Kissing Neanderthals: Humans Locked Lips

A Lock of Lips: Uncovering the Ancient Origins of the Kiss

The simple act of a kiss, a gesture rich with meaning across human cultures, may have roots far deeper and more complex than previously imagined. New scientific inquiries suggest this intimate behaviour is not uniquely human. Researchers now propose that our extinct relatives, the Neanderthals, also engaged in kissing. They might even have shared this tender act with Homo sapiens, rewriting our understanding of their relationship from one of mere coexistence to one of potential affection and intimacy. This idea challenges long-held views of our ancient cousins and paints a more nuanced picture of their social and emotional lives.

An Affectionate Reassessment

The notion that Neanderthals and anatomically modern humans had a very close connection is not new within scientific circles. Previous studies have offered compelling evidence of their close interaction. For instance, researchers discovered that both species shared identical microbes in their mouths. This particular microorganism persisted for a vast expanse of time after their evolutionary paths diverged, strongly indicating the exchange of saliva. Such findings lay the groundwork for a more personal interpretation of their encounters, moving beyond competition for resources to include moments of shared intimacy.

The Oxford Perspective

A recent investigation by Dr Matilda Brindle, an evolutionary biologist at the University of Oxford, lends weight to a straightforward explanation for this microbial sharing. The research suggests the most probable reason is that they were kissing. This hypothesis aligns neatly with genetic evidence showing that modern humans with non-African ancestry carry elements of the Neanderthal genome within their own genetic makeup. This genetic legacy serves as definitive proof of interbreeding. The idea adds a distinctly romantic element to the narrative of human-Neanderthal relations, transforming our perception of their interactions.

Defining an Ancient Act

To explore the deep evolutionary history of kissing, Dr Brindle and her colleagues first needed a universal definition. Previous attempts were heavily human-centric, effectively excluding other animals from the behaviour. The team recognised that animal kisses might not appear identical to the human version. Therefore, they needed a broader framework to analyse the behaviour across different species. This foundational step was crucial for tracing the act's deep evolutionary history and understanding its presence in our primate relatives.

A New Scientific Framework

The researchers developed a definition centered on amicable encounters involving purposeful mouth-on-mouth connection with another individual of the same kind. Their criteria specified some oral motion while ensuring no food was exchanged. This distinction was vital to separate kissing from other similar behaviours. For example, some fish engage in "kiss-fighting" to establish dominance, while many species transfer chewed food to their young. By creating a precise definition, the scientists could accurately identify and study the behaviour's evolutionary path across the primate family tree.

Uncovering Primate Precedents

With a clear definition in place, the team turned its attention to our closest living relatives. They gathered documented accounts of kissing in primate populations across both Asia and Africa, which included species like chimpanzees, bonobos, and orangutans. To corroborate these written accounts, they meticulously reviewed video evidence from platforms like YouTube. This observational data provided a solid foundation for their evolutionary analysis. The fact that these species kiss suggested the behaviour was not a recent human invention but a much older, shared trait.

Tracing the Evolutionary Timeline

By combining the behavioural data from living primates with information on the evolutionary connections among species, the researchers reconstructed the history of kissing. Using a statistical method known as Bayesian modelling, they treated kissing as a biological trait and ran millions of simulations. This powerful analysis allowed them to map the behaviour onto the primate family tree. The results consistently pointed to a single origin for kissing, originating with the predecessors of today's great apes, pushing its emergence back millions of years.

A Behaviour Millions of Years Old

The team's findings suggest that kissing first appeared at some point from 16.9 to 21.5 million years in the past. This places the origin of the behaviour squarely in the era of the ancestral line of the large apes. That this behaviour has been retained over such a vast evolutionary period indicates its significance. It is a behaviour still present in most of the great apes today, underscoring its deep-rooted nature. This discovery fundamentally changes our understanding of how far back this intimate gesture extends in our lineage.

The Neanderthal Connection

The position of Neanderthals upon this extensive evolutionary family tree makes it highly probable that it is highly likely that they also engaged in the act of kissing. Their position as close relatives to Homo sapiens means they would have likely inherited this ancient behaviour. The implications of this are profound, suggesting a shared social and emotional repertoire. It challenges the outdated image of Neanderthals as brutish and unsophisticated, instead portraying them as beings capable of tenderness and complex social bonding, much like ourselves.

An Interspecies Intimacy

The research goes a step further, proposing that this activity may not have been restricted solely to members of their own group. The evidence that modern humans kiss, combined with the strong likelihood that Neanderthals did as well, points to an extraordinary possibility: these two distinct groups may have kissed each other. This conclusion is supported by the aforementioned genetic proof of interbreeding and the sharing of oral microbes. It paints a vivid picture of encounters between our ancestors and their hominid cousins, filled with a level of intimacy previously only imagined.

