How Laughter Works

­First of all, laughter is not the same as humor. Laughter is the physiological respo­nse to humor. Laughter consists of two parts -- a set of gestures and the production of a sound. When we laugh, the brain pressures us to conduct both those activities simultaneously. When we laugh heartily, changes occur in many parts of the body, even the arm, leg and trunk muscles.

Under certain conditions, our bodies perform what the Encyclopedia Britannica describes as "rhythmic, vocalized, expiratory and involuntary actions" -- better known as laughter. Fifteen facial muscles contract and stimulation of the zygomatic major muscle (the main lifting mechanism of your upper lip) occurs. Meanwhile, the respiratory system is upset by the epiglottis half-closing the larynx, so that air intake occurs irregularly, making you gasp. In extreme circumstances, the tear ducts are activated, so that while the mouth is opening and closing and the struggle for oxygen intake continues, the face becomes moist and often red (or purple). The noises that usually accompany this bizarre behavior range from sedate giggles to boisterous guffaws.

­Behavioral neurobiologist and pioneering laughter researcher Robert Provine jokes that he has encountered one major problem in his study ­of laughter. The problem is that laughter disappears just when he is ready to observe it -- especially in the laboratory. One of his studies looked at the sonic structure of laughter. He discovered that all human laughter consists of variations on a basic form that consists of short, vowel-like notes repeated every 210 milliseconds. Laughter can be of the "ha-ha-ha" variety or the "ho-ho-ho" type but not a mixture of both, he says. Provine also suggests that humans have a "detector" that responds to laughter by triggering other neural circuits in the brain, which, in turn, generates more laughter. This explains why laughter is contagious.

Humor researcher Peter Derks describes laughter response as "a really quick, automatic type of behavior." "In fact, how quickly our brain recognizes the incongruity that lies at the heart of most humor and attaches an abstract meaning to it determines whether we laugh," he says.

In the next section, we'll learn why we laugh.

­Philosopher John Morreall believes that the first human laughter may have begun as a g­esture of shared relief at the passing of danger. And since the relaxation that results from a bout of laughter inhibits the biological fight-or-flight response, laughter may indicate trust in one's companions.

Many researchers believe that the purpose of laughter is related to making and strengthening human connections. "Laughter occurs when people are comfortable with one another, when they feel open and free. And the more laughter [there is], the more bonding [occurs] within the group," says cultural anthropologist Mahadev Apte. This feedback "loop" of bonding-laughter-more bonding, combined with the common desire not to be singled out from the group, may be another reason why laughter is often contagious.

Studies have also found that dominant individuals -- the boss, the tribal chief or the family patriarch -- use humor more than their subordinates. If you've often thought that everyone in the office laughs when the boss laughs, you're very perceptive. In such cases, Morreall says, controlling the laughter of a group becomes a way of exercising power by controlling the emotional climate of the group. So laughter, like much human behavior, must have evolved to change the behavior of others, Provine says. For example, in an embarrassing or threatening situation, laughter may serve as a conciliatory gesture or as a way to deflect anger. If the threatening person joins the laughter, the risk of confrontation may lessen.

Provine is among only a few people who are studying laughter much as an animal behaviorist might study a dog's bark or a bird's song. He believes that laughter, like the bird's song, functions as a kind of social signal. Other studies have confirmed that theory by proving that people are 30 times more likely to laugh in social settings than when they are alone (and without pseudo-social stimuli like television). Even nitrous oxide, or laughing gas, loses much of its oomph when taken in solitude, according to German psychologist Willibald Ruch.

Next, we'll learn how we laugh.

­The physiological study of laughter has its own name -- gelotology. And we know that ce­rtain parts of the brain are responsible for certain human functions. For example, emotional responses are the function of the brain's largest region, the frontal lobe. But researchers have learned that the production of laughter is involved with various regions of the brain. While the relationship between laughter and the brain is not fully understood, researchers are making some progress.

For example, Derks traced the pattern of brainwave activity in subjects responding to humorous material. Subjects were hooked up to an electroencephalograph (EEG) and their brain activity was measured when they laughed. In each case, the brain produced a regular electrical pattern. Within four-tenths of a second of exposure to something potentially funny, an electrical wave moved through the cerebral cortex, the largest part of the brain. If the wave took a negative charge, laughter resulted. If it maintained a positive charge, no response was given, researchers said.

During the experiment, researchers observed the following specific activities:

This is different from what happens with emotional responses. Emotional responses appear to be confined to specific areas of the brain, while laughter seems to be produced via 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.)

Read on to learn more about how the brain and laughter are connected.

­When we look more closely at the areas of the brain involved with laughter, the limbic system seems to be central. The limbic system is a network of structures lo­cated beneath the cerebral cortex. This system is important because it controls some behaviors that are essential to the life of all mammals (finding food, self-preservation).

Interestingly, the same structures found in the human limbic system can also be found in the brains of evolutionary ancient animals such as the alligator. In the alligator, the limbic system is heavily involved in smell and plays an important role in defending territory, hunting and eating prey. In humans, the limbic system is more involved in motivation and emotional behaviors.

