148 Fun Facts About Health and Wellness

The famous "10,000 steps a day" target originated where?

It began as a Japanese pedometer marketing campaign: clockmaker Yamasa sold the manpo-kei, or 'ten-thousand step meter', from 1965, and the round number stuck without any clinical basis.

Which structure in the hypothalamus acts as the body's master circadian clock?

The suprachiasmatic nucleus, a cluster of about 20,000 neurons sitting above the optic chiasm, synchronises the body's circadian rhythms to light signals arriving from the retina.

How many minutes of moderate aerobic activity per week does the WHO recommend for adults at minimum?

WHO's 2020 guidelines advise adults to do at least 150 minutes of moderate aerobic activity a week, or 75 minutes of vigorous activity, plus muscle-strengthening on two or more days.

WHO's 2024 study found roughly what share of adults worldwide fall short of recommended activity levels?

The answer is 31%: WHO's 2024 study in The Lancet Global Health found about 1.8 billion adults insufficiently active in 2022, while around 80 percent of adolescents fell short.

How many hours of sleep per night does the National Sleep Foundation recommend for adults aged 18 to 64?

The National Sleep Foundation's 2015 guidance recommends 7 to 9 hours for adults aged 18 to 64; newborns are advised 14 to 17 hours and over-65s 7 to 8.

A full cycle of non-REM and REM sleep takes, on average, how long?

A full non-REM plus REM cycle lasts about 90 minutes and repeats four to six times a night, with more deep sleep early and more REM towards morning.

REM sleep is nicknamed what, since the brain acts awake while the body is paralysed?

Michel Jouvet named REM 'paradoxical sleep' in 1959 because the brain's activity resembles waking while muscles are paralysed; Aserinsky and Kleitman had first linked REM to dreaming in 1953.

Which hormone, secreted by the pineal gland at night, regulates the sleep-wake cycle?

Melatonin is the pineal hormone that rises in darkness; dermatologist Aaron Lerner isolated it in 1958 from cow pineal glands while hunting for a substance that lightened frog skin.

The word "circadian" comes from Latin words meaning what?

Circadian comes from Latin circa diem, 'about a day', coined by Franz Halberg in 1959; in 1729 Jean-Jacques de Mairan showed a mimosa kept its daily leaf rhythm in constant darkness.

How long does a "power nap" typically last?

A power nap is 10 to 30 minutes: short enough to avoid deep sleep and grogginess. A 1995 NASA study found a brief cockpit nap raised pilots' alertness by 54 percent.

NASA research found that a nap of what precise length improved pilot alertness by 54 percent?

The 1995 NASA study led by Mark Rosekind found a 26-minute cockpit nap improved pilots' alertness by 54 percent and performance by 34 percent; longer naps risk sleep inertia.

In healthy adults, caffeine's half-life is roughly how long?

Caffeine's half-life in healthy adults is about 3 to 7 hours (typically near 5); it roughly doubles in women on oral contraceptives and falls 30 to 50 percent in smokers.

Caffeine keeps you awake by blocking receptors for which sleep-promoting molecule?

Caffeine is an adenosine receptor antagonist: adenosine builds up during waking hours and signals sleepiness, and caffeine's similar shape lets it occupy those receptors without activating them.

Health Canada advises healthy adults to consume no more than how much caffeine per day?

Health Canada's limit for healthy adults is 400 mg of caffeine a day, roughly three 8-oz mugs of brewed coffee; a 2017 systematic review of caffeine toxicology found that intake safe.

The WHO says free sugars should make up less than what share of total daily energy intake?

WHO's 2015 guideline puts free sugars below 10% of total energy, about 50 grams or 12 level teaspoons a day, adding that going under 5 percent may bring further benefits.

According to the WHO, adults should limit salt to less than how many grams a day?

Five grams of salt is about a teaspoon and equates to 2 grams of sodium.

How many grams of fruit and vegetables a day does the WHO set as a minimum?

