Why We Cry
Crying is a human characteristic that other animals do not have. Though some species shed tears as a result of pain or irritation, humans are currently known as the only creatures whose tears can be triggered by their feelings. Charles Darwin once declared emotional tears “purposeless.” Contrary to Darwin's declaration, however, scientists have recently found that crying plays a far more important role than was once believed.

First, let's define the terms. Crying is scientifically defined as the shedding of tears in response to an emotional state. These tears are called psychic or emotional tears. Differentiated from psychic or emotional tears, non-emotional tears are divided into two types: basal tears and reflex tears. Basal tears flow continuously to moisturize the eyes. When you blink, basal tears clean your eyes, making the eyes' outer surface smooth, and helping you see clearly. Normally, you are not conscious of the flow of basal tears until your eyes get dry due to their absence. Reflex tears are the tears you shed in spite of yourself when, for instance, you slice a raw onion or encounter a cloud of dust. These tears help clear the eyes of such irritants as the gas from the onion or dust particles.

When a tear is produced from the lacrimal gland, you blink in spite of yourself, spreading the tear as a film across your eye. Your tear then has two fates. First, it can drain down the tiny hole in the corner of the eye, like the sink plug in your kitchen, and then flow through your nose. That is why your nose runs when you cry.

Second, when you are in a state of extreme sadness or pain, you have a really good cry, and your drainage system simply cannot deal with the volume of tears. The excess fluid now flows over your eyelids and down your cheeks. There have been many theories about the origin and function of emotional tears. A prevailing theory in the 1600s held that emotions ― especially love ― heated the heart, which generated water vapor in order to cool itself down. This theory was rejected when Niels Stensen, a scientist in Denmark, discovered in 1662 that not emotions but the lacrimal gland, the tiny structure on the inside corner of the eye, is the proper origin of tears. Stensen's theory was that tears were simply a way to keep the eye moist. A theory that crying removes toxic substances from the body that build up during times of stress gained some popularity in the 20th century, although not scientifically proven.

In recent years, evidence is mounting in support of new theories. One of them is that emotional tears trigger social bonding and human connection. We cry from a very early age to bring about a connection with others, for we come into the world physically and emotionally unequipped to deal with anything on our own. Even though we become more capable as we grow, we never quite grow out of occasional attacks of helplessness. Crying signals to other people that we are experiencing some important problem that is beyond our ability to cope with. In a 2016 study, test subjects were shown a photograph of someone visibly crying, and then shown the same photo with the tears removed. The result: they were much more likely to reach out to the person in the first photo.

All types of tears have three layers: a thin mucus layer that sits directly on the eye, a watery layer in the middle, and a thin oily layer on top that prevents the tear from evaporating. Interestingly enough, scientists have found that the types of tears are chemically different from each other. Compared to basal tears, the watery portion of reflex tears is larger and has higher levels of antibodies that can stop harmful microorganisms. On the other hand, emotional tears contain more protein. One interpretation is that this higher protein content makes emotional tears stickier, so they stick to the skin more strongly and run down the face more slowly, making them more likely to be seen by others. According to that interpretation, the more visible tears are, the more likely they are to bring out compassion from observers. "There must have been some point in time, evolutionarily, when tears became something that automatically set off empathy and compassion in another," says Michael Trimble, a doctor at University College London.

A less touching theory about emotional tears focuses on crying's ability to manipulate others. Researchers believe that not only babies but also adults use tears as a tool for getting what they need, whether they're aware of it or not. Jonathan Rottenberg, an emotion researcher and professor of psychology at the University of South Florida, says that we learn early on that crying can greatly reduce anger from other people. That is why he thinks tears are common in fights between lovers. When someone feels guilty, they have a greater chance of being forgiven as long as tears are running down their face, says Rottenberg. Some researchers are even looking into the molecules in tears to see if there is one that is responsible for reducing aggression.

Then, a question arises: if tears are so important for human bonding, bringing out compassion, and reducing aggression, do people who do not cry have problems making social connections? The answer is, yes, mostly. Psychologists have discovered that such people have a tendency to withdraw and describe their relationship experiences as less connected. Another interesting fact is that while emotional states affect the production of tears, the contrary is also true. For example, patients who have great difficulty producing tears, due to some diseases, also have difficulty identifying their own feelings. As a result, their social relationships tend to become troubled.

Despite its benefits, crying is not always followed by immediate relief. In an experiment in which participants were shown a sad movie and had their mood measured right after watching it, those who had cried were actually in a worse mood than those who had not. However, after some time, the criers reported being in a better mood than they had been before watching the movie. Crying did relieve their mood, provided that they were given enough time for the benefits of crying to set in. Modern research into crying is still young, but evidence is mounting that crying demonstrates our deep connections with our world. So go on and wear your tears with pride.

Your Eyes Are the Windows to Your Soul
Eyes are often called the windows to the soul. Eyes, as it turns out, provide a lot of information about a person's emotional state. One telling example is a smile. When you are truly happy, you smile not only with your mouth but also with your eyes. In contrast, when people fake a smile, they usually forget about their eyes. If the eye is the window into the soul, the pupil is quite literally an opening into the eye. The pupil dilates or contracts to regulate the amount of light entering the eye. We all know that our pupils get smaller in the light and bigger in the dark. This is the pupillary light response.

The pupillary light response is not just a mechanical reaction to light. The pupils also adjust according to our emotions. It is related to an alarm system in the body that prepares us to take action whenever we detect a threat or an opportunity in our environment. Encounter a bear while walking through the woods, and your alarm system goes on alert. Your heart and breathing rates increase, you begin to sweat, and your pupils dilate. The pupils will have adjusted themselves to the threat. Meet an attractive person at a party, and your heart and breathing rates increase, you begin to sweat, and your pupils dilate. The pupils will have adjusted themselves to the opportunity. None of these pupillary responses is under your control. Perhaps that is why eyes are called the windows to the soul, revealing your true emotional state, regardless of your will to control it.