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San Marcos Public Library

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Q. Why do we yawn?

The answer to that is… well…no A. one really knows. However, there are theories. One of the recent theories about why we yawn is that it cools down the brain. A series of experiments in 2011 at Princeton University tested this theory on rats, parakeets and humans. Basically, as outlined in an article from WebMD (DeNoon), here’s what happens:

• When you start to yawn, powerful stretching of the jaw increases blood flow in the neck, face and head.

• The deep intake of breath during a yawn forces the downward flow of spinal fluid and blood from the brain.

• Cool air breathed into the mouth cools these fluids.

Princeton researcher Andrew Gallup adds, “Together these processes may act like a radiator, removing [too hot] blood from the brain while introducing cooler blood from the lungs and extremities, thereby cooling [brain] surfaces.”

Yawn theorists are split into two camps. Like Gallup, one side says yawning must have a physiological cause and a physical benefit. The other side says yawning is a form of communication that offers various social benefits. (DeNoon) It’s a way animals and humans tell each other that they are tired, bored or injured. That’s behind the theory that yawns are “catching” and can be shared between people.

What are some other interesting things about our bodies? What about when you sneeze? Obviously, you sneeze when your nose is trying to dispel foreign matter. However, did you know that your nose and sinuses make about a quart of mucus every day? Mucus is everywhere in your body. It coats the inside of your mouth nose, sinuses, throat, lungs and gastrointestinal track. It keeps your body tissues from drying out. (Duhaime) Mucus also keeps foreign matter from getting into your lungs. The technical term for sneezing is “sternutation.” When someone sneezes, the air (and mucus) in your nose can come out at 100 miles per hour. According to Guinness World Records, a girl from Great Britain sneezed for 977 days and she sneezed more than one million times. (Larsen)

What about coughing? How does that work? Coughing is the way your body removes unwanted things from your throat or lungs. When you cough you breathe in quickly then close your glottis (the spot near the back of your throat and the top of your trachea or windpipe). When your glottis closes, air pressure builds up in your lungs. Then you quickly open your glottis and force an explosive amount of air through your trachea and out your mouth. (Larsen) Your cough can travel at 60 miles per hour. No wonder germs spread so fast and far.

Here are a few other interesting facts on these topics:

• 370 BCE, Greek physician Hippocrates popularized the idea that human health is based on the four humors, one of which is phlegm.

• In 1924, Kleenex Tissue introduced the first disposable facial tissues.

• In 1932, Polish physician Alfred Laskiewicz promoted the idea that nasal irrigation would be good to deal with excess mucus.

• The neti pot, a way of irrigating the sinuses, originated in ancient India but was introduced to the United States in 1972.

• It was in ancient Rome, approximately 750 CE, when it became customary to say “God Bless You” after someone sneezes.

These books, available at the San Marcos Public Library, and website were particularly helpful in writing this column:

• DeNoon, D. J. (2011, September 23). “Why we yawn.” WebMD. Retrieved October 7, 2021, from webmd.com/brain/news/20110923/why-weyawn.

• Duhaime, D. (2017). “Gross body stuff.” Rourke Educational Media.

• Larsen, C. S., & Slack, M. H. (2010). “Crust & Spray: Gross stuff in your eyes, ears, nose, and throat.” Millbrook Press.

• Woolf, A., Antram, D., & Salariya, D. (2017). “You wouldn’t want to live without boogers!” Franklin Watts, an imprint of Scholastic Inc.

Suzanne Sanders is the new columnist for the library. She is the Community Services Manager for the San Marcos Public Library and came from the Austin Public Library in 2015 after having served there as a librarian for over 20 years. She gratefully accepts your questions for this column.