40 entries
Biology
Feathered dinosaurs, rewritten family trees, and gene counts that shrank by an order of magnitude.
Changes here run from 1983 to 2026.
- Disproved22
- Updated8
- Refined6
- Replaced2
- Renamed1
- Reclassified1
- DisprovedNot in textbooks yet
TaughtThree hundred million years ago, dragonfly-like insects grew to the size of hawks. The standard explanation: atmospheric oxygen was around 45% higher than today, and because insects breathe through passive tubes rather than lungs, only that oxygen-rich air could supply a body that large. When oxygen fell, giant insects became impossible.
NowA 2026 study in Nature found that the insect breathing system is nowhere near its oxygen-delivery limit, so oxygen alone cannot explain the giants. The prevailing high-oxygen theory of insect gigantism doesn't hold up.
- UpdatedNot in textbooks yet
TaughtThe brain is the body's most protected organ, sealed off by the blood-brain barrier, a tight lining that evolution spent half a billion years perfecting to keep foreign material out. Environmental particles like microplastics circulate in the body but do not reach the brain.
NowA February 2025 study in Nature Medicine found that human brains contain roughly a plastic spoon's worth of micro- and nanoplastics, far more than the liver or kidneys, and that the amount rose about 50% between 2016 and 2024. The barrier is not the seal it was assumed to be.
- UpdatedNot in textbooks yet
We have no idea what a Denisovan looked like
Changed in2025TaughtDenisovans are an extinct human cousin known almost entirely from a finger bone, a few teeth, and the DNA inside them. There is no skull, and no real idea what their faces looked like.
NowIn June 2025, molecular analysis identified the near-complete "Dragon Man" skull from Harbin, China as Denisovan, the first Denisovan skull ever recognized and the first genuine look at their face.
- Updated
TaughtBeyond ABO and Rh, blood typing is a mostly closed book. The International Society of Blood Transfusion recognises a fixed roster of blood group systems, 44 of them, and the mysteries were solved long ago.
NowIn 2024, researchers at NHS Blood and Transplant and the University of Bristol described the MAL blood group system, the 47th recognised system, finally explaining the AnWj antigen, whose genetic basis had been a mystery since 1972.
- Disproved
TaughtThe only complete wiring diagram of a brain (a 'connectome') belongs to the roundworm C. elegans, with its 302 neurons. Mapping every neuron and every connection in anything more complex is far beyond what anyone can do.
NowOn 2 October 2024, the FlyWire consortium published in Nature the complete connectome of an adult fruit fly brain: all 139,255 neurons and more than 50 million synapses, mapped and annotated. It is the most complex brain ever fully wired up.
- Disproved
Tyrannosaurus rex bared its huge teeth like a crocodile
Changed in2023TaughtPicture T. rex and you picture the teeth: rows of banana-sized daggers jutting out even when the mouth is shut, exposed to the air like a crocodile's. Every model, museum mount, and movie monster agreed.
NowA March 2023 study in Science concluded that T. rex and other big theropods had scaly, lizard-like lips that fully covered their teeth when the mouth was closed. The crocodile-style permanent snarl appears to be wrong.
- Updated
We will never know what killed Beethoven
Changed in2023TaughtBeethoven died in 1827 after years of illness, deafness, and abdominal suffering, and the cause was lost to history. Without a body to examine, the best anyone could offer was speculation: lead poisoning, syphilis, a dozen guesses.
NowIn March 2023, researchers sequenced Beethoven's genome from authenticated locks of his hair and reported, in Current Biology, that he carried strong genetic risk factors for liver disease and had been infected with hepatitis B, a combination that, with his drinking, points to liver failure as the likely cause of death.
- Disproved
All bacteria are microscopic, invisible to the naked eye
Changed in2022TaughtBacteria are single cells so small you need a microscope to see them: a few micrometres across, thousands of times below the threshold of human vision. That tininess is practically part of the definition of a bacterium.
NowIn 2022, scientists described Thiomargarita magnifica in Science: a bacterium whose single cells grow to a centimetre or more, the length of an eyelash, visible to the naked eye and pickable up with tweezers, some 5,000 times larger than a typical microbe.
- Refined
The human genome was fully sequenced in 2003
Changed in2022TaughtThe Human Genome Project finished in 2003, reading all three billion letters of human DNA from end to end. The book of life was complete.
NowThe 2003 sequence was about 92% complete. The hardest 8%, dense repetitive regions, resisted sequencing until 2022, when the Telomere-to-Telomere consortium published the first truly gapless human genome.
- Updated
TaughtDNA begins breaking apart the moment an organism dies. Even in the best-preserved permafrost fossils it degrades into unreadable fragments within a few hundred thousand years, so anything a million years old is far beyond reach; forget sequencing a creature that ancient.
NowIn February 2021, researchers reported in Nature that they had sequenced DNA from mammoth teeth frozen in Siberian permafrost for more than a million years, including one specimen around 1.6 million years old, shattering the previous record held by a roughly 700,000-year-old horse.
