Have you ever seen the movie, The Grinch from year 2000 starring Jim Carey? There comes a point where he is crying and exclaims, “I’m leaking!!!”

That is more or less what it feels like when I cry. I’m so full of pain and angst that it leaks out and makes my face do horrible things. I am an ugly crier. And that’s okay.

But what are tears all about? Why is it that we only leak at certain emotions; happy or sad? Then there are the other tears that protect your eyes from smoke and dust and allergens.

neuronal connection between the lacrimal gland (tear duct) and the areas of the human brain involved with emotion has been established. Scientists debate over whether humans are the only animals that produce tears in response to emotional states.[3][4] Charles Darwin wrote in The Expression of the Emotions in Man and Animals that the keepers of Indian elephants in the London Zoo told him that their charges shed tears in sorrow.

Tears produced during emotional crying have a chemical composition which differs from other types of tears. They contain significantly greater quantities of the hormones prolactinadrenocorticotropic hormone, and Leu-enkephalin,[5] and the elements potassium and manganese.[3]

So there are three different types of tears. Psychic tears (happiness, sadness) are caused by extreme emotions. Basal tears are made to keep the cornea lubricated. Reflex tears (onions, tear gas) come out in response to something else.

Here’s what tears of grief look like:

And tears from laughing:

 

And tears from onions:

In fact, Rose-Lynn Fisher Topography of Tears gets REAL DEEP about the molecular structure of tears.

What purpose do our tears serve?

At least according to one 2011 study, which showed that testosterone and sexual arousal take a dip in men after they smell a woman’s tears. “We conclude that there is a chemosignal in human tears, and at least one of the things the chemosignal does is reduce sexual arousal,” study author Noam Sobel, a neuroscientist at the Weizmann Institute of Science in Israel, told LiveScience after the research was published in the journal Science.

Charles Darwin once declared emotional tears “purposeless,” and nearly 150 years later, emotional crying remains one of the human body’s more confounding mysteries. 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. In babies, tears have the obvious and crucial role of soliciting attention and care from adults. But what about in grownups? That’s less clear. It’s obvious that strong emotions trigger them, but why?

Modern crying research is still in its infancy, 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 says; 

“Tears are of extreme relevance for human nature. We cry because we need other people. So Darwin, was totally wrong.”