98 Fun Facts About Gross

What do house dust mites mostly eat?

Flakes of human skin work their way deep into mattresses, pillows and sofas, so that is where the mites gather; most people meet them while asleep in bed.

House dust mites never bite, so what sets off most dust-mite allergies?

Proteins in their droppings, mostly leftover digestive enzymes, cause the reaction once breathed in; one national survey found the allergen in the beds of about four in five American homes.

Demodex mites are eight-legged relatives of spiders that spend their lives where on the human body?

In facial hair follicles, tucked out of sight: researchers could see the mites on only 14% of volunteers, yet DNA tests found them on every adult they checked.

What is earwax mostly made of?

Shed skin cells, rich in the protein keratin, make up most of it; the ear canal's skin creeps outward like a conveyor belt, and chewing or talking helps work the wax out.

Human earwax comes in which two genetically determined types?

Wet and dry earwax are set by a single letter of DNA in one gene; the dry version, common in East Asia, also leaves people with far less armpit odour.

Over 99% of a fart is odourless gas, so what produces most of the smell in the remaining trace?

Sulfur compounds, led by rotten-egg hydrogen sulfide, matched the scores when two judges sniffed samples for a 1998 study; a charcoal-lined cushion then soaked up over 90% of those gases.

Which medical term names the rumbling of gas moving through your intestines?

Borborygmus comes from a Greek word coined to imitate the noise itself. The rumble is gas being squeezed along the gut, and it is loudest when there is no food inside to muffle it.

What compound is the main source of the smell of faeces, yet is used in low doses in perfumes?

Skatole takes its name from the Greek for dung, yet at low concentrations it smells floral: it occurs naturally in jasmine and orange blossom, which is why perfumers use it.

Which waste compound does the liver make from the toxic ammonia left over when the body breaks down protein?

Urea is the body's safe way to dump spare nitrogen: ammonia would poison the brain if it built up, so the liver converts it and the kidneys flush the result away.

Because it was essential for cleaning wool, which body fluid was taxed in ancient Rome?

Urine left to go stale gave launderers the ammonia that cleaned wool. When his son Titus complained about the tax, Emperor Vespasian held a coin to his nose and asked if it smelled.

The 'sponge on a stick' found in Roman public latrines has traditionally been assumed to be what?

A shared bottom-wiping tool is the classic reading: Seneca mentions the sponge stick, and latrines kept salt water or vinegar to rinse it. Some scholars now argue it only scrubbed the toilet.

Which English court official helped the king on the toilet and became hugely powerful as a result?

The Groom of the Stool brought the bowl, water and towels, and the privacy paid off: he became the king's private secretary, kept his personal accounts and decided who got in to see him.

Which grisly apothecary medicine did European painters also buy as a brown pigment?

Ground-up Egyptian mummies were thought to hold healing bitumen. To keep the trade supplied, dealers later passed off the dried bodies of executed criminals as the real thing.

The "Great Stink" of 1858, when the smell of sewage forced Parliament to act, happened in which city?

Joseph Bazalgette's resulting sewer system still serves nine million Londoners today.

Which famous scientist tested the filth of the Thames in 1855 by dropping pieces of white paper into it?

Michael Faraday wetted the scraps so they would sink and dropped some in at every pier; they vanished from sight before sinking an inch. Punch then drew him handing his card to Father Thames.

The earliest recorded reference to toilet paper, from around 589 AD, comes from which country?

China had paper to spare centuries before Europe: the scholar Yan Zhitui wrote that he dared not use sheets bearing the names of sages for toilet purposes, and by the 14th century it was being mass-produced.

Bed bugs home in on a sleeping person mainly by body warmth and what else?

Carbon dioxide in breath draws bed bugs to a sleeper, along with body warmth. Dirt plays no part, so a spotless bedroom suits them as well as a filthy one.

Head and body lice are thought to have split at which point in human history?

