Summer love is in season—and whether you're kissing someone new or the same lover year after year, our lips just can't seem to get enough lovin'. After all, ask people about their best kiss and you're bound to hear a long tale of romance. And while the person doing the kissing has a lot to do with that woozy, floaty feeling, our bodies are primed to be kissable, according to research in the journal Microbiome.
The sexy study with the incredibly unsexy title—"Shaping the Oral Microbiota Through Intimate Kissing"—details how a hot, passionate smooch leads to bacterial transfers from mouth to mouth. The scientists estimate that swapping saliva also swaps about 80 million bacteria per 10-second kiss. But before you get turned off from locking lips forever, this bacterial sharing can be a good thing. It helps replenish good bacteria, which in turn, can strengthen your immune system. In fact, researchers say that making out can make you less likely to catch a cold. (Fun fact: You're more likely to get sick from shaking hands than from kissing. Think about that next time you're introduced to the office hottie.) Plus, the increase in saliva will help wash plaque off your teeth!
But in order to get us to engage in a steamy moment (of bacterial transfer), our bodies have to make kissing feel incredible. This is why evolutionary psychologists think that our lips are our largest exposed erogenous zone—loaded with over a million nerve endings, and one of the most sensitive areas of our bodies. Human mouths, unlike animal lips, are uniquely flared outward to give even more surface area for that smooch. So whether your lips are touched lightly, kissed hard, or even bitten, receptors light your brain up like a Christmas tree as you process the taste, smell, touch, and pressure.
Once your brain realizes that something amazing is happening, it releases the hormones dopamine and oxytocin, which give you that cuddly, lovey-dovey feeling and leave you craving more. The close embrace that comes with kissing has also been shown in previous researchto lower blood pressure and your heart rate, reduce stress and anxiety, and even improve your memory. We'll pucker up to that!