Hold on tight! A stunning new study reveals that kissing is not just a human love act—it’s a super ancient habit that started roughly 21 million years ago. That’s way before modern humans appeared around 300,000 years ago! Researchers from top universities like Oxford, UCL, and Florida Institute of Technology teamed up to dig deep into this mouth-to-mouth mystery. They didn’t just guess what kissing is; they defined it as “non-aggressive mouth-to-mouth contact without food transfer.” Why? Because some animals press mouths together but for food sharing or fighting. By watching bonobos, gorillas, chimpanzees, orangutans, macaques, and baboons, scientists confirmed that kissing is not just a human thing—it runs deep among our ape cousins. And get this—the team suspects Neanderthals, our closest extinct relatives, probably kissed too. Maybe even with early modern humans! Lead author Matilda Brindle called it “the first time anyone has taken a broad evolutionary lens to examine kissing.” Using a smart statistical tool called Bayesian modeling, which they ran a whopping 10 million times, the researchers rewound history to when the trait might have begun. They found kissing was born once between 21.5 and 16.9 million years ago in the common ancestor of large apes. What sparked this weird, sweet behavior? It might come from mother apes pre-chewing food and passing it mouth-to-mouth to their babies. Over time, this practical act could have evolved into the kissing we know today—a loving sign beyond just feeding. The study opens a new window into our past, making us wonder about love and connection going back millions of years. The full research, titled ‘A comparative approach to the evolution of kissing,’ appeared in the journal Evolution and Human Behavior on November 19, 2025. So next time you share a kiss, remember—you’re part of a tradition millions of years old!