When humans began wearing clothes, some lice moved off the scalp and into the fabric, where body lice live and lay their eggs. Their DNA is now one of the few clues to when people first got dressed.

Cockroaches have no lungs, so what happens if one loses its head?

It can keep breathing because air enters through small holes in each body segment and the brain plays no part. It does not bleed out either, so a headless cockroach can live on for days.

Some cockroaches can survive on which unlikely food source?

The glue on postage stamps is a meal to a cockroach, as are soap, toothpaste, hair and book bindings. Being cold-blooded, they can also go about a month with no food at all.

What do rabbits and guinea pigs do with the soft, sticky pellets called cecotropes that they produce?

Rabbits and guinea pigs eat them as soon as they appear: microbes in the caecum make B vitamins and protein too far down the gut to be absorbed, so a second trip through is the only way to collect them.

Hagfish slime swells to what multiple of its volume in under half a second?

10,000 times is the measured figure, as coiled threads unspool and trap seawater. The slime clogs a predator's gills, and the hagfish ties itself in a sliding knot to scrape the goo off its own body.

Storks and vultures cool down by doing what onto their own legs?

Defecating on their bare legs stands in for sweating, which birds cannot do: the liquid evaporates and carries heat away.

Turkey vultures find carcasses by smelling which gas given off by early decay?

Ethyl mercaptan is the same stink added to odourless fuel gas so people can smell a leak, and oil company engineers noticed turkey vultures gathering wherever a pipeline was leaking it.

In which muscular organ does an owl press leftover fur and bones into the pellet it coughs up?

The gizzard holds back the fur and bones that stomach acid can't dissolve and squeezes them into a lump of its own shape. Unlike hawks, owls have no crop, so prey drops straight into the stomach.

Which reptile defends itself by squirting blood from the corners of its eyes?

The horned lizard eats stinging harvester ants, and a compound from their venom is thought to end up in its blood, which would explain why the squirt tastes foul to dogs, coyotes and wild cats.

Fulmar chicks defend the nest by spraying attackers with what?

Foul-smelling stomach oil gave the fulmar its name, from Old Norse words for foul and gull. On a predatory bird it sets and mats the wing feathers, which can leave the attacker unable to fly.

The Amazon's hoatzin is nicknamed the 'stinkbird' because it does what?

It ferments leaves in its gut like a cow, the only bird that does, brewing them with bacteria in an oversized crop. The result reeks of fresh manure, and the bulky crop makes it a clumsy flier.

Wombats are the only animal known to produce droppings of what shape?

Cubes take shape in the last stretch of the wombat's gut, where stiff and soft bands of the wall squeeze at different speeds. The physicists who worked it out won an Ig Nobel Prize in 2019.

Ambergris, a prized perfume fixative, forms in the digestive system of which animal?

The sperm whale eats squid, and scientists think it coats their sharp beaks in a fatty gut secretion. Fresh, the lump smells faecal; years of sun and salt water turn it sweet and earthy.

Which two chemicals react to make the bombardier beetle's boiling spray?

Hydroquinone and hydrogen peroxide sit together harmlessly until the beetle squeezes them into a chamber of enzymes. The blast nears the boiling point of water and fires in rapid pulses, like a V-1 flying bomb.

The female Surinam toad carries her eggs where until fully formed froglets emerge months later?

Embedded in the skin of her back, each egg gets its own pocket with a lid. The male rolls them on as the pair somersault underwater, and her skin grows up around them within hours.

Which biting pest does the female human botfly catch and load with her eggs to reach a person?

A mosquito does the delivery: the botfly catches one, attaches her eggs to its belly and lets it go. When it lands on a person to feed, the eggs hatch and the larvae burrow into the skin.

Honey is made by bees repeatedly doing what to nectar?

Regurgitating it from bee to bee dries the nectar until it is only about 18 per cent water. At that point mould and bacteria can't grow in it, which is why honey doesn't spoil.

