A kiss might be much more than just a simple sign of affection. What if, in reality, this gesture came from our ape ancestors? A team from the University of Warwick is proposing an intriguing new hypothesis, called the “groomer's final kiss.” Their idea? That this gesture might have originated from grooming behaviors observed in great apes.
In many cultures, social rules have shaped the way people kiss. In Ancient Rome, different types of kisses distinguished relationships: a kiss on the cheek was an
osculum, a kiss on the lips without erotic intention, a
basium, while the
savium referred to a romantic kiss. Even today, these distinctions subtly persist in certain contexts.
Some kisses, like kissing under the mistletoe or a wedding kiss, are linked to well-established rituals and traditions. Around the world, the way people kiss varies. In Europe, a cheek kiss as a greeting is common, but depending on the country, the number of kisses differs. In Belgium, one kiss suffices, while elsewhere, four kisses are sometimes the norm.
Among animals, behaviors similar to human kissing are rare. However, our closest cousins, chimpanzees and bonobos, do kiss, suggesting an evolutionary link. Warwick researchers compared these behaviors and observed that grooming plays a crucial role in maintaining social bonds in great apes, particularly through lip-sucking gestures used to remove parasites.
The study argues that this “lip-sucking,” observed in great apes, could be an ancestor of the human kiss. As humans gradually lost their body hair and no longer needed grooming for hygiene, the social aspect of kissing persisted, with the gesture evolving into a symbol of closeness and attachment.
Researchers point out that this grooming behavior, with a “final suck,” shows striking similarities to the human kiss. Meanwhile, some monkeys, like capuchins, demonstrate attachment by putting their fingers in the eyes and noses of their close ones, suggesting that gestures of affection vary from species to species.
Previous studies also show that the romantic kiss is not universal. A study published in 2015 in
American Anthropologist revealed that less than half of the 168 cultures studied practiced this type of kiss. In indigenous hunter-gatherer cultures, the kiss is even often viewed as repulsive, challenging the idea that kissing is a universal human behavior.
To go further, the researchers suggest closely studying grooming behaviors in monkeys. By observing differences based on the thickness of their fur, we might better understand the evolution of bonding behaviors in our own species, from utilitarian gestures to affectionate kissing.