Your lips are also densely packed with sensory neurons, which are stimulated by the touch of another’s lips. This prompts the release of sebum, which is thought to play a role in bonding.
Kissing May Even Boost Your Immune System and Provide Significant Stress Relief
Psychologists conjecture that kiss-feeding – exchanging pre-masticated food from one mouth to another -- was how babies received the nutrients needed to grow up strong and healthy either in addition to, or after, breastfeeding. This jump starts the digestion process and makes vitamins like B-12 more easily absorbable while also promoting attachment and bonding.