WHO advises at least 400 g of fruit and vegetables a day, excluding starchy roots such as potatoes; that figure is the origin of 'five a day' in roughly 80-gram portions.

According to the WHO, no more than what share of total energy should come from trans fat?

WHO caps trans fat at under 1% of total energy and saturated fat at 10%; its 2018 REPLACE initiative aimed to eliminate industrial trans fat by the end of 2023 and fell short.

From June 2018, the US banned which main industrial source of trans fat from food?

The FDA had ruled in 2015 that partially hydrogenated oils were not generally recognised as safe.

Which hormone from the posterior pituitary makes the kidneys reabsorb water?

Vasopressin, also called antidiuretic hormone, is released from the posterior pituitary when the body is dehydrated and makes the kidneys' collecting ducts reabsorb water, concentrating the urine.

Drinking far too much water can dilute blood sodium into a dangerous condition called what?

Hyponatremia is dangerously low blood sodium; water intoxication from overdrinking is why US Army guidance caps fluid intake at about 1 to 1.5 litres per hour during heavy sweating.

Which of these can humans NOT make themselves, because the gene for the final enzyme is broken?

Humans cannot make Vitamin C because the GULO gene for the final enzyme is broken; guinea pigs and most bats share the defect, which made guinea pigs the classic scurvy lab animal.

Which naval surgeon showed in 1747 that citrus fruit treats scurvy, in an early controlled clinical trial?

James Lind, aboard HMS Salisbury in 1747, gave pairs of scurvy patients cider, vitriol, vinegar, seawater, a spice paste or oranges and lemons; only the citrus pair recovered quickly.

Which 'vitamin' is technically a misnomer, being a secosteroid hormone the skin makes from sunlight?

For most people skin synthesis under UVB light contributes more than diet; US milk is fortified with it.

Which nutrient is a coordination complex built around an atom of cobalt?

Vitamin B12 is built around a single cobalt atom, hence its chemical name cobalamin; Dorothy Hodgkin worked out its structure by X-ray crystallography in 1956.

Which omega-3 fatty acid is essential because the body cannot synthesise it?

ALA, alpha-linolenic acid, is the essential omega-3: animals lack the enzymes to make it and convert only a small fraction into the longer-chain EPA and DHA found in oily fish.

Which nutrient is defined as the part of plant food that human digestive enzymes cannot fully break down?

Dietary fibre is the plant material that resists human digestive enzymes; it comes in soluble forms such as pectin and insoluble forms such as cellulose, and wheat bran is roughly 40 percent fibre.

In which year did UNESCO inscribe the Mediterranean diet as Intangible Cultural Heritage?

UNESCO inscribed the Mediterranean diet on its Intangible Cultural Heritage list in 2010, nominated by Spain, Greece, Italy and Morocco; Cyprus, Croatia and Portugal were added in 2013.

Which scientist coined the term 'body mass index' in a 1972 paper?

Ancel Keys coined 'body mass index' in a 1972 Journal of Chronic Diseases paper; the underlying weight-over-height-squared ratio was devised in 1832 by Belgian astronomer Adolphe Quetelet.

A body mass index of 30 or more puts an adult in which BMI category?

Obese begins at 30; overweight runs from 25 to 29.9 and underweight is anything under 18.5.

Which so-called 'stress hormone' peaks in the early morning around the time of waking?

Cortisol's morning surge is called the 'cortisol awakening response'; made mainly in the adrenal cortex, it raises blood sugar and damps the immune system.

Which Harvard cardiologist coined the term 'relaxation response' in 1975?

Herbert Benson, a Harvard cardiologist, coined 'relaxation response' in his 1975 bestseller of that name after measuring lowered oxygen consumption and heart rate in meditators.

The United Nations set the International Day of Yoga, first held in 2015, on which date?

The UN chose 21 June, the northern-hemisphere summer solstice, after India's proposal in 2014; the first International Day of Yoga was observed in 2015.

How long do the WHO and CDC say you should scrub your hands with soap?

