Animal attraction

　　Pheromones clearly act as sexual attractants in the animal world. Older male elephants, for example, exude sexual prowess with a mix of chemicals the younger bulls can't muster.

　　Milos Novotny of the Institute of Pheromone Research at Indiana University has shown that special molecules produced by male mice can simultaneously attract females and repel, and even anger, rival males. Other studies have found similar responses throughout the animal kingdom.

　　Yet many researchers are not sold on the idea that these odorless compounds play a role in human attraction. Count evolutionary biologist Jianzhi Zhang of the University of Michigan among the skeptical.

　　In 2003, Zhang showed that a gene mutated 23 million years ago among primates in Africa and Asia that are considered to be human ancestors, allowing them to see color. This let the males notice that a female's bottom turned bright red when she was ready to mate.

　　"With the development of a sexual color scheme, you don't need the pheromone sensitivity to sense whether a female monkey is ready to mate," Zhang said. "It's advantageous to use visual cues rather than pheromones because they can be seen from a distance."

　　A study last year, however, suggested that human pheromones affect the sexual area of the brains of women and gay men in a similar manner.

　　动物间的吸引

　　信息素在动物世界里是种致命吸引物。比如，年长的公象就会分泌一种混合了多种化学物质的汗液，这是年轻的公象可望不可即的。

　　印第安那大学信息素研究所的Milos Novotny发现，雄性老鼠分泌的一种特殊的物质可以马上吸引雌性，同事击退、甚至激怒其他的雄性。其他的研究也发现，在整个动物界中都存在这类似的现象。

　　不过，很多研究对于这种没有气味的物质在人类吸引力中的作用并不买账。其中密歇根大学的遗传生物学家Jianzhi Zhang就是持怀疑态度的人之一。

　　2003年，zhang发现，在2千3百万年前生活非洲和亚洲的灵长类人类祖先们，他们身上有一种基因，这让他们可以看到颜色。这让雄性可以注意到雌性的屁股变红，这是他们准备好交配的信号。

　　“随着性色彩系统的发育，他们不需要特别对信息素敏感才可以注意到雌性是非准备好交配。”Zhang说，“用视觉比信息素的优势在于，从很远的地方就可以看到。”

　　不过，在2005年的一项研究发现人类信息素对于女性和同性恋男性大脑区域的作用十分相似。

Sex goes visual

　　Pheromones, like other scents, hitch a ride through the air on other particles, such as water droplets. They generally hover just 10 inches off the ground, however. So odds are slim they'll waft up to a human nose and fuel sudden passion at a nightclub.

　　Watch any construction worker whistling at a passing woman from half a block away, and you can see how visual cues can be more powerful.

　　And while they enter the nose like other scents, that's where the comparison stops. A pheromone's destination is a special organ called the volmeronasal organ, which humans now lack. From here the sexy scent travels along a neural pathway to the brain separate from other scents.

　　Evolution played a role in this, too.

　　After our ancestors began to see color, a gene important in the pheromone-signaling pathway suffered a deleterious mutation, making it impossible for the scent signals to reach the brain, Zhang said. Imagine a train, leaving from Los Angeles to New York, discovers that the tracks in St. Louis are destroyed.

　　Although the classical pheromone pathway in both Old World primates and humans is dysfunctional, the mechanism for producing pheromones still works. Some scientists believe human pheromones might be influencing our decisions along the normal olfactory pathway.

　　视觉吸引

　　信息素就和其他味道一样，需要通过通过空气中的其他微粒进行传播，比如水蒸气。不过它们只在距地面10英寸左右的地方存在。所以但夜总会里，这些气味能够进入鼻子里、并马上点着激情的机会并不大。

　　相反的，如果你见过建筑工人们在女人从老远走过来就大吹口哨的话，你就明白视觉的信息是多么强大。

　　另外，当信息素和其他气味一样进入我们的鼻子，比较就停止了。信息素的最终接收器是一种叫做梨鼻骨的特殊器官，而这种器官是现代人类所缺乏的。从那里，这些性信息素会与其他气味分别随着神经传导到大脑中。

　　在这个过程中，进化选择也起到了一定作用。

　　在我们的祖先能看到颜色之后，一种在信息素分辨中起到重要基因收到了不良的突变，使得气味信号不能进入大脑。我们来想象一列火车，要从洛杉矶出发去纽约，但铁路在圣路易斯就被破坏了。

　　虽然在古代灵长类和人类身上，这种典型的信息素途径失去了作用，制造信息素的功能还继续存在。有些科学家相信人类的信息素会通过正常的气味传导而影响我们的决定。

Lasting relationships

　　The rules of attraction might drive our initial decisions, for better or worse. But lasting relationships are about much more than what we see and smell.

　　Behavior plays a key role, with biology an intriguing contributing factor.

　　One of the oldest theories about attraction is that like begets like. It explains that eerie perception that married couples sometimes look awfully similar.

　　Last year, J. Philippe Rushton, a psychologist at the University of Western Ontario, looked into the relationships of people's genes. Based on a set of heritable personality traits, having similar genetics plays 34 percent of the role in friendship and mate selection, he found.

