While most other animals are born fully formed, humans come into the world vulnerable and physically unequipped to deal with anything on their own. One is that tears trigger social bonding and human connection. Other theories persist despite lack of proof, like the idea popularized by biochemist William Frey in 1985 that crying removes toxic substances from the blood that build up during times of stress.Įvidence is mounting in support of some new, more plausible theories. Some are flat-out ridiculous, like the 1960s view that humans evolved from aquatic apes and tears helped us live in saltwater. In his book, Vingerhoets lists eight competing theories. The heart vapor would then rise to the head, condense near the eyes and escape as tears.įew scientists have devoted their studies to figuring out why humans weep, but those who do don’t agree. A prevailing theory in the 1600s held that emotions-especially love-heated the heart, which generated water vapor in order to cool itself down. Later, in Hippocrates’ time, it was thought that the mind was the trigger for tears. For centuries, people thought tears originated in the heart the Old Testament describes tears as the by-product of when the heart’s material weakens and turns into water, says Vingerhoets. By some calculations, people have been speculating about where tears come from and why humans shed them since about 1,500 B.C. That insight is central to the newest thinking about the science of crying.ĭarwin wasn’t the only one with strong opinions about why humans cry. It’s triggered by a range of feelings-from empathy and surprise to anger and grief-and unlike those butterflies that flap around invisibly when we’re in love, tears are a signal that others can see. Beyond that, researchers have generally focused their attention more on emotions than on physiological processes that can appear to be their by-products: “Scientists are not interested in the butterflies in our stomach, but in love,” writes Ad Vingerhoets, a professor at Tilburg University in the Netherlands and the world’s foremost expert on crying, in his 2013 book, Why Only Humans Weep.īut crying is more than a symptom of sadness, as Vingerhoets and others are showing. Scientific doubt that crying has any real benefit beyond the physiological-tears lubricate the eyes-has persisted for centuries. There’s a surprising dearth of hard facts about so fundamental a human experience. It’s obvious that strong emotions trigger them, but why? But what about in grownups? That’s less clear. In babies, tears have the obvious and crucial role of soliciting attention and care from adults. Though some other species shed tears reflexively as a result of pain or irritation, humans are the only creatures whose tears can be triggered by their feelings. Charles Darwin once declared emotional tears “purposeless,” and nearly 150 years later, emotional crying remains one of the human body’s more confounding mysteries. In fact, there’s also a lot scientists don’t know-or can’t agree on-about people who do cry. “We don’t know anything about people who don’t cry,” Trimble says now.

Sad emotion