Echoes in Our DNA

The genetic record provides undeniable confirmation of these ancient encounters. Recent analysis of ancient genomes has pinpointed the period of gene flow between Neanderthals and modern humans to a window beginning approximately 47,000 years ago. For nearly seven millennia, both populations coexisted and interbred. Consequently, most non-African humans today carry between one and two percent Neanderthal DNA. This genetic inheritance is a direct legacy of the intimate relationships our ancestors formed with their thick-browed relatives across Eurasia.

Rewriting the History Books

While the Oxford study traced the biological genesis of kissing, other research has focused on its cultural history. For a long time, historians believed the earliest written evidence of kissing came from India, around 1,500 BCE. However, a newer analysis of ancient Mesopotamian texts has pushed this date back by a full millennium. Evidence from clay tablets written in cuneiform script shows that kissing was a well-established practice in the Middle East as early as 2,500 BCE.

Clues in Cuneiform

Thousands of ancient clay tablets from Mesopotamia, the region of modern-day Iraq and Syria, have survived to this day. Dr Troels Pank Arbøll, an expert affiliated with the University of Copenhagen, explains that these texts contain clear examples of kissing. The act was considered a part of romantic intimacy, much like it is today. However, it was not restricted solely to romance; the texts also describe kissing as part of friendships and family relations. This discovery reveals that kissing was a common and multifaceted behaviour in multiple ancient cultures.

More Than Just Romance

The Mesopotamian records demonstrate that kissing served various social functions. While it was certainly a component of romantic relationships between married couples, it also appeared in platonic contexts. The evidence suggests that kissing was not a custom that originated in a single region and then spread. Instead, it seems to have been practised independently in various ancient societies over the course of millennia. This widespread presence underscores the behaviour's fundamental role in human social interaction, far beyond purely romantic or sexual contexts.

The Evolutionary Purpose of a Kiss

From an evolutionary standpoint, kissing presents a puzzle. It carries risks, including the transmission of diseases, with no obvious direct benefit for survival. However, researchers propose several compelling functions. In a sexual context, kissing may help in mate assessment. The close proximity allows individuals to subconsciously pick up on chemical signals related to health and genetic compatibility. It could also increase arousal and, by extension, reproductive success. These potential benefits could outweigh the inherent risks.

A Powerful Bonding Agent

Beyond mate selection, kissing plays a crucial role in social bonding. The release of oxytocin, often called the "love hormone," during a kiss fosters feelings of affection and attachment. This chemical process helps to reinforce the connection between partners in a romantic relationship. In a non-romantic context, kissing can strengthen bonds between family members and friends, serving as a gesture of closeness and connection. This bonding function helps to maintain the strong social networks that have been vital to human survival for millennia.

An Unintended Viral Legacy

The rise of kissing as a common human behaviour may have had an unintended consequence: the spread of pathogens. Researchers have linked the emergence of new strains of the herpes simplex virus 1 (HSV-1), which causes cold sores, to the Bronze Age and the increasing popularity of kissing. The intimate exchange of saliva provides an effective transmission route for such viruses. Ancient medical texts from Mesopotamia even describe a disease with symptoms remarkably similar to HSV-1, suggesting a long history of orally transmitted infections.

The Expert View on Primate Behaviour

Dr Jake Brooker of Durham University, an authority on the behaviour of great apes, finds the study's conclusions logical. He notes that because kissing is seen across a diverse group of ape species, its beginnings must be rooted far back in our evolutionary history. He suggests that an examination of various kissing styles in a broader selection of species could reveal an even earlier point of origin. He believes that many behaviours we consider uniquely human, such as the act of kissing, are not exclusive to our species if we observe other animals closely.

An Archaeological Perspective

Professor Penny Spikins from the University of York, who studies the archaeology of our origins, adds a cultural perspective. She points out that kissing is not universal across all human societies, indicating a significant cultural component to the behaviour. Nonetheless, she emphasizes the long-standing importance of emotional bonds for human survival. Methods for fostering closeness and security have held significance for eons. This perspective helps to contextualize the act of kissing within the broader framework of human emotional evolution.

A Gesture of Enduring Connection

The image of our ancient relatives sharing a kiss may seem at odds with our conventional ideas of a brutal and hostile history. However, it should not be a surprise that Neanderthals kissed, or that they even shared kisses with the ancestors of modern humans. This simple act represents a thread of connection that runs through millions of years of evolutionary history. It links us not only to our primate cousins but also to the extinct hominids who walked the Earth before us, reminding us of a shared capacity for affection and social bonding.