Yawning...And Why Yawns Are Contagious

Everyone yawns - babies, kids, teenagers, adults. Some birds, reptiles and most mammals also yawn. However, the reason why we yawn is a bit of a mystery. There is also very little research about yawning because for most people yawning is not a problem. Here are a few things that are known about yawns:

The average duration of a yawn is about 6 seconds. In humans, the earliest occurrence of a yawn happens at about 11 weeks after conception - that's BEFORE the baby is born! Yawns become contagious to people between the first and second years of life. A part of the brain that plays an important role in yawning is the hypothalamus. Research has shown that some neurotransmitters (for example, dopamine, excitatory amino acids, nitric oxide) and neuropeptides increase yawning if injected into the hypothalamus of animals.

You know that when you are bored, you yawn. Scientists have confirmed this observation by comparing the number of yawns in 17-19 year old students who watched music videos to the number of yawns in students who watched an uninteresting color test bar pattern. As you might have expected, people who watched the color test bar pattern yawned more (5.78 yawns in 30 minutes) than those who watched the "MTV-like" video (3.41 yawns in 30 minutes.) The average duration of yawns was also slightly longer in the test bar viewing group. One unexpected finding was that yawns in male students had a longer duration than those in female students.

Many people assume that we yawn because our bodies are trying to get rid of extra carbon dioxide and to take in more oxygen. This may make some sense. According to this theory, when people are bored or tired, they breathe more slowly. As breathing slows down, less oxygen makes it to the lungs. As carbon dioxide builds up in the blood, a message to the brain results in signals back to the lungs saying, "Take a deep breath," and a yawn is produced.

The only problem with the excess carbon dioxide theory is that research shows that it may not be true. In 1987, Dr. Robert Provine and his coworkers set up an experiment to test the theory that high carbon dioxide/low oxygen blood content causes yawning. Air is normally made up of 20.95% oxygen, 79.02% nitrogen), 0.03% carbon dioxide and a few other gases in low concentrations. The researchers gave college students the following gases to breathe for 30 minutes:

• Gas #1 = 100% Oxygen
• Gas #2 = 3% Carbon dioxide, 21% Oxygen
• Gas #3 = 5% Carbon dioxide, 21% Oxygen
• Gas #4 = Normal Air

Breathing 100% oxygen (Gas #1) or either carbon dioxide gas (Gas #2 and #3) did cause the students to breathe at a faster rate. However, neither carbon dixoide gas nor 100% oxygen caused the students to yawn more. These gases also did not change the duration of yawns when they occurred.

The researchers also looked for a relationship between breathing and yawning by having people exercise. Exercise, obviously, causes people to breathe faster. However, the number of yawns during exercise was not different from the number of yawns before or after exercise. Therefore, it appears that yawning is not due to CO2/O2 levels in the blood and that yawning and breathing are controlled by different mechanisms.

So, the question remains - why do we yawn? Dr. Provine suggests that perhaps yawning is like stretching. Yawning and stretching increase blood pressure and heart rate and also flex muscles and joints. Evidence that yawning and stretching may be related comes from the observation that if you try to stifle or prevent a yawn by clenching your jaws shut, the yawn is somewhat "unsatisfying." For some reason, the stretching of jaw and face muscles is necessary for a good yawn.

It is possible that yawns are contagious because at one time in evolutionary history, the yawn served to coordinate the social behavior of a group of animals. When one member of the group yawned to signal an event, all the other members of the group also yawned. Yawns may still be contagious these days because of a leftover response (a "vestigial" response) that is not used anymore. None of this has been proven true and yawns are still one of the mysteries of the mind.

Historical fact, dog lovers look away...

During World War II, Russians used trained dogs strapped with explosives to blow up German tanks by associating the tanks with food. This started off being rather successful as they ended up destroying approximately 25 German tanks using the method. However the tactic was soon discarded as they found a disadvantage, the dogs were more prone to go to the Russian tanks they had been trained on.

Shuttle Landings

The space shuttle lands at a slope 6-7 times steeper than commercial airplanes! Commercial airplanes descend for landing at a "glide slope" of approximately 3 degrees, while the space shuttle glide slope is angled at 20 degrees or more.

The reason for this? Four minutes before touching down, the shuttle is still piloted by computer and moving faster than the speed of sound. As such the shuttle has to perform a manevover known as a "flare" in order to land safely.

Is the Earth getting heavier or lighter?

Is the Earth getting heavier or lighter? After all, we've littered outer space with a lot of space vehicles, satellites and other objects, along with vapor escaping from the atmosphere. However, there's a lot more people and meteorites around nowadays. So which is it?

Definitely heavier, it's believed the Earth gains anywhere from several dozen to several hundred tonnes per day due to meteorites and meteoritic dust, that is 10,000 to 100,000 tonnes a year. Also, mankind has not appreciably altered the mass of the Earth, which is reliably estimated at around 6 sextillion tonnes. The weight of people, incidentally, has not increased the mass of the Earth at all, as we are made up of the things we consume, which are already on Earth (you truly are what you eat).

Timing is everything!

Bargains can be had purely by deciding the correct time to purchase things, a brief guide:

Airline Tickets - (On a Wednesday, approx 21 days before your flight)
Airlines make major pricing changes every week, typically on Tuesday evenings and Wednesday mornings. About 3 weeks from your flight, you'll see plenty of deals out there as airlines scramble to fill seats. Don't wait much longer, she cautions; prices jump significantly from 14 to seven days ahead of departure.

Champagne - (December)
Most people assume that because everyone wants a good bottle of Champagne for New Year's Eve that prices go up during the holidays. But due to fierce competition among the Champagne houses, prices are actually lower during the Christmas holidays than they are at any other time of year.

Electronics & Gadgets - (After new model launches)
When the latest and greatest of a product is released, you'll often see prices drop on what had previously been the best thing out there.

Petrol - (Early Morning)
Most petrol companies adjust their prices between 10am and noon.

Wine - (Early Autumn)
For best selection, you can't beat the harvest season, that is when most vineyards release their latest vintages and all others are heavily discounted.