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12 “fun facts” that fall apart when you check the original source

The Great Wall from space, the tongue map, Viking horns: 12 popular facts traced back to where they started, and to the source that sinks them.

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The Great Wall of China winding over green mountain ridges

Photo: William Olivieri / Unsplash

Most false "fun facts" don't come from nowhere. They come from a specific place: a newspaper cartoon, an opera's creative director, a biography that took liberties, a graph redrawn carelessly. Follow the chain back and you usually find the moment it went wrong, and a better source sitting right next to it.

For each of the twelve below: what people say, where it started, and the strongest source against it. Every link is in the Sources at the end.

1. The Great Wall of China is visible from space

The version that stuck: it's the only human-made thing you can see from the Moon. Scientific American points to a 1932 Ripley's Believe It or Not! cartoon calling the wall "the only one that would be visible to the human eye from the moon".

NASA's caption for a 2004 photo taken from the International Space Station by Leroy Chiao is blunt: the wall "isn't visible from the moon" and is "difficult or impossible to see from Earth orbit without the high-powered lenses used for this photo". China's first astronaut, Yang Liwei, said after his 2003 flight that he hadn't seen it. Some astronauts, Eugene Cernan and Ed Lu among them, say they have seen it from low orbit, but only in certain light, when a low sun makes the wall cast long shadows. From the Moon? Never.

2. Different parts of your tongue taste different flavours

The tongue map, with sweet at the tip and bitter at the back, sat in textbooks for decades. A 2022 review by Charles Spence at Oxford tells how it got there. In 1901 David Hänig measured taste thresholds around the edge of the tongue and found small differences in sensitivity. In 1942 the psychologist Edwin Boring replotted those numbers in a textbook, and, as the taste researcher Linda Bartoshuk later pointed out, his graph gave no way to tell how big the differences were. Later authors turned them into territories.

The biology says otherwise. A 2006 review in Nature by Chandrashekar and colleagues states in a figure caption that "responsiveness to the five basic modalities — bitter, sour, sweet, salty and umami — is present in all areas of the tongue." Spence's review calls it "the now discredited tongue map", while adding that small differences in sensitivity across the mouth are real.

3. Vikings wore horned helmets

This one has a date and an address: Bayreuth, 1876, the first production of Wagner's Ring cycle there. According to the World-Tree Project, based at University College Cork, Carl Doepler, the production's creative director, chose to put horns on the helmets.

Archaeology gives the horns a much older owner. The National Museum of Denmark says the horned helmets sacrificed in a bog near Veksø "were not meant for warriors": they were part of a priestly costume, used in religious rituals. A 2021 study in Praehistorische Zeitschrift radiocarbon-dated glue on the horns, and Popular Science's report on it puts their last use around 950 BC. That's the Bronze Age, not the Viking Age. The Gjermundbu helmet from Norway, one of the few complete Viking helmets ever found, has no horns at all.

4. We only use 10% of our brains

William James wrote in Science in 1907 that "we are making use of only a small part of our possible mental and physical resources". He gave no number. The number is attached to his name in a much-read place: Lowell Thomas's biographical sketch at the front of Dale Carnegie's How to Win Friends and Influence People (1936), which says "Professor William James of Harvard used to say that the average person develops only 10 percent of his latent mental ability."

In Scientific American in 2008, neurologists from Johns Hopkins and the Mayo Clinic took it apart. The brain is about 3% of body weight and uses about 20% of the body's energy, a strange budget for an organ that's 90% idle. Imaging shows most regions active over a 24-hour period. As the Mayo Clinic's John Henley put it: "Evidence would show over a day you use 100 percent of the brain."

5. Einstein failed maths

According to his biographer Walter Isaacson, writing in Time, the claim even made the Ripley's Believe It or Not! newspaper column. In 1935 a rabbi in Princeton showed Einstein a clipping headlined "Greatest living mathematician failed in mathematics." Einstein laughed and answered: "I never failed in mathematics. Before I was fifteen I had mastered differential and integral calculus."

According to Isaacson, in primary school he was at the top of his class and "far above the school requirements" in maths.

6. Toilets flush the other way in the southern hemisphere

This one is half true, which is why it lasts. The Coriolis effect is real and shapes large weather systems. In 1962 Ascher Shapiro opened a paper in Nature with: "Perennially one hears controversy regarding the direction of the vortex in the drain of the bath-tub or the kitchen sink."

Shapiro at MIT and a team in the southern hemisphere (Trefethen and colleagues, Nature, 1965) did find the effect: counter-clockwise in the north, clockwise in the south. But only in tanks set up so that every other influence was kept small. The physics FAQ hosted by DESY explains why: at bathtub scale the effect is "VERY weak", and seeing it takes almost perfectly still water with no thermal currents or vibration, conditions "never occurring in the typical home". For toilets it's blunter: the water "rotates in the direction in which the pipe points". Real effect, wrong scale.