While the structures in this highly developed part of the brain interconnect, research has shown that the amygdala, a small almond-shaped structure deep inside the brain, and the hippocampus, a tiny, seahorse-shaped structure, seem to be the main areas involved with emotions. The amygdala connects with the hippocampus as well as the medial dorsal nucleus of the thalamus. These connections enable it to play an important role in the mediation and control of major activities like friendship, love and affection and on the expression of mood. The hypothalamus, particularly its median part, has been identified as a major contributor to the production of loud, uncontrollable laughter.

In the next section, we'll discuss what makes us laugh.

­Laughter is triggered when we find something humorous. There are three traditional theories about what we find humorous:

Next we'll learn why we don't all think that the same things are funny.

­Experts say that several obvious differences in people affect what they find humorous. The­ most significant seems to be age.

Infants and children are constantly discovering the world around them. A lot of what goes on seems ridiculous and surprising, which strikes them as funny. What's funny to a toddler consists of short and simple concepts, like an elephant joke. Along with the ridiculous and the surprising, children -- much to their parents' dismay -- also appreciate jokes where cruelty is present (it boosts their self-assertiveness) and what we refer to as "toilet humor." To children, a preoccupation with bodily functions is simply another way of exploring their fascinating new environment.

The pre-teen and teenage years are, almost universally, awkward and tense. Lots of adolescents and teens laugh at jokes that focus on sex, food, authority figures and -- in typical rebellious style -- any subject that adults consider off-limits. It is an insecure time of life and young people often use humor as a tool to protect themselves or to feel superior.

As we mature, both our physical bodies and mental outlooks grow and change. Since there is a certain amount of intelligence involved in "getting" a joke, our senses of humor becomes more developed as we learn more. By the time we're grown, we have experienced much of life, including tragedy and success. In keeping with these experiences, our senses of humor are more mature. We laugh at other people and ourselves in shared common predicaments and embarrassments. The adult sense of humor is usually characterized as more subtle, more tolerant and less judgmental about the differences in people. The things we find funny as a result of our age or developmental stage seem to be related to the stressors we experience during this time. Basically, we laugh at the issues that stress us out.

Another factor that affects what we find funny is the culture or community from which we come. Have you ever laughed at a joke and realized that if you were from anywhere else in the world, it just wouldn't be funny? It's a fact of life that culture and community provide lots of fodder for jokes. There are economic, political and social issues that are easy to laugh about, but only the people living in that culture may understand it. For example, a joke from a small country might not have universal appeal because it would be so little understood. The big, influential, much-observed United States might be the exception to this rule. Thanks to media and movies, most people around the world know what is going on here. So jokes about a situation in the United States can be enjoyed pretty much across the globe.

When people say "That's not funny," theorist Veatch says they mean either "It is offensive" or "So, 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. So racist and sexist jokes are offensive to many people who feel strongly about fighting bigotry and prejudice in the world. According to Veatch, when someone says, "So, what's the point?" it indicates the absence of any moral or emotional attachment or commitment to the joke's "victim."

­We've ­long known that the ability to laugh is helpful to those coping with major illness and the stress of life's problems. But researchers are now saying laughter can do a lot more -- it can basically bring balance to all the components of the immune system, which helps us fight off diseases. (See How the Immune System Works.)

As we mentioned earlier, laughter reduces levels of certain stress hormones. In doing this, laughter provides a safety valve that shuts off the flow of stress hormones and the fight-or-flight compounds that swing into action in our bodies when we experience stress, anger or hostility. These stress hormones suppress the immune system, increase the number of blood platelets (which can cause obstructions in arteries) and raise blood pressure. When we're laughing, natural killer cells that destroy tumors and viruses increase, as do Gamma-interferon (a disease-fighting protein), T-cells, which are a major part of the immune response, and B-cells, which make disease-destroying antibodies.

Laughter may lead to hiccuping and coughing, which clears the respiratory tract by dislodging mucous plugs. Laughter also increases the concentration of salivary immunoglobulin A, which defends against infectious organisms entering through the respiratory tract.

What may surprise you even more is the fact that researchers estimate that laughing 100 times is equal to 10 minutes on the rowing machine or 15 minutes on an exercise bike. Laughing can be a total body workout! Blood pressure is lowered, and there is an increase in vascular blood flow and in oxygenation of the blood, which further assists healing. Laughter also gives your diaphragm and abdominal, respiratory, facial, leg and back muscles a workout. That's why you often feel exhausted after a long bout of laughter -- you've just had an aerobic workout!

The psychological benefits of humor are quite amazing, according to doctors and nurses who are members of the American Association for Therapeutic Humor. People often store negative emotions, such as anger, sadness and fear, rather than expressing them. Laughter provides a way for these emotions to be harmlessly released. Laughter is cathartic. That's why some people who are upset or stressed out go to a funny movie or a comedy club, so they can laugh the negative emotions away (these negative emotions, when held inside, can cause biochemical changes that can affect our bodies).

Increasingly, mental health professionals are suggesting "laughter therapy," which teaches people how to laugh -- openly -- at things that aren't usually funny and to cope in difficult situations by using humor. Following the lead of real-life funny-doc Patch Adams (portrayed by Robin Williams in a movie by the same name), doctors and psychiatrists are becoming more aware of the therapeutic benefits of laughter and humor. This is due, in part, to the growing body of humor and laughter scholarship (500 academicians from different disciplines belong to the International Society for Humor Studies).

Here are some tips to help you put more laughter in your life: