July 1st, 2025
Written by: Eve Gautreaux
Most mammals and birds make sounds to communicate with one another, an important sound being a distress call, one that says “Help! Something is wrong!”. Think of a baby bird that is chirping at a certain pitch because it has fallen out of its nest or a kitten loudly meowing because it’s been separated from its mother. These distress calls are a form of crying in animals characterized by distinct sounds, but with no actual tears. Unlike other animals, humans are the only species that exhibit tearful crying, which is the type of crying that comes with the production of tears1.
You may be thinking, “wait, surely other animals have tears though? How do their eyes avoid getting dry? What are those stains under my dog’s eyes?” If so, you’re not wrong! This is because there are technically three types of tears, one of which is a form entirely unique to humans.
The first two types of tears are necessary for eye health and unrelated to distress. Animals constantly produce basal tears to keep eyes moisturized and provide protection. Reflex tears are produced in response to something in the environment that irritates the eye, like dust or the onion you’re chopping while making dinner. The third type of tears—the kind unique to humans—is emotional tears which are produced in response to a strong emotion whether it be pain, sadness, fear, or even joy1. So, if your dog or hamster doesn’t shed a tear when you say “I love you” or when you open your own floodgate of tears in front of them after a particularly bad day, don’t take it personally, they haven’t evolved emotional tears (yet).
This begs the question: why would we evolve the behavior of releasing fluid from our eyes in response to emotions?
Why humans cry: theories of origin
Similar to the baby bird chirping or the kitten meowing, human infants also produce distress calls, to say “help!”. Interestingly, human distress calls are purely sound until we are about 4-8 weeks old when we begin to shed tears1. Some scientists theorize that tears became paired with distress calls due to strong movements of the facial muscles used for producing sounds also pressing on the glands that produce tears3. Although this may answer how tearful crying originated, why was this behavior kept around?
From an evolutionary standpoint, behaviors or traits that help a species survive are favored and become more common in a population. Tears offer the advantage of a visible sign of distress which conveniently reduces the chance of alerting predators to loud sounds3. One study that digitally removed tears from images of human faces found that people had great difficulty with identifying the emotion of the face in the image3. This suggests that among other visible signals of emotion such as facial expressions, tears are important for humans to accurately recognize distress in others. This visible signal is especially useful in humans given our complex range of emotions as well as the unique fact that children, despite having fully developed motor skills such as speaking or walking, are still mentally and emotionally developing and dependent on adults for protection and care3.
Okay, so cavemen and cavewomen had cave-infants that cried tears, and these tears helped all the cavepeople survive. However, we are (arguably) no longer hunted by predators and we even cry when we are happy!? So, what gives? Why do we still cry in the modern day?
Why humans cry: two types of benefits
Interpersonal benefits are those that come from the environment and other people, or in other words, they benefit the crier indirectly. For example, when people see another person crying, they feel more sympathy, empathy, and willingness to help4. This is consistent with the idea that the evolutionary purpose of crying was a visible distress signal sent to get help.
As a bonus for criers, when people are shown images or videos of human faces with or without tears, they view crying faces as warmer, friendlier, more empathetic, reliable, sincere, honest, and less aggressive compared to non-crying faces4. Importantly, viewers said they feel more connected to crying faces versus non-crying faces4. Criers also report feeling better and more connected to others when people responded to their tears positively by offering help or support1. Given that crying increases the desire to help and feelings of connectedness for both criers and cry-onlookers, it is clear that crying plays a major role in social bonding and mutual support in humans.
Intrapersonal benefits are those that directly affect the person crying. Have you ever heard the expression “cry it out” or “have a good cry”? This idea that crying is cathartic, healing, or simply makes a crier feel better is not new, even dating back centuries. The role of the parasympathetic nervous system (the division responsible for relaxation, rest, and recovery) in crying may support this longstanding belief in which it not only helps to regulate emotions but suggests other potential benefits including stress relief, pain relief, improvements in sleep quality and increased immune function5.
The parasympathetic and sympathetic nervous systems affect your internal organs, but in opposite ways. The parasympathetic nervous system decreases arousal and instead promotes relaxation, rest, and recovery while the sympathetic nervous system increases arousal for “fight or flight” responses. For example, the sympathetic nervous system increases heart rate and breathing to prepare for “fight or flight” such as running from a bear or even perceived threats like public speaking. In contrast, the parasympathetic nervous system slows heart rate and respiration to relax the body and allow recovery.
Studies have found that these two parts of your nervous system follow a specific pattern when crying. Sympathetic and parasympathetic activity both increase before crying1. However, once crying begins, sympathetic activity goes back to its original activity level while parasympathetic activity remains high1. Parasympathetic activity increases again after crying stops1. This pattern suggests that, before crying, there is something that increases arousal in our body, like distress, followed by crying in which this arousal decreases and relaxation processes kick in as a recovery mechanism to restore balance and regulate our system both physically and emotionally.
The parasympathetic nervous system includes the vagus nerve which acts like a brake on organs including slowing down heart rate and breathing as well as reducing inflammation and stress responses in the body6. The vagus nerve also helps with emotion regulation and improving mood6. Research suggests that the vagus nerve achieves these effects by sending feedback to regions of the brain that release chemicals including oxytocin, a hormone important for social bonding, and endorphins, our natural pain relievers known to boost mood and reduce stress. One small study measured levels of cortisol, a stress hormone, in women before and after watching an emotional video and found that cortisol levels decreased more in women that cried5. However, more research is needed to support the idea that crying is accompanied by the release of oxytocin and endorphins.
