Mama gorilla, Bandia sits with her newborn in the Great Apes of Harmabee Habitat at the Detroit Zoo on Thursday, Aug. 22, 2024.

Stories centered around true love's kiss might be tales as old as time. And, according to a new study, kisses might even have been around before humans walked the earth.

Humans kiss each other platonically and romantically, and kisses are a huge part of pop culture, even the main subject of songs, movies, and books.

Humans kiss when they say hello, goodbye, apologize, celebrate, or when trying to be romantic.

But, despite the warm feelings kisses give humans, the act has bamboozled scientists.

"A comparative approach to the evolution of kissing," a study published by Evolution and Human Behavior on Nov. 19, aims to change that and even suggests that, like humans, the ancestors of apes and Neanderthals likely kissed, too.

"This is the first time anyone has taken a broad evolutionary lens to examine kissing," Matilda Brindle, lead author and evolutionary biologist at Oxford’s Department of Biology, said in a statement. "Our findings add to a growing body of work highlighting the remarkable diversity of sexual behaviors exhibited by our primate cousins.”

Here's what to know about the study.

Kissing dates back millions of years

Kissing could date back 21.5 to 16.9 million years, according to a news release about the study.

The study suggests that kisses may even predate humans, who have only roamed the Earth for at least 300,000 years, though our species may be older, according to the Natural History Museum of London.

To figure out just how old kissing is, "researchers carried out the first attempt to reconstruct the evolutionary history of kissing using a cross-species approach based on the primate family tree," according to the press release.

Whether it's a smooch on the cheek or a peck on the lips, there are many ways to kiss someone.

But in the study, researchers defined kissing as a non-hostile act of direct oral-to-oral contact that involves movement of the lips or other parts of the mouth without the transfer of food.

Less than half of human cultures kiss

Who and what are performing the act of kissing may be surprising.

Humans, of course, are listed in the study as engaging in both platonic and sexual kissing. But most human cultures actually do not kiss.

“While kissing may seem like an ordinary or universal behavior, it is only documented in 46% of human cultures," said Catherine Talbot, co-author and Assistant Professor in the College of Psychology at Florida Institute of Technology, in a statement. "The social norms and context vary widely across societies, raising the question of whether kissing is an evolved behavior or a cultural invention. This is the first step in addressing that question.”

Primates, who are considered to be like evolutionary cousins to humans, have also been observed kissing.

"Kissing was retained over the course of evolution and is still present in most of the large apes," the press release stated.

Primates that have been observed kissing include:

  • Gorillas- Sexual and platonic kissing is rare
  • Bonobos- Both sexual and platonic kissing are common
  • Chimpanzees- Platonic kissing appears to be common, while sexual kissing appears to be rare
  • Orangutan- Family members platonically kiss to show affection, though it appears to be rare
  • Bornean orangutan- The animals can kiss platonically and sexually, but both appear to be rare.

Ants, birds, and polar bears have also been observed kissing, but most reports of kissing involve primates.

Did neanderthals and humans kiss each other?

It is unknown whether neanderthals kissed platonically or sexually, but some key evidence might suggest they kissed.

Neanderthals lived on Earth around 400,000 to 40,000 years ago, according to the Smithsonian National Museum of History. So what is known about them has been determined through fossils that have been found in Europe and Southwestern and Central Asian

Because ancient humans, Homo sapiens, and Neanderthals, Homo neanderthalensis, shared oral microbiomes, which could've been transferred through saliva, and genetic material through interbreeding, it is possible that humans and Neanderthals kissed while the now-extinct Neanderthals still roamed the Earth, according to the study.

Julia is a Trending reporter for USA TODAY and covers scientific studies and trending news. Connect with her on LinkedIn, X, Instagram, and TikTok: @juliamariegz, or email her at jgomez@gannett.com

This article originally appeared on USA TODAY: Ever wonder why we kiss? The art of smooching could predate humans

Reporting by Julia Gomez, USA TODAY / USA TODAY

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