对于性高潮，我们过去认为它仅限于人类和灵长目动物，”辛辛那提大学医学院(University of Cincinnati College of Medicine)进化生物学家、新发表的那篇论文的作者之一米哈埃拉•帕夫利塞夫(Mihaela Pavlicev)说。“我们没有为了更深入地挖掘和寻找起源而研究其他物种。”

The male orgasm has never caused much of a stir among evolutionary biologists. The pleasure is precisely linked to ejaculation, the most important step in passing on a male’s genes to the next generation. That pleasure encourages men to deliver more sperm, which is evolutionarily advantageous.

男性的性高潮从未在进化生物学家中引起这么大的波澜。这种快感被精确地和射精联系在了一起。射精是将男性的基因传递给下一代的过程中最重要的一步。这种快感鼓励男性分泌更多精液，从进化的角度来说这是有好处的。

For women, the evolutionary path is harder to figure out. The muscle contractions that occur during an orgasm are not essential for a woman to become pregnant. And while most men can experience an orgasm during sex, it’s less reliable for women.

对女性来说，相关进化过程更难厘清。性高潮过程中发生的肌肉收缩，并不是女性怀孕必不可少的。并且尽管大部分男性都能在性交期间体验一次性高潮，性高潮对女性来说却没那么可靠。

In a 2010 survey, 35.6 percent of women said that they hadn’t had an orgasm the most recent time they had sex. Part of the reason for this is anatomy: the clitoris is physically separated from the vagina.

在2010年的一项调查中，35.6%的女性称在上一次性生活中未达到性高潮。造成这种现象的部分原因在于人体结构：阴蒂和阴道在位置上是分开的。

Still, a number of scientists suspect that the female orgasm serves some biological function favored by natural selection. They just need to figure out what it is.

但仍有大量科学家怀疑，女性性高潮具有某种生物学功能，该功能得到了自然选择的青睐。他们只需要找出是什么功能。

“My gut instinct is that something that matters so much at an emotional level — the intense pleasure of orgasm — would seem to have reproductive consequences,” said David A. Puts, an evolutionary anthropologist at Pennsylvania State University.

“我的直觉是，在情感层面上——高潮的强烈快感——这么重要的一件事，似乎应该产生繁衍的后果，”宾夕法尼亚州立大学(Pennsylvania State University)的进化人类学家戴维•A•普茨(David A. Puts)说。

Many hypotheses have been put forward. Dr. Puts and his colleagues have carried out studies to test the possibility that orgasms increase the odds that a woman’s eggs are fertilized by a genetically attractive male.

已有许多假说涌现出来。普茨博士及其同事进行了研究，目的是检验一种可能性：高潮会增加基因出色的男性让女性卵子受精的几率。

Elisabeth A. Lloyd, a philosopher at Indiana University, isn’t buying it. In 2005, she published a book called “The Case of the Female Orgasm,” in which she reviewed 18 published theories about its function.

这并没有说服印第安纳大学(Indiana University)的哲学教授伊丽莎白•A•劳埃德(Elisabeth A. Lloyd)。在2005年，她出版了一本书，名为《女性性高潮的问题》(The Case of the Female Orgasm)，其中对已发表的有关性高潮功能的18种理论进行了综述。

None had strong evidence in its favor, she concluded, and many were undermined by other findings about human sexuality. Years of further research have only strengthened her skepticism.

她得出的结论是，没有一种理论提供了有力的证据，其中不少还遭到了有关人类性行为的其他一些研究成果的削弱。多年的进一步研究让她的疑虑有增无减。

Dr. Lloyd thinks the best explanation for the female orgasm is that it hasn’t served any evolutionary purpose at all. It’s nothing more than the byproduct of the development of the male orgasm. The orgasm is to women, she believes, as nipples are to men.

劳埃德博士认为，对女性性高潮的最佳解释是，它并没有任何进化上的意义，不过是男性性高潮的发展的副产品。她相信，性高潮之于女性就好比乳头之于男性。

But now Dr. Pavlicev and her colleague, Günter P. Wagner of Yale University, are making the case that the human female orgasm has a deep evolutionary history that reaches back to early mammals.

不过，帕夫利塞夫博士与耶鲁大学的京特•P•瓦格纳(Günter P. Wagner)现在提出，人类女性的性高潮拥有可以追溯到原始哺乳动物的悠久进化史。

They began by getting better acquainted with the sex lives of other animals, poring through obscure old journals to gather information on species ranging from aardvarks to koalas.

他们首先更好地了解了其他动物的性行为，从不知名的旧期刊里梳理各物种的信息，范围覆盖了从非洲食蚁兽到考拉等各种动物。

They noted that many female mammals release oxytocin and prolactin during sex — the hormones released by women during orgasms. What’s more, in many of those species, females use a radically different kind of reproduction.

