Long before humans walked the Earth as we know them, our ancestors might have been engaging in a gesture we consider quintessentially human, kissing. A groundbreaking study from researchers at the University of Oxford has revealed that behaviors resembling kissing could date back 16.9 to 21.5 million years, long before modern humans appeared.
The study, recently published by Oxford researchers, proposes that our great ape ancestors—and even Neanderthals—likely practiced some form of mouth-to-mouth contact that was non-aggressive and distinct from feeding behavior. This discovery suggests that the origins of kissing are deeply embedded in evolutionary history.
“To define kissing across species, we considered any mouth-to-mouth contact that is non-aggressive and does not involve food exchange,” explained Matilda Brindle, lead researcher of the study. “This allowed us to compare behaviors in modern primates and make informed inferences about extinct species, including Neanderthals.”
Anthropological Kissing History
Researchers examined hundreds of observational studies on contemporary primates, including chimpanzees, bonobos, and orangutans. Using advanced Bayesian phylogenetic models, the team simulated the evolution of this trait millions of times. The results strongly indicate that kissing-like behaviors were likely present in early ape ancestors and retained in Neanderthals.
The implications of the study are profound. Since kissing leaves no fossil record, understanding its evolutionary origins has long been speculative. By combining behavioral data from living primates with statistical modeling, scientists can now infer that the roots of human affection may extend far deeper than previously imagined.
Interestingly, while kissing is often thought of as universal in human culture, anthropological studies show that only about 46% of societies document kissing in some form. “This highlights the complex interplay between biological predisposition and cultural expression,” Brindle noted.
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Behavior Tracing
From an evolutionary standpoint, kissing may have served several purposes. It could strengthen social bonds, serve as a mate assessment strategy, or play a role in reproductive behaviors. Despite potential risks, such as disease transmission, the persistence of this behavior in both humans and their evolutionary relatives suggests strong social or reproductive benefits.
Stuart West from Oxford University added, “Our study opens a new framework for exploring social behaviors in extinct species. By observing patterns in living primates and modeling their evolution, we gain insight into behaviors we often take for granted as uniquely human.”
While the study sheds light on a behavior often considered purely cultural, it also raises questions for further research. For example, how do environmental and social pressures shape affectionate behaviors across species? And could other forms of social bonding in humans also trace back to ancient evolutionary roots?
This research not only challenges perceptions of what it means to be human but also underscores the shared evolutionary heritage of social and affectionate behaviors across millions of years. The next time someone leans in for a kiss, it may be worth remembering: they could be connecting with a tradition that spans millions of years—long before modern humans existed. (Wage Erlangga)