Both WHO and the CDC say to scrub with soap for at least 20 seconds, about the time it takes to hum 'Happy Birthday' twice; the CDC adds that water temperature makes little difference.

On which date is World Hand Hygiene Day, launched by the WHO in 2009?

World Hand Hygiene Day falls on 5 May; the WHO launched it in 2009 with its 'SAVE LIVES: Clean Your Hands' campaign. The separate Global Handwashing Day is 15 October.

An SPF 15 sunscreen means what fraction of burning UV radiation reaches the skin?

SPF 15 lets about one fifteenth, roughly 7 percent, of burning UVB reach the skin, blocking about 93 percent; SPF 30 blocks about 97 percent, and any sunscreen needs reapplying.

Which chemist is credited with introducing the sun protection factor (SPF) scale?

Franz Greiter, the Austrian chemist behind the Piz Buin brand, is credited with introducing the SPF scale; his own 1946 Gletscher Crème has been estimated at an SPF of about 2.

A sunscreen labelled "broad-spectrum" protects against which two types of radiation?

'Broad-spectrum' means protection against both UVA and UVB; the SPF number measures only UVB, the burning rays, while UVA penetrates deeper and drives skin ageing.

What does the science say about cracking your knuckles and arthritis?

There is no evidence of a link: a 2011 study of 215 people found knuckle-cracking made no difference to hand arthritis rates, however often or for how long they cracked.

Dr Donald Unger won a 2009 Ig Nobel Prize for cracking the knuckles of one hand only, for how long?

Donald Unger cracked the knuckles of his left hand at least twice a day for more than 50 years, about 60 by the 2009 award, and neither hand developed arthritis.

What is the medical name for the wear-and-tear arthritis that erodes joint cartilage?

Osteoarthritis is the wear-and-tear form in which joint cartilage breaks down; it is the most common type of arthritis, usually affecting knees, hips and hands.

What are regions of unusual longevity, like Okinawa and Sardinia's Nuoro province, called?

Blue zones got their name from the blue pen demographers Gianni Pes and Michel Poulain used to circle Sardinia's longest-lived villages on a map in the early 2000s.

Which Greek island is counted among the five Blue Zones?

Ikaria, a Greek island in the eastern Aegean, is one of the five Blue Zones; its reputed longevity is credited to a diet of greens, beans and olive oil, daily naps and strong community ties.

Which Costa Rican peninsula is counted among the original longevity regions?

The Nicoya peninsula on Costa Rica's Pacific coast is one of the five Blue Zones; Osa and Papagayo are other Costa Rican coastal areas, and Azuero is in Panama.

Who introduced the longevity-region concept in 2005 and later formed a company to promote it?

Dan Buettner wrote the 2005 National Geographic cover story 'The Secrets of a Long Life' and founded Blue Zones LLC; Adventist Health bought the company in 2020.

Which Nobel laureate founded probiotic theory, citing yoghurt-eating Bulgarian peasants?

Élie Metchnikoff, the 1908 Nobel laureate, argued in The Prolongation of Life that lactic bacteria in Bulgarian peasants' yoghurt explained their longevity; Lactobacillus bulgaricus had been isolated in 1905.

How does the WHO define probiotics?

Live microorganisms that benefit the host 'when administered in adequate amounts', per a 2001 WHO definition; prebiotics, by contrast, are the fibres that feed them.

What is the American Academy of Pediatrics' daily screen-time limit for children aged 3 to 5?

The AAP's 2016 guidance limits children aged 2 to 5 to 1 hour a day of high-quality programming, ideally co-viewed; a 2019 JAMA Pediatrics study linked heavier screen use to slower white-matter development.

During slow-wave (deep) sleep, humans secrete bursts of what?

Growth hormone is released in pulses during slow-wave sleep, the largest of the day coming soon after sleep onset; all sleep, even a nap, also triggers prolactin release.

In quiet waking, roughly what share of the body's energy does the brain use?

