Nobody knows for sure. But some scientists think that kissing might help us assess a partner's immune system. 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.
没有人知道确切原因。有科学家推测，接吻可帮助我们获得对方免疫系统的信息。人们接吻时，亲密的距离会让彼此感受到对方身体的气味，这些气味中包含着免疫系统兼容性的线索。
But why is that important? Because parents with complementary immune systems have children with a stronger ability to resist disease. Now I see, children that are better at resisting disease are more likely to survive to have their own children. Evolution will favor those who choose partners with compatible immune systems over those who don't, even if they don't even know that they are doing it.
不过，这一点为何如此重要呢？因为父母具有互补性免疫系统，孩子也更容易抵抗疾病。现在我明白了，那些免疫力更强的孩子生存下来的几率与孕育出健康后代的几率更大。人类的进化更偏向于那些具有兼容性免疫系统的伴侣，即使他们不了解自己的行为。
Yes. And it's possible that exchanging saliva may provide other chemical clues to genetic compatibility too. So, then I guess kissing really is about chemistry!
是的。交换唾液或许也提供了一些基因兼容所需的其它化学物质的线索。所以说，接吻还真的是一场化学反应。
译文为秀哈英语翻译，未经授权请勿转载！
