The 2010s
Gluten panic, taste zones, and mobile phones are just a fad.
What you were taught
What we know now
Cattle are dichromats: they lack the cone cells humans use to see red, so a red cape looks dull yellowish-gray rather than a rage trigger. Matadors' red muleta is traditional and helps hide blood from spectators; bulls also charge the larger, often pink-and-gold capote used earlier in the fight. The threatening waving motion of the cape, not its hue, is what drives the charge.
Updated understanding emerged around 2012
What you were taught
What we know now
Chameleons change color primarily for communication and thermoregulation, not to match every background like cartoons claim. Males brighten to signal dominance or darken in fights; color also helps them warm up or cool down because they cannot generate their own body heat. Specialized skin cells rearrange pigments and light-reflecting structures when the nervous system responds to mood, social cues, or temperature. Camouflage can play a role, but it is not the main driver of those rapid shifts.
Updated understanding emerged around 2014
What you were taught
What we know now
George Washington never wore wooden dentures. Surviving sets used materials such as hippopotamus ivory, human teeth, and metal fasteners (including brass and gold)—not wood. Staining and browning from wear and poor cleaning could make ivory look woody, which is the most likely origin of the myth. By his 1789 inauguration he had only one remaining natural tooth; dentist John Greenwood built a special ivory, brass, and gold set for the occasion.
Updated understanding emerged around 2014
What you were taught
What we know now
Napoleon was not unusually short. Three French sources, including his physician Francesco Antommarchi at the 1821 autopsy, recorded him at just over 5 pieds 2 pouces. The French pouce was longer than the British inch (about 2.7 cm versus 2.54 cm), so that figure converts to roughly 1.67 meters, or just under 5 foot 6—average to slightly above average for a French man in the early 1800s. British caricaturist James Gillray popularized the tiny “Little Boney” image around 1803; the affectionate nickname Le Petit Caporal was not a height insult.
Updated understanding emerged around 2019
What you were taught
What we know now
There is no archaeological evidence that Viking Age warriors (roughly 8th–11th centuries) wore horned helmets. Contemporary depictions show bare heads or simple iron or leather headgear, and the only complete helmet securely identified as Viking—the 10th-century Gjermundbu helmet from Norway—has a rounded iron cap and eye/nose guard with no horns. The popular image took off in the 1800s; Carl Emil Doepler’s costumes for Wagner’s Ring cycle in the 1870s sealed the stereotype. Bronze horned helmets from Viksø, Denmark, are Bronze Age ceremonial pieces from the early first millennium BCE, not Viking battle gear.
Updated understanding emerged around 2013
What you were taught
What we know now
Waking a sleepwalker does not cause a heart attack, brain damage, or death; neurologists describe those claims as myth. Sleepwalking (somnambulism) is a partial-arousal disorder, usually in deep non-REM sleep early in the night. Abrupt waking can produce temporary confusion or a startle response that might lead to falls or thrashing, so gently guiding the person back to bed is preferred when possible—but the danger is incidental injury and agitation, not catastrophic medical harm.
Updated understanding emerged around 2019
What you were taught
What we know now
The five-second rule is a myth as a safety guarantee. Rutgers food scientist Donald Schaffner and graduate student Robyn Miranda tested foods and surfaces in 2016 and found bacterial transfer can begin in less than one second. Wetter foods (such as watermelon) pick up more contamination; contact time, moisture, and surface type (tile and stainless steel transfer more than carpet) all matter. Longer contact usually transfers more bacteria, but speed alone does not make dropped food safe.
Updated understanding emerged around 2016
What you were taught
What we know now
Umami is recognized as a fifth basic taste alongside sweet, sour, salty, and bitter; scientists continue to study additional candidates such as fat taste.
Updated understanding emerged around 2015
What you were taught
What we know now
Brontosaurus fossils were always real; for decades the name was sunk as a synonym of Apatosaurus (Riggs, 1903). A 2015 reassessment argued Brontosaurus is distinct enough to count as its own genus again, though not every paleontologist agrees. The myth is treating either version as the final, simple truth.
Updated understanding emerged around 2015
What you were taught
What we know now
Flu shots cannot give you influenza. Needle vaccines use inactivated virus or only part of one flu gene, neither of which can cause flu illness. Feeling sore or tired afterward is usually a mild immune response, not the flu, though you can still catch influenza or another virus later through ordinary exposure.
Updated understanding emerged around 2020
What you were taught
What we know now
The Big Bang theory describes how the universe expanded and cooled from a very hot, dense state. It does not explain what existed before inflation or what caused that state. It maps cosmic history forward from the early universe, not its ultimate origin.
Updated understanding emerged around 2020
What you were taught
What we know now
Trees produce oxygen, but they are not the main global source. Scientists estimate that roughly half or more of Earth's oxygen production comes from the ocean, mainly from phytoplankton. Marine life also consumes a large share of that oxygen, so production and leftover air are not the same claim.
Updated understanding emerged around 2020
What you were taught
What we know now
"Daddy longlegs" is a nickname, not one animal. Harvestmen are arachnids without venom glands or fangs. Cellar spiders are true spiders with mild venom and can bite humans, but there is no evidence they are the most venomous spiders on Earth. The fangs-too-small story is folklore, often attached to the wrong creature entirely.
Updated understanding emerged around 2020
What you were taught
What we know now
In 2017, a photograph appeared to prove that Amelia Earhart survived her plane crash and was taken prisoner by the Japanese. However, it was later proven that the photo was taken two years before her disappearance, leaving the mystery unsolved.
Updated understanding emerged around 2017
What you were taught
What we know now
The hymen is usually a thin ring of tissue around the vaginal opening, not a complete seal. It normally has an opening for menstrual flow, can change through many ordinary activities, and is not a reliable indicator of sexual history or virginity. A fully closed hymen (imperforate hymen) is rare and is a medical condition, not typical anatomy.
Updated understanding emerged around 2015