Why do we yawn?

Like many of us, you probably think that people yawn when they are hungry or tired. Actually, this is not exactly true! After many studies, all scientists do not explain this phenomena the same way.

A whole family happily yawning together

Yawn to make our brain colder

One of those theories is the one of Dean Falk, an anthropologist. He think that we yawn for make our brain colder. Indeed, when we are tired our brain is warmer than its normal temperature. But as a computer, the brain work better when it is not too warm. When we yawn, air go into us by our nostrils and our mouth, making the blood in our head colder, and so our brain colder. It is also a good way to be more concentrated and attentive.

It has been thought that yawning increased the level of oxygen in the body, but studies have shown that is wrong. Indeed, we do not yawn more when we do sport, whereas it is exactly the moment when our body need more oxygen.

Yawn to be under less stress

It allows to relax face muscles and breath deeply. It is by the way recommended to voluntary yawn through the day, especially when you feel stressed, tired or upset.

Yawn is contagious

Scientists discovered that this phenomena concerns only humans and primates, but when you see someone yawn, you will probably yawn too. Maybe even just by reading this text, you are likely to yawn yourselves. However, some people are less susceptible to contagious yawning than others. It depends on our capability of empathy. The more you demonstrate empathy, the more you are susceptible to contagious yawning.

You can check how susceptible to contagious yawning you are by watching this video!

Did you know?

On average, we yawn around 240 000 time in our lives. We yawn even as fetuses, in our mother's wombs. Moreover, all mammals yawn.

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Why are rugby balls egg-shaped?

It could be surprising but first rugby balls were round. Rugby balls have become egg-shaped 50 years later!

An example of beautiful egg-shaped rugby ball

How was the rugby invented?

In 1823, while a football match at the college of Rugby, a town in United Kingdom close to Birmingham, William Webb Ellis, one of the students, grabbed the ball with his hands to drive it into the opponent goal.

The ball provided from the Rugby's shoemaker, William Gilbert who used inflated pork bladders to create it. The ball was still round.

What is the point of an egg-shaped ball?

In 1840, William Gilbert invented egg-shaped balls to avoid that slipped through rugby player's hands, especially when it rained, by wrapping inflated pork bladders with leather.

How the Gilbert's ball became the reference?

However, in 1846, the rugby game rules are officially determined, form and size of the ball are not specified. We have to wait until 1877, to see the egg-shaped ball officially adopted by the Rugby Football Union. Gilbert’s ball was exported firstly to Australia, New Zealand and South Africa, then all over the world. It even became the regulatory standard.

In 1930, rugby balls were changed again to make it more handy for players and more impressive for spectators. Indeed, the more the ball is egg-shaped, the less its trajectory can be calculated.

So now, the length of a rugby ball should be between 280mm to 300mm, the length circumference 740mm to 770mm and the width circumference is 580mm to 620mm. But there are also different sizes for children and women.

Gilbert' s ball is still the reference of rugby ball, it is even use for international competition like the World Cup.

Did you know?

Rugby has only featured in the Olympics four times: 1900, 1908, 1920 and 1924, and US Olympic rugby team is the most successful (won in both 1920 and 1924).

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Why do we have different time zones around the world?

If you have already traveled, you probably know that the time is different according the country you are in. You can even save time by travelling!

For example: if your flight leaves Paris at 10am, he will be in New York at 11am, local time. However, your flight would have lasted in reality 7 hours and have crossed 6 different time zones.

Different time according their own time zone

Until 1891, each town determined its own time according sun’s position. But when industrialization appeared, this method became obsolete. Early in the 20^th century, coordinated universal time was created. From the point of reference of Greenwich, a London’s suburb, 24 different time zones which equally split Earth were created.

Let's check them here:

A world time zone map

Source: timeanddate.com 

Each state has to choose its own according sun’s position and other criteria mentioned below!

Historical reasons

During World War II, Germany imposed its time to France, then to show his support to Nazi, General Franco changed Spain’s time zone. To be coordinated with its ally, United Kingdom also changed its time zone. After the war, London get back its original time zone, but both France and Spain kept the German’s time zone. That is why there is still a time lag of 1 hour between those countries.

Economic reasons

The International Date Line crosses Pacific Ocean and creates some weird situations. For example, the Saoma islands which were aligned with United States’ time zone in 1894, changed to the one of Australia and China because they had not enough days in common with those both last countries to do business with them.

Political reasons

5 time zones cross China, but the government chose the one of Beijing as reference. It is communists’ wishes which are in power since 1946.

Environmental reasons

Time change has been created to saves energy. But for some countries, it is still confused. In Australia, lands are free to decide doing time change or not.

