The History of Kissing: A Gesture That’s Not Universal

In 1439, members of the English Parliament submitted a petition to King Henry VI. Their request was specific: they wanted the kiss omitted from the ceremony of homage, in which subjects swore fealty to the crown. The reason was the plague then sweeping through England again — “the most infectious disease,” as the petition itself put it.^[15] The trouble was that this kiss was no mere pleasantry. Under the custom of the time, skipping it during homage risked voiding the oath itself. Parliament had to beg the king to confirm that “homage performed without a kiss shall be as valid as if the kiss had been given.”^[15] An entire feudal contract, in other words, could hinge on a single kiss.

And yet research suggests this old, weighty custom is far from universal to our species. In 2015, American anthropologists surveyed 168 cultures and found romantic or sexual lip-kissing confirmed in only 46 percent of them — 77 cultures.^[1] In the remaining 54 percent, no evidence of such kissing turned up at all, and in some societies people found the act of pressing mouths together outright distasteful. The physical capacity to kiss is an inheritance tens of millions of years old, dating back to when humans were still great apes. But what cultures actually did with that capacity turned out to vary enormously — a legal oath in one place, a religious rite in another, and in some societies, a practice that simply never took hold.

Only 46% of 168 Cultures Studied — Kissing Is Not a Human Universal

Anthropologist William Jankowiak of the University of Nevada, Las Vegas, and his colleagues published a 2015 paper in American Anthropologist drawing on Yale University’s eHRAF cross-cultural database and a standard comparative sample, surveying 168 cultures in all.^[1] Romantic or sexual lip-kissing was clearly documented in only 77 of them — 46 percent. The remaining 91 cultures showed no trace of it. On that basis, the researchers concluded that romantic kissing is neither a human universal nor even a near-universal.^[1]

One finding stood out in particular: kissing appeared more often in societies with more complex social hierarchies.^[1] The correlation suggests that where gaps in resources and status run wide, choosing a romantic partner may call for more subtle signaling. Small-scale hunter-gatherer societies, by contrast, recorded this kind of kissing relatively rarely. That correlation shouldn’t be read as a measure of how “advanced” a culture is, though. Much of the underlying ethnographic data comes from records compiled by twentieth-century Western anthropologists, and intimate customs in some cultures may simply have been observed or documented less thoroughly than in others.^[1][2] Yale’s eHRAF World Cultures database, in presenting the study, added that in some cultures people regard mouth-to-mouth contact as unhygienic or simply repulsive.^[2] Facial expressions for emotion are a signaling system most of humanity shares, as another article on this site explores — but kissing, it turns out, is far more subject to cultural choice.

The Capacity Itself Is a 20-Million-Year-Old Inheritance

So how old is the underlying physical and behavioral capacity to kiss in the first place? In November 2025, a team led by the University of Oxford turned the tools of evolutionary biology on that exact question. The researchers compiled data on kiss-like behavior reported across multiple primate species, mapped that data onto the primate family tree, and ran statistical models simulating millions of possible evolutionary pathways. The method makes it possible to work backward and estimate the point on the evolutionary tree where a given behavior most likely first appeared.^[3]

The result was striking. Kissing behavior most likely already existed roughly 21.5 to 16.9 million years ago, in the great-ape ancestor shared by humans, orangutans, gorillas, and chimpanzees.^[3] Indeed, mouth-to-mouth contact has been documented in nearly every great ape species except the eastern gorilla. Chimpanzees and bonobos press their lips together as a gesture of greeting or reconciliation, and bonobos sometimes incorporate tongue contact into the act.

The researchers took the argument one step further. Earlier work had already shown that Neanderthals and modern humans not only interbred but shared oral microbes — an analysis of fossilized dental plaque found the two groups carried the same oral bacterial communities up until roughly 112,000 years ago.^[4] If kissing’s origins trace back to the shared great-ape ancestor, the team reasoned, then Neanderthals — who sat between that ancestor and us on the family tree — very likely kissed as well.^[3][4] Co-author Catherine Talbot of the Florida Institute of Technology described the study as the first attempt to treat kissing as a biological trait to be mapped onto the evolutionary tree, rather than a purely cultural invention.^[4]

Why Did It Start? Two Competing Hypotheses

The age of the capacity is now reasonably well established, but why the behavior emerged in the first place remains contested. For a long time, the dominant explanation was the “kiss-feeding” hypothesis: mothers premasticating food and passing it mouth-to-mouth to their offspring, a practical act that over evolutionary time supposedly lost the food and kept only the gesture as a signal. Proponents pointed to the similarity between the tongue-pushing, sucking motions of feeding and those of kissing.

