Science definitively proves that kissing is gross

When we kiss, we're not only sharing a passionate embrace with our lover, but also around several million bacteria. Here's why that might not be such a bad thing.

Anthony Domanico
CNET freelancer Anthony Domanico is passionate about all kinds of gadgets and apps. When not making words for the Internet, he can be found watching Star Wars or "Doctor Who" for like the zillionth time. His other car is a Tardis.
Anthony Domanico
2 min read

Kissing is fun, but it also transmits millions of bacteria, a new study finds. BBC One

Every time we lock lips, we're sharing more than our affections. A new study published in the open-access journal Microbiome found that during a 10-second kiss (with tongue), couples swap about 80 million bacteria.

The study was conducted by Remco Kort, a scientist at the Netherlands Organisation for Applied Scientific Research. Kort asked couples visiting Amsterdam's Artis Royal Zoo if they'd participate in a study on french kissing, and 21 pairs of lovebirds happily volunteered.

Both before and after the couples locked lips, Kort swabbed their mouths to assess their bacterial profiles (we strongly advise against sharing these in online dating profiles). Kort found that, unsurprisingly, couples in a relationship tend to have much more similar tongue-bacteria profiles than two strangers. This makes sense when you consider that most couples are sharing bacteria on the regular. But how many bacteria are shared each time we neck?

Before a second kiss, one member of each couple was asked to drink a yogurt drink, which contains probiotic bacteria not commonly found in the mouth, and the couple was then asked to romantically kiss (with tongue). Kort found that the probiotic bacteria in the yogurt drink were transferred between partners, along with 80 million other bacteria.

But before you go screaming "COOTIES!!" at your partner, realize that kissing and sharing your partner's germs might actually make you healthier. Sharing bacteria diversifies your bacteria profile, which could help bolster your immune system to fight off illness.

"Exposing yourself to more microorganisms has a kind of immunological effect," Kort, a professor of microbial genomics at Amsterdam's VU University and adviser to the Micropia museum for microbes, tells Time. "There are a number of studies that show if the diversity in bacteria increases -- more different types of species -- this is a good thing. If you look at it from this point of view, kissing is very healthy."

So there you have it. Kissing shares millions of bacteria, which is pretty gross but has a positive overall impact to your health. Pucker up.