The human body is stranger than most textbooks let on. Here are organs with surprising histories, from a kidney transplant between twins to a thymus once dismissed as useless; senses, from a chemist's bowl of broth to sunlight that makes people sneeze; records, such as a farmer who hiccupped for 68 years; and body myths corrected, including the tongue map, the carrot cover story and the hat that was supposed to keep in half your heat.
Every tile in a The Human Body game carries one of these. Open one to read it now, or leave them for the board to hand you.
Organs
nine stories
1The brain-injury survivor who drove coaches in Chile
On the tile: Phineas Gage1848
On September 13, 1848, railroad foreman Phineas Gage was packing explosive powder into a hole in Cavendish, Vermont, when it detonated. His tamping iron, 43 inches long and 13.25 pounds, shot through his left cheek and out through his skull. He might not even have lost consciousness. Retellings of his changed character grew until he was portrayed as a shiftless drunk. Yet he later drove coaches in Chile, and a daguerreotype posted online in 2007 as a whaler with a harpoon was identified in 2009 as almost certainly Gage, well dressed and confident, holding the iron.
2Darwin's leftover organ may be a safe house for bacteria
On the tile: Appendix2007
Charles Darwin thought the human appendix was the remains of a larger digestive structure used by extinct ancestors, and many biology texts still call it vestigial. In 2007, Duke University researchers led by William Parker proposed a job for it: a safe haven for helpful gut bacteria, ready to repopulate the gut after an illness such as cholera wipes them out. Two years later, the team reported that the appendix has evolved at least twice and has existed for at least 80 million years. The idea is still being tested.
3The doctor who threaded a tube into his own heart
On the tile: Forssmann1929
In 1929, Werner Forssmann, a young doctor training in surgery near Berlin, wanted to reach a living heart through a vein. His boss said no. According to author Rob Dunn, Forssmann enlisted a nurse by letting her believe she would be the patient, then slid the catheter into his own arm instead, 65 centimeters in all. He walked to the X-ray department, where a picture showed the tip inside his heart. His surgical career stalled, but in 1956 he shared the Nobel Prize.
Why does the heart beat on its own? On a hot summer day in 1906, medical student Martin Flack was studying slices of a mole's heart at a cottage in Kent, England, while his mentor, anatomist Arthur Keith, went bicycling with his wife through cherry orchards. When they returned, Flack showed Keith a structure in the right atrium, just where a large vein enters. They found it in other mammal hearts too. Their 1907 paper described what is now called the sinoatrial node, where the heartbeat normally begins.
In Greek myth, Zeus punished Prometheus by chaining him to a rock and sending an eagle to eat his liver every day. Every night it grew back. Real livers are not that fast, but the storytellers chose well. According to the National Institutes of Health, the liver has a unique capacity among organs to regenerate, and it can regrow to normal size even after up to 90 percent of it has been removed. A 2021 study in mice found that ordinary liver cells, not stem cells, do most of the everyday upkeep.
6The 'graveyard' organ that turned out to make T cells
On the tile: Thymus1961
In the early 1960s, most immunologists considered the thymus a useless organ, a graveyard for dying white blood cells. Jacques Miller, a young Australian-trained doctor studying leukemia in mice in London, removed it from newborn mice, which then wasted away with too few lymphocytes. Critics blamed infections, since his mice were bred in converted horse stables. In 1963, at the National Institutes of Health, he tried germ-free mice and got the same result. The thymus, it turned out, is where T cells develop.
Identical twins have the same DNA, yet their fingerprints differ. The ridges on our fingertips begin to form during the third month of fetal development and are fully formed by the sixth, according to MedlinePlus Genetics from the National Library of Medicine. Genes influence their basic size, shape and spacing, but the finer details are shaped by conditions during development, including the environment inside the womb. The ridges then stay the same for life. Their purpose is not entirely clear, though they likely increase sensitivity to touch.
In late 2016, J. Calvin Coffey of the University of Limerick argued in The Lancet Gastroenterology and Hepatology that the mesentery, the folded tissue that holds the intestines in place, is one continuous structure rather than the fragments described for about a century. In January 2017, headlines announced a new human organ, and Gray's Anatomy had already updated its description. But the mesentery was not new. Leonardo da Vinci had drawn it as a single structure, and anatomists noted that no official body decides what counts as an organ.