If crying offers so many benefits from identifying emotions in others to facilitating social bonding and connection to regulating our emotions and potentially even various aspects of our health, then why isn’t everyone constantly sobbing?
Why people cry (or don’t)
Although crying is a natural process that we never have to learn, it is still subject to significant influence, varying from person to person or even within the same person day to day. So, what determines if and how much we cry?
Age
The term “crybaby” may not be a compliment, but at least it’s scientifically accurate. Not only do babies cry more often than any other age group, but the specific events that trigger emotional crying also change over the lifespan4. For example, pain and discomfort are common triggers in infants and toddlers, likely due to these age groups still being too young to verbally describe pain4. Meanwhile, crying out of empathy and crying in response to positive or moving events (such as witnessing acts of kindness or significant life events like a wedding) becomes more common with age4. These patterns arise from changes in social, mental, and emotional development4. However, some triggers are unchanged with age such as crying in response to loss or helplessness4.
Sex and gender
It is a common stereotype that women cry more than men. Technically, this is true. Women cry over twice as much as men and are more prone to crying in response to a given event4. However, what are these stereotypes rooted in; is it biology or sociology (the effects of society and social behavior)?
If biology were responsible for women crying more than men, then changes in the biological elements that determine sex, such as sex chromosomes or sex hormones, should cause changes in crying. Sex chromosomes are determined the moment an egg is fertilized and therefore any purely biological differences should be present at birth. Yet, male and female infants do not differ in how much they cry4. One of the most dramatic changes in sex hormones happens during puberty. Interestingly, there is no difference in crying between girls before and after puberty, suggesting that sex hormones do not affect crying behavior4.
Several studies that found differences in crying between men and women also asked the participants to report their views on gender, crying, as well as other questions related to their personality and background. The differences in crying between men and women were linked to differences in gender roles4. Specifically, people who either identified with more feminine traits or who were less likely to endorse traditional gender roles tended to cry more. Women were more likely to fall within this group. Meanwhile, people who identified as being more masculine or endorsed traditional gender roles tended to cry less, and most of these people were men. Importantly, the more feminine-leaning, less traditional group in which most women belonged to had greater belief that crying is healthy and helpful compared to the masculine-identifying, traditional group that most men belonged to4. Together, this suggests that women may cry more due to feeling more comfortable and as a conscious choice based on the belief that it is helpful. Meanwhile, men may cry less not only due to conformity with traditional gender roles that typically discourage crying in men, but also due to a belief that crying won’t help them.
So, where does the difference in views and beliefs come from?
Culture
Culture determines how often people cry, as well as how large the difference in crying is between men and women. Wealthier, more democratic, extraverted, and individualistic countries are correlated with more crying4. What do these characteristics have in common? Each offers more freedom and empowerment of self whether it be literal freedom, financial freedom, or freedom of expression. With this line of thinking, it would make sense why someone who feels free would also feel more comfortable to engage in yet another form of expression: crying.
Personality
So, why are there still differences in crying among people of the same age and the same sex in the same culture? The answer is personality traits! For example, extraversion and empathy are correlated with higher crying proneness to both positive and negative events4. People who tend to experience more negative emotions are more likely to cry when something bad happens4. Another survey found that those that cry more easily demonstrate more positive behavior towards others such as helpfulness and acceptance4.
In conclusion, humans have evolved the unique and extraordinary behavior of tearful, emotional crying, and there is growing evidence of its numerous benefits both for one’s own wellbeing and for humanity. And yet, so many of us hesitate to use this built-in tool that our cave-ancestors unknowingly created. One can’t help but wonder if this were a new skincare product or a new smartphone being sold claiming to improve your life just as much, would you buy it? Just on the off chance it works?
Perhaps the next time you feel the urge, that lump in your throat or pricking at your eyes, go ahead and cry it out, no matter who you are.
References
1. Bylsma, L. M., Gračanin, A. & Vingerhoets, A. J. J. M. The neurobiology of human crying. Clin. Auton. Res. 29, 63–73 (2019).
2. Dartt, D. A. Neural regulation of lacrimal gland secretory processes: relevance in dry eye diseases. Prog. Retin. Eye Res. 28, 155–177 (2009).
3. Gračanin, A., Bylsma, L. M. & Vingerhoets, A. J. J. M. Why only humans shed emotional tears : Evolutionary and cultural perspectives. Hum. Nat. 29, 104–133 (2018).
4. Bylsma, L. M., Gračanin, A. & Vingerhoets, A. J. J. M. A clinical practice review of crying research. Psychotherapy (Chic.) 58, 133–149 (2021).
5. Gračanin, A., Bylsma, L. M. & Vingerhoets, A. J. J. M. Is crying a self-soothing behavior? Front. Psychol. 5, 502 (2014).
6. Ottaviani, M. M. & Macefield, V. G. Structure and functions of the vagus nerve in mammals. Compr. Physiol. 12, 3989–4037 (2022).
Cover photo by lakapadane from Freepik.
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