The Evolution of Kissing: A 21 Million Year Journey

A groundbreaking study has shed light on the evolutionary origins of kissing, tracing this ubiquitous behavior back approximately 21 million years. The research, published in the journal Evolution and Human Behaviour, presents compelling evidence that the common ancestor of humans and other great apes likely engaged in this intimate practice.

The study's methodology involved a meticulous examination of kissing-like behaviors across various species in the animal kingdom. To ensure consistency in their comparisons, the researchers established a precise definition of a 'kiss': non-aggressive, directed oral-oral contact with some movement of lips or mouthparts and no food transfer.

This rigorous approach allowed the scientists to construct an 'evolutionary family tree' of kissing, identifying its presence in diverse species including wolves, prairie dogs, polar bears, and even albatrosses. However, the focus remained primarily on primates, particularly apes, to elucidate the human evolutionary trajectory of this behavior.

Intriguingly, the study also posits that Neanderthals, our closest extinct human relatives, likely participated in kissing. This hypothesis is bolstered by previous genetic research revealing shared oral microbiomes between modern humans and Neanderthals, suggesting prolonged saliva exchange over hundreds of thousands of years.

While this research provides valuable insights into the antiquity and prevalence of kissing, it does not definitively answer the question of why this behavior evolved. Existing theories range from it being a vestige of grooming behavior in our ape ancestors to serving as an intimate method of assessing a potential partner's health and compatibility.

Dr. Matilda Brindle, the lead researcher from the University of Oxford, emphasizes the importance of studying this behavior beyond its romantic connotations in humans. She argues that understanding kissing as a shared trait with our non-human relatives opens new avenues for exploring its biological and evolutionary significance.