The World’s First Kiss Happened as Far Back as 21 Million Years Ago: Study

A recent peer-reviewed study claims to have pinpointed the first kiss.

Published in the Journal of the Human Behavior and Evolution Society this year and made available online on Nov. 19, the study suggested that the world’s first kiss took place “somewhere between 21.5 and 16.9” million years ago — well before the existence of humans.

Titled “A comparative approach to the evolution of kissing” the study noted, “Ancestral state reconstructions across the Afro-Eurasian monkeys and apes suggest that kissing first evolved in the ancestor to the large apes, after the split with the small apes.”

Kissing is defined “as non-agonistic interactions involving directed, intraspecific, oral-oral contact with some movement of the lips/mouthparts and no food transfer,” according to study co-authors Matilda Brindle, Catherine F. Talbot and Stuart West.

The researchers noted that, in non-humans, “kissing has been observed in most large apes and some Afro-Eurasian monkeys,” while similar behaviors “that are sometimes termed kissing, but which do not meet all the criteria in our definition, have been observed in a diversity of other organisms including mammals, birds, fish and even insects.”  

They emphasized, “Kissing can be observed across the animal kingdom.”

Explaining why this matters, the study’s authors said they’re hopeful their “basic observational data” will provide “a useful starting point for further research into the adaptive function of kissing that highlights hypothesis generation and testing within a phylogenetic [evolutionary] framework.”

The researchers concluded, “We suggest that kissing is an ancient and phylogenetically conserved trait within the large apes, including extinct human species.”

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“This conclusion is consistent with kissing having been observed in a variety of animals,” they added. “We highlight promising future avenues of enquiry for understanding why kissing evolved, with our preliminary data highlighting a potential association with a high degree of postcopulatory sexual selection (via the proxy of mating system).”