A panel of scientists examined the mystery of what happens when hearts throb¹ and lips lock. Kissing, it turns out, unleashes² chemicals that ease stress hormones³ in both sexes and encourage bonding in men, though not so much in women.

"Chemistry look what you've done to me," Donna Summer crooned in Science of Love, and so, it seems, she was right.

A panel of scientists examined the mystery of what happens when hearts throb and lips lock. Kissing, it turns out, unleashes chemicals that ease stress hormones in both sexes and encourage bonding in men, though not so much in women.

Chemicals in the saliva⁴ may be a way to assess a mate, Wendy Hill, dean of the faculty⁵ and a professor of neuroscience at Lafayette College, told a meeting of the American Association for the Advancement⁶ of Science on Friday.

In an experiment, Hill explained, pairs of heterosexual college students who kissed for 15 minutes while listening to music experienced significant changes in their levels of the chemicals oxytocin, which affects pair bonding, and cortisol, which is associated with stress. Their blood and saliva levels of the chemicals were compared before and after the kiss.

Both men and women had a decline in cortisol after smooching, an indication their stress levels declined.

For men, oxytocin levels increased, indicating more interest in bonding, while oxytocin levels went down in women. "This was a surprise," Hill said.

In a test group that merely held hands, chemical changes were similar, but much less pronounced, she said.

The experiment was conducted in a student health center, Hill noted⁷. She plans a repeat "in a more romantic setting."

Hill spoke⁸ at the session on the Science of Kissing, along with Helen Fisher of Rutgers University and Donald Lateiner of Ohio Wesleyan University.

Fisher noted that more than 90 percent of human societies practice kissing, which she believes has three components⁹ -- the sex drive, romantic love and attachment¹⁰.

Men tend to think of kissing as a prelude¹¹ to copulation, Fisher said. She noted that men prefer "sloppy¹²" kisses, in which chemicals including testosterone can be passed on to the women in saliva. Testosterone increases the sex drive in both males and females.

"When you kiss an enormous part of your brain becomes active," she added. Romantic love can last a long time, "if you kiss the right person."

 堂娜•萨莫在《爱情的科学》中唱道：“你对我所做的一切似乎都是化学作用。”现在看来，她是对的。

日前，一组科学研究人员探究了接吻的奥秘。研究发现，接吻会使人体产生能够降低男女双方压力激素的化学物质，并能增强男性的亲密感——不过这一效果在女性身上并不明显。

拉斐特学院神经科学系主任、温迪•希尔教授在上周五召开的“美国科学进步协会”的研讨会上称，唾液中的化学物质可能是人们评价伴侣的一种途径。

希尔解释说，在一个实验中，研究人员让大学生异性情侣在听音乐的同时接吻15分钟，结果发现这些情侣体内的催产素（oxytocin）和考的索（cortisol）两种化学物质水平发生了明显变化。“催产素”是一种影响男女之间亲密感的激素，而考的索则与压力水平有关。研究人员对这些情侣接吻前后血液和唾液中所含的这两种化学物质的水平进行了对比。

研究结果显示，接吻后男性和女性体内的考的索水平都出现了下降，这表明他们的压力水平有所降低。

同时，男性体内的催产素水平上升，这表明他们对亲密的渴望增强，而女性体内的催产素水平则有所下降。希尔说，“这很奇怪”。

她说，从只发生牵手行为的控制小组的试验结果看，研究对象体内同样也发生了化学变化，但不如接吻后的变化那么明显。

希尔介绍说，该试验在一个学生健康中心进行。她打算在“更加浪漫的环境中”再做一次试验。

希尔在研讨会的“接吻科学”会议上作了发言，同时发言的还有罗格斯大学的海伦•费舍尔和俄亥俄州卫斯理大学的唐纳德•拉特纳。

费舍尔指出，超过90%的人类社会有接吻行为，她认为接吻有三个要素，即性冲动、浪漫的爱情和彼此的依恋。

费舍尔说，男性倾向于将接吻视为做爱的前奏。她说男性喜欢“湿吻”，这种接吻方式会将含有睾丸激素的化学物质通过唾液传给女性。而睾丸激素会增强男女双方的性冲动。

她说：“人在接吻时，大脑的很大一部分会活跃起来。”浪漫的爱情能持久，“如果你吻对了人”。

Vocabulary:

as a prelude to:作为……的前奏