Unlocking the History of Kissing: How Our Ancient Ancestors Set the Stage 21 Million Years Ago

The act of kissing may date back much further than we thought. Recent research suggests it began around 21 million years ago with the ancestors of humans and large apes. Kissing likely emerged before modern humans, which appeared about 300,000 years ago.

Interestingly, the study, published in Evolution and Human Behavior, indicates that Neanderthals, our closest extinct relatives, probably kissed too. They might have even shared kisses with early humans.

Matilda Brindle, an evolutionary biologist at Oxford, led the research. She remarked, “This is the first time anyone has taken a broad evolutionary lens to examine kissing.” Her findings contribute to understanding the amazing variety of sexual behaviors in our primate relatives.

Understanding Kissing

To explore the history of kissing, researchers needed to define it clearly. They distinguished kissing from other mouth-related behaviors seen in nature. For example, some animals transfer chewed food to their offspring or engage in “kiss fighting” to assert dominance. The researchers defined kissing as non-aggressive mouth-to-mouth contact without food transfer. Various species, including bonobos and chimpanzees, have been observed kissing.

Using Bayesian modeling, the team analyzed how kissing might have evolved. They found that it likely began in a common ancestor of large apes between 21.5 and 16.9 million years ago. However, kissing did not appear in groups like macaques and baboons, suggesting different evolutionary paths for kissing in those species.

One theory is that kissing evolved from the practice of mothers transferring food to their young. This nurturing behavior might have transformed into the affectionate kiss we know today.

Comparing Past and Present

The idea that Neanderthals engaged in kissing isn’t entirely new. Anthropologist April Nowell pointed out that previous studies hinted at a similar behavior. For instance, a 2017 study found shared microbes in the dental plaque of Neanderthals and modern humans, suggesting they may have kissed. These findings, however, could also result from shared food or water.

Despite these insights, it remains unclear how common kissing was among early humans and Neanderthals. Even today, kissing isn’t universal; about half of cultures engage in it. This variability might have existed in our ancestors as well.

Kissing persists in many species, but scientists are still figuring out why. Some believe it could help individuals choose better mates. Subtle cues from a potential partner’s saliva might reveal health, genetic compatibility, and other important traits. Kissing could also strengthen social bonds, potentially benefiting immune systems by allowing the exchange of microbes.

The exploration of kissing’s origins gives us a fascinating glimpse into our evolutionary past and highlights the complexities of human connection. To learn more about Neanderthals, check out this insightful quiz.

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