1. You practiced your kissing stance in the womb.
Two-thirds of people tilt their head to the right when they kiss. Weirdly, this is a habit you might pick up before you're even born, according to Women's Health. Most fetuses tilt their head to the right while in the womb as well. So it looks like you start practicing pretty early.
2. Kissing might determine the fate of your relationship.
Couples that are really good at making out together tend to have healthier relationships, according to Sheril Kirshenbaum's The Science of Kissing. So if you can't make out without having an argument, well...that should tell you something.
3. Kissing releases endorphins and oxytocin.
Making out is going to get you feeling happy and positive and less stressed.
4. Your lips are actually more sensitive than your junk.
It's part of the reason we love kissing so much. Our lips are super-sensitive according to Krista A. Bloom. You have a ton of nerve endings in your lips: approximately 10,000. The clitoris only has 8,000.
5. Kissing is healthy for you ... it can even make you live longer.
A variety of studies show that couples that kiss regularly tend to live longer. Even a good-bye kiss before work has huge benefits. And no, this doesn't mean those teenagers that are constantly making out in the mall are going to be immortal.
6. Open-mouth kissing transfers testosterone.
Guys move toward open-mouth kissing faster. It can actually "share" their testosterone, which can increase their partner's libido, according to a study conducted at the University of Albany.
7. The French didn't have a term for "French kiss" until 2013.
According to the Associated Press, France just added the term galocher to their dictionaries a few years ago, although French kissing was popularized after British soldiers saw how passionately the French kissed while visiting during World War I. It was also once known as the "Florentine kiss."
8. You exchange 80 million different microbes every time you kiss.
A study published in the Microbiome Journal found that you exchange 80 million microbes whenever you kiss someone new. That's more than the 77,000 different microbes you'll find in a public bathroom. Couples, however, have more microbes in common, since consistent kissing means they eventually meet a happy microbe medium.
9. But it boosts your immune system.
That same study found that swapping microbes actually helps out your immune system, so next cold season your best bet is to drink some orange juice and French everyone you meet.
10. Kissing has gone in and out of style.
According to Psychology Today, the earliest known mention of (non-romantic) kissing dates back to the fifth century B.C. Erotic kissing first gets mentioned in the Kama Sutra, but then it fell out of style after Rome fell. People started kissing again in the 11th century, when "courting" became popular.
11. The longest kiss on record lasted 58 hours, 35 minutes, and 58 seconds.
Think about that world record the next time you see some gross PDA.
12. The study of kissing is called philematology.
13. You can get mono and herpes through kissing.
They're two of the few diseases you can transmit through kissing, but they're not exclusive to kissing. Mono can get transmitted through coughing and sneezing. Herpes can be transmitted through oral, anal, and genital sex.
14. Not all cultures kiss.
A lot of cultures didn't kiss each other on the lips until European explorers introduced them to it. Inuits famously rubbed noses and smelled each other's cheeks. Some cultures in the Middle East and Asia still look down on kissing in public.
15. There's a reason the bride and groom kiss at weddings.
According to Kissing Christians by Michael Philip Penn, kissing used to be a means to sign a contract.
16. Humans aren't the only animals that kiss.
Cows, puffins, squirrels and even snails also kiss, although chimpanzees are the only animals whose kisses resemble a human kiss. All the other ones look like awkward face-touching.
17. French kissing uses 34 face muscles.
While a quick kiss only uses two face muscles, a deep, passionate kiss uses all 34 of the muscles in your face.
18. And it can burn up to five calories in a few seconds.
So if you make out for 10 hours, you can skip the gym.
19. Passionate, deep kisses do a better job of getting you in the mood.
It's because they elevate your blood pressure and make your heart beat faster, according to Dr. Ava Cadell. It sends blood through your body, which makes it easier for you to get excited.
This article originally appeared on Cosmopolitan.com. Minor edits have been made by the Cosmo.ph editors.