Real or Myth? 14 Popular Claims, Checked

Some facts get repeated so often that they feel checked. They arrive in a numbered carousel, they sound like the sort of thing that would be true, and they can go round for years before anyone asks where they came from.

We took fourteen of them and looked for the earliest and most reliable source we could find for each.

Nine are myths. Three are partly true. One cannot be settled either way. One holds up. The partly-true ones are the most interesting, because a half-right claim lasts much longer than a wrong one: there is always something real underneath to point at.

01The verdicts

All ✕Doesn't hold up◐Partly✓Holds up?Can't confirm

01 Sharks die if they stop swimming ◐Partly True only for the sharks called obligate ram ventilators, which include great whites, makos and whale sharks: they have lost the ability to pump water over their gills, and would die from lack of oxygen if they stopped swimming.

02 You swallow eight spiders a year in your sleep ✕Doesn't hold up Swallowing one is possible, but "it would be a strictly random event".

03 The Great Wall of China is visible from space ✕Doesn't hold up Generally not to the unaided eye from low Earth orbit.

04 Einstein failed maths at school ✕Doesn't hold up Shown the claim in a newspaper column in 1935, he replied: "I never failed in mathematics.

05 Marie Antoinette said "let them eat cake" ✕Doesn't hold up The line is in Rousseau's Confessions, Book VI, where he recalls the saying of "a great princess" who, told that the peasants had no bread, answered qu'ils mangent de la brioche: let them eat brioche.

06 Bulls charge because they see red ✕Doesn't hold up Cattle have two kinds of colour-sensing cone, not three: they are dichromats, and colour-blind to red.

07 Vikings wore horned helmets into battle ✕Doesn't hold up The only Viking-age helmet preserved whole, from a warrior's grave at Gjermundbu in Norway, has no horns, and no contemporary source mentions Vikings wearing horned headgear, according to the National Museum of Denmark.

08 Goldfish have three-second memories ✕Doesn't hold up In experiments at the University of Plymouth, goldfish learned to push a lever for food, and when the lever worked for only one hour a day, they learned to press it at the right time.

09 Milk is at the back of the shop so you walk past everything ◐Partly Milk is usually at the back.

10 Bison run into storms to get through them faster ◐Partly The behaviour is real; the reason is not shown.

11 Napoleon said never to interrupt an enemy who is making a mistake ?Can't confirm The idea has been credited to him for a long time, but no record from Napoleon himself has turned up.

12 Lightning never strikes the same place twice ✕Doesn't hold up It often strikes the same place again and again, especially tall, pointed, isolated objects.

13 We only use 10% of our brains ✕Doesn't hold up "We use virtually every part of the brain, and that [most of] the brain is active almost all the time," the Johns Hopkins neurologist Barry Gordon told Scientific American.

14 Honey never spoils ✓Holds up This one holds up. Honey is very low in water, acidic (a pH of roughly 3 to 4.5), and contains small amounts of hydrogen peroxide made by an enzyme from the bees, so very little can grow in it.

6 of 14 shown · a mix of every verdict Show all 14 ▾

02How to read the sheet

Every row opens. Inside is what the sources say and where they come from.

• True: it holds up.
• Partly true: something real is in there, but the popular version has added or changed something that matters.
• Unverified: no record we could find settles it either way.
• Myth: it does not hold up.

---

03The one that is really about all the others

The spider claim is worth singling out, because it is the whole problem in miniature.

The claim itself has nothing behind it. Rod Crawford, the arachnid curator at the Burke Museum in Seattle, told Scientific American that “a sleeping person is not something a spider would willingly approach”. Swallowing one is possible, but, as the same article puts it, “it would be a strictly random event”.

Then there is the correction you may have heard: that the “eight spiders a year” statistic was invented in 1993 by a columnist named Lisa Birgit Holst, writing in a magazine called PC Professional, to show that people will repeat anything they read.

That story is also made up. The fact-checking site that first told it now says that “PC Professional” and the columnist “do not exist”, that her name “is an anagram of the phrase ‘this is a big troll’”, and that the story was planted in April 2001 as a joke for its long-time readers. The spider claim was already going round before that: the same page quotes a 1999 trivia list that has a version of it.

So a made-up fact picked up a made-up origin story about made-up facts. The second story is satisfying to pass on, because telling it casts the teller as the one who knew better.

It is easy to relax once a claim seems to have been seen through; that is when the second story slips in.

04What the partly-true ones have in common

Look at the three together and the same shape appears each time.

• Some sharks do die if they stop swimming. What was added is the word sharks, with no qualifier.
• Bison do face into storms. What was added is the reason: that they know it gets them through faster.
• Milk is usually at the back of the shop. The intent behind that is argued both ways, even by people who work in the trade.

In each case the core is a fact, and the addition is the part nobody has shown. The addition is what makes it shareable, which may be why it is the part that gets added.

The Napoleon line has a related shape. The idea has been credited to him since at least 1827, but the earliest book we found that does so was written in his voice by someone else, and the snappy wording came decades later.

05How to check one yourself

• Ask what the original source would even look like. “Goldfish remember for three seconds” would need someone to have tested goldfish memory and found three seconds. The tests that have been done found memories lasting months.
• Search for the earliest version, not the most popular one. Sort by date. If the oldest version you can find is only a few years old, it is not ancient wisdom.
• Take a second look at claims that come with a moral. A fact that also happens to be good advice has had a reason to be improved.
• Check the correction as carefully as the claim. The spider story is the reason.

How we checked this · Last checked September 2026

• Each claim was traced to the earliest and most reliable source we could find, listed below. Where a claim could not be settled, it is marked rather than guessed at.

Checked September 2026. Where a claim could not be settled, it is marked rather than guessed at.

How we check every article →

06Sources