The red food colouring carmine (E120), used in yogurt, sweets and lipstick, is made from what?

Crushed insects, to be exact: female cochineals from the prickly pear cacti of Mexico, dried and ground. The Aztecs dyed with them, and once Spain shipped the dye home in the 1520s it displaced kermes, Europe's older insect red.

The 'confectioner's glaze' that makes sweets shiny is a resin secreted by which insect?

The lac bug crusts tree twigs in southern Asia with the resin, better known as shellac. Melted into flakes, the same stuff was pressed into 78 rpm gramophone records until vinyl took over.

Kopi luwak coffee is made from beans that have passed through which animal?

The Asian palm civet is said to pick only the ripest coffee cherries. The price brought a grimmer method: reporters have found civets kept in battery cages and force-fed the fruit.

Casu martzu, a Sardinian sheep's-milk cheese banned from sale, contains what?

Live fly maggots do the ripening: cheese flies lay eggs in cracks in the pecorino, and the grubs digest it into a soft, creamy paste. Sardinians eat it grubs and all.

Iceland's pungent delicacy hákarl is the fermented meat of which animal, toxic if eaten fresh?

Shark, specifically the Greenland shark, whose fresh flesh is toxic. Weeks of fermenting break the toxins down, and by the time the meat has hung to dry it reeks of ammonia.

Surströmming, said to be one of the most putrid-smelling foods on earth, is fermented what?

Baltic herring keeps fermenting inside the sealed tin until it bulges. In 2006 airlines including British Airways and Air France banned the cans as potentially explosive, to the fury of Swedish producers.

Kiviak, a Greenlandic winter dish, is made by fermenting up to 500 whole small birds inside what?

A seal skin is stuffed with little auks, beaks and feathers included, then sewn shut, sealed with fat and left under a heavy rock for months. It is eaten during the Arctic winter, often at celebrations.

What kind of substance cures a century egg?

An alkaline mix of clay, ash and lime does the job heat normally does: over weeks it sets the raw white into a dark, translucent jelly.

The durian's smell has got it banned from public transport and many hotels in which two cities?

Singapore and Bangkok both bar the fruit from public transport. In 2018 an Indonesian airliner sat on the tarmac until sacks of durian were hauled out of the hold, after passengers revolted at the smell.

The word 'skunk' comes from an Algonquian word combining 'fox' with what?

To urinate plus fox: the Algonquian name amounts to 'urinating fox'. English borrowed it in the 1630s and later made it a verb, so to skunk an opponent is to beat them without letting them score.

Plutarch wrote that Egypt's sacred scarabs, all male, reproduced how?

By depositing semen into a ball of dung, the story went, since no female beetles were thought to exist. The ball rolling along looked like the sun crossing the sky, so the scarab became Khepri, god of the rising sun.

Bacteria were once said to outnumber your own cells ten to one; what is the newer estimate?

About as many: roughly 38 trillion bacteria to 30 trillion human cells. Most of the bacteria sit in the colon, so the researchers noted that one trip to the toilet may tip the balance back to human.

Through which body opening do sea cucumbers 'breathe', drawing water into their respiratory trees?

The anus pumps water in and out, and that current gives the sea cucumber away. Slender pearlfish follow it, back in tail first and spend the day hiding inside, slipping out at night to feed.

Naked mole-rat workers turn into devoted babysitters after eating hormone-rich droppings from whom?

The colony's queen is its only breeding female, and while she is pregnant her droppings carry the hormone estradiol. Workers that feed on them grow more responsive to crying pups, just in time for the litter.

Which coral-crunching reef fish excretes the ground-up rock as fine white sand, helping to build tropical beaches?

Parrotfish scrape coral rock with beak-like teeth that never stop growing, digest the edible parts and pass the rest as sand, which piles up into beaches and even small islands.

