Well, actually...

American economist Thomas Sowell famously said, "Endless repetition does not make something true."

I used to run into examples of this principle all the time when I was a teacher -- widely-accepted, and rarely-questioned, incorrect statements that still somehow classified as "stuff everyone knows."  One that immediately pops to mind, and that I had to debunk just about every year, was that daddy-longlegs (also called "harvestmen"), those familiar arachnids in just about everyone's cellars and attics, are "actually deadly poisonous but their fangs are too small to pierce human skin."  There's no truth to this whatsoever; they don't even have poison glands, and their chelicerae ("fangs") aren't hollow like a spider's.  They are, in fact, entirely harmless.

In the interest of making at least a minuscule inroad into ridding the public consciousness of some of the most egregious of these, today I present to you an extremely incomplete list of commonly-accepted falsehoods that have spread by word-of-mouth and now become ubiquitous.

The Latest Gossip by François Brunery (ca. 1900) [Image is in the Public Domain]

How many of these have you heard -- and how many did you believe?

1. Turkey meat is not high in the amino acid tryptophan -- or at least, no higher than any other protein source.  Tryptophan isn't why you're sleepy after Thanksgiving dinner; it's much more likely to be overeating, consumption of wine, and the general energetic letdown we all experience after a big event.
2. The pronunciation of words with an s, c, or z in Castilian Spanish, where the usual sibilant is sometimes replaced by a coronal fricative /θ/ (usually written in English as "th"), did not occur because there was a king who lisped and all of his fawning courtiers wanted to make him feel better by imitating him.  In fact, the phonetic shift seems to have been gradual, spreading across the region in the sixteenth and seventeenth centuries, and may have been driven by the need to differentiate words (like siento "I feel" and ciento "one hundred") that otherwise would have been pronounced identically.
3. The seasons are not caused by the Earth being closer to the Sun in summer; in fact, during the Northern Hemisphere's summer the Earth is actually farther away from the Sun than it is in winter.  The seasonal changes in temperature are almost all due to the twenty-three degree axial tilt of the Earth.  Nor is it true, as I've seen claimed in some hyper-religious posts, that "if the Earth was only a few feet closer or farther away from the Sun than it is, it would be boiled or frozen" -- so, goes the claim, God placed the Earth in exactly the right spot, and can I get a hallelujah?  In fact, the Earth's orbit is elliptical enough that it's about five million kilometers closer to the Sun at perihelion than it is at aphelion, and we neither roast at one nor are flash-frozen at the other.  So you may well think that God directs the universe, but if that's your proof, you might want to reconsider.
4. Despite what you may have learned from such historical documents as Hagar the Horrible, Vikings did not go into battle wearing horned helmets.  Horns (or antlers) on headgear would have been a serious hindrance to fighting, and the Vikings were way smarter than to do anything that slowed down the highly lucrative plunder and pillage.  Extant horned or antlered headgear seems to have been mostly ceremonial in use, probably by shamans to invoke animal spirits.
5. Lemmings don't engage in mass suicide by diving off cliffs or swimming out into lakes and drowning when they get overcrowded.  This complete fabrication became a popular belief because of a 1958 Disney movie called White Wilderness which depicted it happening; it turns out that the scene was filmed using lemmings that had been purchased from Inuit children for a quarter a piece, and the unfortunate rodents were shoved off a cliff repeatedly to get enough footage for the film.
6. Albert Einstein did not fail high school mathematics; in fact, by fifteen he had mastered both differential and integral calculus.  He did fail his first entrance exam for the Swiss Federal Polytechnic School, but this was probably because he was two years younger than most of the rest of the students who attempted it.  (He did really well on the science and math portions.)  He did, however, as an adult say to a frustrated physics student, "Do not worry about your difficulties with mathematics; I can assure you that mine are far worse," but this was more overly modest of the great man than it was accurate.
