爱情的科学－为什么田鼠会坠入爱河？

Why do voles fall in love? / 为什么田鼠会坠入爱河？

The details of what is going on—the vole story, as it were—is a fascinating one. When prairie voles have sex, two hormones¹ called oxytocin and vasopressin are released. If the release of these hormones is blocked, prairie-voles' sex becomes a fleeting² affair, like that normally enjoyed by their rakish montane cousins. Conversely, if prairie voles are given an injection of the hormones, but prevented from having sex, they will still form a preference for their chosen partner. In other words, researchers can make prairie voles fall in love—or whatever the vole equivalent of this is—with an injection.

像往常一样，最让人着魔的是田鼠爱情故事的进展细节。当草原田鼠性交时，其体内会释放两种称作催产素和抗利尿激素的荷尔蒙。如果这些荷尔蒙的释放被阻断，草原田鼠的性生活便成了短暂的艳遇，它们就会像生性放荡的山区堂兄那样去尽享受风流韵事。 相反，如果给草原田鼠注射以上荷尔蒙，虽然阻止它们性交，它们依然会钟情于已选择的伴侣。换句话说, 不过就一剂注射，研究者们便能让草原田鼠落入情网，不管草原田鼠的感觉如何，反正它们会产生与爱相类似的神经反应。

A clue to what is happening—and how these results might bear on the human condition—was found when this magic juice was given to the montane vole: it made no difference. It turns out that the faithful prairie vole has receptors for oxytocin and vasopressin in brain regions associated with reward and reinforcement, whereas the montane vole does not. The question is, do humans (another species in the 3% of allegedly monogamous mammals) have brains similar to prairie voles?

研究者找到一条与正在发生情形相关的线索，这一线索与如何使上述结果作用于人类有关。线索的结论是：当把这一魔术般的汁液注入山区田鼠体内，其反应与草原田鼠如出一辙。这就证实了，在忠诚的草原田鼠大脑内，与奖赏与强化相关联的区域中，具有一种催产素和抗利尿激素的荷尔蒙受体, 然而山区田鼠却没有。 问题是: 人类——据称是3%实行一夫一妻制的哺乳动物中的另一物种，是否也具有和草原田鼠相似的大脑结构？

To answer that question you need to dig a little deeper. As Larry Young, a researcher into social attachment³ at Emory University, in Atlanta, Georgia, explains, the brain has a reward system designed to make voles (and people and other animals) do what they ought to. Without it, they might forget to eat, drink and have sex—with disastrous⁴ results. That animals continue to do these things is because they make them feel good. And they feel good because of the release of a chemical called dopamine into the brain. Sure enough, when a female prairie vole mates, there is a 50% increase in the level of dopamine in the reward centre of her brain.

为对上述疑惑刨根问底，就需要“挖”得更深一些。一位来自佐治亚州，亚特兰大Emory大学，研究社会附属关系的学者Larry Yong，他对此的解释是，田鼠(以及人类和其他动物)的大脑内具有一套奖赏系统用以鼓励它(他)们去做生物应该完成的行为。如若不然，动物将忘记进食，饮水和性行为，从而招致灾难性的后果。动物们不断重复这些行为是因为那使它们感到快乐。这种快感是一种称作多巴胺的化学物质在大脑中的释放使然。当雌性草原田鼠交配时，在大脑奖赏系统中枢，多巴胺水平会有50%的上升，而这已完全足够让这些“女士”们产生上面提到的那种快感。

Similarly, when a male rat has sex it feels good to him because of the dopamine. He learns that sex is enjoyable, and seeks out more of it based on how it happened the first time. But, in contrast to the prairie vole, at no time do rats learn to associate sex with a particular female. Rats are not monogamous.

与草原田鼠近似，雄性家鼠性交时，因多巴胺分泌同样会感到快乐。当它体验到性让它感到愉悦，便会参照初次经历去搜寻更多机会。但与草原田鼠相反，家鼠决不会学习把性与某个特定的雌性个体关联起来。毕竟家鼠不是“一夫一妻制”的哺乳动物。

This is where the vasopressin and oxytocin come in. They are involved in parts of the brain that help to pick out the salient features used to identify individuals. If the gene⁵ for oxytocin is knocked out of a mouse before birth, that mouse will become a social amnesiac⁶ and have no memory of the other mice it meets. The same is true if the vasopressin gene is knocked out.

抗利尿激素和催产素就是从这里进入这个科学传说的。它们参与了大脑一些部分的工作，以帮助选出用于辨别个体的显著特征。 如果在老鼠出生前，DNA⁷中的抗利尿激素基因即被剔除, 那只老鼠将会成为一个社会性失忆个体，它也不会对遇到的其他老鼠留下任何印象。如果催产素基因缺损，以上命题同样成立。

The salient feature in this case is odour. Rats, mice and voles recognise each other by smell. Christie Fowler and her colleagues at Florida State University have found that exposure to the opposite sex generates new nerve cells in the brains of prairie voles—in particular in areas important to olfactory⁸ memory. Could it be that prairie voles form an olfactory “image” of their partners—the rodent⁹ equivalent of remembering a personality—and this becomes linked with pleasure?