　　"The main theory is that some genes work well in combination with each other," Rushton told LiveScience. "If these genes evolved to work in combination, then you don't want to break that up too much for your offspring. Finding a mate with similar genes will help you ensure this."

　　If your spouse is genetically similar, you're more likely to have a happy marriage, for example. Child abuse rates are lower when similarity is high, and you'll also be more altruistic and willing to sacrifice more for someone who is more genetically like you, research shows.

　　It probably comes as little surprise people are drawn to individuals with similar attitudes and values, as psychologist Eva Klohnen at the University of Iowa found in a 2005 study of newlywed couples. These characteristics are highly visible and accessible to others and can play a role in initial attraction.

　　When it comes to sticking together for the long haul, researchers have shown that likeness of personality, which can take more time to realize, means more.

　　Comedy can also help a relationship. But the importance of humor is different for men and women, says Eric Bressler of McMaster University.

　　A woman is attracted to a man who makes her laugh, Bressler found in a 2005 study. A man likes a woman who laughs at his jokes.

　　长久的关系

　　人与人之间的吸引规律可能最促使我们做出最初的决定，不论决定是好还是坏。但是维持一段关系就远不是光看或者闻闻就够了。

　　行为起到了重要的作用，这其中生理原因发生了复杂的影响。

　　有一条很古老的吸引规律是，已婚的夫妻看起来出去的相似。在2005年，西安大略州大学的心理学家Philippe Rushtopn研究了人类基因之间的关系，根据一系列有遗传性的人格特征，他发现，拥有相似的基因在朋友关系或选择配偶中起到了34%的作用。

　　”主要的观点是有些基因，当结合在一起的时候将发挥更好的作用。”Rushton说，“如果这些基因在一起工作是进化的结果，那为了后代着想，你最好不要拆开他们。找到一个和你基因相似的伴侣能帮你确保这一点。”

　　如果你和伴侣基因相似，你的婚姻可能会更幸福。研究发现，如果相似度高，虐待子女的比例就比较低，而且你也会更愿意帮助那些和你基因相似的人、为他们奉献自己。

　　说到我们会被态度和价值观相似的人吸引，人们可能不会吃惊，而这正式爱荷华大学的心理学家Eva Klohnen2005年对新婚夫妻做的研究中所发现的。这些特点非常明显、而且也会很容易被别人发现，这在最初的吸引中发挥了作用。

　　而对那些老夫老妻，研究人员发现，那些需要更长时间才能发现的人格特征上相似性，更有影响。

　　喜剧也对经营一段关系有帮助。不过幽默感的重要性对男人和女人不太一样，麦克马斯特大学的Eric Bressler说。2005年，他的一项研究，发现女人会被那些能让让她笑的男人吸引。而男人则喜欢那些会被他的笑话逗笑的女人。

True love

　　Somewhere amid attraction and sex, we all hope, are strong feelings of love. But which of all the motivations really drives us?

　　Interestingly, brain scans in people who'd recently fallen in love reveal more activity related to love than sex. "Romantic love is one of the most powerful of all human experiences," says Helen Fisher, an anthropologist at Rutgers University. "It is definitely more powerful than the sex drive."

　　The rules of attraction make up a pretty long list. No scientist knows the order of the list. But near the top is perhaps one of the toughest characteristics to gauge in advance in the search for the perfect partner.

　　Despite all their differences, men and women place high value on one trait: fidelity.

　　Cornell University's Stephen Emlen and colleagues asked nearly 1,000 people age 18 to 24 to rank several attributes, including physical attractiveness, health, social status, ambition, and faithfulness, on a desirability scale.

　　People who rated themselves favorably as long-term partners were more particular about the attributes of potential mates. After fidelity, the most important attributes were physical appearance, family commitment, and wealth and status.

　　"Good parenting, devotion, and sexual fidelity—that's what people say they're looking for in a long-term relationship," Emlen says.

　　真爱？

　　不论是吸引还是性爱，我们都希望是源于浓浓爱意。不过到底是那个动机最终促使我们行动呢？

　　有趣的是，对那些才坠入爱河的人进行的脑部扫描发现，和爱有关的活动比和性有关的更多。“浪漫的爱情是在人类所有的体验中最强烈的一种。”罗特格斯大学的人类学家Helen Fisher说，“它绝对比性冲动要强烈得多。”

　　我们可以列出一长串的吸引法则。没有人知道哪个更为重要。不过名列前茅的应该是那些寻找完美伴侣时所提出的要求。

　　不论区别多大，男人和女人都对一项品质很重视：忠诚。

　　康奈尔大学的Stephen Emlen和同事们采访了近1000名18-24岁的年轻人，让他们对一些特征的吸引程度打分，这些特征包括了身体的吸引力，健康，社会地位，工作野心，忠诚度等。

　　人们对长期伴侣的要求比暂时的伴侣要求更具体，仅次于忠诚的特征包括身体吸引、对家庭的承诺、财产和地位。

　　“能当个好父母、奉献精神、性方面的忠诚，这些是人们在寻觅长期伴侣时看重的东西”