npr.org – If your partner’s kiss is on your lips, his microbes are, too. A passionate kiss that lasts more than 10 seconds transfers about 80 million bacteria, researchers say. The evidence, published Sunday in the journal Microbiome, comes from 21 couples, ages 17 to 45, who made out for science. (Tough gig.) Each couple had their mouths swabbed and spit to catalog measure the bacteria in their mouths. Even before kissing, the couples had similar mouth bacteria.