Golda Meir once said, “Those who do not know how to weep with their whole heart do not know how to laugh either.” But you probably have been in situations where you have found yourself weeping bitterly, except without your whole heart, if you have ever chopped an onion.
As it happens, there are three motivations to lacrimate, or, to shed tears, which results in the production of three different types of tears: basal tears, reflex tears, and emotional, or psychic tears. Basal tears coat the eye on a constant basis, lubricating it, protecting it from infections, and feeding it nutrients that it needs. The salt concentration of basal tears is similar to that of blood plasma, and they also contain enzymes and immune proteins. Reflex tears have a different composition than basal tears, and are shed in response to exposure to irritants in order to wash them out of the eye. A classic example of reflex tears is the heavy and uncontrollable crying while chopping onions. Both basal and reflex tears serve fairly straightforward physiological and evolutionary functions – other animals definitely shed these two types of tears, indicating that eyes require these two goals be met. However, lacrimating in response to deep emotion appears to be a somewhat random response. There must be some goal, psychological, biochemical, or evolutionary, that humans fulfill by an observable eye-washing.
Dr. Stephen Sideroff, a licensed clinical psychologist, consultant and assistant professor of psychiatry at UCLA, and a clinical director of the Moonview Treatment Center in Santa Monica, California, explains crying in psychological terms. “It’s a release,” he explains, a way of relieving the “buildup of energy with feelings.” But on a deeper level, it needs to be asked, of all the possible ways to relieve emotional energy, why this? Why crying?
The biochemical theory explains the phenomenon further. Most people tend to feel better after a good cry. This may be because psychic tears are qualitatively different than basal or reflex tears, containing more protein-based hormones such as prolactin, as well as more manganese. The release of these two substances balances stress levels and releases chemical buildup in the body. This sudden releace may explain why people feel a sense of relief, as if a burden has been lifted, after crying.
The most popular theories about crying, however, relate to its evolutionary effects. Dr. Robert Provine, a neuroscientist at the University of Maryland, Baltimore County, calls the evolution of psychic tears “a breakthrough in the evolution of humans as a social species.” He proposes that there is something called the “tear effect,” which he studied by asking a group of 80 undergraduates for their interpretations of the emotion in photographs of people crying. Some photos were original, showing a face flooded with tears, while other photos had the tears digitally removed. While the tear-filled photos were interpreted both as being more sad as well as unequivocally sad, less sadness and even other emotions, such as puzzlement or awe were ascribed to the tearless photos. Consequently, Dr. Provine that tears may have evolved to strengthen the expression of emotion.
Other scientists point to the “secondary gain” of crying. Crying can signal not only emotion itself, but can be a signal for attention or to win sympathy, support, and comfort from onlookers, possibly even to manipulate them. Imagine back in the history of humans, or even nowadays in places where food is tragically scarce, and there is a person crying from starvation. Other members of the community may tend to relegate the food to the crier because he seems to need it most. In this way too, the signaling of emotions has an evolutionary advantage. On the other hand, other research indicates that it is if not impossible, it is extremely difficult to cry fake tears.
Personal experience can demonstrate that some people cry more easily than others. Get a group of friends get together to watch a “tear-jerker,” and it is quite likely that while some people will be bawling hysterically, others in the group will appear stoic. Why some people cry more easily than others is still a mystery, although some correlations are found to sex, personality, and experience of personal trauma or tragedy.