The Science of Tears

Researchers look at why humans get weepy.

December 11, 2015
Sometimes, you just can’t help it. Maybe you’re watching a sad movie, or thinking about the friend who moved away. Next thing you know, there is a lump in your throat, your eyes are watering, and you have tears running down your cheeks.
Why do people cry when they are emotional? What are tears? 
Scientists are working hard to find the answers to these questions.
Three Tear Types
Ad Vingerhoets is a professor of psychology at Tilburg University, in the Netherlands. He is one of the few scientists in the world who has studied crying. 
According to Vingerhoets, there are three types of tears. Basal tears are the first type. They act as a protective barrier between the eye and the rest of the world. Next are reflex tears. They wash your eyes clean when something gets in them. Finally, there are emotional tears. “These are released in response to emotional states,” explains 
Vingerhoets. “Especially when we feel helplessness.”
Face It: We’re Crybabies
Scientists believe that crying has something to do with how humans developed and learned to depend on each other. “Humans are very complex social creatures,” says Lauren Bylsma, a professor of 
psychiatry at the University of Pittsburgh, in Pennsylvania. “It seems that tears serve to elicit help and support from others.” 
She says another reason we weep is that humans have the longest developmental period of almost any animal. It takes a long time to grow up.
Vingerhoets agrees. “I think that the reason humans shed emotional tears has to do with our prolonged childhood,” he says. “That’s the time when we are still dependent on adults for love and protection and care. The major advantage of tears is that you can target them at a specific person.”
Vingerhoets says this ability to target someone could have come in handy in prehistoric times, when humans were living among dangerous animals. Loud, vocal crying could attract predators. Tears were a safer way to get 
attention. “In this case, it is better to use a silent signal 
to ask for help,” he says. Vingerhoets and Bylsma do frequent studies to better understand why humans cry. According to Bylsma, there is still much more to discover. “It’s surprising,” she says, “how much we still don’t know.”
To see close-up images of tears by artist Rose-Lynn Fisher, go to

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