Laughter may have begun as a gesture of shared relief at the passing of danger. Laughter is a kind of social signal, and its purpose is related to making and strengthening human relations. The physiological study of laughter is called gelotology. Laughter is primitive, an unconscious vocalization. It's social and contagious, and we laugh at the sound of laughter itself. Did you know that the average adult laughs about 17 times a day? Everyone has the capacity to laugh, and there are no known disorders that disable laughter. Let's go more in depth to the reasons why we laugh.


There are three theories about reasons why we laugh:

The Incongruity Theory: Humor arises when things that normally don’t go together replace familiarity and logic. It is suggested that a joke is funny because we are expecting one outcome in the end, but another happens instead. That anticipation takes the form of logical thought mixed with emotion and is influenced by our past experiences and our thoughts. When something in the joke happens unexpectedly, our brains are forced to switch gears, creating a new line of thought, with new emotions. We experience this incongruity between the different parts of the joke as humorous.

The Superiority Theory: This is when we laugh at someone else's stupidity, mistakes, or misfortune. We feel superior to the person, and experience a certain detachment from the situation, so are therefore able to laugh at it. This usually happens during bullying or making fun of people.

The Relief Theory: This is the basis for a device moviemakers have used effectively for a while. In action films or thrillers where tension is high, the director uses comic relief at just the right times. He builds up the tension or suspense as much as possible and then breaks it down slightly with a side comment, letting the viewer relieve himself of built up emotion, just so the movie can build it up again! An actual story/situation creates tension within us. As we try to cope with two sets of emotions and thoughts, we need a release and laughter is the way of cleansing our system of the built-up tension and conflict.

Age has a big role in why some people find some things funny. Infants and children appreciate jokes with cruelty in them (boosting self-assertiveness), or "toilet humor" (exploring their new environment). Preteens and teenagers laugh at jokes about food, sex, and authority figures, or any subject adults say is off-limits. Since there is a certain amount of intelligence needed to get a joke, our senses of humor become more developed as we learn more. The adult sense of humor is usually characterized as more subtle, more tolerant and less judgmental about the differences in people. They laugh at issues that stress them out. When people say, "That's not funny" it means either "That's offensive" or "What’s the point?" For someone to find a joke or situation offensive, he must have some attachment to the principle or person being demeaned or put down in the joke. Someone asking, "So, what's the point?" indicates the absence of any moral or emotional attachment or commitment to the joke's "victim." Finding something funny has a lot to do with what kind of person you are.


You may be wondering, "How exactly do we laugh? What is going on inside our brain?" The brain's largest region, the frontal lobe, is responsible for all emotional responses. Some research on this is still going on. For example, subjects were hooked up to an electroencephalograph (EEG) and their brain activity was measured when they laughed. It was found that with 0.4 seconds’ exposure to something potentially funny, an electrical wave goes through the cerebral cortex. If the wave has a negative charge, laughter results, but with positive, no response is given. The left side of the cortex (the layer of cells that covers the entire surface of the forebrain) analyzes the words and structure of the joke. The brain's large frontal lobe, which is involved in social emotional responses, becomes very active. The right hemisphere of the cortex carries out the intellectual analysis required to "get" the joke. Brainwave activity then spreads to the sensory processing area of the occipital lobe (the area on the back of the head that contains the cells that process visual signals). Stimulation of the motor sections evokes physical responses to the joke. All this is different from what happens with emotional responses. Emotional responses are confined to specific areas of the brain, while laughter seems to be produced through a circuit that runs through many regions of the brain. This means that damage to any of these regions can impair one's sense of humor and response to humor, experts say. Laughter starts with an electrical charge, and it's up to that negative or positive charge to decide whether you think something is funny!


You have probably noticed that when people laugh really hard, they sometimes shed tears. We shed tears as reactions of our bodies to things like a speck of dust in the eye, cutting onions, cold wind, etc. There are certain nerves in the head that you can sever to lose this reflex. Crying because of emotion has a different neurological mechanism from crying due to physical causes. Even if you cut the nerves that make your eyes water in response to physical stimuli, you can still tear up over something that makes you sad, and you can still tear up from laughing. This is called physical or psychogenic tearing, not related to reflex tearing. You tear up in response to emotion, good or bad, because of signals in the higher centers of your brain that tell your tear glands (the lacrimal gland) that you're sad or happy. Signals travel through the parasympathetic pathways, the part of your nervous system that controls, among many other things, bodily secretions such as tears. Signals are a part of complicated patterns of emotion that the body instantly recognizes. If we look at other things your body is doing while you weep, it's not too surprising that you can cry while laughing also. The facial expressions of laughing and crying are similar, and even your breathing pattern is similar (first you take a long deep breath, and then you let out short, sharp breaths, in both laughing and weeping). Even though it seems like crying and laughing are opposites, they have many things in common.


When you think of laughter, you probably think about tickling. Laughter is an involuntary response to ticking. Beneath your skin are millions of tiny nerve endings that alert the brain about temperatures. Is your hand burning because you are touching the stove? Do you need to put on another jacket to stay warm? When these nerve endings are lightly stimulated, they send message to the brain, and the brain analyzes it. A light touch resulting in tickling is a result of the analysis of two parts of the brain: The somatosensory cortex is responsible for analyzing touch (the pressure associated with it), and the signal sent from the skin's sensory receptors also passes through the anterior cingulated cortex, which creates happy feelings. Together, the two parts of the brain create a tickling sensation. Why we can't tickle ourselves is because the cerebellum, located at the back of the brain and responsible for movement, can predict a self-tickle and alerts the rest of the brain that it's coming. As a result, the intensity of the sensation is muted. This is called sensory attenuation, or the process by which the brain filters out unnecessary information in order to concentrate on the important stuff. A predictable light touch from your own fingers appears to not be worth your mind's attention, so your brain discards the information before it has a chance to enter your consciousness. Tickling and laughing are connected together in interesting ways.


Laughing is a complex action that we do without thinking. It's the one language that everyone can understand, and even babies laugh at as early an age as four months, long before they learn how to speak. 11% of daily laughter is occasioned by jokes, media prompts another 17%, but most of it, 72% arises spontaneously in social interaction. Again, as mentioned before, laughter is a social signal that is used to strengthen relationships. Although we already know quite a bit, there is still much to discover and learn about the mysteries of gelotology.


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