THE SCIENCE OF TEARS

01.10.13

Why Do We Cry?

Neurologist Michael Trimble, the author of the new book Why Humans Like to Cry: Tragedy, Evolution, and the Brain, surveys the many theories of why we shed tears and what we get out of it—especially when we cry in sympathy or after we read a good book.

Over time there has been much speculation about the purpose served by emotional crying. A problem with these theories is that they remain largely theories, entangled with the complexities of the over-determined nature of any individual act of crying. Ancient ideas that held that tears were one way to get rid of bad humors continue to surface. For example, William Frey’s assessments of the chemical constituents of tears led him to the view that noxious chemicals, which build up as a result of stress, are removed from the body in crying, literally an excretory process: purgation by another means. This has some associations with the theory of catharsis, a view that is linked to purification and cleansing.

In a slightly different version of these ideas, it has been suggested that tears drain off excess emotional energy, restoring a homeostasis. This was a favored theory of the early Freudian pre-psychoanalytic theories. In Freud’s collaborative work with Josef Breuer (1842–1925), the word “catharsis” first appears in Studies on Hysteria, where it is explained that an injured person’s reaction to a trauma is cathartic only if it is complete, such as in revengeful action. It is through language, as a substitute for action, that the effect can be modified when incomplete—these were ideas that were to lead from the cathartic to the psycho- analytic therapies. Kotter, a therapist himself, refers to crying as a “defence against other internal drives”; it is an act of regression and a retreat to the earliest preverbal stage of life.

While there is good evidence that crying makes people feel better, there is little evidence showing any cathartic effect of crying, if by that is meant some sort of peaceful relief from tension or another emotion. No cathartic effect of crying has been observed when people are asked to cry as opposed to suppressing their tears while watching sad events. James Gross and colleagues showed a sad film to 150 women and measured a number of physiological and behavioral indices noting differences between those who cried and those who did not. They were also able to compare measurements in the pre-cry phase with the actual crying spell. Crying, associated with self-reported experiences of sadness and pain was distinguished by increased heart rate, increased skin conductance, decreased breathing  rate, and increased somatic activity.

They discussed the implications of their findings for two different theories of crying, the physiological recovery hypothesis, which implies a restoring of homeostasis akin to catharsis, and the physiological arousal hypothesis, which implies increased emotional activity. Their results favored the arousal hypothesis, but they cautioned that the main effects of crying may not have been observable over the short time intervals of their study, and that the “catharsis” may occur later.

Lutz reviewed all the evidence available to him, including psychotherapeutic and psychoanalytic studies, and concluded that there was no hard evidence for a cathartic effect of tears, even for so-called cathartic therapy, in which patients are asked to recall as vividly as possible their traumatic experiences. Randolf Cornelius likewise concluded that, in contrast to a catharsis, “crying is associated with increases in arousal, tension and negative affect … Crying does also not appear to be necessarily beneficial to one’s health, as the cathartic model of crying would predict.”

If crying is not physiologically beneficial, what then is the purpose of emotionally aroused tears? Is it entirely psychological? Recurrent sociological interpretations emphasize the communicative value of crying. Crying, like a shout or a sneeze, attracts the immediate attention of others. Tears provoke an emotional response in the observer which, in the more skeptical views, not only elicits sympathy but acts as a manipulative tool. As Shakespeare put it:

And if the boy have not a woman’s gift
To rain a shower of commanded tears,
An onion will do well for such a shift.

Several surveys have confirmed that women cry more than men, but this difference is not observable in infants and it becomes apparent only around puberty. In babies, crying has been referred to as an acoustic umbilical cord: the instant appeal to a mother of a baby’s crying is obvious. This has been discussed in the psychoanalytic theories of John Bowlby, crying being a part of attachment behavior; in a child it is a signal of the departure of his or her parents, especially the mother—essentially separation. Kotter also views crying as a means of bonding between individuals, but of all ages, and suggests it is a powerful way of obtaining help and emotional support.

