The science and mystery behind human tears

Human beings are the only species that sheds emotional tears: from Darwin to the latest research, we explore the mystery and meaning of tears that arise from the deepest feelings

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Charles Darwin thought so, in fact, his landmark scientific work branded emotional tears an utterly “uselessly curious” creation. Today, the opposite can be said: that this most private, intimate act is not pointless. It’s more than a biological reflex but one that defines us, a universal language unmediated and talking to the heart.

Tears flow from humans for just about everything: pain, joy, nostalgia, a song, and the memories that resurface after some scene in a film. Why do we cry like this among the millions of living species on earth? Why is it linked with such a very complicated array of human emotions? Scientists keep working on that, but until the mystery is revealed, let’s examine a few interestingly astonishing truths already out.

Three types of tears, three unique functions

Tears are not all alike. In fact, there exist three main kinds, each for a different purpose:

• Basal Tears: These are the invisible, unwavering tears that lubricate and guard our eyes. A small biological miracle essential in everyday well-being.
• Reflex Tears: These flow when we chop an onion or when a speck of dust irritates our eyes. Their role is quite straightforward: to clean the eyes of external agents.
• Emotional Tears: Now, here’s something unique. In the case of emotional crying, the cause isn’t some immediate physical irritation but rather is triggered deep in the brain areas linked with complex feelings.

Ancient cultures sought poetic explanations for this phenomenon. To the Hebrews of the Old Testament, tears represented a broken heart. The Greeks believed the mind produced them. It wasn’t until 1662 that a Danish scientist named Niels Stensen discovered the lacrimal gland, proving that, in fact, there was a physical origin to tears. But despite this discovery, the mystery behind emotional tears remained unclear.

Which brings us to Darwin, who considered emotional tears “purposeless.” But was he right? We now understand that though emotional tears are essentially a solution of water, mucus, and antibacterial proteins, their meaning runs much deeper. They are produced through a complex interaction of brain and body.

Crying: a gift that evolves with age

Human crying begins early, though not as we might imagine. Newborns cry, for example, but without tears-which only appear weeks later when the lacrimal glands mature. That first wailing, however, does the trick: to grab a caregiver’s attention.

But why do adults cry visible tears due to emotions? The most popular theory is that emotional crying has evolved to communicate. Tears silently signal distress without drawing attention to oneself, whereas a loud cry does. In other words, they are a silent language that reinforces social bonding and empathy.

As we grow older, the relationship to crying is more varied. We cry as children for physical pains. When one grows older, crying starts conveying what words could not: sadness, nostalgia, even joy, or anger. On this level, crying can be a form of social glue binding people together in moments of shared feeling.

Crying: taboo for men?

Tears aren’t equal across all individuals. In fact, frequency is one such dimension that brings a wide variation between men and women. The studies indicate that women cry two to three times more frequently than men. Why? Combination of biological and cultural factors.

First, there are the hormones: testosterone seems to suppress crying, and prolactin, which is higher in women, may promote it. But in most societies males are socialized not to cry, to be tough.

There’s more: personality and context count. Empathetic people or those prone to emotional sensitivity cry more. Even fatigue or a glass of wine can lower the threshold for tears.

Why crying feels good

There’s a reason we often feel better after a good cry. Crying isn’t just a release emotionally but is also therapeutic, as it lets out chemicals in the body that help soothe and often helps bind people who are around at such times.

A hug or words of care at the sight of our tears multiply all these effects manifold, elevating the entire experience into a great moment for deep connectivity.

Thus, whereas Darwin considered emotional tears as some sort of evolutionary mistake, the understanding now is that crying forms part of what it means to be human.

Source: PMC