7. Apologies to Pink Floyd, but there is no permanently dark side of the Moon.  Because the Moon is tidally locked, the same side faces the Earth all the time; put another way, its periods of rotation and revolution are the same.  Any given spot on the Moon is (like the Earth) in sunlight at some times and in darkness at others, and what length of time it spends in each depends on latitude and where the Moon is in its orbit.
8. There is absolutely no mention that Mary Magdalene in the Bible was a prostitute (reformed or otherwise), nor that she was the same person as the unnamed woman who anointed Jesus's feet in Luke chapter 7, or the adulterer whom Jesus saved from being stoned in John chapter 8.
9. People don't "use only ten percent of their brain."  There's no way evolution would have favored the production of a huge, complex organ like the brain, and then we only ever get to use ten percent of it.  In fact, over the course of your life you use pretty much the whole thing, even if at any given time only a fraction of the neurons are firing.  If you could get your whole brain to fire at once, the result wouldn't be superpowers, it'd be a body-wide and probably fatal seizure.
10. Sharks can, in fact, get cancer.  The mistaken belief that they never do was popularized in a book by William Lane and Linda Comac with the creative title Sharks Don't Get Cancer, and was used as part of a campaign to sell shark cartilage capsules as a cure-all.
11. Speaking of fish, three South American fish with scary reputations are pretty close to harmless.  Piranhas rarely attack humans, and while they'll bite, there are no recorded incidents of people (or other large animals) being "skeletonized" by them, Vashta Nerada-style.  The strong-jawed pacu fish do not wait for male skinnydippers and bite off their testicles; that claim started as a joke when a biologist commented that the pacu has grinding teeth capable of chewing (tree) nuts.  Last, the infamous candiru catfish of the Amazon does not swim up people's urethras and get lodged there.  They parasitize other fish, hooking onto the gills, but (like most parasites) are very host-specific.  The likelihood of having a candiru go up your urethra, even if you were urinating while submerged in a stream where candiru live, is (according to American marine biologist Stephen Spotte) "about the same as being struck by lightning while simultaneously being eaten by a shark."
12. Catherine the Great, empress of Russia in the eighteenth century, did not die while attempting to have sex with a horse.  Admittedly, she was apparently very fond of sex, but with people.  She died at age 67 of what was clearly a stroke.  The rumor started because of some attempts to discredit her (and Russians in general) published in Germany, and there's no truth to it whatsoever.
13. Cracking your knuckles doesn't cause arthritis.  Like any repetitive motion, it can cause inflammation if you do it compulsively, but done occasionally, it's completely harmless.
14. The word crap did not originate as back-formation from the name of nineteenth-century businessman Thomas Crapper, who improved the design of (but did not invent) the flush toilet.  Crap traces its origins to medieval Latin; and Crapper's name is actually an altered version of cropper, meaning farmer.
15. Somewhat along the same lines: fuck is not an acronym for either "For Unlawful Carnal Knowledge" or "Fornication Under Consent of the King."  The former is supposedly what was written above the heads of adulterers confined to the stocks; the latter, what was allegedly stamped on marriage documents, giving a couple the right to lawfully do the deed.  Neither is even close to true.  Nor does "fuck you" originate as a corruption of "pluck yew," supposedly an expression meaning to draw a longbow made of yew-wood.  And while we're at it, the middle finger as a sign of contempt has nothing to do with archery, either, despite the story that Welsh bowmen captured by the English supposedly had their index fingers cut off so they couldn't draw, but showed those Silly English Types-uh by drawing their bows using only their middle fingers.  In fact, "fuck" is a good old Indo-European root with a very long history (from the reconstructed word *peuk, meaning "to prick" or "to jab", and therefore a cognate to words like "poke," "point," "punch," and "pugnacious").  The middle finger has been used as a rude gesture at least since the time of the ancient Greeks, where it meant -- as it still does today -- "fuck you" or "stick it up your ass."

So there you have it.  Only a drop in the bucket, I'm quite sure -- as James Randi put it, the reason we need debunkers is because there's so much bunk out there.  But perhaps this cleared up a few things?

One can only hope.

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