Why Do Humans Cry?


Crying as a response to an emotional state has always been seen as something uniquely human. There is, however, some debate as to whether elephants display the same kind of behaviour. We know that elephants do cry, but whether they cry in response to loss, grief or sadness is more contentious. Based on the behaviour of elephants – which is all we have to go by – there are indications that they can experience joy, grief, rage, stress and compassion. Marc Bekoff is one evolutionary biologist who believes that examples of elephants crying can be associated with feelings of grief; as he writes in Psychology Today. This view was also expressed in the controversial book When Elephants Weep, written by Jeffrey Mason and Susan McCarthy.

It is likely that elephants cry for some of the same reasons we do, and possibly different reasons as well. Regardless of whether elephants cry as an emotional response, what we do know is that humans can cry as a response to a wide range of emotions: rage, grief, sadness, joy and ecstasy. But what is the purpose of crying? Is there some sort of adaptive or survival value to it?

There are competing theories which attempt to explain the strange behaviour of crying as an emotional response. One theory simply states that emotional tears are a response to joy, sadness, distress or physical pain – the tears themselves have no function; they are merely a by-product of an emotional state. However, if this were true, then why is it only humans (and possibly elephants) who weep in response to sadness, distress or physical pain? We know that other non-human animals can experience these emotional states, so why do they not also weep?

Another theory suggests that emotional crying has a cathartic effect; that crying simply makes us feel better in the face of a negative emotional state. The first proper study investigating the cathartic effect was carried out by Lauren Bylsma, who published her results in a paper entitled, When is Crying Cathartic? (2008). What Bylsma found was that crying is only cathartic in particular social contexts; having social support, for example, can facilitate a feeling of relief and release of inner tension. In other words, emotional crying does not always make people feel better. That said, the majority of participants in their study did report a better mood following crying.

Further research has explained why we feel better after crying. Studies have shown that emotional tears contain higher levels of stress hormones than 'reflect tears' (those produced to flush out they eye when it is irritated) and 'basal tears' (those produced to protect the eye and keep it moist). Whether a person is experiencing a victory or a crisis, the body produces more stress hormones. Emotional tears balance our stress levels by releasing excess stress hormones, such as cortisol and corticotropin. Emotional tears also contain more manganese than reflex or basal tears. Manganese is an element which affects our temper, the release of which can improve our mood. 

While Bylsma’s study suggests that crying can be cathartic in certain social contexts and for most people, some scientists have proposed a more over-arching and complex theory which seeks to explain, in evolutionary terms, why humans cry. An evolutionary explanation of emotional tears says that they are a form of non-verbal communication. They are messages that contain a request for help and humans have evolved the ability to cry emotionally because these messages have proved to be effective at eliciting altruistic behaviour from others.

A more detailed version of this theory is based on the assumption that in many species of animals the appearance and behaviour of a newborn can elicit parental care. Since newborns have no verbal means of communication, they have to find other ways to elicit care from its parents. Parents who respond in the appropriate way to this non-verbal communication will increase the fitness of the child, which subsequently increases the likelihood of this form of communication (and the parental response to it) being favoured by natural selection. It has been observed in some species that older offspring imitate the behaviour of newborns in order to elicit the same caring response from its parents, thereby increasing its chances of survival. Thus, the crying behaviour of humans is favoured by natural selection because it resembles the crying behaviour of newborns and so it prompts helping behaviour.

The resemblances between adult crying and newborn crying are pretty clear: the wetting of the face with tears, the jerking respiration, screaming, the closed and wrinkled eyes, and the open mouth. Humans evolved to display these appearances and changed physical appearances in order to receive assistance from others. This theory, along with the 'cathartic theory', may explain why humans cry in response to a negative emotional state, but they don't seem to explain why humans cry out of joy or happiness. A different evolutionary theory of emotional crying has emerged, although in some ways it is similar to the one just described. Oren Hasson, an evolutionary biologist from Tel Aviv University, says that by blurring vision, tears lower defences and reliably function as a signal of submission. They can also function as a cry for help or to encourage group cohesion.

Hasson argues that by blurring your vision with tears, an attacker will recognise that you are expressing submissiveness and therefore be more likely to show mercy towards you. Moreover, this display of vulnerability could attract sympathy from others and perhaps gain their strategic assistance. And if people cry in a group, this allows them to bond over the fact that they have all lowered their defences, fostering a sense of mutual trust and a recognition of shared emotions. Thus, according to this theory, people may cry out of happiness in order to receive validation of their emotions from others and to strengthen mutual bonds. 

Hasson does point out, however, that this evolutionary behaviour is only effective in certain contexts – it is unlikely to be effective at work, for example, where one’s emotions should be hidden. This is a very original theory which postulates that crying evolved in order to handicap the individual. This handicap then elicits mercy from an attacker or sympathy from bystanders witnessing the attack, or it can increase group cohesion. In Hasson's view, emotional tears most likely evolved as an advantageous form of non-verbal communication. 

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I'm a freelance writer who is interested in a variety of subjects, especially those which are philosophical, complex and involve a multitude of perspectives. I created this blog in order to share my thoughts, and to encourage debate and discussion about the most fascinating topics I can think of. Get in touch: samwoolfe@gmail.com