Castoreum, a secretion once used in vanilla and raspberry flavourings, comes from sacs near the tail of which animal?

Beaver castor sacs ooze the yellowish goo that the animals use to mark territory; perfumers still prize it, but the food industry now gets through only about 100 kg a year.

Females of which predatory insect are notorious for sometimes eating their mates once mating is over?

Praying mantis females on poor diets are the likeliest to make a meal of a partner, yet in one species 83% of males still walk away from an encounter alive.

In which deep-sea fish does the tiny male bite onto a much larger female and sometimes fuse into her body?

Anglerfish males latch on with their mouths because mates are so rare in the deep; the first scientists to catch females mistook the attached males for parasites.

The prized Asian delicacy bird's nest soup is made from nests that swiftlets build out of what?

Their own saliva sets into the interwoven strands of the nest, and the best nests rank among the most expensive animal products people eat, at thousands of dollars a kilogram.

Despite the seafood name, the fried dish 'Rocky Mountain oysters' of the American West is made from what?

Bull testicles are skinned, coated in seasoned flour and deep-fried, sometimes after being pounded flat; Canadians know the same dish as prairie oysters.

Despite the myth about binge-eating Romans, what was a 'vomitorium' in an ancient amphitheatre really?

A crowd exit passage is all it ever was: the name comes from the Latin for 'to spew forth', because these corridors let spectators pour out of the stands at speed.

Fatbergs, the rock-like masses that clog city drains, form when cooking grease binds with which 'flushable' product?

Wet wipes do not break apart when flushed, so fat and oil set hard around them; one mass found under Whitechapel in 2017 weighed 130 tonnes, and part of it was turned into biodiesel.

The joeys of which Australian animal eat 'pap', a runny form of their mother's faeces, to prepare for a diet of leaves?

Koala mothers make the pap in the cecum, and it is packed with the microbes a joey needs before it can cope with eucalyptus, which is toxic to most other mammals.

Which giant Sumatran plant, whose flower spike can top three metres, smells of rotting flesh to lure carrion beetles?

Titan arum heats its spike to about human body temperature to pump out the stench in pulses, and the smell can be picked up as far as 800 metres away.

The parasite Cymothoa exigua enters a fish through its gills, then destroys and takes the place of which body part?

The tongue withers after the parasite clamps on and cuts off its supply, and the fish then uses the animal in its place like a prosthetic.

What kind of organism takes over carpenter ants, making them clamp onto a leaf before it sprouts from their heads?

A fungus called Ophiocordyceps steers the infected ant down to the humid forest floor, kills it within days and grows a stalk from its head to release spores.

The parasite Toxoplasma gondii makes infected rats lose their fear of, and even seek out the scent of, which animal?

Cats are the only animals in which the parasite can reproduce sexually, so a rat that strolls towards the smell of one is delivering it to exactly where it needs to be.

Some ants 'farm' which sap-sucking garden pests, guarding them in return for the sugary honeydew they excrete?

Aphids tended by ants are kept safe from predators such as ladybirds, and they respond by releasing their sugary waste in smaller, richer drops.

Many figs are pollinated by which tiny creature, the female of which dies inside the fruit and is digested by it?

A wasp that has laid her eggs and delivered her pollen dies inside the fig, whose own enzyme, ficain, then breaks down her body and absorbs the nutrients.

Which songbird, nicknamed the 'butcher bird', stores its kills by impaling them on thorns and barbed wire?

Shrike males do most of the impaling, and the grisly larder is thought to work mainly as a display that shows prospective mates how good a hunter and territory they would get.

Which African mammal oozes a red, oily fluid from its hide that works as both a sunscreen and an antiseptic?

Hippopotamus secretions get their colour from a pigment named hipposudoric acid; despite a much-repeated rumour, the red tint does not turn the animal's milk pink.

Which tree-dwelling rainforest mammal climbs down to the ground only about once a week to relieve itself?