The brain uses about 20% of the body's resting energy despite being roughly 2 percent of its mass; use falls markedly during non-REM sleep, when the brain restocks its ATP.

How many stages does the American Academy of Sleep Medicine divide non-REM sleep into?

Since 2007 the AASM has used 3 non-REM stages, N1, N2 and N3, merging the old stages 3 and 4; a normal night runs N1, N2, N3, back to N2, then REM.

What resting heart rate range does the American Heart Association call normal for adults?

Normal resting heart rate is 60 to 100 bpm: above 100 at rest is tachycardia and below 60 bradycardia, though ultra-trained endurance athletes may rest near 40.

Blood pressure is conventionally measured in which unit?

Millimetres of mercury (mmHg) recall the mercury column of the classic gauge; the AHA counts normal resting pressure as under 120/80, and the gap between the two numbers is the pulse pressure.

Which German physician's 1868 book fixed 37 °C as the 'normal' human body temperature?

Carl Wunderlich's 1868 book, drawing on over a million readings from some 25,000 patients, fixed 37 °C as normal; later studies have found the average runs a few tenths lower.

A 2020 Stanford study put the average human body temperature at roughly what?

About 36.4 °C, or 97.5 °F: the 2020 Stanford analysis of US records back to the 1860s found average body temperature had fallen below the 19th-century 37 °C standard.

On alternate-day fasting, a 'fast day' means eating under what share of your usual energy needs?

25% of usual energy, on alternating days; other methods include the 5:2 diet and time-restricted eating within a set window of hours.

Which New Orleans dentist is credited with inventing dental floss, recommending waxed silk thread in 1819?

Levi Spear Parmly, a New Orleans dentist, recommended waxed silk floss in his 1819 book A Practical Guide to the Management of the Teeth; Codman and Shurtleff first sold unwaxed silk floss in 1882.

The word 'endorphin' is a contraction of which two-word phrase?

Endorphin contracts 'endogenous morphine', the body's own opioid; John Hughes and Hans Kosterlitz at the University of Aberdeen identified the first such peptides, the enkephalins, in 1975.

Long static stretching before exercise is discouraged as it can temporarily reduce what?

Long static stretches temporarily reduce strength and peak performance, a 2013 meta-analysis found, regardless of age, sex or training status, so a dynamic warm-up is recommended before exercise.

Which school's researchers created the sports drink Gatorade in 1965?

Researchers at the University of Florida led by Robert Cade created Gatorade in 1965 after coach Ray Graves asked for something to replace what his sweating Gators were losing.

Red Bull was developed from which Thai energy drink?

Krating Daeng is itself modelled on Japan's Lipovitan, and its name simply means Red Bull in Thai.

Which UK holiday firm first declared a January 'Blue Monday' in a 2005 press release?

Sky Travel's 2005 press release invented Blue Monday with a formula attributed to Cliff Arnall; it was a marketing stunt, and the equation has been widely mocked as pseudoscience.

Since 2007 the EU has barred marketing foods under which buzzword unless an approved health claim backs it up?

'Superfood' is a marketing invention with no scientific definition, which is exactly why regulators decided it needed evidence behind it.

The world's first food pyramid was published in 1974 in which country?

Sweden's cooperative KF published the first food pyramid in 1974, devised by Anna-Britt Agnsäter after a 1972 push to identify cheap, nutritious basics during high food prices.

In 2011 the USDA ended 19 years of pyramids by switching to which nutrition guide?

MyPlate replaced the pyramid in June 2011: a plate split into fruit, vegetable, grain and protein sections with a dairy cup beside it, replacing the 2005 MyPyramid.

Who introduced the term 'glycemic index' in 1981?

Jenkins devised it at the University of Toronto to rank how quickly carbohydrate foods raise blood glucose after a meal.

In conventional medicine, the ketogenic diet is used mainly to treat what in children?

The ketogenic diet has treated drug-resistant epilepsy in children since the 1920s; around half of those who try it see seizures fall by at least half, and the benefit can persist after stopping.