- Disproved
TaughtA protein is a chain of amino acids that folds into a specific three-dimensional shape, and that shape determines what it does. Predicting the shape from the sequence alone is one of biology's hardest unsolved problems, and may remain so for decades.
NowIn 2020 DeepMind's AlphaFold solved structure prediction to near-experimental accuracy, and by 2021 its public database held predicted structures for nearly every protein known to science, over 200 million. Demis Hassabis and John Jumper shared the 2024 Nobel Prize in Chemistry for it.
- Updated
No dinosaur was built for swimming
Changed in2020TaughtDinosaurs were land animals. Some may have waded at the water's edge, but none was a true swimmer; nothing in the fossil record showed a non-bird dinosaur adapted to move and hunt underwater the way a fish or a crocodile does.
NowIn April 2020, a nearly complete Spinosaurus tail from Morocco, described in Nature, changed that. The tail was a tall, flexible fin shaped for propulsion, not balance. Robotic models of it produced real thrust in water, making Spinosaurus the first non-bird dinosaur known to have been adapted for active swimming.
- Refined
Sunflowers always turn to follow the sun
Changed in2016TaughtSunflowers track the sun across the sky all day, every day, throughout their lives.
NowOnly young sunflowers track the sun. Once mature, the flower stops moving and faces permanently east. The tracking is driven by a circadian rhythm, shown in a 2016 study in Science.
- Renamed
Brontosaurus never existed
Changed in2015TaughtBrontosaurus was a mistake. The name was withdrawn in 1903 and the animal is really an Apatosaurus. Stop saying Brontosaurus.
NowA 2015 study using a large statistical analysis of diplodocid anatomy concluded that Brontosaurus is distinct enough from Apatosaurus to be its own genus. The name is back, though not every paleontologist agrees.
- Disproved
You are left-brained or right-brained
Changed in2013TaughtLogical, analytical people are left-brained. Creative, artistic people are right-brained. It is a personality type rooted in your brain.
NowA 2013 study analyzing over 1,000 brains found no evidence that people have a stronger left or right network overall. Some functions are lateralized; personalities are not.
- Refined
98% of your DNA is useless junk
Changed in2012TaughtOnly about 2% of the genome codes for proteins. The rest is evolutionary debris: junk DNA with no function.
NowMuch of the noncoding genome regulates when and where genes switch on. The ENCODE project reported in 2012 that most of the genome is biochemically active, though how much is genuinely functional is still fiercely argued.
- Disproved
Tongue rolling is a simple dominant trait
Changed in2011TaughtRolling your tongue is controlled by a single gene. Take a class survey, fill in the Punnett square, find out who is dominant.
NowIt is not a single-gene trait. Identical twins frequently differ, and people can learn to do it. The geneticist who proposed it publicly retracted the claim in 1975.
- Disproved
Humans and Neanderthals never interbred
Changed in2010TaughtNeanderthals were a separate species that modern humans replaced. They died out and left no descendants.
NowThe draft Neanderthal genome, published in 2010, showed that people with ancestry outside Africa carry roughly 1 to 2% Neanderthal DNA. They are in your family tree.
- Disproved
You have a learning style, and teaching to it helps
Changed in2009TaughtEveryone is a visual, auditory, or kinesthetic learner. Find yours and you will learn better when material is presented that way.
NowA 2008 review commissioned by Psychological Science in the Public Interest found essentially no credible evidence for the core prediction. Matching teaching to a supposed style does not improve learning.
- Disproved
Chameleons change color to match their background
Changed in2008TaughtA chameleon changes color to blend in with whatever it is sitting on.
NowColor change is mostly communication and temperature regulation, signaling mood, dominance, and readiness to mate. Camouflage is a secondary use at best.
- Replaced
Human evolution was a straight march of progress
Changed in2004TaughtThe famous parade: an ape stands up, becomes Australopithecus, then Homo erectus, then Neanderthal, then us. One species at a time, each better than the last.
NowHuman evolution is a branching bush with many species coexisting. At times several kinds of human shared the planet, and the discovery of Homo floresiensis in 2004 made that impossible to ignore.
- Disproved
Goldfish have a three-second memory
Changed in2003TaughtA goldfish forgets everything after about three seconds, which is why it can live happily in a small bowl.
NowGoldfish form memories lasting months. They can be trained to respond to signals, navigate mazes, tell colors apart, and learn to press a lever at feeding time.
- Updated
Humans have around 100,000 genes
Changed in2003TaughtThe human genome contains roughly 100,000 genes: we are complicated animals, so we must need a lot of them.
NowAbout 19,000 to 20,000 protein-coding genes. The Human Genome Project's draft in 2001 and completion in 2003 cut the estimate by a factor of five.
- Refined
Humans have five senses
Changed in2000TaughtSight, hearing, smell, taste, and touch. Five senses.
NowDepending on how you count, humans have somewhere between nine and thirty-something senses. The list Aristotle wrote down leaves out balance, body position, temperature, pain, and several internal senses.
