Kissing: Reflections on Humans and Other Animals Making Out

We're in the dark about why kissing evolved in some human cultures and animals.

Posted Feb 11, 2016

Do dogs make out?

A couple of years ago, while I was at a dog park and having a great time watching dogs play, I heard a young girl screaming to her mom, "Look, look -- Rosie is making out with Henry!" I turned around just as her mom said, "Dogs don't make out," and caught Rosie and Henry in the act (for more on the etymology of the phrase "making out" please click here). Rosie was licking Henry's muzzle and inner mouth with a good deal of zeal, and he just stood there and didn't seem to mind it one bit. Henry then reciprocated, they went at it together until mom yelled "Stop it right now!", and I suppose what we were witnessing was some version of doggie make out. I'd seen it before and have seen it many times since.

I don't know if dogs really make out, but Valentine's day is approaching and, of course, because it's become such a moneymaker for a wide variety of products, TV ads show pricey gifts and humans couples kissing as they exchange products that few if any really need. People also buy Valentine's gifts for dogs and other household companions, but all I've ever witnessed when the gift is given is a quick peck on the head and something like, "You're such a good dog, I love you."

A recent essay by Jeremy Adam Smith called "The Subversive Power of the Kiss" made me think about the evolution of kissing. Kissing has only evolved in around half of human cultures and isn't all the common among nonhuman animals (animals). You wouldn't know how rare it actually is from all the hoopla about kissing and countless pictures of all sorts of humans and other animals engaging in this activity. And, there's no shortage of pondering about different aspects of kissing in these pages

One interesting idea that's emerging from research is that there might be gender differences in who gets what out of kissing, at least in humans. The subtitle for Dr. Smith's thoughtful essay reads, "Just in time for Valentine's Day, a wave of studies suggests that the rise of romantic kissing is linked to the changing roles of women." He nicely considers many other theories for the evolution of kissing but in the end, it's not at all clear why kissing has evolved. Smith concludes, "So why do couples kiss? For pleasure, sure, but there’s more to kissing than what meets the lips. From an evolutionary perspective, it seems, women kiss for freedom and control. If men seem to enjoy it, too—well, that might be just a happy accident."

Do other animals really kiss and swap saliva and smells like we do and for the same reasons?

There's no shortage of articles about kissing by nonhuman animals. A Google search for "Do animals kiss?" generated about 26,900,000 hits and some websites with pictures of a wide variety of animals kissing in their own sorts of ways. I found an essay by Melissa Hogenboom called "Why do humans kiss each another when most animals don't" to be a good summary of what we know and what we think we know about the evolution of kissing in humans and other animals. The teaser for her essay reads, "A new study finds that half of human cultures don't practice romantic lip-on-lip kissing. Animals don't tend to bother either. So how did it evolve?" We also learn that kissing is a rather recent practice. 

Ms. Hogenboom writes:

Yet everyone surely remembers their first kiss, in all its embarrassing or delightful detail, and kissing continues to play a big role in new romances.  

At least, it does in some societies. People in western societies may assume that romantic kissing is a universal human behaviour, but a new analysis suggests that less than half of all cultures actually do it. Kissing is also extremely rare in the animal kingdom.

So what's really behind this odd behaviour? If it is useful, why don't all animals do it – and all humans too? It turns out that the very fact that most animals don't kiss helps explain why some do.

The research article to which she refers is called "Is the Romantic–Sexual Kiss a Near Human Universal?" in which the researchers conclude, based on an analysis of 168 cultures: 

Despite frequent depictions of kissing in a wide range of material culture, we found no evidence that the romantic–sexual kiss is a human universal or even a near universal. The romantic–sexual kiss was present in a minority of cultures sampled (46%). Moreover, there is a strong correlation between the frequency of the romantic–sexual kiss and a society's relative social complexity: the more socially complex the culture, the higher frequency of romantic–sexual kissing.

We also learn that it's possible that "kissing is just a culturally acceptable way to get close enough to another person to detect their pheromones... So if you want to find a perfect match, you could forego kissing and start smelling people instead. You'll find just as good a partner, and you won't get half as many germs. Be prepared for some funny looks, though." Taste might also be important when we swap saliva

In Ms. Hogenboom's essay, relying on renowned primatologist Frans de Waal's observations of kissing, we read,

Our closest relatives, chimpanzees and bonobos, do kiss. Primatologist Frans de Waal of Emory University in Atlanta, Georgia, has seen many instances of chimps kissing and hugging after conflict. For chimpanzees, kissing is a form of reconciliation. It is more common among males than females. In other words, it is not a romantic behaviour. Their cousins the bonobos kiss more often, and they often use tongues while doing so. That's perhaps not surprising, because bonobos are highly sexual beings.

What's really happening in hearts and heads during kissing

All in all, we really don't know much about the evolution of kissing, whether other animals kiss the ways we do and for the same or similar reasons, or the neurobiology of kissing. Perhaps neuroimaging studies, when interpreted with care, will shed some light on the hows and why's of kissing -- what's happening in hearts and heads -- and its relationship to romance and love (please see, for example, Dr. Joe Pierre's essay called "Your Brain in Love" where kissing isn't even mentioned). Along these lines, I did find one short video called "The anatomy of kissing and love in magnetic resonance imaging (MRI) scanner."

So, where to from here? For now, sage advice seems to be do it with a willing partner, enjoy it, try different styles, and go from there, and let the academics have at it about the nitty-gritty details of how and why lips and tongues meet in myriad ways. And, if you have the good fortune of sharing your life with a dog or other animal, let them kiss too. How can that be a bad idea in a world in which violence dominates all sorts of media

Marc Bekoff's latest books are Jasper's Story: Saving Moon Bears (with Jill Robinson), Ignoring Nature No More: The Case for Compassionate Conservation, Why Dogs Hump and Bees Get Depressed: The Fascinating Science of Animal Intelligence, Emotions, Friendship, and Conservation, Rewilding Our Hearts: Building Pathways of Compassion and Coexistence, and The Jane Effect: Celebrating Jane Goodall (edited with Dale Peterson). (Homepage:; @MarcBekoff)

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