The CDC recommends hand sanitiser with at least what alcohol content?

Concentrations from 60% up to 95% work best; much stronger and the alcohol evaporates before it can kill germs.

Long-term exposure above roughly what sound level can cause permanent hearing loss?

85 dB is about the level of heavy city traffic, which is why US employers must start hearing-conservation programmes at that point.

Under the '20-20-20 rule' for screen strain, how far away should you look every 20 minutes?

20 feet, roughly six metres, for 20 seconds relaxes the focusing muscles and eases the symptoms grouped as computer vision syndrome.

Roughly what share of adults worldwide have lactose malabsorption?

About 65% of adults worldwide have lactose malabsorption; losing lactase after childhood is the ancestral human state, and lifelong tolerance is a recent mutation in populations with a dairying history.

More than how many virus types are associated with the common cold?

More than 200 virus types cause colds; rhinoviruses alone account for roughly 30 to 80 percent and come in over 100 serotypes, which is why no vaccine exists.

Meatless Monday was relaunched in 2003 as a public-health campaign with which university?

Ad man Sid Lerner relaunched Meatless Monday in 2003 with the Johns Hopkins Bloomberg School of Public Health, aiming to help Americans cut saturated fat intake by 15 percent.

The Veganuary pledge to eat vegan for a month was first held in which year?

Veganuary was first held in January 2014, launched by Jane Land and Matthew Glover with about 3,300 sign-ups; it grew into a global pledge run by the UK-based charity of the same name.

On which date is World No Tobacco Day observed each year?

World No Tobacco Day falls on 31 May every year; the World Health Assembly created it in the late 1980s, after a one-off no-smoking day in 1988, to spotlight preventable tobacco deaths.

World Health Day, marked since 1950, falls on which date?

7 April was chosen by the First World Health Assembly in 1948, and each year's edition carries a different theme.

Which swimmer's purple cupping bruises drew worldwide attention at the 2016 Rio Olympics?

Michael Phelps's back gave the ancient suction therapy a publicity boost, though evidence for any benefit remains weak.

The word 'siesta' comes from a Latin phrase for which hour, counting from dawn?

Siesta derives from hora sexta, the sixth hour after dawn, which put the rest around midday; Spanish influence spread the nap across Latin America and the Philippines.

'Sauna culture in Finland' joined UNESCO's intangible heritage list in which year?

Finland's sauna culture was inscribed in December 2020, the country's first entry on UNESCO's intangible heritage list; Estonia's Võromaa smoke sauna tradition got there in 2014.

Transcendental Meditation was developed by which teacher?

Maharishi Mahesh Yogi began teaching the silent-mantra technique in India in 1955 and toured the world from 1958; The Beatles' 1968 stay at his Rishikesh ashram made it famous.

Dutch cold-exposure athlete Wim Hof is known by what nickname?

The Iceman has held Guinness records for swimming under ice and for running a barefoot half marathon on snow.

In the kombucha starter called a SCOBY, what does the 'B' stand for?

Bacteria and yeast form the symbiotic culture; the rubbery disc, nicknamed the 'mother' or 'mushroom', ferments sweet tea.

Who founded the 1979 Stress Reduction Clinic behind mindfulness-based stress reduction?

Jon Kabat-Zinn founded the Stress Reduction Clinic at the University of Massachusetts Medical Center in 1979; its eight-week programme is described in his 1990 book Full Catastrophe Living.

Teenager Randy Gardner's famous 1964 sleep-deprivation record kept him awake how long?

Gardner stayed awake 264 hours, just over 11 days, in January 1964, monitored by Stanford's William Dement; afterwards he slept under 15 hours and recovered without lasting harm.

Which hormone, produced mainly in the stomach, is nicknamed the 'hunger hormone'?

Ghrelin, secreted mainly by the stomach, rises before meals and falls after; its name nods to the root 'ghre', to grow, since it also stimulates growth-hormone release.

In 1847 Ignaz Semmelweis told Vienna doctors to wash their hands in what?