In 2024, however, primatologist Adriano Lameira of the University of St Andrews in Scotland directly challenged that account in a paper published in Evolutionary Anthropology.^[5] He proposed an alternative: the “grooming kiss” hypothesis. When apes groom one another, they sometimes finish by pursing their lips and lightly sucking away any remaining debris or dirt. Lameira argues that this closing gesture gradually became detached from grooming and hardened into an independent signal — the kiss.^[5]

Lameira’s central objection is one of direction. Food-passing moves something outward, from inside the mouth to outside; kissing pulls inward. The two motions run in opposite directions. The feeding hypothesis also fails to explain why two fully grown adults, with no food involved whatsoever, press their mouths together at all.^[5] The grooming hypothesis, by contrast, fits neatly with the fact that grooming among apes is fundamentally a social act that confirms trust and bonding. Even so, this hypothesis has not won universal acceptance among scholars, and the debate between the two camps remains very much open.

The Earliest Written Record — Pushed Back a Thousand Years

If the behavior itself dates back to our ape ancestors, when does it first appear in writing? Until 2023, the accepted answer pointed to Bronze Age South Asian texts, the Vedic literature, dated to roughly 1500 BCE. Then a 2023 paper in Science by Assyriologist Troels Pank Arbøll of the University of Copenhagen and Sophie Lund Rasmussen overturned that consensus.^[6]

Reexamining cuneiform tablets from Mesopotamia, the two researchers confirmed that kissing already appears in written records from around 2500 BCE — pushing the earliest known reference back by roughly a thousand years.^[6] The tablets mention kissing both as an intimate act between lovers and in contexts describing friendship or family relationships. The University of Copenhagen noted that this suggests kissing was not invented in one place and then spread outward, but was likely already a well-established practice across multiple ancient societies.^[7]

There’s an intriguing postscript to the research. The team also pointed out that an ancient Mesopotamian medical text describes a disease called “buʾshanu,” whose symptoms — blistering around the mouth — closely resemble a modern herpes infection.^[6] Arbøll cautioned, however, that if kissing had already been a widespread, long-standing practice, then pathogen transmission through kissing had probably also been occurring at some steady background rate for just as long — and he urged against reading the finding as evidence that kissing was somehow especially dangerous.^[7]

Rome: Even Kisses Came With Rank

As written records accumulated, kissing increasingly became subject to social norms and law. The ancient Romans did not lump all kisses together. Latin had at least three distinct words for it, later sorted by grammarians according to their use: osculum for a polite kiss on the hand or cheek, basium for the affectionate kiss shared by spouses or lovers, and savium for a deep, passionate kiss.^[8][16] It’s basium that appears in the poet Catullus’s famous line to his lover Lesbia, “give me a thousand kisses” (da mi basia mille).

In Rome, kissing was more than a romantic gesture — it was also a tool of law and surveillance. Under a custom known as ius osculi, the “right of the kiss,” male relatives were entitled to kiss their female relatives on the mouth to check for the smell of alcohol.^[9] Pliny the Elder, in his Natural History, records that Cato the Elder explained the purpose of this custom as detecting whether a female relative smelled of “temetum,” strong wine.^[9] Drinking was taboo for Roman women at the time, and being caught with alcohol on one’s breath could raise suspicions of infidelity, leading to divorce or punishment. The kiss, in effect, doubled as a breathalyzer. Public displays of affection were tightly policed too: Cato, in his role as censor, went so far as to expel a senator named Manilius from the Senate for kissing his own wife in broad daylight — deeming it soft and improper conduct.^[8]

Kissing was also restricted for health reasons on at least one occasion. The Roman historian Suetonius records in his Lives of the Caesars that the emperor Tiberius issued an edict banning the everyday courtesy kiss exchanged at court (cotidiana oscula).^[10] Suetonius’s own account, however, does not give a reason for the ban; he lists it alongside a restriction on New Year’s gift-giving, as one of several measures aimed at promoting austerity.^[10] It was a different writer, the naturalist Pliny the Elder, who explicitly linked kissing to disease. In his Natural History, he wrote that during Tiberius’s reign a blistering skin condition called “mentagra,” which covered the entire face, arrived in Rome and spread — particularly among the aristocracy — through the customary greeting kiss.^[14] In other words, the popular story that “Rome banned kissing because of disease” is really a later fusion of two separate primary sources: Suetonius’s account of the ban and Pliny’s account of the illness. Even so, read together, the two records do suggest that Romans were already grappling with the idea of controlling kissing on public-health grounds. That said, the custom ran too deep to be suppressed for long.