In infancy, screaming leads to engorgement of the blood vessels in the eyes, and the latter leads to contraction of muscles around the eyes, to protect them from the resulting increased pressure. Tears were a reflex response of the lachrymal glands to these events.
Why Humans Like to Cry
“Why Humans Like to Cry: The Evolutionary Origins of Tragedy.” By Michael Trimble. $21.23; Oxford University Press; 256 pages. ()

Around the age of three to four months, the relationship between an infant and the surrounding environment takes on a more organized communicative role, with greater self-regulation, and crying becomes tailored, with more specific interpersonal purposes. There are few studies of the neurological accompaniments of tearing in infants, but around this time the electroencephalogram shows distinct changes, with increased synchronous activity. Brain imaging studies have shown the activation of certain brain areas linked with emotion (to be discussed later) in mothers hearing infant crying compared to simple noise. The meaning of these activations is unclear, but they imply a cerebral interplay between infants and mothers in relation to crying.

Crying in a baby leads the mother to pick it up and offer the breast or some other means of pacification. This theme was put into an evolutionary perspective by Paul MacLean, whose work on the organization of emotion in the brain was stimulated in the 1950s by clinical observations of emotional changes in some people with epilepsy. As a comparative anatomist, MacLean viewed animal behaviors as evolutionary adaptations of the brain. He was one of the pioneers of understanding the circuits in the brain which are involved in emotions and expression, a theme taken up in the next chapter. In his original descriptions of the limbic system—the brain structures linked to emotion—MacLean noted an organization stretching back to our reptilian past. He used the expression “the triune brain” to explore three different major components of the mammalian brain, which he referred to as the proto-reptilian, the limbic, and the neocortical. In his scheme, the limbic system evolved alongside the developing social complexity of the mammals.

He attributed to the limbic structures (which will be described in greater detail in the next chapter) three key mammalian behaviors: nursing and maternal care; audio-vocal communications, vital for maintaining maternal-offspring contact; and play. Key to MacLean’s ideas was that “the history of the evolution of the limbic system is the history of the evolution of the mammals, while the history of the evolution of the mammals is the history of the evolution of the family.” In other words, the development of the limbic system was an essential prerequisite for the development of certain characteristic mammalian behaviors. A characteristic of a young mammal is its need for the presence of its mother, and everything that involves. A reptile hatching from an egg must not cry out for its mother, or else it will be readily detected by predators and eaten. In contrast, a mammalian infant depends on the separation cry for succor and security. If there is no cry, the infant will not survive. The development of family, sibling, and later peer-relevant behaviors, including emotional and interpersonal bonding, correlates with and is related to the evolutionary development of these limbic structures.

Other ideas about crying fluctuate between the sociological and the biological. Darwin noted that the main expressive movements during crying (and other actions such as laughing or blowing the nose) lead to a rise of pressure in the chest and abdomen, which leads to increased blood pressure in the eyes. In order to prevent damage to the eyes, the muscles around them contract. Darwin considered that this protective contraction “was a fundamental element in several of our most important expressions.” In infancy, screaming leads to engorgement of the blood vessels in the eyes, and the latter leads to contraction of muscles around the eyes, to protect them from the resulting increased pressure. Tears were a reflex response of the lachrymal glands to these events. The act of contraction of the muscles around the eyes caused alterations in the activity of several facial muscles around the mouth, increasing the expression of the gesture. Darwin observed that young infants before the age of two to four months cry out violently, and have their eyelids firmly closed, but even though their eyes become suffused with tears they do not shed them. Supporting a view that the primary function of tears is to lubricate the eyes and nostrils (to aid smell), and that irritation of the eyes leads to stimulation of the lachrymal glands, Darwin  suggested that with evolutionary time, the slight irritation became enough to lead to the free secretion of tears. In the human, by later childhood, these reflexes become habitual, being evoked by lesser circumstances than those that arouse the infant: the habits associated with screaming in children become linked to suffering and the relief of suffering. For Darwin, habitual actions can become hereditary and he reasoned that, in comparison to many other emotional gestures, “weeping probably came on rather late in the line of our descent; and this conclusion agrees with the fact that our nearest allies, the anthropomorphous apes, do not weep.” He concluded, with regards to the pleasure of crying, that “by as much as the weeping is more violent or hysterical, by so much will the relief be greater—on the same principle that the writhing of the whole body, the grinding of the teeth, and the uttering of piercing shrieks, all give relief under an agony of pain.”