Semmelweis ordered handwashing in chlorinated lime solution in 1847; the doctors' clinic had about three times the maternal death rate of the midwives', and mortality collapsed, yet his peers rejected him.

Under the 2017 US guidelines, stage 1 hypertension begins at which resting blood pressure?

Stage 1 hypertension starts at 130/80 under the 2017 ACC/AHA guidelines; normal is under 120/80, 'elevated' is 120 to 129 over under 80, and stage 2 starts at 140/90.

Which psychologist introduced the term 'burn-out' in a 1974 paper on staff exhaustion?

Herbert Freudenberger, a German-born American psychologist, coined 'burn-out' in 1974 from his own exhaustion at a New York free clinic; the WHO's ICD-11 classed burnout as an occupational phenomenon in 2019.

The burpee, invented in 1939 as a fitness test, is named after a man of what profession?

Royal H. Burpee, a New York physiologist, devised the move for his 1939 Columbia University doctoral thesis as a four-count fitness test; the push-up and jump were added later by others.

The Couch to 5K running plan builds from nothing to a 5 km run over how many weeks?

Josh Clark's 1996 Couch to 5K plan takes nine weeks of three runs a week, building from run-walk intervals to a 30-minute run; the NHS later adopted it as a free app.

American Charles Osborne's record-setting attack of hiccups lasted how long?

Osborne hiccupped for 68 years, from 1922 to 1990, an estimated 430 million hiccups; they stopped about a year before he died in 1991.

Sir William Cubitt introduced the treadmill in 1818 for use in which institutions?

Cubitt's 1818 treadwheel was built for prisons: inmates at Bury St Edmunds gaol climbed an endless staircase to grind grain and cure their 'idleness', and Brixton installed one in 1821.

Russian kettlebells are traditionally weighed in which unit, equal to about 16.4 kg?

The pood, about 16.4 kg, is the traditional kettlebell unit; the girya began life as a counterweight for weighing crops in 18th-century Russian markets before strongmen picked it up.

The WWII rumour that carrots gave RAF pilots night vision was spread to hide what?

The story hid the RAF's new airborne radar, crediting ace John 'Cat's Eyes' Cunningham's night kills to carrots; carrots supply vitamin A, but not enough to see in the dark.

Joseph Pilates originally called his exercise method what?

His 1945 book Return to Life through Contrology frames it as an art of controlled movement, not a therapy.

Which US Air Force physician's 1968 book Aerobics kicked off the modern fitness boom?

Kenneth Cooper was puzzled that strong men often fared badly at running and swimming, and built a points system around endurance instead.

Jane Fonda's Workout, the first non-theatrical video ever to top home-sales charts, was released in which year?

The 1982 tape was based on a routine by Leni Cazden and sold alongside a book and a double-LP record.

Parkrun began in 2004 as a free Saturday time trial in which London green space?

Bushy Park's 13-runner time trial, organised by Paul Sinton-Hewitt, grew into a worldwide weekly 5K with millions of registered runners.

Which soft drink did Atlanta pharmacist John Pemberton launch in 1886 as a patent medicine for headaches?

Coca-Cola began as a non-alcoholic rewrite of Pemberton's French Wine Coca, forced on him by Atlanta's new temperance law. He sold the rights shortly before he died in 1888.

Which Bee Gees hit do first-aid trainers use to time CPR because its beat matches the recommended rhythm?

Stayin' Alive runs at about 103 beats per minute, inside the 100 to 120 chest pushes a minute that rescuers are taught. Trainees who learn with the tune also remember the skill better months later.

Which animal appears on the staff at the centre of the World Health Organization's emblem, an ancient Greek symbol?

The snake belongs to Asclepius, the Greek god of healing, whose cult made use of live snakes. The WHO shows it coiled round his staff, set over the United Nations' map of the world.

'Sphenopalatine ganglioneuralgia' is the scientific term for which brief pain, common in migraine sufferers?

