There is nothing as romantic as two lovers sharing a kiss.
恋人之间相互接吻是一件多么美妙浪漫的事情啊。
But scientists have come up with an evolutionary explanation which perhaps threatens to kill the passion.
但是科学家们最近根据进化理论做的一项研究结果可能会让接吻听起来没有那么浪漫了。
Academics think that kissing helps partners share bacteria, shoring up their immune systems and enabling them to better fight disease.
科学家们发现接吻有助于双方分享细菌，增强免疫力，并能够帮助双方更好地抵御疾病。
As many as 80 million bacteria are transferred during a ten-second kiss, according to Dutch biologists.
荷兰的生物学家称，仅仅接吻10秒钟就能传播8000万个细菌给对方。
Humans carry trillions of bacteria in the body, which together make up a ‘microbiota’ – a complex mix of bugs which play a crucial role in digesting food and warding off infections.
其实我们每个人体内都携带有数以万计的细菌，这些细菌组合在一起就形成了“菌群”，这些“菌群”在消化系统和免疫系统中发挥着至关重要的作用。
Remco Kort, from the Netherlands Organisation for Applied Scientific Research - or TNO - said his team set out to discover the evolutionary reason for kissing.
荷兰应用科学研究组织的雷姆科·科尔特和他的团队已经开始从进化论方面探索接吻的原因。
After testing 21 couples, they think kissing helps form a shared microbiota, a similar mix of bacteria living in the body.
在对21对情侣进行测试以后，科尔特他们发现接吻有助于双方在各自体内形成一个共同的“菌群”。
He said: ‘Intimate kissing involving full tongue contact and saliva exchange appears to be a courtship behaviour unique to humans and is common in over 90 per cent of known cultures.
他说：“包括舌头接触和唾液交换的亲密接吻似乎是人类独有的一种求爱行为，接吻在目前所知的90%的文化中都很常见。”
‘Interestingly, the current explanations for the function of intimate kissing in humans include an important role for the microbiota present in the oral cavity, although to our knowledge, the exact effects of intimate kissing on the oral microbiota have never been studied.
“有趣的是，目前的研究发现人类的亲密接吻对口腔中的微生物有重要作用，而就我们目前所知，还没有人研究过接吻对口腔微生物群的确切影响。”
‘We wanted to find out the extent to which partners share their oral microbiota, and it turns out, the more a couple kiss, the more similar they are.’
“因此，我们想研究情侣间口腔微生物群的相似程度，事实证明，情侣间接吻越多，他们的菌群越相似。”
The researchers, whose findings are published in the journal Microbiome, found that couples who share nine intimate kisses a day had a very similar microbiota, meaning they would be better prepared to deal with similar infections and digest similar food.
发表在《微生物》杂志上的该项研究结果指出，每天热吻9次的情侣间存在非常相似的微生物群，这意味着他们能更好地应对相同感染、消化相同的食物等。
Scientists have long warned that modern obsession with hygiene and cleanliness has driven a boom in allergies and health problems.
科学家们一直警告称，现代人的过度“洁癖”正是导致过敏等诸多健康问题的主要原因。
According to the ‘hygiene hypothesis’, increasing prevalence of allergies such as asthma are caused because we are not exposed to enough germs in our daily life.
根据“卫生假说”理论，现代人之所以哮喘等过敏疾病高发，都是因为我们在日常生活中与细菌接触不够。
Professor Graham Rook, an immunologist at University College London, has gone so far as to say that picking food off the floor, buying a dog and regularly kissing your relatives are some of the best ways to ward off allergies.
伦敦大学的免疫学家格雷厄姆·鲁克教授甚至表示，想要避免过敏，可以把掉到地上的食物捡起来照吃不误、或者可以养狗、经常跟伴侣接吻等。
Speaking at Cheltenham Science Festival earlier this year, he advised that when a baby spits out its dummy, a mother should lick it clean and put it back in the infant’s mouth.
在今年年初举行的切尔滕纳姆科学节上，鲁克教授还建议，当婴儿吐出奶嘴后，母亲应该舔干净并直接塞回婴儿嘴里。
He said the problem is that the modern body is at a ‘constant state of alert’ because it is not used to living with germs.
他称因为现代人的身体不适应和细菌共存，所以一直处于高度戒备状态。
‘When the immune system is not needed it should get turned off completely,’ he said.
“当人体不需要免疫系统的时候，它就应该完全关闭。”
‘What happens these days is that often it is on a constant state of alert and it is not turned off completely.
“但现在，我们的身体经常处于戒备状态，免疫系统从没休息过。”
‘It will do something completely pointless like attacking grass pollen wafting past in the breeze, or attacking the neighbour’s cat when it happens to walk past, then you are going to have allergic problems.’
“因此，它就会做出一些毫无意义的防卫，比如攻击风中的花粉，或者攻击碰巧走过的邻居家的猫，这样就导致了过敏问题。”