Biology 103
2002 Second Paper
On Serendip

We all like to laugh, and generally it makes us feel better. Laughter is a common physiological phenomenon that researchers are just beginning to study. What exactly happens when we laugh? What makes us laugh? Is it true that laughter is contagious? Is laughter healthy?

When we laugh, the brain pressures us to simultaneously make gestures and sounds. Fifteen facial muscles contract, the larynx becomes half-closed so that we breathe irregularly, which can makes us gasp for air, and sometimes, the tear ducts become activated (1). Nerves sent to the brain trigger electrical impulses to set off chemical reactions. These reactions release natural tranquilizers, pain relievers and endorphins (2).

There are three different theories for what people find humorous. The incongruity theory is when people's logical expectations don't match up with the end of the situation or the joke. The relief theory is when tension is built up and we need a release of emotion; this is commonly seen in movies in what we refer to as 'comic relief' (1). The relief theory also takes into account laughing at forbidden thoughts (6). The third is called superiority theory, when we laugh at someone else's mistakes because we feel superior to them (1). While what people find humorous can be divided into these three generic categories, many factors affect a person's sense of humor, which is why we don't all laugh at the same things. The main factor seems to be a person's age (1). We have all seen young children laugh at jokes that they don't "get" just because they understand the format for riddles (4). There is always a certain amount of intelligence involved in understanding a joke, no matter how basic or stupid the joke may seem (1). So the older a person gets, the more she learns, and her sense of humor will usually become more mature.

However, laughter also occurs in situations not necessarily considered to be typically humorous. Psychologist and neuroscientist Robert Provine, from the University of Maryland, studied over 1,200 "laughter episodes" and determined that 80% of laughter isn't based around humor (3). We laugh from being nervous, excited, tense, happy or because someone else is laughing (4). The listener isn't just laughing in response to the speaker, either. Provine found that in most conversations, speakers laugh 46% more than listeners do (3). I think the fact that speakers laugh more than listeners implies a kind of nervousness and need for acceptance on the speaker's part. They subconsciously think that if they laugh, the people listening to them will also laugh, and the listeners laughing makes the speaker feel more comfortable.

Conversationalists who think that if they laugh they will also make their audience laugh may not be too far off. It is widely accepted that laughter makes people laugh, even if they do not know the original context that caused laughter. The ability of laughter to cause laughter indicates that humans might have "auditory "feature detectors"--neural circuits that respond exclusively to this species-typical vocalization"(3). These detectors trigger the neural circuits that generate laughter. A laugh generator that is initiated by a laugh detector may be why laughter is contagious (3). So people who are laughing with someone else may not be able to control themselves, even if they do not know what caused the original laugh.

What we consider normal, healthy laughter doesn't come in different forms. Laughter is rigidly structured the same way as any animal call. All types of laughter should be a series of short vowel-like syllables such as 'ha-ha-ha' or 'tee-hee-hee' that are about 210 milliseconds apart (3). When it doesn't follow that structure, laughter usually sounds unnatural or disturbing. Laughter that sounds like 'haa-haaa-haaaaa', that gets louder instead of quieter, or that interrupts the structure of a sentence are all examples of odd laugh forms (5). I realized that many of the examples of 'unhealthy' laughter are what we use in our society to depict villains. Since laugher is structured like animal calls, it is almost as though when we hear something that doesn't follow those patterns, we instinctively know that it is menacing or unnatural.

We often laugh because we're happy, but laughing can also make us happy - and healthy. Laughter releases endorphins, neurotransmitters that have pain-relieving properties similar to morphine and are probably connected to euphoric feelings, appetite modulation, and the release of sex hormones (7). Studies have shown that laughter boosts the immune system in variety of ways. Laughter increases the amount of T cells, which attack viruses, foreign cells and cancer cells, and gamma interferon, a protein that fights diseases (8). It increases B-cells, which make disease-destroying antibodies (1). Immunoglobulin A, an antibody that fights upper respiratory tract infections, and immunoglobulins G and M, which help fight other infections, levels all rise due to laughing (8). The amount of stress hormones are also reduced by laughing, some of which are hormones that suppress the immune system (1). So when you feel better after laughing, you really are happier and healthier.

Laughing is also a full body workout. Some researchers estimate that laughing 100 times is as much of a workout as 15 minutes on an exercise bike (1). This raises the question of exactly what type of laughing do they mean? The kind where your stomach hurts by the time you are finished, or any type of laughing? Also, the average adult only laughs seventeen times a day, so it would take a little more than five days to get the equivalent of 15 minutes on an exercise bike through laughing. Laughing exercises the cardiovascular system by lowering blood pressure and increasing heart rate, which any aerobic exercise will do (6). It probably improves coordination of brain functions, which increases alertness and memory, and helps clear the respiratory tract from coughing (8). Laughter increases blood oxygen; and strengthens internal muscles by tightening and releasing them (6). One doctor says that 20 seconds of laughing works the heart as hard as three minutes of hard rowing (8). My friends who are rowers say that this is practically impossible, but the fact that research indicates that laughing gives you that much of a workout means it must be good for you, even if not to such an extent.

Laughter is a very complex physical process. There are theories on how to classify what we find humorous, which in turn makes us laugh. But even if these categories are correct, there are other things that cause laughter. Any extreme emotion can make people laugh, which is sometimes why we laugh in what are considered socially inappropriate moments (like funerals or car accidents). Someone else laughing also triggers laughter, so it really is contagious. There is a great deal of research that indicates that laughter is healthy for you in a variety of ways, such as boosting the immune system and reducing stress. So if you feel like you're getting sick or you don't have much energy, stop worrying about going to the gym or the health center. You just need to find funnier friends.

References

1)How Stuff Works, "How Laughter Works".
2)Body Manifestations, by Dr. Sarfaraz K Niazi, 2/9/94.
3)American Scientist, Jan-Feb 1996. "Laughter", by Robert Provine.
4)"The Best Medicine", by Raj Kaushik, from The Halifax Herald Limited, 1/20/02.
5)Nature Science Update, "A Serious Article about Laughter", by Sara Abdulla.
6)Laughing Out Loud to Good Health
7)Bartleby.com, using the Colombia Encyclopedia as a reference.
8)MDA Publications, Quest, Volume 3, Number 4, Fall 1996. "Is Laughter the Best Medicine?" by Carol Sowell.


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