Brain freeze fades within a couple of minutes, and pressing the tongue against the roof of the mouth to warm it is the standard trick for hurrying it along.

Which antibiotic, found by chance in 1928, was turned into a usable drug by Howard Florey's team at Oxford?

Penicillin turned up when mould spoiled one of Alexander Fleming's culture plates, but it stayed a curiosity until the Oxford team purified it in 1940. Fleming, Florey and Ernst Chain shared a Nobel Prize.

Which breakfast cereal was created for patients at John Harvey Kellogg's Battle Creek Sanitarium in Michigan?

Corn flakes later split the Kellogg brothers: Will wanted to add sugar and sell them to the public, while John, the sanitarium's health-reforming doctor, was opposed.

Which German word, borrowed into American English, literally means 'health'?

Gesundheit is what German speakers say after a sneeze. Spanish 'salud' and Italian 'salute' work the same way, wishing the sneezer well rather than blessing them.

Arctic explorers have been poisoned by eating polar bear liver, which holds a toxic overdose of which nutrient?

Vitamin A builds up in the organs of top Arctic predators, which is why Inuit hunters have long refused to eat the liver of a polar bear or a bearded seal.

Which medicine-cabinet staple did Johnson & Johnson cotton buyer Earle Dickson invent for his accident-prone wife?

Band-Aid began in 1920 as squares of gauze that Dickson spaced along a roll of tape, so his wife Josephine could dress her own kitchen cuts. The idea made him a company vice president.

Which word for isolating the sick comes from the forty days that ships had to wait off plague-era Venice?

Quarantine comes from the Venetian 'quarantena', meaning forty days. Crews and cargo arriving from plague ports had to sit out the wait at anchor before anyone could come ashore.

Florence Nightingale earned the nickname 'the Lady with the Lamp' nursing British soldiers in which war?

In the Crimean War, her hospital at Scutari lost ten times more soldiers to illnesses such as typhus than to battle wounds. Nightingale showed it in charts and became the Royal Statistical Society's first female member.

Which disease, the only human one ever wiped out, did the World Health Organization declare eradicated in 1980?

Smallpox infects only humans in nature, so a global vaccination drive left it nowhere to hide: the last natural case came in 1977. The only other eradicated disease, rinderpest, struck cattle.

Which substance, at about 96 per cent mineral, is the hardest in the human body?

Enamel has no way to regenerate, so a chipped or worn tooth cannot grow its coating back the way a broken bone knits itself together.

Which painkiller, sold by Bayer since 1899, is a synthetic cousin of a compound found in willow bark?

Aspirin was Bayer's brand name for acetylsalicylic acid, but the company lost or sold its rights to the trademark in many countries, which is why any maker there can use the word.

Which form of radiation did Wilhelm Röntgen discover in 1895 and use to photograph the bones of his wife's hand?

X-rays took their name from the symbol for an unknown, because Röntgen had no idea what the radiation was. On seeing the picture of her hand, his wife said, 'I have seen my death.'

Which medical instrument did French doctor René Laennec invent in 1816 from a rolled-up sheaf of paper?

The stethoscope began as a paper cylinder that Laennec held to a young woman's chest. He heard her heart more clearly than he ever had with an ear pressed to a patient, and without the embarrassment.

Which blood type, given in emergencies when a patient's own type is unknown, is called the 'universal donor'?

O negative red cells carry none of the A, B or RhD markers that a recipient's immune system could attack. AB positive is the mirror image, the universal recipient.

Which word familiar from modern drug trials comes straight from the Latin for 'I shall please'?

Placebo pills contain no drug, yet can ease symptoms through expectation alone. The trick also runs in reverse: an inert pill that makes people feel worse because they expect harm is a nocebo.

Which hormone did Frederick Banting's Toronto team first inject into a dying 14-year-old boy in 1922?

Insulin's first patient was Leonard Thompson, who lay dying of diabetes in Toronto General Hospital. Its discoverers then sold the patent to the University of Toronto for a token dollar.

