A researcher has proposed a new hypothesis about the origin of kisses, and it might not sit well with you.
No one knows for certain when humans first began to kiss. However, the act of pressing lips to another person, whether in a friendly or romantic context, is not universal. This suggests that culture likely plays a significant role here, rather than instincts. Interestingly, this practice is not exclusive to humans, as some primates also engage in it. Based on this observation, primatologist and evolutionary psychologist Adirano Lameira from the University of Warwick in Britain has proposed a hypothesis regarding the origins of kissing, as reported by UNN referencing Science Alert.
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The researcher believes that early kisses were part of the everyday practice of caring for one another among our ancestors. Lameira reached this conclusion by observing primate behavior: when one primate helps another groom itself, it often encounters a problem, such as a parasite, and leans down to remove it with its lips, gently sucking it away. The researcher suggests that although humans have lost the necessity for such grooming over time, the almost ritualistic act of kissing has persisted.
"The hygienic significance of partner care in human evolution has diminished due to the loss of fur. However, even the brief grooming sessions that remain, as expected, would have preserved the final stage of the 'kiss', ultimately becoming the last trace of a once-ritualistic behavior for signaling and cementing social and kinship bonds," the scientist posits.
References to kissing between humans date back thousands of years. Thus, this aspect of interaction is immune to fleeting trends. In the past, it has been suggested that kissing is related to feeding infants pre-chewed food. However, kissing involves protruding lips and a degree of sucking, while feeding a child pre-chewed food requires pushing it into the child's mouth. Therefore, this assumption seems somewhat questionable. Another theory proposes that kisses could have originated from the ritual of sniffing. But this raises the question of why mouths should be involved in this process?
Lameira argues that the practice of kissing is part of social interaction, rituals that strengthen social bonds and provide comfort. This conclusion is based on the understanding that humans, like primates, are social beings. Among primates, one of the most common forms of social interaction is grooming—caring for another member of the social group, focusing on their skin and fur by cleaning, removing parasites, dead skin cells, debris, and dirt. Aside from its immediate hygienic purpose, such activity helps establish and maintain alliances, hierarchy, and cohesion through contact, which triggers the release of endorphins that reduce stress and promote a sense of well-being. Thus, the bond between those who provide care and those who receive it is further strengthened.
However, compared to primates, humans spend 89% less time caring for others—we have lost fur and developed methods for self-care. Nonetheless, the researcher believes we may have retained rudimentary remnants of this important ritual. Lameira refers to this as the "last kiss of the groomer." From such a touch, a kiss from one mouth to another could have naturally evolved later. However, the further evolution of kissing depended on cultural and social contexts, according to the researcher.