9The student who found insulin's islands without knowing it
On the tile: Langerhans1869
In February 1869, a 21-year-old Berlin medical student named Paul Langerhans presented a thesis on the microscopic anatomy of the pancreas. As one commentator put it, he concluded that he had found nothing new and hoped his examiners would be tolerant. Yet he had described little islands of clear cells scattered through the gland, staining differently from the tissue around them. He could suggest no function except that they might be lymph nodes. Today they are called the islets of Langerhans, and they include the cells that make insulin.
1The chemist who tasted something new in his broth
On the tile: Umami1907
Chemist Kikunae Ikeda noticed that his favorite broth, dashi, had a taste that was not quite sweet, sour, salty or bitter. As a professor in Tokyo, he began in 1907 by boiling down 90 pounds of kombu kelp and, over the following months, extracted a single ounce of crystals that carried the flavor. They were glutamate, and he named the taste umami. He turned the discovery into a seasoning, Ajinomoto, known today as MSG. In the early 2000s, scientists located glutamate receptors on the human tongue, putting his idea on firm footing.
2The hole in your vision that an octopus does not have
On the tile: Blind spot1668
Each human eye has a blind spot, roughly 7.5 degrees across, where nerve fibers and blood vessels pass through the retina to leave the eye, leaving a patch with no light receptors. French physicist Edme Mariotte wrote about his experiments locating it in 1668. We rarely notice, because the two eyes' blind spots fall in different places and the brain either fills in the gap or ignores it. An octopus has no such hole: its nerve fibers run behind the retina.
Stepping from dim light into bright sunlight makes some people sneeze, and the trait runs in families. Its medical name abbreviates, fittingly, to ACHOO syndrome. Estimates of how many people have it range from 18 to 35 percent. The number of sneezes tends to be the same from one episode to the next, typically two or three, and military studies found the trigger is a change in light intensity. The Greek philosopher Aristotle wondered about it and blamed the sun's heat. Exactly how light sets off a sneeze remains unknown.
Try to tickle yourself and almost nothing happens. At University College London, neuroscientist Sarah-Jayne Blakemore found the reason: when you move, the brain predicts the touch you are about to feel and damps it down. Her team used a robot arm that let people stroke their own palm with a piece of foam, and a delay of 200 milliseconds made the stroking feel much more ticklish. Other researchers later asked lucid dreamers to tickle themselves in their dreams. It felt no stronger than tickling themselves awake, and some dream characters refused to help.
5The bitter powder that only some people can taste
On the tile: Arthur Fox1931
In 1931, DuPont chemist Arthur Fox was working with a powdered chemical called PTC when some of it blew into the air. A colleague complained that it tasted bitter. Fox, who had been much closer, tasted nothing. He handed out crystals to friends, family and fellow scientists, and some found them bitter while others tasted nothing at all. Studies soon showed the ability runs in families, and a gene called TAS2R38 was later found to explain much of the difference. Not all of it, though: some people's sensitivity even varies from day to day.
6The West African berry that makes lemons taste sweet
On the tile: Miracle berry1725
In 1725, a European explorer, the Chevalier des Marchais, described people in West Africa picking a small berry and chewing it before meals. The fruit, now called the miracle berry, makes sour foods such as lemons taste sweet. Its secret is a protein called miraculin, which binds to the tongue's sweet receptors: at neutral acidity it blocks them, but when something sour arrives, it switches them on. In the 1970s, an American company tried to sell it as a sweetener, but folded after the FDA required years more testing.
Underwater, most people see a blur, because the curved surface of the cornea supplies two-thirds of the eye's focusing power in air and loses it in water. Yet children of the Moken, sea nomads of Southeast Asia, gather food from the sea floor without goggles. In 2003, a team at Lund University in Sweden found their underwater vision more than twice as sharp as that of European children. The Moken children constrict their pupils and focus their lenses to the known limit of human performance. Later, trained European children improved too.
Hearing for high-pitched sounds tends to fade as people age. Howard Stapleton of Merthyr Tydfil, Wales, put that to work in the Mosquito, a device that makes an annoying high-pitched noise meant to be audible to teenagers loitering near shops but not to adults. The same sound became a phone ringtone that students could hear and, probably, their teachers could not. The Mosquito sound is pitched at 17.4 kilohertz, above the roughly 16 kilohertz limit of the average adult. In 2006, Stapleton won the Ig Nobel Peace Prize.