- Updated
There are four basic tastes
Changed in2000TaughtSweet, salty, sour, and bitter. Four tastes, no more.
NowUmami is the fifth, confirmed when its receptor was identified in 2000. Evidence for a distinct fat taste is now strong, and a sixth is plausible.
- Disproved
You only use 10% of your brain
Changed in2000TaughtHumans use only about 10% of their brains. Imagine what we could do if we unlocked the rest.
NowBrain imaging shows virtually all of the brain is active over the course of a day, and there is no dormant 90%. Damage to almost any region causes deficits.
- Disproved
You cannot grow new brain cells
Changed in1998TaughtYou are born with all the neurons you will ever have. Every one you lose is gone forever, so do not hit your head.
NowAdult neurogenesis occurs in the hippocampus, demonstrated in humans in 1998. The extent in adults remains genuinely contested, but the absolute claim is dead.
- Refined
Dinosaurs went extinct 65 million years ago
Changed in1996TaughtDinosaurs ruled the Earth and then went completely extinct 65 million years ago. Birds may be distantly related to them.
NowBirds are dinosaurs, not relatives of dinosaurs. Non-avian dinosaurs died out about 66 million years ago, but the group survives: there are roughly 11,000 living dinosaur species.
- Disproved
Dinosaurs were scaly, sluggish reptiles
Changed in1996TaughtDinosaurs were cold-blooded, slow-moving, scaly reptiles: essentially oversized lizards.
NowMany dinosaurs had feathers, and the group was active and warm-blooded or something close to it. The first clearly feathered dinosaur, Sinosauropteryx, was described from China in 1996.
- Disproved
Bulls charge at the color red
Changed in1995TaughtRed enrages a bull. That is why matadors use a red cape.
NowCattle are dichromats and cannot distinguish red from green. Bulls charge the movement of the cape, not its color. The cape is red to hide blood.
- Disproved
Houseflies only live for 24 hours
Changed in1995TaughtA housefly lives for a single day. Try to feel sympathy for it.
NowHouseflies live around 15 to 30 days as adults. The one-day lifespan belongs to mayflies, and even they spend most of a year as aquatic nymphs first.
- Disproved
Different parts of your tongue taste different things
Changed in1993TaughtThe tongue map: sweet at the tip, salty and sour along the sides, bitter across the back.
NowAll taste regions of the tongue detect all basic tastes. The map came from a mistranslation of a 1901 German paper, and there was never good evidence for it.
- Refined
Nobody knows what killed the dinosaurs
Changed in1991TaughtScientists have many competing theories about the dinosaur extinction: climate change, disease, volcanoes, mammals eating the eggs, or possibly an asteroid.
NowAn asteroid roughly 10 km across struck what is now the Yucatán Peninsula about 66 million years ago. The Chicxulub crater was confirmed in 1991 and the impact is the accepted primary cause.
- Disproved
Bats are blind
Changed in1990TaughtBats cannot see at all. They navigate purely by echolocation, which is why we say "blind as a bat."
NowNo bat species is blind. All have functional eyes, many see well in low light, some see ultraviolet, and the large fruit bats rely on vision rather than echolocation.
- Disproved
Camels store water in their humps
Changed in1990TaughtA camel's hump is a water tank. That is how it crosses the desert without drinking.
NowHumps store fat, not water. The fat is an energy reserve; the camel's desert endurance comes from a suite of other adaptations, including red blood cells that survive extreme dehydration.
- Replaced
Life is divided into five kingdoms
Changed in1990TaughtAll living things belong to one of five kingdoms: Animalia, Plantae, Fungi, Protista, and Monera.
NowCarl Woese's three-domain system, proposed in 1977 and formalized in 1990, puts Bacteria, Archaea, and Eukarya at the top level. Archaea turned out to be as different from bacteria as you are.
- Disproved
Ostriches bury their heads in the sand when frightened
Changed in1990TaughtA frightened ostrich sticks its head in the sand, believing that if it cannot see the predator, the predator cannot see it.
NowNo ostrich has ever done this. They would suffocate. The impression comes from ostriches lowering their heads to the ground, either to turn their eggs in a ground nest or to lie flat when hiding.
- Disproved
Dogs see in black and white
Changed in1989TaughtDogs are completely colorblind. Their world is a grayscale film.
NowDogs have two types of cone cell and see blues and yellows. They cannot distinguish red from green, which is why a red ball vanishes into green grass for them.
- Reclassified
The giant panda is not really a bear
Changed in1986TaughtDespite the name, giant pandas are more closely related to raccoons than to bears. Their classification is a long-standing puzzle.
NowMolecular evidence settled it: the giant panda is a bear, in the family Ursidae. The red panda is the one that is not, and sits in its own family.
- Disproved
Lemmings commit mass suicide by jumping off cliffs
Changed in1983TaughtWhen lemming populations get too large, the animals instinctively march to the sea and hurl themselves off cliffs to thin the herd.
NowLemmings do not commit suicide. The belief comes largely from Disney's 1958 documentary White Wilderness, in which the filmmakers threw the animals off a cliff themselves.