Sealed With a Kiss

A single intimate smooch can transfer upwards of 80 million bacteria.

Bob Grant
Bob Grant

From 2017 to 2022, Bob Grant was Editor in Chief of The Scientist, where he started in 2007 as a Staff Writer.

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WIKIMEDIA, ROBERT & MIHAELA VICOLLocking lips spreads more than just love. A healthy dose of microbes are also swapped between kissing couples, according to a study published today (November 17) in Microbe. Researchers in Amsterdam swabbed the mouths and collected saliva from 21 couples visiting a zoo in the city both before and after they shared 10-second kiss. They found that the couples tended to have similar microbes inhabiting their mouths, likely because they share kisses, food, and space on a regular basis. “Apparently, being with somebody for an extended amount of time and having a relationship leads to a similar collection of bacteria on the tongue,” Remco Kort, lead author and biologist at the Netherlands Organization for Applied Scientific Research, told Time.

But when the researchers had one partner sip a probiotic yogurt drink, which contains bacteria not normally present in the mouth, prior to kissing...

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