Scanning the brains of people in love is also helping to refine science's grasp of love's various forms. Helen Fisher, a researcher at Rutgers University, and the author of a new book on love*, suggests it comes in three flavours: lust, romantic love and long-term attachment. There is some overlap but, in essence, these are separate phenomena, with their own emotional and motivational systems, and accompanying chemicals. These systems have evolved to enable, respectively, mating, pair-bonding and parenting.

对恋爱中人们大脑的扫描，也有助于使科学对各种形式爱情的领会变得更为精确。Rutgers 大学的一位研究人员Helen Fisher，同时是一本关于爱情的新书作者，她提出，爱会以三种滋味出现：欲望，浪漫的恋爱和长期的附属关系。三种滋味的爱情虽有一些重叠，但本质上是截然不同的现象，并且具有各自的情绪和激发系统，以及相伴的体内化学物质。这些系统通过进化后以分别让交配，伴侣联接和养育子女成为可能。

Lust, of course, involves a craving for sex. Jim Pfaus, a psychologist at Concordia University, in Montreal, says the aftermath of lustful sex is similar to the state induced by taking opiates. A heady mix of chemical changes occurs, including increases in the levels of serotonin, oxytocin, vasopressin and endogenous opioids (the body's natural equivalent of heroin). “This may serve many functions, to relax the body, induce pleasure and satiety, and perhaps induce bonding to the very features that one has just experienced all this with”, says Dr Pfaus.

首先当然是欲望，包括对性的强烈渴求。蒙特利尔Concordia大学的一位心理学家，Jim Pfaus说道，贪欲的性行为其结果和使用鸦片引起的状况颇相类似：一种令人兴奋的混合化学变化，包括血液复合胺(5羟色氨)，催产素，抗利尿激素和内非肽(身体内的海洛英的天然同等物) 的水平升高。“这可能提供许多功能，如放松身体，产生快乐和满足感, 也可能导致把某些特征与刚才的全部经历联结起来，”Pfaus博士补充道。

Then there is attraction, or the state of being in love (what is sometimes known as romantic or obsessive love). This is a refinement of mere lust that allows people to home in on a particular mate. This state is characterised by feelings of exhilaration, and intrusive, obsessive thoughts about the object of one's affection. Some researchers suggest this mental state might share neurochemical characteristics with the manic phase of manic depression. Dr Fisher's work, however, suggests that the actual behavioural patterns of those in love—such as attempting to evoke reciprocal responses in one's loved one—resemble obsessive compulsive disorder (OCD).

接下来便是两性吸引，双方处于相爱的状态 (就是我们所知的浪漫的、或强迫性的恋爱)。这是纯粹的欲望的升华，它使人们总能回到某个特定配偶身边。这种状态的特征，是兴奋感和对情感对象打扰式的和强迫性的思恋。一些研究员提到，这一心理状态可能和狂躁状态的躁郁症有相同的神经化学特征。Fisher博士的工作揭示了恋爱人群真实的行为模式，比如：试图唤起被爱者的报答——类似于强迫性混乱症(OCD)。

 
That raises the question of whether it is possible to “treat” this romantic state clinically, as can be done with OCD. The parents of any love-besotted teenager might want to know the answer to that. Dr Fisher suggests it might, indeed, be possible to inhibit feelings of romantic love, but only at its early stages. OCD is characterised by low levels of a chemical called serotonin. Drugs such as Prozac work by keeping serotonin hanging around in the brain for longer than normal, so they might stave off romantic feelings. (This also means that people taking anti-depressants may be jeopardising their ability to fall in love.) But once romantic love begins in earnest, it is one of the strongest drives on Earth. Dr Fisher says it seems to be more powerful than hunger. A little serotonin would be unlikely to stifle it.

这又产生一个问题，即是否可能和处理OCD一样，用病理学方式来“处治”这种浪漫状态。任何沉醉于爱情的青少年，他们的父母可能都想知道相应的答案。Fisher博士提出，抑制浪漫爱情的可能性确实存在，但只能是在感情发展的最初阶段。OCD的特征，是血液中一种叫血液复合胺(5羟色氨)的含量较低。如果Prozac等药物让血液中的复合氨在大脑中停留得比正常时间更久，这些药品就可能阻止浪漫感觉的出现。(这也意味着服用抗抑郁药物的人们可能正在危及他们彼此相爱能力。)真挚浪漫的爱情一旦开始，它就成为了地球上最强大的动力之一。Fisher博士说，这种欲望比食欲强大得多，一点儿血液中的复合氨不太可能扼杀心中如此强烈的情感。

Wonderful though it is, romantic love is unstable—not a good basis for child-rearing. But the final stage of love, long-term attachment, allows parents to co-operate in raising children. This state, says Dr Fisher, is characterised by feelings of calm, security, social comfort and emotional union.

尽管浪漫的爱情如此奇妙，但它却并不稳定——这绝非养儿育女的良好基础。而爱情的最后阶段，即长期的附属关系，却使父母在养育孩子方面得以精诚合作——这种状态，Fisher博士认为，它的特征恰恰是平稳感、安全感、社会性的慰籍以及情感的最佳结合。

Because they are independent, these three systems can work simultaneously—with dangerous results. As Dr Fisher explains, “you can feel deep attachment for a long-term spouse, while you feel romantic love for someone else, while you feel the sex drive in situations unrelated to either partner.” This independence means it is possible to love more than one person at a time, a situation that leads to jealousy, adultery and divorce—though also to the possibilities of promiscuity and polygamy, with the likelihood of extra children, and thus a bigger stake in the genetic future, that those behaviours bring. As Dr Fisher observes, “We were not built to be happy but to reproduce.”

因为三个阶段的系统彼此独立，所以他们可能同时工作而导致危险的后果。如Fisher博士解释的那样，“你可能对长期配偶有深深的附属感，同时你又因另一人而感受到浪漫的爱情，其间，你又由于第三位异性而产生性驱动力。”这种独立性意味着你可能同时爱上多个异性而导致妒忌、私通和离婚——尽管也有可能是乱交、一夫多妻、和随之而来的额外生育，即最终一个更大的预期基因赌注。正如Fisher博士所述，“我们不是为快乐却是为了生殖而被创造的。”

The stages of love vary somewhat between the sexes. Lust, for example, is aroused more easily in men by visual stimuli than is the case for women. This is probably why visual pornography is more popular with men. And although both men and women express romantic love with the same intensity, and are attracted to partners who are dependable, kind, healthy, smart and educated, there are some notable differences in their choices. Men are more attracted to youth and beauty, while women are more attracted to money, education and position. When an older, ugly man is seen walking down the road arm-in-arm with a young and beautiful woman, most people assume the man is rich or powerful.

爱情的各阶段在性别之间略有差别。例如，与女性相比，男性的欲望更容易被视觉刺激唤醒。这或许就是为什么视觉色情对男性而言更加流行。虽然男人和女人用同样的强度表达浪漫的爱情，也同样会被可靠、和蔼、健康、聪明和有教养的伴侣所吸引，但不同性别在选择配偶时还是有着一些显著的不同。男性更易被年轻和美貌所吸引，而女性更多会青睐于金钱、教育和地位。当人们看到苍老而丑陋的男人手挽着年轻美丽的女子漫步道旁，大多数都会设想此公不是腰缠万贯，便有大权在握。