50 Fun Facts About Gross

What do house dust mites mostly eat?

A single mite produces about 2,000 droppings in its ten-week life, and those droppings are the allergen, not the mite.

Detectable dust-mite allergen was found in the beds of roughly what share of surveyed US homes?

Europe fared a little better at 68 percent; the mites simply prefer humid places.

Demodex mites live in the hair follicles of your face. Roughly what share of elderly people carry them?

A small 2014 study found them on every adult tested; they eat skin cells and oil, and mate at the mouth of the follicle.

What is earwax mostly made of?

On average about 60 percent of it is keratin, the same protein as your hair and nails.

There are two genetically determined types of human earwax. What are they?

A single letter change in one gene decides it; the dry, flaky type is common in East Asia and among Native Americans.

Over 99% of a fart is odourless gas. What produces most of the smell in the remaining trace?

Hydrogen sulfide tracks most closely with how bad people rate the smell, followed by methyl mercaptan.

The scientific study of intestinal gas has what name?

Flatus, the medical word, covers gas from the stomach or bowels; a fair share of it is simply swallowed air.

Does everyone's flatulence contain the same greenhouse gas that cows belch?

In one study, only five of nine adults carried the microbes needed to make it.

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

Its name comes from the Greek skato-, meaning dung; diluted enough, it smells of flowers.

Roughly what percentage of urine is water?

The rest is mostly urea, plus salts and whatever pigments you ate; asparagus can turn it green.

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

Stale urine, called lant, supplied the ammonium salts that whitened cloth in the fulling trade.

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

Recent scholarship suggests it may have been a toilet brush after all; either way, the sponge was rinsed in vinegar and shared.

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

Under Henry VIII the job came with a bowl, water, towels and a duty to monitor the royal bowels; it was abolished only in 1901.

From the 12th century on, what was the apothecary medicine 'mummia' made from?

It began as a word for bitumen; when supplies ran short, dealers substituted whole embalmed bodies, and painters used the powder as 'mummy brown'.

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?

He wrote to The Times that near the bridges the muck 'rolled up in clouds so dense that they were visible at the surface'.

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

The scholar Yan Zhitui wrote that he dared not use paper bearing the names of sages 'for toilet purposes'.

How long can a bed bug survive without feeding?

That is why infestations are so hard to clear; Egyptian fossils show they have been biting people for 3,500 years.

Head lice and body lice are thought to have split into subspecies at what point in human history?

The genetic split, 30,000 to 110,000 years ago, is one of the odder clues to when we got dressed.

Cockroaches do not have lungs. What happens if one loses its head?

They breathe through spiracles along the body; some species can also go 45 minutes without air and a month without food.

Some cockroaches can survive on which unlikely food source?

The American cockroach also eats leather, book bindings, hair, dead insects and dirty laundry.

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

The pellets come from the caecum packed with vitamins and protein; a second pass through is the only way to absorb them.

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

It clogs a predator's gills; the hagfish then ties itself in a travelling knot to scrape the goo off its own body.

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

The habit is called urohidrosis; bird droppings are urine and faeces combined, so the liquid evaporates and chills the skin.

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

Their olfactory lobe is unusually large; the same compound is added to natural gas so humans can smell leaks.

Owls cough up fur and bones as pellets. How soon after a meal does a pellet form?

School dissections of unsterilised pellets have caused salmonella outbreaks, because rodent viruses survive the trip.

Several species of horned lizard defend themselves by squirting what from the corners of their eyes?

They can aim it about five feet, and it tastes terrible to dogs and coyotes, possibly thanks to a diet of venomous ants.

Fulmar chicks defend the nest by spraying attackers with what?

The name comes from Old Norse for 'foul gull'; the oil mats a predator's feathers so it cannot fly.

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

The bacterial fermentation gives it a manure-like smell, so locals hunt it only in dire need.

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

The physicists who worked out how won an Ig Nobel Prize.

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

Fresh, it smells faecal; aged, sweet and earthy. A 127 kg lump found off Yemen in 2021 was valued at $1.5 million.

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

The reaction heats the mix to near the boiling point of water and goes off with an audible pop.

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

They sink into honeycomb-like pockets in her skin and pop out four to five months later.

Which is the only botfly species whose larvae routinely grow inside human flesh?

The 'bot' in the name simply means maggot; the resulting lump under the skin is a warble.

Honey is made by bees repeatedly doing what to nectar?

Hive bees pass it mouth to mouth for up to 20 minutes, blowing bubbles to evaporate the water.

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

Carminic acid makes up about a fifth of a dried cochineal insect's weight; it was a major Spanish colonial export.

The 'confectioner's glaze' that makes candy shiny is shellac, a resin secreted by what?

The female lac bug secretes it on trees in India and Thailand; the same stuff finished Victorian furniture and coats supermarket citrus.

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

Wild-collected beans have sold for $1,300 a kilogram.

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

The larvae's digestion softens the cheese until it weeps a liquid called làgrima, 'teardrop'.

Iceland's national dish hákarl is shark that has been fermented and hung to dry for how long?

The ammonia smell is so strong that first-timers are told to pinch their nose and follow with a shot of Brennivín.

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

Swedish producers once won a royal decree banning sales of the new season's tins before the third Thursday in August.

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

Beaks and feathers go in too; the polar explorer Knud Rasmussen is said to have died from a bad batch.

What kind of substance cures a century egg?

The pH climbs to between 9 and 12 over weeks or months; the ammonia and hydrogen sulfide give the flavour.

The durian's smell is so strong that it is banned from hotels and public transport in which cities?

Fans call it the king of fruits; the smell can linger for days.

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

The animal sprays from its anal glands; the name has been an insult in English since 1841.

The ancient Egyptians revered the scarab beetle, believing it reproduced how?

They linked it to Khepri, god of the rising sun; the pupa's mummy-like shape may have added to the mystique.

Vampire bats feed only on what?

Three species do it, all in Central and South America.

Roughly how many non-human cells, mostly bacteria, live on and in your body compared with your own cells?

The old ten-to-one figure was a rough guess; newer estimates put the two counts in the same ballpark.

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

Pearlfish exploit this by living inside the sea cucumber's cloaca for shelter and food.

Naked mole-rats eat their own droppings partly to share and assess hormones from whom?

The habit also nourishes pups after weaning and is part of the species' eusocial behaviour.