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No one really knows why we yawn, maybe it has some useful purpose - it does allow us to take in more oxygen and expel carbon dioxide, it also increases heart rate a bit. Yawning could keep the brain aroused in situations where sleep is unwanted - like first period maths lessons or 9 am meetings.

Why we yawn when we see others yawning has baffled scientists for ages and a number of suggestions have been put forward to explain this phenomenon. What we do know is that yawning is an involuntary action - our brain does it without us thinking about it. Even very young babies yawn, showing that it's a built in action (chimps do it too by the way). Just thinking about yawning can trigger the bit of the brain that causes a yawn and, chances are when reading this you will end up yawning at least once!

My favorite explanation for why we yawn when we see others yawn is that it's a throw back to the days of our ancestors when we lived in groups. Yawning could have been a sign that it was time for the group to go to sleep or change activities. It's important, after all, that all group members were ready to do the same thing at the same time.

It appears that there is some relationship between yawning and our ability to 'put ourselves in other peoples shoes'. Not all people can 'catch' a yawn when they see someone else yawning and these people also appear to be less able to understand things from other people's points of view. This is an important skill for being able to get along with others - it lets you sympathize with them and understand how they feel. So yawning is maybe just a by-product of us being able to use our own experience to understand how others are feeling. Maybe it's due to accidental 'cross-wiring' in the brain that occurs when the 'thinking about others' part of the brain is stimulated.

Another theory is that yawning is a way of baring our teeth at potential enemies - something along the lines of "I may be sleepy but you'd be stupid to attack me, just look at my vicious teeth!". Could it be that the reason a yawn is contagious is that a whole group of sleepy primates showing teeth together is less likely to be the target of a predator?

Food and drink
Why does asparagus make wee smell?
Why do beans make you fart?
Why does corn come out like it went in?
How does jello work?
How do they get the fortune in the cookie?
What are the crystals in cold vodka?

Health and disease
Can getting cold give you a cold?
What causes a hangover?
Why does my eye twitch?
Why are allergies increasing?
Do we age in space?

Human nature
Why are horror films scary?
Do dogs find things funny?
Why does an itch, itch?
Why do men have nipples?
Why do papercuts hurt?
Why do we sneeze?
Will my eyes fly out if I sneeze?
What causes sneezing fits?
How does stomach acid work?
Why do we like to eat different things?
Is tongue rolling hereditary?
Why is yawning contagious?
Why does poo smell?

Animal kingdom
Do animals suffer from allergies?
Do badgers cough?
Can you whistle for a bat?
Why can bumblebees fly?
Why don't mice like cheese?
Why is chicken pox called chicken pox?
Can chocolate kill dogs?
Why does a bag of water repel flies?
Do hedgehogs like milk?
Why do you never see baby pigeons?
Why are there no tricoloured cats?
Why do some cats have extra toes?
How do fish end up in volcanic lakes?

The laws of physics
Why is the sky blue?
How come boiling water becomes ice on a cold day?
How does gravity work?
Why does boiling water make a noise?
Why does hot water freeze faster than cold?
What causes rainbows?
Why are clouds white?
Why does helium make your voice squeaky?
Why does the horizon moon look so big?

Bits and pieces
Why are there dimples in golf balls?
Why do Polo mints have holes?
Why does spaghetti break into three pieces?
Why are kitchen sponges so smelly?
How do they get the stripes in toothpaste?

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