Ashley Montague observed that in infants who cry without tears, the mucous membranes of the nasopharynx quickly desiccate, an effect which is harmful to the delicate cilia and secretary cells of the nasal passages, which would increase the chance of infection. Since tears run from the eye into the nasolacrymalducts, he suggested that they serve as an adaptive trait counteracting the damaging effect of tearless infant crying. Crying evolved in humans as opposed to other primates because of the prolonged period of postnatal development, and, in view of the antiviral and antibacterial constituents of tears, the more the youngster cries the healthier he or she is. Taking his theory further, he observed that men have larger nasal passages than women, hence the greater amount of overflow down the female face: males blow their noses while females blub.

From crying with tears comes weeping in sympathy, a social response which, as will be argued later, is conditioned or underpinned by a neurobiological basis linked to empathy. Crying as an emotional response is evoked in many settings. Some people cry at the slightest emotional wave, while for others a storm is needed before the flood. Some personality styles seem more prone to instant tearing than others; the hysterical can be contrasted with the obsessional. The impressionistic hysteric, responding to the immediacy of every situation, characteristically emotionally labile, and easily perturbed by the slightest emotional breeze, seems the opposite of the highly obsessional, whose intense control over the release of feelings is bounded by emotional and muscular rigidity.

In one study of personality and crying, the circumstances of crying in the previous year were rated, and personality questionnaires filled out by 70 male and 70 female volunteers. The death of a friend and breaking up rated highest in terms of occasions. Women cried more frequently and intensely than men, and in both sexes crying positively correlated with personality variables related to empathy. In men, but not women, neuroticism was positively correlated and masculinity negatively correlated with crying. In an unpublished study quoted by Vingerhoets and Cornelius, in which empathy was measured in nearly 500 adolescents, proneness to crying and empathy were strongly correlated in both boys and girls, while in another study empathy was associated with crying but only in females. Reviewing the available literature on personality and crying, Vingerhoets and colleagues concluded that positive associations could be claimed between crying proneness and neuroticism, extroversion, and empathy. As will become clear later, the link between crying and empathy, confirmed by other investigators, is important in understanding human emotional responses, and is echoed by an underlying neuroanatomy.

Koestler referred to the “logic of the moist eye” in The Act of Creation. He noted different situations in which weeping occurred. Rapture was self-transcending, which led to quiescence, tranquility, and catharsis. No specific voluntary action could consummate the moment; as he pointed out, you cannot take a stunning visual panorama home with you—as every photographer knows. He equated this response with altered activity of the autonomic nervous system. When weeping in sympathy with another, or on viewing a tragic film, he suggested that two psychological processes occur: identification, which he equated with introjection or empathy, and vicarious emotions. Thus, catharsis, in a physiological sense, has been difficult to substantiate, but the results are by no means conclusive. More work on the delayed responses to crying, in which the aftermath of the tearing is evaluated in comparison with the states before, needs to be carried out, and more sophisticated studies using, for example, the newer methods of brain imaging could be rewarding. However, the surveys reveal that with some occasions of crying people experience what they call a cathartic experience, and that the feeling is usually positive.

Some people feel so much grief that they simply cannot cry. In the play Titus Andronicus, Shakespeare explores a grief that exceeds tears. In The Tin Drum, Gunter Grass describes the Onion Cellar, a bar in postwar Germany where the guests are given only onions and knives. The seven skins of the onions are peeled away, the onions are then chopped, and people no longer see anything because their eyes overflow with tears. People go to the cellar just to share painful memories and cry. The protagonist reflects how “the juice” brought forth what the world and the world’s suffering could not: “a round human tear ... the rains came, the dew fell ... the tragedy of human existence was spread fully before [them].”

From the book Why Humans Like to Cry by Michael Trimble. Copyright 2012 by Michael Trimble. Reprinted with the permission of Oxford University Press.