Kiss and Tell

You can never forget your first kiss: the range of emotion surging through the body as your lips meet for the first time. As humans we are compelled to kiss, but what causes humans to want to exchange saliva and bacteria with another person? The answer to this is evolution and chemicals of course. In Sheril Kirshenbaum new book the “The Science of Kissing: What Our Lips Are Telling Us," it explains the origin and continuation of kissing. The scientific word for kissing is osculation and the definition of a kiss is the “mouth to mouth orientation of two individuals or the pressing of one’s lips on some other part of another’s body.” So now that we know what a kiss is, there are many questions that must be asked.

When did kissing begin and Why? Kissing has perplexed scientist for years. Even Darwin pondered the origin of the kiss. The explanation he asserted was kissing was innate or perhaps hereditary. This theory has been combated by anthropologists who would believe the kiss is a learned behavior. This kissing debate seems to stem from the many different reasons people kiss. Therefore looking at the evolution of the kiss is complex. It can be assumed that since the origin of the kiss cannot be pinpointed, the reasons for the behavior cannot be ascertained. This means that kissing was not likely developed from one single behavior. The scientific obscurity continues because kissing has no clear classification system that characterizes the different types of kisses or related behaviors. One theory of why kissing evolved was suggested by V.S. Ramachandran of UC San Diego, it says we are drawn to the color red. This was because our primate ancestors needed to detect ripe fruit. This recognition of red would allow them to survive and produce viable offspring. Therefore this attraction to the color propagates and attracts mates based on the color of the lips. It was found in a study that when male volunteers were shown photos of women wearing various lipstick shades. The men consistently chose red as the most attractive.

So after attractive and the lips meet, what exactly happens in the body? First a chemical cascade occurs, the pupils dilate, the heart rate increases and breathing becomes irregular. Dopamine is release, which excites the reward centers in the brain. A good kiss often leads to the rise in a chemical called oxytocin that leads to strong feelings of attachment. Kissing also allows for us to unconsciously assess the compatibility of our mate. Genes called the major histocompatibility complex (MHC) control the effectiveness of our immune systems. This means that if a diverse MHC is detected when kissing another person the connection may be more memorable. This is because this match would lead to offspring with healthy immune systems. In the end, nature is really choosing if a first date will lead to a second. Understanding the kiss is multifaceted, but it all comes down to the chemistry.