Scientists considered kissing a habit and incorporated it into the picture of the entire ape family. They used a unique mathematical method, running 10 million different scenarios to understand the probability of kissing in each.
US News, 21 Nov 2025 (BNN Web)
If you thought kissing was a uniquely human part of romance, you’d be mistaken. The first kiss occurred long before humans walked the Earth. The first kiss happened between two ape ancestors in the dense forests of ancient Africa, 16.9 to 21.5 million years ago.
How Did Kissing Start? How Did Scientists Figure It Out?
For the first time, researchers investigated the entire family tree of various apes. They tried to determine which animals practiced mouth-to-mouth contact and how old this habit is.
Their results suggest that kissing was present in the ancestors of great apes 21.5 to 16.9 million years ago. While things have changed over time, this habit has persisted. Even today, great apes like chimpanzees, bonobos, and orangutans are seen kissing each other.
An Oxford scientist stated, “This is the first time anyone has tried to understand kissing from such a broad perspective.”
The Biggest Challenge: Identifying a ‘Kiss’ in Animals
Scientists faced the challenge of accurately identifying kissing-like behaviors in animals. Often, animals touch mouths, but it isn’t truly a kiss.
Therefore, they developed a simple definition: gentle and calm mouth-to-mouth contact that does not involve food sharing. Based on this definition, they studied all apes. This behavior was clearly observed in chimpanzees, bonobos, and orangutans.
Do Insects, Birds, and Bears Kiss Too?
According to this definition, they found that various creatures like insects, birds, and bears also engage in kissing-like behavior, but most reports are found in primates.
Lip-to-lip contact existed long before humans. This behavior evolved in our ancestors—chimpanzees, bonobos, and orangutans. Research published in Evolution and Human Behavior also indicates an 84% probability that Neanderthals were the first hominids to kiss.
Calculations Based on Viewing Kissing as a Habit
Scientists considered kissing a habit and incorporated it into the picture of the entire ape family. They used a unique mathematical method, running 10 million different scenarios to understand the probability of kissing in each.
An Oxford professor remarked, “Such behaviors are not found in bones, but by combining modern knowledge and science, we can estimate what our ancient ancestors did.”
