Science myths that refuse to die

Myth: Most of your brain sits idle, waiting to be unlocked.

Reality: Neurologist Barry Gordon of Johns Hopkins told Scientific American the idea is "so wrong it is almost laughable." Over a day, virtually all of the brain is used, and the organ is about 3% of body weight but consumes about 20% of the body's energy (Scientific American).

Why it persists: it flatters us with hidden potential, and it echoes a real but narrower truth that only a fraction of neurons are firing at any one moment.

Myth: The wall is the one human structure you can see from orbit, or even from the Moon.

Reality: The Moon version dates at least to a 1932 Ripley's Believe It or Not! cartoon. In 2003, China's first astronaut, Yang Liwei, said he had not seen the wall, prompting a revision of Chinese school textbooks. A 2004 photo taken from the International Space Station by Leroy Chiao appears to show a section, but Chiao was not sure what he was seeing. The wall is narrow and blends with surrounding terrain (Scientific American, 2008).

Why it persists: it sounds like a perfect measure of the wall's scale, and it was repeated in textbooks for decades.

Myth: Every lap of the bowl is a brand-new world to a goldfish.

Reality: In a 1994 study, goldfish learned to press a lever for food, and then to restrict their pressing to a single one-hour feeding window each day, a schedule maintained over four weeks. When food stopped, their anticipatory pattern persisted for several days (Gee, Stephenson & Wright, 1994). That is not possible with a three-second memory.

Why it persists: it's a comforting excuse for keeping fish in small bowls, and fish faces are hard for humans to read.

Myth: A red cape enrages a bull.

Reality: Cattle have two cone types, peaking around 444–455 nm and 552–555 nm, which gives them dichromatic colour vision broadly like other hoofed mammals (Jacobs, Deegan & Neitz, 1998). They lack the separate long-wavelength cone that makes red vivid to most humans, so whatever provokes a charge, it isn't redness as we see it.

Why it persists: the red muleta is the most memorable image of a bullfight, and "seeing red" is already an idiom for anger.

Myth: A spot that has been hit is safe.

Reality: The US National Weather Service says lightning "often strikes the same place repeatedly, especially if it's a tall, pointy, isolated object," and that the Empire State Building is hit an average of 23 times a year (NWS).

Why it persists: it began as a figure of speech about bad luck and got taken literally.

Myth: Sweet at the tip, bitter at the back, sour and salty on the sides.

Reality: Taste receptor cells for each basic quality are found in taste buds throughout the tongue and mouth (Chandrashekar et al., 2006). The map traces to a 1901 thesis by David Hänig, which found only small sensitivity differences; a 1942 textbook replot by Edwin Boring exaggerated them, and later textbooks turned that graph into zones (Spence, 2022).

Why it persists: it was a neat classroom diagram, and small regional differences in sensitivity do exist.

Myth: Sight, hearing, smell, taste, touch: that's the full list.

Reality: The five-sense list is a tradition, not a biological count. Proprioception, the sense of the position and movement of your own body, has dedicated sensory neurons and is essential to coordinated movement (Tuthill & Azim, 2018). Balance, temperature and pain are commonly counted separately too; the total depends on how you define a "sense."

Why it persists: five is tidy, and the senses that work quietly in the background are easy to forget.

Myth: Habitual knuckle cracking wears out your joints.

Reality: A 2011 case-control study of 215 people found osteoarthritis in 18.1% of knuckle crackers and 21.5% of non-crackers, not a significant difference, and no link with how long or how often people cracked (deWeber et al., 2011). An earlier survey of older patients also found no correlation (Swezey & Swezey, 1975), and a 2018 review concluded that observational studies "have failed to show an association" (Rizvi et al., 2018). Physician Donald Unger famously cracked the knuckles of only one hand for decades and reported no arthritis in either (Unger, 1998), a charming experiment with a sample size of one.

Why it persists: the noise sounds like damage, and parents wanted a reason for children to stop. It is a textbook case of post hoc reasoning when arthritis later appears.

Myth: Seasons are caused by Earth's changing distance from the Sun.

Reality: "Earth's tilted axis causes the seasons," says NASA. Earth is closest to the Sun (perihelion, about 91.4 million miles) in January and farthest (aphelion, about 94.5 million miles) in July, the opposite of what the myth predicts for the Northern Hemisphere (NASA Space Place).

Why it persists: closer-is-hotter is intuitive, and textbook diagrams often exaggerate the ellipse of Earth's orbit.

Myth: Deoxygenated blood is blue until it meets air.

Reality: Blood is always red; it is darker when it carries less oxygen. Veins look blue because of the way skin and tissue scatter and absorb different wavelengths of light before it reaches your eye (Kienle et al., 1996).

Why it persists: anatomy diagrams colour veins blue and arteries red as a convention, and veins do look blue through skin.

Myth: Put a chameleon on a plaid shirt and it turns plaid.

Reality: In southern African dwarf chameleons, the species with the most dramatic colour change are those with the most conspicuous social displays, and researchers "found no evidence for the crypsis hypothesis" (Stuart-Fox & Moussalli, 2008). Panther chameleons shift colour by actively tuning a lattice of guanine nanocrystals in skin cells, mostly during contests and courtship (Teyssier et al., 2015). Their resting colours do provide camouflage, but rapid change is mostly about communication.

Why it persists: "chameleon" became a byword for blending in long before the biology was studied.

Myth: Medieval windows are thicker at the bottom because glass flows downward over centuries.

Reality: Using viscosity estimates for medieval and modern glass compositions, materials scientist Edgar Zanotto calculated that window glass could flow noticeably at room temperature only "over incredibly long times, which exceed the limits of human history" (Zanotto, 1998). Uneven panes come from historical manufacturing methods.

Why it persists: glass is technically an amorphous solid, which sounds like a loophole, and the thick-bottomed windows are real.

Myth: Spiders crawl into sleeping mouths several times a year.

Reality: Arachnologists at the Burke Museum say "There's no evidence of it — no specimens, no eyewitness accounts, nothing!" (Burke Museum). The widely repeated story that a 1993 magazine column invented the statistic to show how easily false facts spread has itself never been confirmed (Mental Floss).

Why it persists: it is just plausible enough to be unsettling, and a precise number makes it sound measured.