7. Marie Antoinette said "Let them eat cake"

The line comes from Jean-Jacques Rousseau's Confessions, Book VI. In English translation, Rousseau recalls "the thoughtless saying of a great princess, who, on being informed that the country people had no bread, replied, 'Then let them eat pastry!'" In the French original it's Qu'ils mangent de la brioche. He never says who the princess was.

He can't have meant Marie Antoinette. The scene sits in the year he spent as a tutor to M. Mably's children in Lyon, which by his own account came before he arrived in Paris in the autumn of 1741. According to the Palace of Versailles, she was born in Vienna on 2 November 1755. The anecdote is older than she is.

8. Lemmings jump off cliffs in mass suicide

Disney's White Wilderness (1958) showed lemmings hurling themselves into the sea. According to the Alaska Department of Fish and Game, the scenes were shot in Alberta, a landlocked province, in an area with no native lemmings. The animals were reportedly bought from Inuit children in Manitoba and filmed on a snow-covered, lazy-Susan-style turntable. The "sea" was a river, cropped tight. The same article cites a 1983 investigation by a CBC producer, Brian Vallee, which found the scenes were faked, and says the lemmings were thrown off the cliff by the filmmakers.

Real lemmings are less cinematic: when food runs short they spread out, sometimes cross water, and some drown. That's dispersal, not suicide.

9. Listening to Mozart makes babies smarter

The study behind it wasn't about babies: in 1993 Rauscher, Shaw and Ky reported in Nature that college students did better on a spatial task after ten minutes of Mozart. By January 1998 the Governor of Georgia, Zell Miller, was asking the state legislature for $105,000 to give every baby born in the state a cassette or CD of classical music, according to Connecticut's Office of Legislative Research. In the end Sony offered to provide the recordings free.

Then came the replications. A 1999 meta-analysis in Nature by Christopher Chabris found that any effect was small and came entirely from one specific type of task. A 2010 meta-analysis from the University of Vienna, pooling about 40 studies and more than 3,000 participants, found "no support" for spatial gains specifically due to listening to Mozart. Play Mozart because it's Mozart.

10. Columbus proved the Earth was round

The story goes that learned men in Salamanca warned Columbus he'd sail off the edge. The scene people picture is in Washington Irving's A History of the Life and Voyages of Christopher Columbus (1828). In Irving's dramatised council of Salamanca, "to his simplest proposition, the spherical form of the earth, were opposed figurative texts of scripture."

Educated Europeans had known the Earth was a sphere for centuries by then. Take De sphaera, written in the early 13th century by Johannes de Sacrobosco, a scholar at the University of Paris. The University of Edinburgh's entry for its 14th-century copy calls it probably the most successful astronomy textbook of its time, notes that it "describes the Earth as a sphere", and says it survives in hundreds of manuscript copies.

11. Ostriches bury their heads in the sand

The original source is nearly two thousand years old, and it doesn't say sand. Pliny the Elder's Natural History (Book X, chapter 1) mocks the ostrich's "stupidity": the birds "imagine, when they have thrust their head and neck into a bush, that the whole of the body is concealed." Somewhere along the way the bush became sand.

The San Diego Zoo explains what people probably saw. When an ostrich can't escape, it "flops to the ground and remains still, with its head and neck flat on the ground in front of it," and from a distance the pale head and neck blend into the soil.

12. Nero fiddled while Rome burned

The ancient sources disagree with each other. Suetonius says Nero watched the fire of AD 64 from the tower of Maecenas and sang the whole "Sack of Ilium" in his stage costume. Tacitus says Nero was staying at Antium at the time and didn't return to Rome until the fire was nearing his house. He mentions the singing only as a story that "had spread".

One of the two main sources puts him out of town, and the singing is a story one told as fact and the other flagged as hearsay. Neither mentions a fiddle.

How to check a "fun fact" yourself

  • Find the oldest version, not the most repeated one. If the trail ends in a cartoon, an opera or a film, you've learned something.
  • Read the source you're pointed to. James never gave a percentage. Rousseau never named a queen. Pliny never said sand. In each case, opening the book was enough.
  • Prefer whoever measured. A Nature paper, a museum that holds the object, an agency that took the photo. A list article citing another list article isn't a source.

FactShot is a deck of twelve cards a day for iPhone and iPad. Every card names the reference it came from, next to the explanation. Naming a source isn't reading it, though, and as this list shows, reading is the step that counts. The facts come with a verified source; answers from the app's AI don't. There's no Android or web version; on anything else, the habits above do the job.

Frequently asked questions

Can you see the Great Wall of China from space?

Not from the Moon. From orbit, NASA calls it "difficult or impossible to see" without powerful lenses; a few astronauts report seeing it when a low sun casts long shadows.

Do we really only use 10% of our brains?

No. Imaging shows most regions active over a day. The 10% figure appears in the opening sketch of Dale Carnegie's 1936 bestseller, pinned on William James, who never gave a number.

Do toilets flush the other way in Australia?

Not because of the Earth's rotation. The Coriolis effect is real but far too weak at that scale. A toilet swirls the way its pipes point the water.

Sources

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