Why Do We Cry? The Science of Emotional Tears

A sad film, a goodbye at the airport, a wedding speech, a piece of music: sometimes tears come before we can stop them. Babies cry from their first breath, and adults still cry in every culture on Earth. Yet humans seem to be the only animals that cry because of their feelings. Why did we evolve to do this?

Three kinds of tears

Tears are made by the lacrimal glands above each eye, and not all tears are the same:

• Basal tears keep the surface of the eye moist, clean and nourished all day long. Every blink spreads a thin film.
• Reflex tears pour out when something irritates the eye: dust, smoke, wind, or the sulphur compounds released by chopping onions. They wash the irritant away.
• Emotional tears come with sadness, grief, joy, anger, frustration or relief. As far as we know, only humans shed them.

Many animals make tears to protect their eyes, and many make distress calls, but there is no good evidence that any other species weeps from emotion.

Why cry? A signal to others

Charles Darwin thought emotional tears had no purpose, merely a side effect of tightening the muscles around the eyes. Modern researchers disagree. The leading idea is that tears are a social signal.

Tears are a very visible, hard-to-fake sign that someone is in distress or overwhelmed. In studies, faces with tears are judged as sadder and more in need of help than the same faces without tears, and people feel more willing to comfort them. Tears may also calm conflict: it is hard to stay angry at someone who is crying.

This makes sense from the start of life. A baby cannot survive without adults, and crying is its most powerful way to call for care. Interestingly, newborns usually cry with few tears in their first weeks; emotional tears develop as babies grow.

Does crying make you feel better?

Many people say that a “good cry” brings relief. In a 2014 review, psychologists Asmir Gračanin, Lauren Bylsma and Ad Vingerhoets looked at the evidence. They found signs that crying can be self-soothing: after an initial rise in arousal, it may activate the parasympathetic nervous system, the body’s calming system, slowing breathing and heart rate.

But the effect is not guaranteed. People tend to feel better after crying when they receive comfort and support, or when the situation that made them cry is resolved. Crying alone, or in front of people who react badly, can leave people feeling worse.

A chemical message?

Tears may carry a hidden message too. In a 2011 study, Noam Sobel’s team at the Weizmann Institute collected emotional tears from women watching sad films. Men who sniffed these tears, without knowing what they were, showed lower testosterone and reduced sexual arousal compared with men who sniffed salt water. The tears were odourless, so the effect seemed to be a chemical signal. The finding is intriguing, and researchers are still exploring what it means.

Who cries more?

Crying varies a lot between people. On average, women in many countries report crying more often than men. That difference probably reflects both biology and social expectations about when it is acceptable to cry. Crying very often, or being unable to cry at all, can sometimes be linked to depression or other conditions.

In short

• There are three kinds of tears: basal, reflex and emotional.
• Emotional tears appear to be unique to humans.
• Their main role is probably as a social signal that draws comfort and help.
• Crying may be self-soothing, activating the body’s calming system.
• Relief is more likely with support; crying does not always help.
• A 2011 study found emotional tears may carry a chemical signal.