In February 2015, a mother photographed a dress she meant to wear to her daughter's wedding and sent the picture along. Her daughter saw white and gold. The dress was blue and black. A friend posted the photo online at the end of the month, and one BuzzFeed page drew 28 million views in a day. Vision scientists blame color constancy: the brain guesses what light is falling on a scene and subtracts it. Assume cool skylight and the dress turns white and gold; assume warm light and it stays blue and black.
1The tallest man on record carried his father upstairs
On the tile: Robert Wadlow1940
Guinness World Records calls Robert Wadlow of Alton, Illinois, the tallest man in medical history for whom there is irrefutable evidence. When he was last measured, on June 27, 1940, he stood 8 feet 11.1 inches. At age nine, he could carry his father, who was 5 feet 11 inches tall, up the stairs of the family home. His shoes were size 37AA. Less than three weeks after that final measurement, he died at 22 from an infected blister on his ankle caused by a poorly fitted brace.
In 1965, Jeanne Calment of Arles, France, was 90 and had no family left. She sold her home en viager, a French arrangement that pays the seller for life: a local notary, André-François Raffray, would pay her 2,500 francs a month and take possession when she died. Raffray died in 1995, at 77, having paid about double the property's value, and his family had to keep paying. Calment died in 1997 at 122 years and 164 days, the oldest verified age of any person in recorded history.
In 1922, Charles Osborne was handling a hog for butchering on a Nebraska farm when he fell, and he began to hiccup. He did not stop for 68 years, the longest attack of hiccups confirmed by Guinness World Records. At 20 to 40 hiccups a minute, he hiccupped an estimated 430 million times. No doctor found a cure, so he learned to breathe between hiccups to hide the sound. He married twice and had eight children. One morning in February 1990, the hiccups stopped. He died the following year.
4The two-hour marathon barrier, broken for the record
On the tile: Sabastian Sawe2026
In 2019 in Vienna, Eliud Kipchoge ran a marathon in 1:59:40, but it could not count as a world record: he had rotating pacemakers, drinks delivered by bicycle and no open competition. The barrier fell under record-eligible conditions in April 2026 at the London Marathon, where 31-year-old Kenyan Sabastian Sawe won in 1:59:30, a world record. He ran the second half in just over 59 minutes. Ethiopia's Yomif Kejelcha, running his first marathon, finished only 11 seconds behind.
At 14, James Harrison received blood transfusions during major chest surgery, and he pledged to become a donor. His plasma turned out to be rich in anti-D, a rare antibody used to make medicine for pregnant women whose blood is at risk of attacking their unborn babies. Known in Australia as the man with the golden arm, he donated every two weeks from age 18 until 81, and his donations are credited with helping save 2.4 million babies. He died in 2025, aged 88.
In April 1929, an editor at a Moscow newspaper noticed that his reporter Solomon Shereshevsky never took notes when the day's assignments were handed out. Challenged, Shereshevsky repeated a long newspaper passage word for word, so the editor sent him to a young psychologist, Alexander Luria. Luria gave him ever-longer lists of numbers and words, and when he retested him more than 15 years later, the lists were still there. Luria's 1968 book made him famous as the man who could not forget. The truth was subtler: remembering took him conscious, creative effort.
7The doctor who rode a rocket sled to 632 miles an hour
On the tile: John Stapp1954
In the late 1940s, the military held that a force beyond 18 g, or 18 times the pull of gravity, would be fatal. Air Force flight surgeon John Paul Stapp tested that on himself, riding rocket sleds that slammed to a stop. He cracked ribs and broke both wrists. On December 10, 1954, in New Mexico, he rode a sled called Sonic Wind to 632 miles an hour and stopped in little more than a second, enduring more than 40 g. Afterward he thought he had been permanently blinded, but his sight returned.
8The sea nomads whose spleens are built for diving
On the tile: Bajau divers2018
The Bajau, sometimes called sea nomads, have lived on houseboats off Indonesia, Malaysia and the Philippines for more than 1,000 years, diving for food with wooden goggles and homemade spearguns. In 2015, geneticist Melissa Ilardo took an ultrasound machine to a Bajau village in Indonesia and found their spleens about 50 percent larger than those of a neighboring land-based group, even among villagers who never dive. The spleen stores oxygen-carrying red blood cells for a breath-hold. Her team linked the difference to a gene called PDE10A.
In 1983, a 61-year-old potato farmer named Cliff Young entered the first Sydney to Melbourne ultramarathon, 875 kilometers long. He shuffled rather than ran and was known for training in gumboots. While other runners stopped to rest, Young kept going, and he won in five days, 15 hours and 4 minutes. According to his friend, ultramarathon historian Philip Essam, his coach mistakenly woke him three hours early on the first night, and when Young found himself ahead, he kept going that way. Other ultrarunners later adopted the Young shuffle.
