Skip to main content

Why Do We Yawn?

 



   We all do it, and even some animalsa s well, when we’re ready to go to sleep and sometimes when we awake.We do it when we’re bored, and we might do it under stress. We can even catch it from another person, but as common as yawning is, scientists have struggled to explain why we yawn. Recent research suggests some possible explanations.

 

    One theory among chasmologists—scientists who study yawning—is that the act is a form of social behavior. Contagious yawns are quite common—about half the people who see or hear a yawn will yawn too. Christian Hess of the University of Bern in Switzerland thinks the easy spread

of yawns helped early humans learn to

synchronize their desire to go to sleep and

awake at the same time, allowing them to

coordinate their daily activities.

Maryland psychologist Robert Provine

is one chasmologist who thinks a yawn

stirs up our brains. So when we’re sleepy, a

yawn wakes us up, and if we need mental

sharpness to deal with stress, the yawn

provides it. As part of this theory, the yawn

could be stimulating the flow of

cerebrospinal fluid, which clears out

chemicals in the brain that make us sleepy.

The brain-stimulating yawn also has a

social component: Provine says a

contagious yawn spawned by stress could

signal members of a group to prepare for

danger.

Instead of synchronizing bedtimes or

sweeping out unwanted chemicals, a yawn

could regulate temperature. That’s the

theory of Andrew Gallup, a psychologist at

the State University of New York at

Oneonta. Basically, he says, “We yawn to

cool our brains.” Yawning increases the

flow of blood to the brain, forcing out

warm blood that has gathered there.

Simultaneously, the yawn brings cooling

air into the body through the mouth and

nose. A typical yawn, Gallup said, can

lower the temperature in the brain by 0.2

degrees Fahrenheit. A string of yawns can

lower it by half a degree more.

Working off this theory, Gallup and

some scientists in Vienna tested the

incidence of contagious yawning at

different temperatures. Their results

suggested that contagious yawning most

often takes place when the outside

temperature is in a “thermal window” of

around 68 degrees Fahrenheit (20 degrees

Celsius). Yawning decreases when the

outside temperature and body temperature are close, or when it’s cold outside.

Comments

Post a Comment

Popular posts from this blog

How Will the Universe End?

    In 1929, Edwin Hubble discovered that the universe is not in fact static, but expanding. In the years following his discovery, cosmologists took up the implications of the discovery, asking how long the universe had been expanding, what forces caused the expansion, and whether it will ever cease.    Cosmologists are pretty confident about the first question: just shy of 14 billion years. A great deal of evidence supports the predominant answer to the second question: The universe rapidly emerged from a singularity in an event that cosmologists call the Big Bang. The third question is a bit more mysterious, and the answer relies on an obscure, confounding phenomenon known as dark energy. The density of dark energy in the universe determines its ultimate fate. In one scenario, the universe does not possess enough dark energy to forever counteract its own gravity and thus ends in a “Big Crunch.” Under this scenario, the universe’s gravity will overcome its expansio...
Post a Comment
Read more

What Causes Volcanic Lightning?

      On March 10, 2010, Eyjafjallajökull volcano, a caldera in Iceland covered by an ice cap, erupted. It sent plumes of clouds across most of Europe and the Atlantic Ocean. Photos of the eruption show lightning originating and ending in the cloud of ash that hovered over the volcanic opening.    The largest volcanic storms are similar to supercell thunderstorms that spread across the American Midwest. But while those thunderstorms are fairly well understood, volcanic lightning still remains mysterious. The remote location of volcanoes and infrequent eruptions make volcanic lightning difficult to study. In general, lightning occurs through the separation of positively and negatively charged particles. Differences in the aerodynamics of the particles separate the positive and negative. When the difference in charge is great, electrons flow between the positive and negative regions. A lightning bolt is a natural way of correcting the charge distributi...
Post a Comment
Read more

Why Do We Have Fingerprints?

      Many  scientists once thought fingerprints help us hold onto objects. From an evolutionary perspective, getting a better grip on tools or weapons would have made life easier for early humans. In 2009, Dr. Roland Ennos of Manchester University designed an experiment that tested the gripping power of our fingerprints. He used a machine equipped with weights to pull strips of Perspex, a kind of acrylic, across a subject’s fingertips. The machine measured the amount of friction created as the acrylic passed over the tip. In the real world, a high amount of friction between two solid objects in contact with each other would indicate a better grip. In the experiment, the fingertips created some friction on the acrylic, but not as much as Ennos had expected.     Ennos compares our fingerprints to the tires on a race car. Ridges in the tire reduce the surface area of the tire in contact with the road, which reduces friction. The ridges on fingertips have the ...
Post a Comment
Read more