By Gillian MacBeth Louthan | Source

Kissing triggers a “cocktail” of brain chemicals like dopamine, oxytocin, and serotonin that cause feelings of pleasure, bonding, and attachment. It also involves neural messages from the lips, which are highly sensitive, and can lower stress hormones like cortisol. Beyond these effects, kissing can serve biological purposes like assessing a partner and strengthening the immune system by exposing the body to new germs.

Kissing activates an intense sensory experience. Human lips and tongues are densely packed with sensory neurons that send a flood of information to the brain’s somatosensory cortex, a region that is highly stimulated by the mouth compared to other body parts. This sensory input, combined with the activation of five of the twelve cranial nerves, creates a thrilling and emotionally charged sensation

 Dopamine: This “feel-good” chemical is released in the brain’s pleasure centers, potentially leading to cravings and addictive feelings associated with kissing.

Oxytocin: Known as the “love hormone,” oxytocin is released during kissing, fostering feelings of bonding, trust, and attachment.

Serotonin This neurotransmitter is also released, which can contribute to feelings of happiness and affection, and in some studies has been linked to obsessive thoughts about a partner.

Cortisol:  Levels of this stress hormone decrease during a kiss, helping to reduce anxiety and promote relaxation.

Neural stimulation and sensory input The lips are packed with a high concentration of nerve endings, more so than many other parts of the body, which send a large amount of sensory information to the brain. This stimulation can lead to a more intense brain response than other physical sensations, contributing to the pleasure and emotional connection associated with kissing.

MATE SELECTION Kissing may have evolved as a way to “taste” a potential partner, gathering information about genetic compatibility and health through saliva. (proving the point you have to kiss a lot of frogs before you find a prince!)

IMMUNE SYSTEM SUPPORT By exchanging germs through kissing, partners can expose each other to new bacteria, which can help strengthen their immune systems over time.

BONDING Kissing reinforces social bonds, whether romantic, platonic, or familial. It can signal affection and create a sense of closeness.