Leading expert in neurology Michael Trimble, British professor at the Institute of Neurology in London, examines the physiology and the evolutionary past of emotional crying.
Trimble explains that biologically, tears are important to protect the eye. They keep the eyeball moist, flush out irritants and contain certain proteins and substances that keep the eye healthy and fight infections. He explains that in every other animal on planet Earth, tears seem to only serve these biological purposes.
However, in humans, crying or sobbing, bawling or weeping seems to serve another purpose: communicating emotion. Humans cry for many reasons- out of joy, grief, anger, relief and a variety of other emotions. However, our tears are most frequently shed out of sadness. Trimble said that it was this specific communicative nature of human crying that piqued his interest.
“Humans cry for many reasons,” he told Scientific American. “But crying for emotional reasons and crying in response to aesthetic experiences are unique to us.”
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