The defensive mime theory: what it is and what it says about emotions

Facial expressions such as laughing, crying and smiling could have a common origin.

Long before the advent of language in the human species, non-verbal communication already existed. Through gestures, we can communicate: we smile, we cry, we shrug, we raise our eyebrows… These behaviors are common and innatebut they are also symbolic, that is, they represent and communicate feelings and thoughts.

Although some of them, if we think about it, are quite strange: Why do we show our teeth to express kindness? Why does salt water escape from our eyes to seek comfort from others? Why do we laugh to show that something amuses us?

In the field of anthropology, it is widely recognized the importance of the face in interaction and social intelligence. We ourselves are able to infer feelings and communicate through facial expressions.

Although we currently know the adaptive functions of other types of human behavior, such as emotions; they are our way of reacting to psychological pain or pleasure. The adaptive function of human facial expressions remains largely unknown.

Several current hypotheses have attempted to define the evolutionary roots of smiling, laughing, and crying. Recently, the defensive mime theory has been proposed for the explanation, which proposes defensive reflexes as the common origin of the three behaviors. In this article, we will explain in detail this recent theory of evolution and the evolution of smiling, laughing and crying from it.

    What does the theory of defensive mime say?

    We’ve all cried at one point or another, or started laughing in the midst of our own drama. Some ancient Greek philosophers and poets already noticed the similarity between laughing and crying, especially as the degree and intensity of emotional expression increased. But… Why are laughter, smiles and tears so similar? This similarity may not indicate the same root.

    Defensive imitation theory proposes that certain human emotional expressions they originally evolved as exaggerated and prolonged imitations of our own defensive reflexes.

    When we are faced with life-threatening situations or our physical integrity, our body reacts immediately and automatically by shortening the muscles. For example, in the startle reflex, muscle groups involving the neck and back contract.

    These defensive reflexes produce a change in body posture or expression, and therefore they transmit information about the internal state of the person. This information can be used by some threatening animals. But, suppressing reflexes is not an option, since these are necessary for survival, for example, when the contraction of leg muscles facilitates flight.

    However, this knowledge of the inner state and apparent helplessness can be beneficial for the animal itself. If animals are aware that others can interpret their reactions, they can consciously imitate them..

    For example, an animal may simulate a fear reflex, with its characteristic muscular expression, to manipulate the behavior of those around it. The animal around him may interpret fear as a sign of vulnerability and attack. In reality, this behavior was what the former sought, reversing the roles of victim and executioner. Then, by developing imitated defensive actions, the animals could have learned to manipulate the behavior of others.

    According to the defensive mime theory, these defensive reflexes could be in the origin of the social and symbolic expressions we know as smiling, laughing and crying. This can adequately explain the physical formation of a wide range of emotional expressions, but not all of them.

      Study of defensive reflexes

      A group of researchers realized that many human emotional expressions were also extraordinarily similar to another domain of behavior; reflective behaviors in primates. For several years, they studied a set of reflexes responsible for protecting different parts of the body, focusing in particular on the startle reflex, in addition to other blocking and withdrawal reflexes.

      These reflexes and their actions usually last less than a second, but can be studied by videotaping and measuring the muscle activity involved. Examining them in detail, they observed that they resembled the set of muscular actions involved in smiling, laughing and crying.

      At this time, they established the premise of whether these reflexes or defensive actions could have been the origin of human emotional expressions, sowing the seed of the theory of mime or defensive imitation.

      The first scientist to systematically study the human shock reaction was Lévi-Strauss, at the beginning of the 20th century, using a film camera. For his study, he used a rather unethical procedure; he fired a gun behind the head of psychiatric patients he had not reported.

      He observed, through the recordings, a consistent set of movements in the first hundredths of a second; each component was apparently useful in protecting a part of the body. As for the torso, the contraction of the muscles of the eyelids and the face to protect the eyes, the tilting of the head downwards and forwards to hide the teeth and the face, the contraction of the shoulders to protect and the neck. Finally, the curvature of the torso shortens the body, making it smaller, and therefore more difficult to reach. These “protective” movements occurred in different areas of the body.

