The evolution of kisses: how were they born?

The kiss, that act of pressing the lips against the surface of another’s as a sign of affection, affection or desire is a widespread expression in modern society. If we think about this emotional demonstration beyond its psychological significance, we are faced with a habit that can be counterintuitive and harmful, as we will see later.

The act of kissing can contain around 80 million bacteria that are transmitted to the receptor, and not all of them have to be good. Any pathogen found in saliva can be transmitted by this affect mechanism, whether it is a virus, bacteria, fungus, or other sufficiently small parasite.

It is for this reason that, if we apply common sense, it is time to ask: What is the evolution of kisses? What evolutionary meaning has a behavior that can endanger the survival of those who carry it out? How were kisses born?

As you can see, an act seemingly so simple and devoid of biological meaning (albeit one loaded with emotion) closes a series of unknowns to be resolved. Immerse yourself with us in the world of kisses, not from a romantic point of view but biological, because the reflections that arise will surprise you.

    The evolution of kisses: from organic to romantic

    The first answer necessary to chain the rest of the relevant questions is, in fact, to find out what is the origin of the kiss. The first record of kiss-like behavior we know of today is in the Vedas, Ancient texts of Indian literature which consolidated the foundations of the Vedic religion (pre-Hindu). Thus, this first test dates back 3,500 years.

    Moreover, civilizations as ancient as the Sumerians were already creating poems in which the presence of the kiss was highlighted as an act of affection and romanticism. We will not continue to cite historical examples, because it is clear that the concept we want to convey: the kiss has been with humans for many, many years.

    What is most striking (and of course harder to explain) is trying to answer this question: why did the kiss happen? There are different theories that explore a possible answer, And we show them below.

    Do we learn to kiss or is it part of our genetic code?

    The first consideration in this area is whether the kiss is a learned act or based on the most basic human instinct. Unfortunately, we don’t have a clear answer, but of course there has been some speculation.

    In favor of the theory that this display of affection is instinctive we find different proofs: For example, kissing-like behaviors are prevalent in the animal kingdom, whether through beak rubbing on birds, licking dogs, or contact between the antennae of insects. Anyway, we also find an animal that embraces like us: the bonobo.

    Bonobos exchange saliva in multiple situations when using the kiss to calm tensions after hierarchical quarrels, to comfort each other, to strengthen relationships in the group, or simply for no apparent reason. This is not at all surprising, because we share with these primates 98.7% of DNA, which of course explains why some behaviors are so similar between the two species.

    However, the evolutionary concept of the “kiss” is something that is often attributed beyond the primate group (or birds, perhaps) in a wrong way. Can we conceive of the antennal play between insects as an act of affection? Unfortunately, there is not enough evidence to attribute such significance to it. Yes, it can be used for conspecific recognition, and to provide information from male to female before breeding, but from there to affection or affection … there’s a good piece.

    On the other hand, there are some arguments that weaken the theory that the act of kissing is a hereditary behavior. 90% of cultures kiss each other (but not all romantically, as we will see below), but the remaining percentage do not.. How is it that these individuals do not kiss if it is something genetic and suitable for all of our species?

      Why did we kiss?

      We kissed for passion, romance, affection, affection, etc. All of these psychological impulses are amply described, but we are not referring to this. Why do we kiss like animals? What is the primitive evolutionary explanation for this behavior? Again, there are several theories in this regard and none have been fully confirmed.

      According to several researchers, the act of kissing may have evolved in humans by the previous word-of-mouth regurgitation behavior from mother to child, A relatively widespread form of parental care in the animal world (especially mammals and birds). Since we do not want to generate nausea in any reader, we will limit ourselves to saying that the most passionate (French) kissing and regurgitation behaviors share quite similar mechanisms.

      On the other hand, it was postulated that the kiss responds to a clear mechanism of sexual selection. From a biological perspective, when we approach the face of another human being, we gain a very valuable (albeit unconsciously) amount of information. For example, studies have shown that certain groups of female samples feel more biologically attracted to men with pheromones that show their genetic profile to be distant: we count.

      From an evolutionary point of view, reproduction between parents is detrimental to any species, because it reduces the genetic variability of the population and therefore makes it more vulnerable to possible environmental changes. Pheromones can report the two components of a pair (to some extent) as being genetically related, thus avoiding reproduction if they are related and giving rise to offspring with less variability. Of course, these assumptions should be taken with a grain of salt, as the experiments are conducted in laboratory environments and the social component is not taken into account.

      In addition to a concept as abstract as that of pheromones, there are other mechanisms that are much more obvious. For example, bad breath is usually a sign of an underlying disease or condition. Getting closer to the face of a potential partner allows us to doubt their state of health, and therefore the quality of their genes.

      The kiss is not as universal as we thought

      Until recently, it was repeatedly said in the media that the kiss is present in 90% of cultures. It’s half true and half false, as a study published in 2015 showed that kissing as a romantic act is only present in 46% of sampled cultures.

      Yes, most people on the planet kiss (eg a mother to a child), but less than half do so with sexual intent. This, of course, challenges the theory that the kiss as we know it in the West is a gear engaged in the human genome.

      other considerations

      As well as providing biological evidence for the individual we have embraced, not everything is based on a set of genetic benefits. Kisses also promote the release of oxytocin, dopamine and endorphins, Neurotransmitters essential in the sensation of pleasure and well-being.

      In addition, it has been shown that in couple relationships, an increase in the frequency of kissing decreases stress levels, strengthens the bond and even results in lower blood cholesterol levels. Therefore, in addition to its subjective emotional component, the kiss has an obvious physiological benefit: improving the well-being of the individual.


        As we have seen, the evolution of kisses is a question that oscillates between the levels of gray and never in absolute affirmations. The very evolutionary origin of kisses lies in a land of constant speculation, because we don’t even know if kissing is genome-oriented behavior of our species or if it is a trait acquired through learning.

        Anyway, one thing is clear: despite the diseases that can be transmitted by him, the kiss brings much more positive than negative. Illnesses come and go quickly, while maternal affection, emotional bonding, affection, and love are much more permanent concepts over time.

        Bibliographical references:

        • Castleman, M. (2015). Kisses. The International Encyclopedia of Human Sexuality, 633-647.
        • Jankowiak, WR, Volsche, SL and Garcia, JR (2015). Is the romantic sexual kiss almost universal ?. American anthropologist, 117 (3), 535-539.
        • What’s in a kiss? The Science of Smoothoching, Retrieved September 30 from,being%20a%20basic%20human%20instinct.
        • Why are we kissing, Retrieved September 30 from,people%20will%20make% 20strong% 20 offspring.

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