他们注意到，许多雌性哺乳动物会在性交过程中释放催产素和催乳素，也就是人类女性高潮过程中释放的荷尔蒙。此外，在这类物种里，有不少物种的雌性采用与人类截然不同的繁衍方式。

While women release an egg each month, other female mammals, such as rabbits and camels, release an egg only after mating with a male.

人类女性每个月排一次卵，其他一些雌性哺乳动物则是与男性交配后才会排卵，比如兔子和骆驼。

Ovulatory cycles evolved in only a few lineages of mammals, including our own, Dr. Pavlicev and Dr. Wagner found. Before then, our ancient mammal ancestors originally relied on ovulation triggered by sex with a male.

帕夫利塞夫博士与瓦格纳博士发现，只有少数哺乳动物种群进化出了排卵周期，包括我们人类。在那之前，我们古老的哺乳动物祖先起初是依赖与雄性交配来激发排卵的。

Those early mammals developed a clitoris inside the vagina. Only in mammals that evolved ovulatory cycles did the clitoris move away. Based on these findings, Dr. Pavlicev and Dr. Wagner argue that the female orgasm first evolved as a reflex to help females become pregnant.

这些原始哺乳动物身上出现了位于阴道内的阴蒂。只有进化出了排卵周期的哺乳动物，阴蒂才移去了别处。在这些发现的基础上，帕夫利塞夫与瓦格纳提出，人类女性性高潮起初进化出来，是作为帮助女性怀孕的一种条件反射。

When early mammals mated, the clitoris could send signals to the brain, triggering hormones that released an egg. Once the egg became fertilized, the hormones may have helped ensure it became implanted in the uterus.

原始哺乳动物交配时，阴蒂可以向大脑发送信号，释放出激发排卵的荷尔蒙。一旦卵子受精，这些荷尔蒙或许有助于保证它在子宫里着床。

This arrangement has worked well for mammals that rarely encounter males. It helps females make the most of each mating.

这种安排对于很少遇见雄性的哺乳动物来说是不错的。它帮助雌性最大限度地利用每次交配的机会。

But eventually some mammals, including primates like us, started spending their lives in social groups. Females had access to regular sex with males, and orgasm as an ovulatory mechanism was no longer so useful. Our female forebears instead evolved a new system: releasing eggs in a regular cycle.

不过，后来有一部分哺乳动物，包括我们这样的灵长目，开始以社群的形式生活。雌性有了与雄性频繁性交的机会，高潮作为排卵机制的作用就不那么重要了。我们的雌性祖先于是进化出了一种新机制：按照周期规律地排卵。

As the original purpose of the orgasm was lost, the clitoris moved away from its original position. Dr. Wagner speculated that this shift was part of evolution’s dismantling of a sensor system: “You don’t want to have the old signal sending noise at the wrong time,” he said.

随着性高潮的初始意义丧失，阴蒂就离开了原来的位置。瓦格纳猜测，这种移位相当于进化在废除一个感官系统：“你不想要古老的信号系统在错误的时间发出噪音，”他说。

“Basically, we don’t know why this happened,” he added. But across mammalian species, “it’s just a very strong evolutionary pattern.”

“基本上，我们并不知道其中的原因，”他还说。不过在哺乳动物种群中，“这的确是一种非常明显的进化模式。”

Dr. Lloyd and Dr. Puts welcomed the new study as a provocative addition to the debate over the female orgasms.

劳埃德与普茨对这项新研究表示欢迎，认为它加入了有关女性性高潮的辩论，能够激发探讨。

“I’m pretty excited that it’s being published,” Dr. Lloyd said, “because people are going to start talking about female orgasms and getting a fresh look at how much we don’t know about female orgasms, and thinking hard about what we need to know.”

“它的发表让我很兴奋，”劳埃德说，“因为大家会开始谈论女性的性高潮，重新审视我们在这方面有多么大的认知空白，努力思考我们需要了解些什么。”

The new theory may shed light on how the human female orgasm first evolved, but Dr. Pavlicev and Dr. Wagner said that it doesn’t settle the debate about its current role in women. “All directions are open,” Dr. Wagner said.

这项新理论或许有助于揭示人类女性性高潮起初如何进化而来，不过帕夫利塞夫与瓦格纳表示，这并不能平息有关它对女性今时今日起到的作用的讨论。“所有方向都有可能，”瓦格纳说。

Dr. Wagner said that deciphering the history of the female orgasm might improve reproductive medicine.

瓦格纳认为，解开女性性高潮历史的谜团，也许能推进生殖医学的发展。

“I think you’re looking at the whole woman’s reproductive system a little differently when you have a model for how it might have evolved,” he said.

“我想，当你有了女性生殖系统可能怎样进化而来的模型，就会对这整套系统有不太一样的认识，”他说。