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Q: Why do we kiss? Is kissing on lips a learned behavior or basic instinct?

Just wondering from a psychological or biological point of view…is kissing something we learn or its something we are born knowing? If it’s something we’re born knowing, why would that be? If it’s something that we teach each other, what is the reason behind it?


Well, if you look at from an evolutionary perspective, it becomes quite clear that our closest living relatives (and therefore, in all likelihood, our ancestors) kissed and used multiple forms of physical affection. Therefore, we can surmise that kissing is an biological behavior, one which played an important evolutionary function.

“The oldest evidence of a kissing-type behaviour comes from Hindu Vedic Sanskrit texts from over 3,500 years ago. Kissing was described as inhaling each other’s soul.”

However, according to a recent BBC article, which cited an article that looked at 168 cultures from around the world, only 46% of cultures kiss in the romantic sense.

Nonetheless, kissing exists on many planes–not only sexual or romantic. And it is only one of many physical behaviors that indicate intimacy.

In fact, many animals “kiss” in some way. Chimps and bonobos kiss much like humans do, and especially in the case of Bonobos, for seemingly similar reasons. (See my post on animal genomes for more information on mating/affectionate behavior among primates:

Birds touch beaks, nibble, and other such things that can be seen as the equivalent to human kissing-especially during courtship rituals with a potential mate.

There are many other versions of species kissing to show love: dogs licking, cats touching noses, nuzzling and nose-rubbing, feather preening, etc…

This is evidence that kissing is fundamentally a biological, evolved behavior which functions for various purposes.



A male and a female chimpanzee (Pan troglodytes) looking deeply in each others eyes

Chimpanzees kiss and embrace after a fight (Credit: C.O. Mercial/Alamy)

Whether or not this is evidence that kissing is instinctual is another matter. 

To fully answer this question, we’d also have to take into account the great deal of historical, psychological, sociological and anthropological factors that have to do with how, when and why humans kiss. But, as this is not my area of expertise and far too much to delve into here, I recommend doing some research on your own on the evolution of kissing techniques.  (Do a quick google search on how”french kissing” came to be in the United States, for an amusing read).

I will say that while kissing is indeed a natural human behavior, it is also a learned one.

If, for example, a child were raised in an environment in which he never experienced or witnessed kissing, he would not automatically understand what kissing was. He or she might,  perhaps, press his mouth or face to a person he loves…because it is an instinctual trait or desire. But this is all purely hypothetical.



I can give you one interesting non-hypothetical example this question brought to mind, from an area of study I am more familiar with:

Primates that have been separated from their mothers at infancy serve as one example of the way in which the instinctual desire to “groom” still manifests itself in their behavior. Grooming, while not quite comparable to human kissing, is an extremely intimate and important element in Chimpanzee social interaction. It is used to maintain friendly ties among family and community members, and mother apes will “groom” their infants, sometimes to reduce the stress of weaning, or just to sooth them. When a young chimp is taken from its parents, however, they will often start “self-grooming” in harmful, obsessive ways; they do so in an attempt to reassure themselves and replicate the crucial physical intimacy what they are lacking from their mother. This is also seen in similar cases with parrots, who obsessively “feather pluck” when stressed and unable to preen one another.

So, in some sense, these examples can give some insight into how kissing–or any act of intimacy among humans or animals–is both a learned and instinctual trait that plays a hugely important role in our psychology, social development, well-being, and our relations to others.

Here’s a link to a BBC article that explains more on this subject:



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