Three-toed sloth toilet trips are tidy affairs: the animal digs a hole for its waste and covers it over afterwards, then heads back up into the canopy for another week.

When attacked, some sea cucumbers defend themselves by shooting what out of their bodies?

Their internal organs, chiefly the intestine, are thrown out to scare off crabs and fish, and the animal regenerates a full new set within a few weeks.

Parasitic horsehair worms growing inside a cricket eventually drive the cricket to do what fatal thing?

The worm makes its host seek out water and drown itself because the adult parasite lives and mates in fresh water, where it wriggles free of the body.

Which prized Roman sauce was made by salting fish innards and leaving them out in the sun?

Garum gave food a savoury umami hit much as soy sauce does now, and Pliny noted that the sludge left over from making it became a fish paste of its own, called allec.

In Tudor England, which night-shift worker dug out the human waste from household privies?

Gong farmer was a job allowed only after dark because the public found it so off-putting, and 'gong' was the word for both a privy and what it held.

In the 'Cadaver Synod' of 897, what did Pope Stephen VI do with the dug-up corpse of Pope Formosus?

Stephen VI put it on trial some nine months after Formosus died, found the corpse guilty and voided his papacy; a later synod banned trying the dead ever again.

In the Erfurt disaster of 1184, about sixty nobles died when a floor gave way and dropped them into what?

A cesspit lay under the hall where King Henry VI was holding court; the combined weight of the gathering broke the floor, and some of the nobles perished in the human waste beneath.

Which godson of Elizabeth I designed an early flushing toilet, long before the plumber Thomas Crapper was born?

John Harington called his device the Ajax, a pun on 'jakes', the slang of the day for a toilet, and the cheeky book he wrote about it got him banished from the queen's court.

Wealthy ancient Romans fattened which small rodents in terracotta jars before serving them as a delicacy?

Dormice were shut in a dark, lidded jar called a glirarium that tricked them into hibernating and piling on fat, then served dipped in honey and poppy seeds.

An 1856 US law lets American citizens claim unoccupied islands for the nation if they hold deposits of what?

Guano, the built-up excrement of seabirds and bats, was so prized as a fertiliser that the 'guano mania' of the 1850s pushed Congress into passing the act.

Which trade once softened its raw material by pounding dog or pigeon excrement into it?

Leather tanning relied on enzymes made by microbes in the muck to make hides supple, a step known as bating; modern tanneries use purified enzymes instead.

After Albert Einstein died, which part of him was kept for over twenty years in mason jars inside a cider box?

His brain was taken out by the pathologist Thomas Harvey, apparently without the permission of Einstein or his family, and cut into about 240 small blocks for study.

Which philosopher asked for his body to be dissected, then preserved and put on display as an 'auto-icon'?

Jeremy Bentham left written instructions before he died in 1832, and even suggested that country gentlemen could line their driveways with varnished auto-icons of their relatives.

Isinglass, long used to clear the haze from cask ales and wine, is made from which dried part of a fish?

The swim bladder, once dried and processed, makes the yeast in a cask clump into a jelly-like mass that sinks to the bottom; the name probably comes from an old Dutch word for sturgeon bladder.

Balut, a boiled egg eaten from the shell with its developing embryo inside, usually comes from which bird?

Duck eggs are incubated for two to three weeks before cooking, and fans disagree on timing: some want the embryo still mostly liquid, others old enough to have soft bones.

Which country's orange Mimolette cheese gets its grey rind from mites deliberately added to its surface?

France makes Mimolette around Lille, where it began as a take on Dutch Edam; in 2013 US inspectors held up a ton of it for carrying more than six mites per cubic inch.

In which country is huitlacoche, maize swollen into grey galls by a smut disease, prized as a delicacy?

Mexico uses the tumour-like galls, which can swell to four or five inches across, as a filling for quesadillas and in soups; it has been pitched to wary Americans as the 'Mexican truffle'.

