人類爲什麼會接吻? 這是一場化學反應!
People kiss for the simple reason that it feels good. Our lips are full of sensitive nerve endings, which activate sensory areas in the brain.
人們接吻的原因很簡單，就是它會讓你感覺良好。我們的嘴脣佈滿了神經末梢，這些神經末梢連接着大腦相應的神經區域。Kissing boosts the levels of neurotransmitter substances such as dopamine, serotonin, and oxytocin.
接吻使一些神經遞質物質迅速增加，例如多巴胺，血清素以及催產素。Dopamine triggers craving and desire, serotonin elevates a person's mood, and oxytocin is involved in forming emotional attachments.
多巴胺觸發人們的慾望，血清素能使人們情緒激昂，催產素會對情緒的變化有影響。
Besides humans, the only animals that scientists have ever seen kissing are our closest ape relatives, chimpanzees, and bonobos, and even then it is a rare occurrence. So scientist think there must be a better explanation for it.
除了人類，科學家發現唯一有接吻行爲的動物，就是我們的猿類近親，黑猩猩和倭黑猩猩，即使在它們之中這種現象也極少發生。所以科學家們認爲人類要接吻還有更好的理由。
Some scientists have theorized that kissing might help us assess a partner's immune system.
有科學家認爲接吻可以獲取對方免疫系統的信息。When people kiss, they come close enough to sample the scent of each other's bodies. And that scent may contain clues to immune system compatibility.
當人們接吻時，相互間足夠近的距離使他們可以感受到對方的氣味。這些氣味中包含着免疫系統兼容性的線索。Parents with complementary immune systems have children with a stronger ability to resist disease. Children that are better at resisting disease are more likely to survive to have their own children.
具有互補性免疫系統父母的孩子更容易抵抗疾病。而這些抵抗疾病更強的孩子也能更好的生存下來並孕育健康的下一代。Exchanging saliva may provide other chemical clues to genetic compatibility too. So, kissing really is all about chemistry!
交換唾液或許也提供了基因兼容所需的其它化學物質的一些線索。所以接吻真是一場化學反應！
