Life is full of tiny everyday mysteries, most of which we just accept without asking questions. We did the asking for you in this slide show, so sit back and take a moment to learn more about these quirky, quotidian facts of life!
1. Why do we shake hands with people?
The origin of the handshake lies in medieval history. By offering a right hand to a stranger, a hand that could otherwise be used to draw a sword, men were overtly displaying their intentions of peace toward one another. Nowadays, from signing a treaty to settling a bet with friends, "shaking on it" remains a symbolic sign of agreement.
2. Why do airplanes suddenly plunge during thunderstorms?
During normal flight conditions, the lift force produced by an airplane is equal to its weight, so the plane flies at a steady level. Most of the lift is produced by the wings, which are set at a slight angle to the oncoming wind. If the angle increases, the plane produces more lift and will climb, and if the angle decreases, the plane will descend. When a plane flies into stormy conditions, it will often encounter patches of rapidly rising or descending air. As the plane flies into these patches, the angle at which the wings meet the wind changes, causing the plane to suddenly climb or descend.
3. Why do we have bad breath in the mornings?
Almost everybody wakes up with bad breath. The unpleasant smell comes from bacteria living in your mouth. The bacteria are in fact in your mouth day and night, but while you're sleeping, the flow of saliva -- and thus oxygen -- decreases greatly. This allows the anaerobic bacteria to multiply, feeding on leftover food particles and skin cells. The waste product of this process often contains sulfur, and this is what smells so unpleasant.
4. Why do we blush?
When you're embarrassed or ashamed, your body releases a tiny amount of adrenaline. Adrenaline causes blood vessels in your face to dilate, allowing more blood to flow to your cheeks. This causes reddening, or blushing. Sociologically, blushing may be useful as a means of communication, as it can act as a wordless signal. For example, if we blush when we're attracted to someone, we are allowing what's on our minds to be known without having to say a thing.
5. Why do onions make you cry?
When you slice through an onion, you cause a series of chemical reactions to occur within its cells. A gas called propanethiol S-oxide is released into the air and travels upward into your eyes. The gas then reacts with the water in your eyes to form a mild sulfuric acid, which causes itchiness. Your brain reacts by producing more water, or tears, to dilute the irritant and protect your eyes.
6. Why are wedding rings worn on the fourth finger?
There was an ancient belief that a vein, known as the "vena amoris," or "vein of love," ran directly from the fourth finger of the left hand to the heart. It was thought that this direct blood flow to the heart made it the perfect candidate for a wedding ring, as it solidified the union of love. However, in reality the veins running from the fourth finger are no different from those of any other finger, and it seems as if shrewd marketing, hearsay and tradition have designated the fourth finger as the "ring finger."
7. Why do geese fly in a "V" formation?
When geese fly in a flock, they tend to form a "V" shape, with each bird flying slightly higher than the one in front of it. This causes a reduction in wind resistance, making the flock more aerodynamic and allowing those flying at the back of the formation to glide easily. The birds take it in turns to fall to the back, meaning that as a group they are able to fly for longer. Another benefit of the V shape is that every bird is visible and easy to track. For the same reason, fighter pilots use this "squadron" formation.
8. Why do gentlemen prefer blondes?
The science behind what people find attractive remains largely theoretical. However, a consensus emerges among theorists: We are generally attracted to people who are most likely to protect and preserve our genes as a human race. For example, we are more likely to be attracted to a healthy young face than an old diseased one because this increases the chances of producing healthy offspring. Following this theory, it is believed by some that the reason blond hair, which is much rarer than brown or black hair, is deemed more attractive is due to a subconscious human desire for a bigger, and therefore healthier, gene pool.
9. Why are there seven days in a week?
The root of our seven-day week lies in Babylonian mathematics. The Babylonians realized that a lunar cycle, i.e. a month, was 27.25 days long. However, they also realized that the number 28 is a perfect number -- it is the sum of all the numbers that divide into it (1+2+4+7+14 = 28). They therefore designated a month as 28 days long, and eventually chose to split it into four cycles of seven days, giving us our seven-day week.
10. Why is Friday the 13th unlucky?
The number 13 has long been stigmatized. In an ancient Norse myth, a dinner party of 12 is interrupted when a 13th guest crashes the event and kills the god of joy and gladness. Within Christian traditions, too, 13 is an unlucky number to have at a dinner party -- there were 13 people at the Last Supper of Jesus Christ. And to top it all, a correctly tied hangman's noose has 13 knots. Meanwhile, Friday also carries negative connotations. Eve was rumored to have given Adam the apple on Friday, thus bringing about the downfall of mankind. And to make matters worse, many believe Jesus was crucified on a Friday. It is no wonder then, that when the two are combined, Friday the 13th is considered so unlucky that many people decide to stay at home.
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