There is nothing as romantic as two lovers sharing a kiss. But scientists have come up with an evolutionary explanation which perhaps threatens to kill the passion.
Academics think that kissing helps partners share bacteria, shoring up their immune systems and enabling them to better fight disease.
As many as 80 million bacteria are transferred during a ten-second kiss, according to Dutch biologists.
Sharing those germs means both partners are equipped to ward off the infections they might introduce to each other later on.
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.
Remco Kort, from the Netherlands Organisation for Applied Scientific Research – or TNO – said his team set out to discover the evolutionary reason for kissing.
‘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,’ he said.