It's not just pain that causes us to cry - welling up is an evolutionary trait for communication, argues one scientist
If you've ever welled up reading a tragic novel, sobbed listening to an epic opera or wept over beautiful poetry, take comfort: it means you're human.
UK author and neurologist Michael Timble, who recently published the book Why Humans Like To Cry, claims that humans' proclivity to cry from emotion stems from an evolutionary trait that helped us communicate before spoken language. Tears of sadness, anguish or joy - or witnessing those of others and responding with empathy - have, he argues, been a vital part of our evolution.
Crying in response to music, art or other aesthetic experiences are also unique to humans.
It's this adjunct function of our tears - alongside the bio-mechanical function of keeping our eyeballs moist, healthy and free of irritants - that really sets us apart from other species, he said.
Speaking with Scientific American magazine, Trimble said that while tearing occurs in animals in response to irritants in the eye, "Crying tears, for emotional reasons, is unique to humans...Emotional crying makes us human."
He argues that crying in response to emotional and physical distress or "the development of sophisticated facial gestures associated with suffering, and with loss and bereavement" developed long before language.
"The identification of tears as a signal for distress [loss, bereavement, pain] was an important addition the so called Social brain," he said.
He hopes his work encourages us to embrace our emotions, especially men who typically are reluctant to admit to crying or to show emotion publicly.
"Our ability to feel empathy and with that to cry tears, is the foundation of a morality and culture which is exclusively human," he said.