Why Do We Cry? The Science Behind Tears


Why Do We Cry?

The Science Behind Tears

Most of us start crying when we feel sad, under intense stress, or angry. Sometimes, people even cry because of happiness.

But did you know that humans are the only known living beings who shed tears due to emotions?

Although many animals cry loudly after birth to express pain or discomfort, their brains do not appear to have the neural pathways needed to produce tears in response to complex emotions.

Scientists understand how tears are produced, but why humans cry emotionally — and why tears flow during strong feelings — is still not fully understood.


What Are Tears?

According to Dr. Mary Banierehelavet, a postdoctoral fellow at the Institute of Human Biology in Switzerland, tears consist of five main components:

  • Mucus
  • Electrolytes
  • Water
  • Proteins
  • Lipids

Speaking to the BBC World Service program Crowd Science, she explained that each of these components serves a different purpose. For example:

  • Proteins help fight viruses and bacteria
  • Electrolytes are minerals essential for bodily functions

Three Types of Tears

Researchers say there are three types of tears:

1) Basal Tears

These are always present on the surface of the eyes and keep them moist.

2) Reflex Tears

These are produced when dust, smoke, or an insect enters the eye.
This sensation is detected by nerve cells in the cornea.

The cornea is the transparent protective outer layer of the eye, and it contains more nerve cells than any other part of the body.

These nerves can detect:

  • Temperature
  • Pressure
  • Dryness

Signals from these nerves travel to a brain region called the lacrimal nucleus, which controls tear production.


Emotional Tears

The third type of tears is emotional tears — and they are the most complex.

The parts of the brain that control emotions are connected to the tear-producing system, but this connection is more complex than a simple reflex response.

According to Professor Ed Vingerhoets from Tilburg University in the Netherlands, crying often reflects a mix of emotions rather than a single feeling.

He says:

“Emotions are rarely pure. They are often a combination of multiple feelings.”


How Crying Changes with Age

According to Vingerhoets:

  • Physical pain is a major cause of crying in children
  • Adults cry more due to empathy, sadness, and social emotions
  • As we grow older, we increasingly cry over the suffering of others

Positive emotions such as:

  • Extreme happiness
  • Major achievements
  • Natural beauty

can also trigger tears.


Does Crying Make Us Feel Better?

Many people say they feel relieved after crying, but scientists continue to study whether this is always true.

Psychologist Lauren Bylsma from the University of Pittsburgh found that:

  • Heart rate increases before crying
  • This reflects activation of the body’s “fight or flight” system
  • Once crying begins, the calming nervous system becomes more active

However, Vingerhoets emphasizes that crying does not always make people feel better — especially those suffering from depression or burnout.

It also depends on:

  • What we are crying about
  • Whether the situation is under our control
  • Whether people around us are supportive

Tears: A Social Signal

Research suggests that tears can influence other people’s behavior.

An Israeli study found that:

  • Men who smelled emotional tears from women became less aggressive than those who smelled a salty solution

Scientists believe tears act as a social signal, showing that we need help and encouraging empathy and support from others.


Children’s Tears and Evolution

A baby’s crying activates caregiving responses in adults’ brains.

According to Vingerhoets, human tears may have evolved because:

  • Human childhood lasts longer
  • Children depend on parents for extended periods

One theory suggests that a child’s crying may reduce adult aggression, serving as a protective mechanism.


Why Do Some People Cry More?

According to Lauren Bylsma:

  • Men cry about once a month on average
  • Women cry four to five times a month

This difference may be linked to:

  • Neurological factors
  • Hormonal differences
  • Personality traits
  • Levels of empathy

She also found that:

  • More empathetic people tend to cry more
  • Neurotic or extroverted individuals are also more likely to cry

Conclusion

Crying is not just a sign of weakness — it is:

  • A biological response
  • An emotional expression
  • A social signal

As Vingerhoets puts it:

“Crying is a symbolic marker that tells us this moment truly matters.”

 

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