Generations of students learned that the tongue has taste zones: sweet at the front, salty and sour on the sides, bitter at the back. It is wrong. Receptors for all of these tastes are spread across the tongue. The map traces to a 1901 paper by German scientist David Hänig, who found small differences in sensitivity around the tongue's edges. His graph showed each taste's changes relative to itself, not against the others. In the 1940s, Harvard psychologist Edwin Boring redrew it with no meaningful scale, and the neat zones were born.
The idea that people use only 10 percent of their brains is, as Johns Hopkins neurologist Barry Gordon told Scientific American, "so wrong it is almost laughable." No one knows exactly who started it. It has been linked to psychologist William James, who argued that we use only a small part of our possible mental resources, and it has also been attached to Albert Einstein. Brain imaging shows that over a day we use virtually all of the brain, an organ that makes up about 3 percent of body weight but uses about 20 percent of the body's energy.
3You do not lose most of your body heat through your head
On the tile: Body heat2008Myth busted
A 1970 US Army survival manual said that 40 to 45 percent of body heat is lost through the head. The idea likely came from 1950s military experiments in which volunteers wore Arctic survival suits that left only their heads uncovered, so that is where most of their heat escaped. In 2008, Indiana University researchers pointed out in the BMJ that if the claim were true, going without a hat would feel as cold as going without pants. Heat loss is roughly proportional to exposed skin, and the head is only about 7 percent of the body's surface.
A widely repeated claim says the bacteria in your body outnumber your own cells ten to one. It traces back to an old back-of-the-envelope calculation. In 2016, researchers Ron Sender, Shai Fuchs and Ron Milo counted again, using up-to-date data for a 154-pound reference man. They estimated about 38 trillion bacteria and 30 trillion human cells, the same order of magnitude, with all those bacteria weighing only about 0.2 kilograms, less than half a pound. Red blood cells turned out to be the largest share of our own cells.
A popular idea holds that people are left-brained or right-brained, depending on personality and thinking style. Some brain functions really are lopsided: language regions such as Broca's area are concentrated on the left, while parts of a network that controls attention lean right. But in 2013, University of Utah researchers analyzed resting brain scans from 1,011 people aged 7 to 29 and found no sign that some people have stronger left-brain or right-brain networks overall. Lateralization, they concluded, is a local property of brain networks, not a whole-brain type.
6Swallowed gum does not stay inside you for seven years
On the tile: Swallowed gumMyth busted
The childhood warning that swallowed gum stays inside you for seven years has little basis in fact, gastroenterologists told Scientific American. Gum base is largely indigestible, but the digestive tract's normal waves push it through, and it comes out "pretty unmolested," as pediatric gastroenterologist David Milov put it. If the legend were true, he said, colonoscopies would find years of gum, yet a swallowed piece usually turns out to be no more than a week old. People have chewed gum for a long time: tooth-marked lumps of birch bark tar survive from Stone Age Europe.
Biology classes often use tongue rolling as the classic example of a simple dominant gene. The idea goes back to geneticist Alfred Sturtevant, who described it that way in 1940. It did not hold up. Some children who cannot roll their tongues learn to later, and family studies found rolling children with two non-rolling parents. In 1952, a study of 33 pairs of identical twins found 7 pairs in which one twin could roll and the other could not. By 1965, Sturtevant said he was "embarrassed to see it listed in some current works as an established Mendelian case."
8You do not swallow eight spiders a year in your sleep
On the tile: Eight spidersMyth busted
The claim that people swallow eight spiders a year in their sleep is not true, spider experts told Scientific American. Spiders have no interest in us. As biologist Bill Shear put it, "Spiders regard us much like they'd regard a big rock." A sleeping person is also alarming to a spider: breathing, a beating heart and snoring all make vibrations, which warn spiders of danger. Rod Crawford of Seattle's Burke Museum says people tell him they swallowed one, but they never seem to have the evidence. It usually got flushed away.
Many parents are sure that sugar makes children bounce off the walls. A 2008 review of medical myths in the BMJ found at least a dozen high-quality studies on the question, and none showed a difference in behavior between children who ate a lot of sugar and those who did not. The belief may say more about the grown-ups. When parents think their children have been given a sugary drink, even one that is really sugar-free, they rate their children's behavior as more hyperactive.