科學家揭示接吻的奧妙

"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 saliva may be a way to assess a mate, Wendy Hill, dean of the faculty and a professor of neuroscience at Lafayette College, told a meeting of the American Association for the Advancement 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 noted. She plans a repeat "in a more romantic setting."

Hill spoke 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 components -- the sex drive, romantic love and attachment.

Men tend to think of kissing as a prelude to copulation, Fisher said. She noted that men prefer "sloppy" 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•薩莫在《愛情的科學》中唱道：“你對我所做的一切似乎都是化學作用。”現在看來，她是對的。

日前，一組科學研究人員探究了接吻的奧祕。研究發現，接吻會使人體產生能夠降低男女雙方壓力激素的化學物質，並能增強男性的親密感——不過這一效果在女性身上並不明顯。

拉斐特學院神經科學系主任、溫迪•希爾教授在上週五召開的“美國科學進步協會”的研討會上稱，唾液中的化學物質可能是人們評價伴侶的一種途徑。

希爾解釋說，在一個實驗中，研究人員讓大學生異性情侶在聽音樂的同時接吻15分鐘，結果發現這些情侶體內的催產素（oxytocin）和考的索（cortisol）兩種化學物質水平發生了明顯變化。“催產素”是一種影響男女之間親密感的激素，而考的索則與壓力水平有關。研究人員對這些情侶接吻前後血液和唾液中所含的這兩種化學物質的水平進行了對比。

研究結果顯示，接吻後男性和女性體內的考的索水平都出現了下降，這表明他們的壓力水平有所降低。

同時，男性體內的催產素水平上升，這表明他們對親密的渴望增強，而女性體內的催產素水平則有所下降。希爾說，“這很奇怪”。

她說，從只發生牽手行爲的控制小組的試驗結果看，研究對象體內同樣也發生了化學變化，但不如接吻後的變化那麼明顯。

希爾介紹說，該試驗在一個學生健康中心進行。她打算在“更加浪漫的環境中”再做一次試驗。

希爾在研討會的“接吻科學”會議上作了發言，同時發言的還有羅格斯大學的海倫•費舍爾和俄亥俄州衛斯理大學的唐納德•拉特納。

費舍爾指出，超過90%的人類社會有接吻行爲，她認爲接吻有三個要素，即性衝動、浪漫的愛情和彼此的依戀。

費舍爾說，男性傾向於將接吻視爲做愛的前奏。她說男性喜歡“溼吻”，這種接吻方式會將含有睾丸激素的化學物質通過唾液傳給女性。而睾丸激素會增強男女雙方的性衝動。

她說：“人在接吻時，大腦的很大一部分會活躍起來。”浪漫的愛情能持久，“如果你吻對了人”。

Vocabulary:

as a prelude to:作爲……的前奏