Beondegi, a Korean street snack served steaming in paper cups, consists of the boiled pupae of which creature?

Silkworm pupae are what is left once the silk has been unwound from the cocoons, and the snack spread across South Korea when silk production boomed after the Korean War.

In which Southeast Asian country are fried tarantulas a famous roadside snack, especially in the market town of Skuon?

Cambodia's vendors fry a palm-sized species that is bred in holes in the ground or foraged from nearby forest, and Skuon's spider stalls have become a tourist attraction.

Which tiny songbird do gourmets traditionally eat whole while hiding their heads under a large napkin?

Ortolan diners are said to hide in order to shield their shame from God, though others say the napkin simply traps the aroma; France banned hunting the bird in 1999.

Scandinavian lutefisk gets its jelly-like texture because the dried cod is steeped for two days in what?

Lye leaves the cod so caustic, with a pH of 11 to 12, that it cannot be eaten until it has spent another four to six days soaking in cold water that is changed daily.

On a restaurant menu, 'sweetbreads' are neither sweet nor bread but which parts of a calf or lamb?

Thymus and pancreas are the two glands sold under the name; the thymus kind comes only from young animals, because in older ones the gland is replaced by fibrous tissue.

Gelatin, the wobble in gummy sweets and marshmallows, is made by breaking down which protein from animal hides?

Collagen for the food industry comes mostly from pigskin, split cattle hides and bones, which are washed, stripped of hair and degreased before the protein is broken down.

Researchers in Amsterdam calculated that a ten-second intimate kiss passes roughly how many bacteria between partners?

80 million was the average, worked out by giving one partner in each couple a probiotic yoghurt drink and counting how many of its marker microbes reached the other's mouth.

Doctors sort human faeces into seven types, from hard lumps to watery, using a scale named after which English city?

Bristol Royal Infirmary doctors devised the chart in 1997; types 3 and 4, both likened to a sausage, are the ideal, and type 4 has been nicknamed the 'perfect poop'.

The sharp 'chlorine smell' of a busy swimming pool comes mostly from chlorine reacting with what?

Swimmers' sweat and pee carry nitrogen compounds that chlorine turns into chloramines, and those, not the chlorine itself, cause the smell, the stinging eyes and the irritated airways.

Whose middle finger sits in a gilded glass egg on display at a science museum in Florence?

Galileo Galilei lost the finger, along with a thumb, a tooth and a vertebra, to admirers who took them when his remains were moved to a grand tomb 95 years after his death.

What name is given to a newborn's first bowel movement, a sticky, tar-like, dark green substance?

Meconium is made of what the baby swallowed in the womb, including cells from the gut lining, fine body hair and amniotic fluid, and unlike later nappies it is almost odourless.

The closest relative of the human pubic louse lives on which great ape, from whose lice ours split in prehistory?

Gorillas carry Pthirus gorillae, which parted ways with our own species some 3.3 million years ago; our head and body lice belong to a different genus, closer to those of chimps.

A bacterium behind smelly feet, Brevibacterium linens, also gives which notoriously pungent cheese its smell?

Limburger starts out firm and crumbly like feta and only develops its notorious smell at about three months, once the same microbe that thrives on human feet has done its work.

Which pigment, an end product of worn-out red cells being broken down, gives human faeces their brown colour?

Stercobilin is so dependable a sign of faeces that scientists test river water for it to measure faecal pollution; it was first isolated in 1932.

In 1876, what fell from the sky over a Kentucky farm for several minutes, an event later blamed on vultures?

Chunks of red meat landed around a woman making soap on her porch; locals favoured the theory that a passing flock had thrown up its last meal, as the birds do when startled.

Which substance, nicknamed 'grave wax', can form in a corpse buried in wet, airless ground?

Adipocere was first described in 1658 by Sir Thomas Browne, who examined a body ten years in a churchyard and found its fat set as hard as castile soap.