What is the biological advantage of crying when emotional?
Ad Vingerhoets, Tilburg University, The Netherlands
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Tearful human emotional crying evolved from the separation calls or distress vocalisations made by the offspring of all mammals and several bird species when they are separated from their mother.
Crying in animals is mainly limited to vocal activity and to infancy, but humans continue to produce emotional tears for their whole lifespan. When children grow older, the importance of the auditory component diminishes, whereas the visible element – the tears – gains prominence.
Human crying can be triggered by many things. Lovesickness, helplessness and grief are significant antecedents throughout life. Other triggers change with age, reflecting changes in emotional, cognitive and social development. For example, physical pain and discomfort are often triggers for infants and toddlers, but tend to lose their importance after late adolescence. On the other hand, empathic crying, which occurs in response to the suffering of others, increases with age. A similar pattern is seen for tears triggered by extraordinarily positive or moving situations.
Tears help observers recognise the need to provide support and comfort. They are an evolved adaptation that promotes helping behaviour in others by inducing feelings of empathy and social connectedness.
Barbara Finlay, Cornell University, New York, US
“Crying in response to the suffering of others increases with age, as do tears triggered by extraordinarily moving situations”
Members of social species benefit in many ways by communicating their internal states to each other. Recognition of need, and consequent protection and provisioning of weaker or younger individuals, has been observed in various primates, meerkats, whales and elephants outside immediate parental bonds.
Humans, though, are “hypersocial” and routinely help injured or ill group members, independent of age or relatedness. Even the subjective experience of pain and the performance of “sickness” behaviour may be amplified in humans in situations like childbirth or viral infection, compared with other less social species. The descendants of those who complained effectively and received help are more likely to be with us than those of the stoic!
But how do humans recognise cries for help? In the absence of obvious physical damage, what are the main ways of communicating pain and distress? Mammals normally produce tears due to chemical or physical irritation, but humans also produce emotional tears. These are part of a suite of physical changes in humans employed for communication.
Together, these changes extend the avenues available to communicate our internal states and emotions. For example, studies show that the addition of tears to faces previously described as sad made them seem sadder, acting as an intensifier.
Of the many instruments of the orchestra of expression, tears come in at moments of high intensity, pulling the observer in more strongly.
Michael Trimble, University College London, UK
Homo sapiens are the only living species to cry as an emotional expression. The development of the capacity to cry in our hominid ancestors depended on many biological adaptations. These include the development of the facial muscles – especially around the eyes and mouth – and the size and connectivity of the brain that allowed the development of “theory of mind“: the ability to recognise the behaviour and feelings of another person. The brain had such adaptive connectivity to draw together areas concerned with memory, language (including the language of music intonation), theory of mind and the nerve centres that lead to the release of tears.
Tears evoke prosocial behaviours and enhance bonding. Nowhere is this seen better than between a mother and infant.
Ada Mournian, Wellington, Somerset, UK
At a fundamental level, crying is an excretory process. It is one of the ways the body (though it may not feel like that initially) by the release of the hormones oxytocin and various endorphins.
What the body is getting rid of is an interesting part of the answer. It could be stress hormones or other “feelings” such as fear. Manual therapists have reported patients who cry, often profusely, when their network of connective tissue, or fascial system, is manipulated. This may sound a bit “woo-woo”, but I experienced the release of fear trapped in my body for over 20 years when scar tissue from an operation was massaged. The feeling rushed up my spine and resulted in a flood of tears. The release provided recognition of an emotion that I hadn’t consciously known about previously.
“I still remember the reaction in the supermarket when I bought their entire stock of ketchup for my experiments”
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