The Middle Ages: A Kiss Was a Binding Oath

In medieval Europe, kissing became central to both religious and legal procedure. Church mass included a “kiss of peace,” in which congregants pressed their mouths together to share a gesture of peace. Records from the diocese of York in England, dated to 1248, are the earliest known reference to the practice shifting: by the thirteenth century, congregants increasingly kissed a small wooden tablet bearing a sacred image — the “pax” — one after another, instead of kissing each other directly. Concerns about the sexual, social, and hygienic implications of direct kissing are thought to have driven the change.^[13]

Under feudalism, a kiss was the act that made a contract binding. The twelfth-century Flemish chronicler Galbert of Bruges recorded a homage ceremony from 1127: a new count and his vassal clasped hands, spoke their oaths of fealty aloud, and finally sealed the agreement with a kiss.^[11] In a society where gesture and ritual mattered more than any written document, the kiss was what formally sealed a spoken vow — and without it, the validity of the oath itself could be called into question. The English Parliament’s 1439 petition mentioned earlier was precisely the moment this ancient custom collided head-on with a new threat: a fresh outbreak of plague.^[12][15]

In art and story of the same period, kissing also carried a darker meaning: betrayal. The most famous example is the “Kiss of Judas” in the New Testament, where Judas, one of Jesus’s own disciples, identifies him to Roman soldiers by kissing his cheek. The scene shocked contemporaries precisely because kissing had traditionally been a sacred gesture confirming friendship, trust, and peace. By turning a sign of trust into an instrument of betrayal, the story inadvertently proves just how much social weight a kiss carried at the time. The Italian painter Giotto di Bondone depicted the scene around 1305 in a fresco in the Scrovegni Chapel in Padua.

Even with the pax tablet as a substitute, the kiss of peace gradually lost its force. Disputes over who got to kiss the pax first became increasingly common, and some congregants came to treat participation in the ritual as an easy stand-in for the more demanding preparations required for communion. As a result, the Catholic liturgy scaled the practice back over time; by the seventeenth century, it survived mainly among clergy and nobility.^[13] Like Rome’s alcohol-detecting kiss or the kiss that sealed a vassal’s oath, the medieval kiss of peace gradually shed its original legal and religious weight and drifted, over time, toward the private gesture of affection we recognize today.

The Roman funerary relief below does not depict a kiss, but it expresses a couple’s legal bond through clasped hands. It’s a useful reminder of just how precisely Romans distinguished the meaning of physical contact — as finely as they distinguished their words for a kiss — and how much social and legal weight they attached to those distinctions.

A Gesture Half the World’s Cultures Chose

Let’s return to the question we started with. The capacity to kiss is an inheritance dating back some 20 million years, to when humans were still great apes. Neanderthals, and the distant cousins who split off from our lineage before them, likely knew the gesture too. But what to actually do with that ancient capacity was left entirely up to culture. Some societies gave the gesture the force of law, using it to seal a vassal’s oath. Others made it part of sacred ritual. Still others turned it into a tool of surveillance, used to detect the smell of alcohol on someone’s breath. And in more than half of the cultures ever studied, this gesture was never linked to romance at all.

So what about today? Break the 2015 findings down by region and the picture gets more complicated. In the Middle East, all ten cultures in the sample practiced romantic kissing; Asia came in at 73% and Europe at 70%. North America sat at 55%, and in Central America the researchers found no evidence of it at all.^[19] That distribution does not map onto the familiar “West versus the rest” storyline. The highest rates were not in Europe but in the Middle East and Asia.

To us, kissing now feels like a gesture that belongs everywhere. Two things are probably tangled together in that impression. One is real change: film and advertising, migration and urbanization have almost certainly widened the reach of the gesture. The other is illusion. Justin Garcia, one of the study’s authors, said the findings were “a real reminder of how Western ethnocentrism can bias the way we think about human behavior.”^[19] The very sense that everyone does this may be the bias the researchers were warning about. And the 46% figure, it bears repeating, comes from tallying twentieth-century ethnographic records — it is not a present-day global survey. That number is less a fixed property of our species than a snapshot of one moment in the record.

That collision between an old greeting custom and a new epidemic wasn’t confined to medieval England, either. Six centuries after Parliament asked Henry VI to waive the ceremonial kiss, the same instinct resurfaced across the English-speaking world during the COVID-19 pandemic: in April 2020, Dr. Anthony Fauci, then the United States’ top infectious-disease official, told a Wall Street Journal podcast, “I don’t think we should ever shake hands ever again,” and the elbow bump briefly displaced the handshake as the default American greeting.^[17] France’s government went further that same spring, with the health minister formally urging citizens to set aside la bise, the customary cheek kiss.^[18] For readers who spent 2020 nodding at friends instead of touching them, the 1439 petition to Henry VI reads less like a medieval curiosity and more like a rehearsal for the same bargain people keep striking whenever disease makes an old greeting suddenly feel risky.

In the end, the history of kissing traces a single root branching into countless different paths. A gesture that likely began in the grooming behavior of apes went on to live entirely different lives: a token of love on a Mesopotamian clay tablet, a measure of propriety in the Roman Senate, a symbol of both vow and betrayal in medieval churches and courts. That one motion could carry such radically different meanings is, perhaps, the clearest evidence of just how much culture can build on top of biological instinct.