British author Harry Oliver has just released in the U.S. "Black Cats & Four-Leaf Clovers" (Perigee), a book that explores the origins of superstitions and old wives' tales from around the world.
Black cats: Are they really unlucky?
Today, AOL News delves into 13 of Oliver's weirdest and wackiest superstitions and how they came to be ...
1. Don't Walk Under a Ladder: After researching this superstition for a year at the British Library in London, Oliver says the belief's most-cited origin points to "a ladder forming a triangle with the wall and the ground, suggesting the Holy Trinity." Apparently, walking through that triangle would show disrespect to the Trinity and therefore bring bad luck. Another possible (and much simpler) origin: Where there's a ladder, there's usually someone working on top and walking underneath could lead to all sorts of cartoonish accidents, like a hammer falling on someone's head.
2. Black Cats Bring Bad Luck: Oliver says black cats are notoriously linked to witchcraft, which is why some people think they're unlucky. However, there are two sides to this one. Allegedly, if a cat crosses your path it's considered unlucky, but if a cat walks toward you, it's a good omen. Should the first scenario happen, though, Oliver says the "only way to avert the back luck is to spit."
3. Never Light Three Cigarettes With the Same Match: This superstition originated in military circles and dates back to those long nights in the trenches during World War I. "If three soldiers smoked at once, enemy snipers would easily detect them," says Oliver. "If they used the same match to light all three cigarettes, snipers would notice the match burning after the first one and would have enough time to load guns, aim and fire at the unlucky third smoker."
4. Carrots Are Good for Your Eyesight: Though some studies have shown that the vitamin A in carrots is good for the eyes, the vegetable alone isn't enough to spark 20/20 vision. Oliver says this old wives' tale -- or smart attempt by parents to get their children to eat their veggies -- originated as a myth during World War II. "That's when British pilots where rumored to be eating enormous amounts of carrots to see from high altitudes and in the dark. The rumor was widely spread to throw the public off from the fact that radar had been invented and was being used against the enemy," he says.
5. Cross Your Fingers: If you look hard enough, you can see this superstition has religious roots. Oliver says that crossing your fingers is a type of holy protection because the two overlapping fingers form a "slanted cross." This "good luck" ritual varies around the globe -- in Switzerland, people fold their thumbs in and wrap their other fingers around them instead of the standard index-and-middle-finger combination.
6. Don't Open an Umbrella in The House: The origins of this belief are simple -- what's designed for the outdoors should remain outside. While today's version of the old umbrella superstition is said to simply bring "bad luck," Oliver says there used to be a much darker cloud hanging over the belief in ancient times. "In earlier versions, opening an umbrella inside was an omen of death," he explains.
7. Always Have Something in the Oven: This old Jewish superstition could be considered "family friendly." Supposedly, leaving an oven empty will cause one's family to go hungry in the future. To avoid famine, it's enough to leave a baking sheet or a pan in the oven at all times as a precaution. "This belief is linked to ancient rituals in which food was left for household gods in order to ensure protection of the family," Oliver explains.
8. Wear Underwear Inside Out: When having a bad day, superstition suggests that turning your underwear inside out can make it all better. Oliver isn't quite sure where this odd belief came from, but we wouldn't be surprised if originated on a wild college campus somewhere, perhaps during a post-party "walk of shame."
9. Kiss a Mustachioed Man, End Up a Spinster: There are more superstitions revolving around marriage than we can count, and that includes "kissing a dark-skinned man at a wedding." If a woman does this, she'll supposedly get a marriage proposal shortly thereafter. But watch who you're smooching, ladies. If a woman kisses a man with a mustache and finds a stray hair on her lip after, she's destined to be a spinster.
10. Don't Praise Babies in China: If you're in China and you come across an adorable newborn baby, do not under any circumstances compliment the little one. In China, it's considered "unlucky" to praise babies because it "attracts the attention of ghosts and demons." Instead, Oliver says it's customary to "talk badly about babies" to keep evil entities away. Rather than getting upset, parents are told to convert those insults into praise quietly in their heads.
11. Don't Chew Gum at Night in Turkey: Even if your breath stinks, popping in a stick of gum after dinner in Turkey is a bad idea. "It's thought that if you're chewing gum at night in Turkey, you're actually chewing the flesh of the dead," says Oliver. Gross.
12. Lucky Four-Leaf Clovers: Because of how scarce four-leaf clovers really are, just finding one in a field is lucky in and of itself. Oliver says the rare leaf represents everything one could possibly desire in life: "wealth, fame, love and health."
Unlucky 13. The number 13 -- and Friday the 13th -- are considered unfortunate in many places, and the reasons go back to the Bible. Remember, Jesus had 13 disciples until one of them -- Judas -- betrayed him.
Although some superstitions have ancient roots, skeptic Joe Nickell thinks it's all a bunch of baloney.
Nickell, senior researcher at the Center for Inquiry in Amherst, N.Y., says superstitions aren't the least bit grounded in scientific evidence, so therefore, they can't be taken seriously.
"Superstitions work backwards from the way science works. People start out with a belief and then look for any little bit of evidence that may support it. In science, we start with evidence first and then draw a belief," he explains.
Because superstitious folks "select" their own evidence -- like when you see a black cat and then choose to harp on the worst part of your day -- Nickell believes superstitions are nothing but "a perversion of evidence."
In all his time as a skeptic, he's never once found a superstition grounded in "cause and effect" -- nothing that proves that certain actions cause "good" or "bad" luck.
And boy, has he tried.
From time to time, Nickell and his staff at the Center for Inquiry hold "Superstition Bashes" on Friday the 13th where they test out every common superstition to prove or disprove them.
They run through a "Superstition Obstacle Course" where they walk under ladders, open an umbrella indoors and even break a mirror into tiny pieces.
"We've never found any correlation between those events and alleged 'bad' luck afterward," Nickell says. "Superstitions are bad thinking. There's nothing rational about them, no matter where they come from. They're just a belief for which no scientific proof exists."