1. There's a reason you always lean one way
Not everybody tilts their head the same way when they go into a kiss, but research conducted in the UK found that up to 74 percent of people turn their heads to the right when they got down to it. But why is this? Apparently, whether you are right or left-handed tends to affect whether you'll lean right or left. Although, there are also plenty of lefties out there who will be mirroring their partner's movement to avoid knocking heads.
2. Teeth are more important than you'd think
While you probably don't think too much about your partner's teeth when you're kissing them, it is apparently very important when deciding to kiss for the first time.
A study published in Evolutionary Psychology asked women aged 18 to 24 which features they notice the most when deciding whether to kiss someone or not. The one that ranked highest was healthy-looking teeth, more so than general attractiveness, lips, or eyes.
3. It helps reduce stress
While obviously doing anything fun can relieve stress, kissing can actually affect our stress levels on a chemical level.
Oxford University researchers assigned 52 people in relationships to kiss more or less often over a six-week period, then took blood tests to see how much Cortisol (the stress hormone) they had in their bloodstream. They discovered that couples who kissed more than usual were significantly less stressed after six weeks than those who did it less.
4. You can really catch an STI through a kiss
According to the World Health Organization, nearly 70 percent of people under the age of 50 carry herpes, which makes it pretty hard to avoid at some point. Fortunately, it can just be a cold sore on your lips or in your mouth, but if you don't want to spread it, it's recommended that you avoid this kind of contact during this period, even with a long-term partner.
5. Kissing in public isn't just about affection
This study, in the Journal of Sex Research, surveyed 349 men and women aged 17 to 35 about how they feel about PDA. They found that one-third of the participants made out in public primarily because they wanted others to see it. Apparently, men in the study said they thought it made them look good, while the women wanted to make other women, or exes, jealous.
6. There can be millions of bacteria in one kiss
Researchers conducting a study for the science journal Microbiome had one person drink a probiotic drink, full of useful bacteria, then kiss their SO for 10 seconds. Taking samples from their tongues and saliva afterwards, they found that this 10-second kiss transferred up to 80 million bacteria.
Thankfully, much of the bacteria we share is commonplace and not harmful, and can even protect you against more serious microorganisms.
If there's one thing to learn from all of this, it's that after a long stressful week at work, it would do you good to plant a kiss or ten on your partner once you get home. Just try not to think too much about the 80 million bacteria.