Thus, there is not only 24 time zones through the world in reality but 37, and even 43 when we take into account time change. But when time zones didn’t exist, there were around 300 different time zones, just through the North of America!

Finally, we are making progress :)

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Why is smoking addictive?

Before giving explanations, let's start with some depressing figures!

An addict person smoking his cigarette

• “Tobacco kills up to half of its users”
• “Tobacco kills around 6 million people each year. More than 5 million of those deaths are the result of direct tobacco use while more than 600 000 are the result of non-smokers being exposed to second-hand smoke”. (World Health Organisation, 2015)

Now you're warned, so we can move on!

Firstly you have to know that there are two main kind of addiction: physical and psychological.

The physical addiction comes from the nicotine contained in the tobacco. This molecule is able to imitate a natural neurotransmitter named acetylcholine by biding itself to dopaminergic receptors. Once those receptors activated, a hormone named dopamine is released and create a similar feeling of pleasure as we feel when we are doing sport or when we are laughing, for example.

When a smoker quits smoking, his body needs its dose of nicotine to satisfy this feeling, otherwise, withdrawal symptoms will appear such as dizziness, insomnia, constipation, cough, hunger and temper.

Some animal experimentations show that the nicotine is not the only one cigarette component which create addiction. The cigarette smoke contains more than 4000 different substances. Two of them are able to block molecules in charge of degrading dopamine contained in the blood. So the more dopamine stays in the blood, the more feeling of pleasure will last. And we don’t even know yet how many of the other substances create addiction too…

The psychological addiction consists in assimilate the cigarette as a solution to fight against stress, sadness, boredom, anger etc. Moreover, a smoker’s brain positively associates the cigarette with all he lives so smoking become a habit and even a reflex. That is why for example, some smokers can’t drink their coffee or finish a good meal without smoking.

For further information and advice to stop smoking, you can read the report published by Action on Smoking on Health organisation in January 2016 ;)

Do you know benefits of quitting smoking?

• After 48 hours : Senses of taste and smell are improving
• After between 2 weeks and 3 months: The functioning of the lungs can be improved up to 30%
• After 1 year: The risk of cardiovascular disease is reduced by half
• After 5 years: The risk of mouth, lung, throat and esophageal cancers is reduced by half
• After 10 years: The risk of a lung cancer is similar to the one of a non-smoker

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Why do we use QWERTY keyboards?

Take a moment to observe your keyboard. The letters seem to be randomly arranged but it is not actually truth!

The famous QWERTY keyboard

In the USA, through the standardization period, there was a huge competition to create a single typewriter standard.

In 1873, the first typewriter is commercialized by Remington & Sons. It was designed by Christopher Sholes, Wisconsin senator and sometime newspaper editor, and it already used the QWERTY keyboard.

The QWERTY keyboard's ancestor

Indeed, his original prototype used alphabetical order, but the bars was colliding with each other and jamming because most common letters were close. So Sholes arranged them in another way, by considering frequency and combinations of letters to prevent key clashed. QWERTY keyboard was adopted as the standard not only for English, but also for most European languages.

In 1936, Dr August Dvorak and his brother-in-law have patented the DVORAK keyboard. Its layout is more efficient because it requires less fingers movement than QWERTY, so the typing speed is better. It comes from the fact that commonly used vowels and consonants are in the middle row. That allows to type around 400 words in English language just in that row, as compared to about 100 words on QWERTY. But this design was never adopted because people had already learned how to use the inefficient QWERTY keyboard at fast speeds and had disagreed to learn a new one.

What about the AZERTY keyboard?

France’s 100 years old AZERTY keyboard (the equivalent of the English language QWERTY) will probably be reconfigured because the government ruled that it encourages bad writing.

Indeed, you can see on the ministry website that "today it is practically impossible to write French correctly using a keyboard that has been bought in France". (LOL)

More surprisingly, AFNOR group recorded that "certain European countries like Germany and Spain respect French writing better than the French are able to because their keyboards permit it!" (LOLOL)

A man struggling with his keyboard 

The main problem identified by the culture ministry is the difficulty for French writers to use "certain accented characters - and especially in upper-case".

So the Culture ministry has commissioned to AFNOR to elaborate by the summer a new norm which match with its expectations. 

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Why do mosquito bites itch?

Everybody knows this horrible feeling which can make crazy! A red bump on your skin which persistently itch you!

A damn mosquito biting a poor human 

As you probably know, mosquito season starts slowly in the spring, peak in the summer and tapers off when the weather gets cold. Mosquito is the most active a few hours before sunrise and a few hours after sundown, be careful!

