<p>A symbol of affection and intimacy, a kiss is one of the few gestures in most human cultures and carries similar symbolism. But from where did humans learn to kiss? That’s a question shrouded in mystery, and some evolutionary anthropologists say the behaviour of kissing—reaching someone with protruded lips followed by a sucking action—is rooted in millions of years of primate evolution. The first known archaeological evidence describing a kiss dates back to ancient Mesopotamian clay tablets from 2500 BC. However, paleontological evidence from fossils of Neanderthal teeth tartar shows modern-day humans and Neanderthals exchanged saliva more than 100,000 years ago. Whether that is through kissing, swapping spit or sharing food is unknown. </p>.<p>Anthropologists, so far, have identified three possible hypotheses on why kissing may have evolved in humans. The first points to behaviours like sniffing, possibly for potential mates, which later morphed into kissing. But this does not explain why one would make protruded lips to sniff. The other hypothesis posits that kissing evolves from the nursing behaviour of premastication—where parents chew up food for their young ones and put it in their mouth. This behaviour, seen even today in birds and some mammals, does not explain why kissing is prevalent among adults who do not need their food chewed up. </p>.<p>A recent review points to another hypothesis: kissing may have evolved from grooming, a behaviour seen in all great apes and part of their repertoire. According to it, kissing may have started as the last step of the fur grooming ritual, called the ‘groomer’s last kiss.’ It’s a behaviour where a groomer approaches the individual being groomed with protruded lips and makes a suction movement to remove parasites and other debris found in the coat.</p>.<p>Even today, all great apes practice this ritual, vital to building social bonds between individuals. However, as humans evolved, we lost most of our fur, and elaborate grooming rituals of picking out parasites weren’t necessary. Over time, our grooming rituals shortened, and what remained was just the groomer’s last kiss. Although the origins might sound disgusting, given the symbolism of kissing today, it’s commendable that it’s one of the few ape behaviours that has remained unchanged in us for at least 7 million years. That is if this hypothesis turns out true!</p>
<p>A symbol of affection and intimacy, a kiss is one of the few gestures in most human cultures and carries similar symbolism. But from where did humans learn to kiss? That’s a question shrouded in mystery, and some evolutionary anthropologists say the behaviour of kissing—reaching someone with protruded lips followed by a sucking action—is rooted in millions of years of primate evolution. The first known archaeological evidence describing a kiss dates back to ancient Mesopotamian clay tablets from 2500 BC. However, paleontological evidence from fossils of Neanderthal teeth tartar shows modern-day humans and Neanderthals exchanged saliva more than 100,000 years ago. Whether that is through kissing, swapping spit or sharing food is unknown. </p>.<p>Anthropologists, so far, have identified three possible hypotheses on why kissing may have evolved in humans. The first points to behaviours like sniffing, possibly for potential mates, which later morphed into kissing. But this does not explain why one would make protruded lips to sniff. The other hypothesis posits that kissing evolves from the nursing behaviour of premastication—where parents chew up food for their young ones and put it in their mouth. This behaviour, seen even today in birds and some mammals, does not explain why kissing is prevalent among adults who do not need their food chewed up. </p>.<p>A recent review points to another hypothesis: kissing may have evolved from grooming, a behaviour seen in all great apes and part of their repertoire. According to it, kissing may have started as the last step of the fur grooming ritual, called the ‘groomer’s last kiss.’ It’s a behaviour where a groomer approaches the individual being groomed with protruded lips and makes a suction movement to remove parasites and other debris found in the coat.</p>.<p>Even today, all great apes practice this ritual, vital to building social bonds between individuals. However, as humans evolved, we lost most of our fur, and elaborate grooming rituals of picking out parasites weren’t necessary. Over time, our grooming rituals shortened, and what remained was just the groomer’s last kiss. Although the origins might sound disgusting, given the symbolism of kissing today, it’s commendable that it’s one of the few ape behaviours that has remained unchanged in us for at least 7 million years. That is if this hypothesis turns out true!</p>