这里的显著特征是气味。耗子、老鼠和野鼠靠嗅觉区分彼此。Christie Fowler和她的同事在佛罗里达州大学的研究中发现，把草原田鼠暴露给异性可使其大脑产生新的神经细胞——在对嗅觉记忆至关重要的一些区域尤其如此。人类是靠个性特征来记住某一个人的。那么草原田鼠会构造一个嗅觉“形像”去记住伴侣吗？这与性愉悦是否存在关联呢？

Dr Young and his colleagues suggest this idea in an article published last month in the Journal of Comparative Neurology. They argue that prairie voles become addicted¹⁰ to each other through a process of sexual imprinting¹¹ mediated¹² by odour. Furthermore, they suggest that the reward mechanism¹³ involved in this addiction¹⁴ has probably evolved in a similar way in other monogamous animals, humans included, to regulate pair-bonding in them as well.

Young博士和他的同事在上个月《比较神经学期刊》的文章中提到了这种想法。他们认为草原田鼠通过一个由气味做媒介的性烙印过程使配偶彼此沉溺于对方。此外，他们还提到，与这彼此沉溺上瘾相关的奖赏机制在其他的一夫一妻制动物（包括人类）生理系统中，或许也进化成了相似的方式，以规范他们的配偶联结关系。

1 hormones   

n. 荷尔蒙，激素 名词hormone的复数形式

参考例句：

• This hormone interacts closely with other hormones in the body. 这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。
• The adrenals produce a large per cent of a man's sex hormones. 肾上腺分泌人体的大部分性激素。

2 fleeting   

adj.短暂的，飞逝的

参考例句：

• The girls caught only a fleeting glimpse of the driver.女孩们只匆匆瞥了一眼司机。
• Knowing the life fleeting,she set herself to enjoy if as best as she could.她知道这种日子转瞬即逝，于是让自已尽情地享受。

3 attachment   

n.附属物，附件；依恋；依附

参考例句：

• She has a great attachment to her sister.她十分依恋她的姐姐。
• She's on attachment to the Ministry of Defense.她现在隶属于国防部。

4 disastrous   

adj.灾难性的，造成灾害的；极坏的，很糟的

参考例句：

• The heavy rainstorm caused a disastrous flood.暴雨成灾。
• Her investment had disastrous consequences.She lost everything she owned.她的投资结果很惨，血本无归。

5 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

6 amnesiac   

记忆缺失的，（引起） 遗忘（症）的

参考例句：

• Synopsis: An amnesiac spy awakens in a world overrun by zombies. 一个记忆缺失的特工在一个僵尸遍野的世界苏醒。
• These memories can generally be recovered through psychotherapy or after the amnesiac state has ended. 实际上，这些记忆并没有真正丧失，在经过心理治疗或病愈之后，这些记忆还可以恢复。

7 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

8 olfactory   

adj.嗅觉的

参考例句：

• He is to develop a sensor to substitute for the olfactory abilities of dogs.克罗克将研制一种传感器用以代替狗的嗅觉功能。
• Based on these findings, Keller suspects that each person has an olfactory blind spot.根据这些发现，凯勒推断，每个人都有一个嗅觉盲区。

9 rodent   

n.啮齿动物；adj.啮齿目的

参考例句：

• When there is a full moon,this nocturnal rodent is careful to stay in its burrow.月圆之夜，这种夜间活动的啮齿类动物会小心地呆在地洞里不出来。
• This small rodent can scoop out a long,narrow tunnel in a very short time.这种小啮齿动物能在很短的时间里挖出一条又长又窄的地道来。

10 addicted   

adj.沉溺于....的，对...上瘾的

参考例句：

• He was addicted to heroin at the age of 17.他17岁的时候对海洛因上了瘾。
• She's become addicted to love stories.她迷上了爱情小说。

11 imprinting   

n.胚教，铭记（动物生命早期即起作用的一种学习机能）；印记

参考例句：

• He gathered her to himself, imprinting kisses upon her lips and cheeks. 他把她抱过来，吻着她的嘴唇和面颊。 来自辞典例句
• It'seems likely that imprinting is an extreme case of conditioning. 看来似乎铭记是适应的一种极端的情况。 来自辞典例句

12 mediated   

调停，调解，斡旋( mediate的过去式和过去分词 )； 居间促成； 影响…的发生； 使…可能发生

参考例句：

• He mediated in the quarrel between the two boys. 他调解两个孩子之间的争吵。
• The government mediated between the workers and the employers. 政府在工人与雇主间搞调和。

13 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

14 addiction   

n.上瘾入迷，嗜好

参考例句：

• He stole money from his parents to feed his addiction.他从父母那儿偷钱以满足自己的嗜好。
• Areas of drug dealing are hellholes of addiction,poverty and murder.贩卖毒品的地区往往是吸毒上瘾、贫困和发生谋杀的地方。