Why Would I Ever Kiss You?!: Analyzing Kissing Behavior in Humans

Think to the most emotionally satisfying moment in your favorite romantic comedy, is it a kiss? Is it a passionate embrace? Or is it simply the rise and fall of the story that keeps you coming back to these films? Humans have a lot of odd social behaviors, which are seldom observed by other animals in the animal kingdom. One of these fascinating behaviors is kissing. The meeting of two mouths with over 6 billion bacteria, as an activity to be closer with someone. It seems counterintuitive to the maintenance of our health to be consistently exchanging bacteria with others, but, it helps maintain a healthy immune system (Booth, 2019). Furthermore, kissing has been shown to produce oxytocin, “the love hormone” that helps builds emotional connection with someone (Scheele et. al., 2013). In a situation where a behavior is important for immune system maintenance and provides you with neurochemicals that promote intimacy with others, it should be easy to understand the positive elements of sharing a kiss.

Immune Support

With the combination of up to 12 billion bacteria every time lips meet; it would be understandable to give up kissing entirely and to commit to a life of celibacy. This way, you are protecting your immune system from foreign pathogens and theoretically you should be healthier. The interactions of varying bacteria can be helpful for the maintenance of our immune system. Immunologist around the world have argued over the hygiene hypothesis, in which preventing exposure to pathogens is more harmful than consistent exposure to non-lethal pathogens. In other words, a healthy exposure to various harmful bacteria can provide you with a stronger immune system. Another plus being you will likely feel closer with the person you share kisses with as oxytocin is produced with kisses.

“The Love Hormone”

Oxytocin has been given the title of the love hormone by many researchers as it consistently appears in situations of intimacy; kissing, cuddling, etc. In a study by Scheele et. al. (2013), male participants were given intranasal oxytocin and asked to perceive female faces. The treatment group significantly chose their female partners face as more attractive, showing evidence for oxytocin being critical in romantic bonds. As kissing appears to increase feelings of intimacy, it is likely a good indicator for relationship health. In a study by Busby et. al. (2020), 1605 participants in committed relationships were asked about kissing frequency in addition to other elements of a relationship. The study found that kissing frequency had a significantly positive association with all aspects of sexual experiences as well as overall relationship satisfaction.

Kiss to your Heart’s Content

With many health benefits to kissing, it is easy to understand why humans have been kissing for all of history. Kissing would fall into the Old Friends hypothesis shared by immunologist in which sharing common bacteria is important for immune system health. People in relationship can also share how kissing can promote intimacy. In a study by Floyd et al. (2009), married couples were instructed to increase their kissing frequency and they experienced improvements in perceived stress and relationship satisfaction. It is safe to say that with someone you feel safe with, kissing will only increase the level of satisfaction in your relationship. The two of you should feel healthier and happier together with a kiss every now and then.


Booth, S. (2019, May 5). Bacteria in your mouth can affect your brain. Healthline. Retrieved from https://www.healthline.com/health-news/bacteria-in-your-mouth-can-find-its-way-to-your-brain#:~:text=Mouth%20bacteria%20101,promote%20health%2C%20others%20provoke%20disease.

Busby, D. M., Hanna-Walker, V., & Leavitt, C. E. (2020). A kiss is not just a kiss: Kissing frequency, sexual quality, attachment, and sexual and relationship satisfaction. Sexual and Relationship Therapy, 1–17. https://doi.org/10.1080/14681994.2020.1717460

Floyd, K., Boren, J. P., Hannawa, A. F., Hesse, C., McEwan, B., & Veksler, A. E. (2009). Kissing in marital and cohabiting relationships: Effects on blood lipids, stress, and relationship satisfaction. Western Journal of Communication, 73(2), 113–133. https://doi.org/10.1080/10570310902856071

Kissing and your health. Kissing and your health – Better Health Channel. (n.d.). Retrieved May 16, 2022, from https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/kissing-and-your-health

Scheele, D., Wille, A., Kendrick, K. M., Stoffel-Wagner, B., Becker, B., Güntürkün, O., Maier, W., & Hurlemann, R. (2013). Oxytocin enhances brain reward system responses in men viewing the face of their female partner. Proceedings of the National Academy of Sciences, 110(50), 20308–20313. https://doi.org/10.1073/pnas.1314190110

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