There are several reasons we cry; dust in the eye, chopping an onion or lubricating a dry eye. And this is a trait we share with almost every other land-based animal. Still, crying isn't just a physical response to stimuli; we also cry as an emotional response to situations to express ourselves or show that we need help.
The question is, do other animals cry in emotional response to stimuli, or are their reactions purely biological? Join us as we explore the phenomenon of crying and why its purpose is different across species.
Do Animals Cry?
It depends on how you define crying; some animals produce tears, but their function is to lubricate the eye rather than express emotion. When humans think about crying, we think about an emotional response - usually sadness, sometimes happiness - to a given response. But we are the only animals in the kingdom to express these emotions through tears.
We produce tears through our lacrimal glands. Many animals possess these glands, though they are only activated for reflex tears (such as if the animal gets poked in the eye).
Why Do Humans Cry?
In the science of crying, there are three key reasons why humans produce tears:
- Basal Tears: our eyes automatically create these tears are a form of lubrication
- Reflex Tears: these occur as a physical response to an external stimulus, such as cutting an onion or being poked in the eye
- Emotional Tears: these occur as an emotional response to external stimuli and are the only type of tears that we have any control over
Charles Darwin was among the first scientists to propose an evolutionary theory for crying. He believed our crying response began as babies when we would scream for our mothers. As we screamed, we would close our eyes tightly, thus stimulating the lachrymal glands to produce tears. And this early association would remain with us throughout life.
Other scientists, such as William Frey, hypothesize that crying could still serve as a biological response. For example, it could clear toxins from our bodies. But this theory is largely disproven, and scientists have yet to form conclusive reasoning for this reaction.
Still, crying is a behavior that evolves throughout our lives. As babies, we cry because we need something; feelings of helplessness continue to make us sad as we grow, but once we reach adulthood, we are less likely to cry from pain. And this is most likely because we no longer need to attract the attention of our mothers to look after us.
Instead, with age comes empathy, and we begin to cry for the woe of other people - even those that aren't real (books, movies, etc.). And this leads current researchers to believe that crying has a social function; it is almost like a performance we enact to express what we're feeling inside.
Why Don't Animals Cry?
Many animals make distress calls, but only in humans did these calls become synonymous with the production of tears. One possible reason for this is the importance of visual clues in human communication. Because we walk on two legs, we have our faces pointed forwards - combined with the fact that visual cues are so integral to our understanding, we have developed the most expressive face in the animal kingdom. This may be why we cry emotional tears.
A team of scientists in Croatia suggested that it could be these highly expressive faces and the evolution of the orbicularis oculi muscle that makes crying emotional tears possible.
Take a look at the majority of other land-based animals. You'll notice they walk on all fours, often with their heads close to the ground (dogs, cats, rodents, etc.) - therefore, other senses, such as smell and hearing, are far more important to these creatures, which could be why they use other forms of distress call.
Another reason scientists believe we may be the only animals to cry is that it could be seen as a sign of weakness, which would be detrimental to their survival in the wild. But psychologist Ad Vingerhoets suggests that this weakness could work to our advantage. When we cry, we openly display our sense of helplessness and show that we are not a threat, which could make others more likely to help us.
What Does It Mean When We See Animals Cry?
Many pet owners claim that their pets - especially dogs - can express their emotions through crying, and they have the pictures to prove it. But if tears aren't used as a form of emotional expression, then what's happening here?
Most likely, these tears allow the animal to lubricate its eyes.
If the eye is watery or the tears persist, it could indicate an issue or infection (which could also explain why the animal feels a little down). In these instances, it is a good idea for a vet to conduct a check-up to check for infection or scratches to the eye itself.
Some animals, such as elephants, do cry during times of stress - still, even these tears are quite different from our own as they do not come from tear ducts. What's actually happening is that elephants look like they're crying more often than other animals because they lack the drainage canals possessed by most other animals that would usually remove moisture created by the eyes.
Tears released by elephants (and other animals) are physical reflex responses to irritants and debris; they are not triggered by the parasympathetic nervous system and do not carry the same meaning as human tears.