      Later studies have shown that the degree of reflex response varies greatly depending on the situation and the person. Someone who is very calm may have a very small response that involves only slight tension in the muscles around the eyes. A person under stress or anticipatory anxiety will respond more broadly, using more muscle groups. As the degree of reflex increases, it spreads from the eyes (where it is strongest) to other parts of the face, and finally to other parts of the body.

      There are two main types of reflexes that serve to defend different areas of the bodythese work together and represent the initial, involuntary response that protects the body.

      After the initial reflex, there is also a set of reflexive, slower and more complex reactions. This second phase involves a series of so-called peripersonal neurons. These neurons already take into account where the threatening stimulus comes from, if it comes from the left, the corresponding eyelid will close faster.

        Evolution of emotional expressions

        There is a diversity of opinions on how signals evolve in animals. Information-based theories posit that signals evolve to transfer information from one animal to another about the environment. Non-information theories explain that signals evolve because they have a direct effect on the behavior of others.

        Evolution of the smile

        As for the evolution of the smile, it is striking to note how much showing teeth, an obvious sign of threat, has managed to become a sign of non-aggression. However, it appears that the exposure of the teeth as a threat and as a sign of non-aggression are fundamentally different and do not involve the same muscles. Be non-aggressive (smile) related to defensive actions, eye protection.
        In this case, no attempt is made to define whether the human smile is a defensive action in itself or an evolution of it. It is suggested that the smile appeared rather as an exaggerated imitation of this same defensive action. The animals understood that thanks to this grimace, they could influence the behavior of others and prevent aggression. more than one evolution would be a conscious appropriation.

        If we think about it, in the present we often use this “protective” smile. For example, when we make a driving mistake that involves another person, we often smile forcedly, as an apology and to avoid anger.

          Evolution of laughter

          Could laughter be explained by an evolutionary process similar to that of smiling, mimicking defensive reflexes? Laughter appears to be a loud, exaggerated, and widespread imitation of a defensive reaction. Even the tears, which she sometimes produces, would be a reflex response to protect the eyes, according to the defensive mime hypothesis.

          The debate about animals capable of laughing is still open, this feature was considered unique to some monkeys and humans. A recent study concluded that smiling is widespread among animals; Cows, dogs, foxes, and some birds, such as magpies, exhibit this behavior in addition to primates. Ethologists have described a gesture, common among many mammals, called a playful face with an open mouth.

          Laughter could then have evolved from the game. Let’s say two animals are playing combat. A hit on the nose, with its consequent tears, would be a sign that a boundary has been crossed and would end the game. Laughter also modulates the response, if it is soft the game continues, if it intensifies the game ends. An example would be laughter caused by tickling.

          But, we humans laugh in different contexts, outside of lie-fighting and tickling. Although it seems that laughter would perform the same function, it would be a reinforcement of a behavior. In the case of comedy, laughter serves as a reinforcement to modulate the behavior of the actor.

            Evolution of crying

            Crying, unlike laughing, is something that seems unique to humans, which makes comparative studies with other animals difficult. Animals make sounds to ask for help. Human crying would be a sign to seek the comfort of others.

            For the evolutionary explanation of crying, based on defensive reflexes, we would first have to forget about tears; crying is not just the liquid that comes out of our eyes. Crying is accompanied by a series of muscular movements which are very reminiscent of the defensive action aimed at protecting the eyes, already described by Strauss.

            But, why is comfort sought by mimicking the reflexes that normally trigger a heavy blow to the face. Behind the cases of consolation that have occurred in primates, there is a first aggression or fight. Therefore, it is adaptive to have a mechanism to comfort the victim later and repair the friendship.

            Crying would not in itself be a facial protection action, but an imitation of the set of defensive actions who seek the same consolation that was offered, among the monkeys, after the assault.

            Bibliographic references

            • Graziano MSA; (2022), The origin of smiling, laughing and crying: the theory of defensive mimicry.

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