Both male and female mosquito feed on flower nectar. Only female mosquito bite humans, and she does only because she needs the protein in our blood to produce her eggs.

So female mosquito pierces your upper skin with her proboscis, which is a mouthpart kind of a straw. That allows her to drink fluids. After that, she looks for a blood vessel and when she finds one, she releases saliva into. Her saliva contains an anti-coagulant that keeps the blood flowing. It allows her to drink the blood quickly and avoids that her proboscis get blocked.

As a response of the presence of her saliva, your body will produce antibodies called histamine to fight it. When histamine reaches the area of skin where the mosquito bit you, it causes a swelling of your blood vessels. That is why you usually see a red bump, called wheal, appears.

When the blood vessels swell, it also cause nerves to become irritated. Your body comes out this nerve irritation as an itching sensation.

You have to know that scratching the wheal only make this worse because it causes more irritation, so your body thinks it needs more histamine to fight the foreign substance. So the more you scratch, the more it will, the itchier it will get, and the longer it will last.

How to stop mosquito bites from itching?

Using things you can find in your kitchen

• -          Cut a lemon into pieces and rub gently on the affected area
• -          Apply some honey to the red bump
• -          Apply apple vinegar to the bite
• -          Mix one tablespoon of baking soda with one pint of warm water and rub gently on the affected area

Using things you can find in your bathroom

• -          Clean the bite area with rubbing alcohol
• -          Apply toothpaste on the bite
• -          Rub a bar of wet soap and wait few hours before washing off

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Why do dogs wag their tails ?

The most common idea is that a wagging tail means that the dog is happy. Actually, this is no exactly true!

Indeed, dogs use their tails to communicate strong emotions. It could be annoyance, anger as well as hapiness. So by a wagging tail, a dog can try to convey "Please, pet me!" or "Don't even try to come closer, idiot".

As their language is mostly based on the position and the motion of their tails, we have to observe it to get their emotional state.
Basically, a relaxed dog will hold his tail in its natural position, a nervous dog will hold his tail lower than its natural position, and if a dog is scared, he will truck his tail between his legs.

But it is more complicated than that because it also depends on what breed the dog is. For example, when a husky curves his tail over his back, that means he is relaxed while for a labrador, that reveals an aroused state.

As dog's eyes are more sensitive to movements than details or colors, the speed of the wag reveals how excited the dog is.

Moreover, it appears that when dogs feel generally positive, their tails wag more to the right side and conversely, when they feel negative, their wagging tail will be more to the left side.

Besides observing their tails, you will be much better off looking at their whole body. So stiffened muscles, dilated pupils or ears pinned back are signs that you should back off!

It is also interesting to know that dogs wag their tails only when other animals or humans are around. When they are alone, they don't need to communicate so they don't wag their tail, in the same way people don't talk alone (even if you do, I will not judge you).

To conclude, be aware of dog's body language or you could be bitten!

3 dogs happily wagging their tails

Did you know ?

A dog could understand between 250 and 300 words. Let's start to train yours!

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Why is the sky blue ?

Every day, when we go outside, we can see that the sky is blue. But, why blue ?

The blue sky you would like to see everyday

To summarize, the sunlight is made up of all colors of the rainbow. Those colors are defined by a specific wavelength, each color has its own.

When all colors are mixed, it seems white. But it is also possible to break them down to observe colors separately.

Our atmosphere is composed of an incredible number of molecules, dust and minuscule water droplets. Sunlight interacts with our atmosphere, without him, the sky would be black. It is the case in the moon, where stars, Earth and sun are visible in a black sky.

All colors don't interact in the same way with our atmosphere, according its wavelength. The shortest wavelength (blue color) is the most scattered by our atmosphere. That is why the sky is blue.

How blue the sky is depends on the air quality. As dust and water droplets don't scatter the sunlight, the blue will be mixed with white light when the air quality is polluted or humid. On the contrary, in mountainous areas and during sunny days, the sky will be deep blue because of the really pure air quality.

In the evening, when the sun is low, the sunlight is slanting and wavelengths have to cross a bigger atmosphere surface. In this case, wavelengths corresponding to red and orange colors are the most scattered and some of the blue light is scattered away. That is why sunsets are red and orange.

The blue sky mystery is now solved!

You can also have a look at this video published by Brain Stuff - HowStuffWorks on Youtube for further information.

Bonus: Why is the ocean blue ?

When sunlight hits the ocean, the water absorbs long wavelength (red color) and very short wavelength (purple) like a filter, and blue light is absorbed the last. So the light that we see is mostly made up of blue wavelengths.

Water in a glass is clear because there aren't enough water molecules to absorb the light.

I hope you enjoyed this article!

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