Why do humans kiss? #historical #history #drkate #biggesthistory #medieval #onthisday

Added: 2026-05-09

[00:00:00]Why do human beings kiss? From an evolutionary point of view, this behavior doesn't actually make that much sense. Think about it. You have to get really close, like as close as you possibly can to another person to be able to kiss them, which makes you very vulnerable. And in your average 10-minute smooch, you will exchange about 80 million bacteria. So, the potential for disease is astronomical.

[00:00:23]So, why do we do it? Scientists don't know, but they have put forward some theories. There was a piece of research published last week by researchers at the University of Oxford that managed to pinpoint when we started locking lips.

[00:00:37]They look at a lot of different animals to try and establish a sort of evolutionary family tree. They're predominantly looking at primates who who lock lips with one another. Humans, chimps, bonobos, we all kiss each other.

[00:00:49]I'm just jumping in from the future to clarify that when I said we all kiss each other, I did mean within our own species. And by looking at where this behavior turns up, they have estimated that we started to kiss about 21 million years ago, or at least our shared ancestor was kissing. They also suggest that Neanderthals would have enjoyed a good tongue lashing as well. And I love that for them because it doesn't look like Homo sapiens treated them particularly well. So, if they had a bit of a smooch, then good [music] for them.

[00:01:18]One of my favorite things to come out of this paper is actually how they define kissing, which is right underneath me.

[00:01:23]And they go for this definition: a non-agonistic interaction involving directed intraspecific oral-oral contact with some movement of the lips {slash} mouth parts and no food transfer. I will never call it anything else. Just detouring just slightly, the other bit that I like is this bit. And they're going through different primates and they're giving examples. They come to the gorillas who who give each other platonic kisses rarely, but erotic kisses, they do have this particular example in male-to-male intermission, which means exactly what you think it means. So, gay gorillas have been caught kissing, hurrah. So, the behavior of kissing has been around for over 21 million years, but it doesn't actually explain why we do it.

[00:02:06]>> [music] >> Now, non-agonistic interaction involving directed intraspecific oral-oral contact with some mouth and lip movement and no food transfer can be romantic, but it doesn't have to be. Yeah, all right, we smooch people that we fancy, but we also kiss children, and we kiss pets, and we kiss [music] people at work. Just a work work one of those jobs. In fact, this piece of research came out in 2015, and they looked the world over and concluded that only about 46% of cultures used the romantic kiss. But the friendly, loving kind of kiss, that's almost universal.

[00:02:40]So, [music] why do we do it? Freud reckoned that we do it because as infants we develop an oral fixation, and that helps soothe us. But that doesn't really work because if it was all about sublimating breastfeeding, then wouldn't we just keep doing that? So, here are the major theories. Number one, that this is a throwback to pre-mastication behavior. That once upon a time we fed our young by kind of like with our mouths, with a kind of like kiss-feeding. And that the behavior might have developed from there. Number two, that kissing was once part of a kind of like a grooming ritual, like you see monkeys grooming one another, and a kiss might have been part of that. So, like really really what you're doing when you're kissing people is looking for parasites. And I guess that one's about like that it's actually it's a bonding thing to do. It's [music] a nice thing to do for someone. And another big theory is that it is about mate selection. That what you're doing when you get that close for somebody and you're basically playing tonsil tennis with them is on a subliminal, primal level, you're really checking their health.

[00:03:36]And your little monkey brain is trying to work out whether or not this is a suitable person for you to procreate with. Which I can see the sense in that, but if only 46% of the world's cultures are actually doing romantic kissing, that one doesn't kind of work, does it?

[00:03:50]But ultimately, we don't really know why we do it. We know that we've been doing it for a very long time, and we know that it feels nice, and it releases all kinds of lovely things like endorphins when we're doing it. But what purpose it serves, bit of a mystery. The two leading theories being that we're either trying to feed one another, or we're checking each other for ticks.