Which anaesthetic, nicknamed 'laughing gas', did dentist Horace Wells test in 1844 by having his own tooth pulled?

Nitrous oxide got its nickname from the chemist Humphry Davy. Wells saw it at a travelling show, and the very next day let a colleague pull his wisdom tooth while he breathed it from a bag.

Which muscle, the largest in the human body, holds the trunk upright and lets humans stand erect?

Gluteus maximus is unusually big in humans. Other primates have much flatter hips and cannot stay standing, so the muscle that shapes the buttocks is a signature of walking on two legs.

Which butterfly-shaped gland in the neck releases the hormones that set the body's metabolic rate?

Thyroid hormones cannot be made without iodine, and worldwide a shortage of it is the most common cause of an underactive gland. That is why many countries add iodine to table salt.

Which disease's name comes from the Italian for 'bad air', a relic of the belief that swamp fumes caused it?

Malaria kept its 'bad air' name even after 1897, when Ronald Ross found the parasite inside a mosquito and showed that the swamps were guilty only of breeding them.

Which disease's vaccine did Jonas Salk decline to patent in 1955, asking 'Could you patent the sun?'

Polio's vaccine made Salk a hero overnight when its success was announced. Asked on television who owned the patent, he answered, 'Well, the people, I would say.'

Which Latin-dance workout did Colombian instructor Beto Pérez create after forgetting his usual aerobics music?

Zumba grew out of the salsa and merengue cassettes Pérez happened to have with him in Cali that day. He first called the class 'Rumbacize'.

Which fifth basic taste did Tokyo chemist Kikunae Ikeda identify in 1908 while studying kelp broth?

Umami is the savoury taste of glutamate. A year after Ikeda named it, his discovery went on sale as Ajinomoto, the world's first seasoning built on it: MSG.

Which fruit carries warnings on many medicine labels because its compounds block an enzyme that breaks drugs down?

Grapefruit contains furanocoumarins that knock out CYP3A4, an enzyme that processes almost half of all drugs, so an ordinary dose can build up in the blood like an overdose.

Which sweet food should babies under one year old never be given, because it can carry botulism spores?

Honey can hold dormant spores that grow inside a young baby's intestines and release their toxin there. After the first birthday it is considered safe.

Irish-born cook Mary Mallon, held in isolation in New York for over two decades, was nicknamed after which disease?

Typhoid never made Mallon ill herself. She was the first person in the US identified as a symptom-free carrier, and she is believed to have infected up to 57 people through her cooking.

In which South African city did surgeon Christiaan Barnard perform the first human heart transplant in 1967?

Cape Town's Groote Schuur Hospital hosted the operation. Patient Louis Washkansky woke and talked with his wife, but died 18 days later of pneumonia as anti-rejection drugs weakened his defences.

Which disease did London doctor John Snow trace to a contaminated water pump on Broad Street in 1854?

Cholera was widely blamed on foul air, or 'miasma', until Snow's study of the deaths around one Soho pump made the case that tainted water was carrying it.

Which wellness practice, known in Japan as 'shinrin-yoku', did a government ministry begin promoting in the 1980s?

Forest bathing means spending unhurried time among trees. Tomohide Akiyama, head of Japan's Forestry Agency, coined the term in 1982 to encourage more people to visit the country's woods.

Which bitter compound from cinchona bark gives tonic water its taste and makes it glow under a UV lamp?

Quinine was first stirred into fizzy water as a guard against tropical fever. Modern tonic holds far less of it, and far more sweetener, than the original medicinal version.

What makes the 'lub-dub' sound of a human heartbeat that a doctor listens for through the chest wall?

Valves snapping shut make both beats. 'Lub' is the pair between the upper and lower chambers closing, and 'dub' is the two exit valves closing a moment later.

'Borborygmus', from a Greek word that probably imitates the sound, is the scientific name for which bodily noise?

Stomach rumble is the sound of muscle contractions pushing the gut's contents along. It grows louder about two hours after the stomach empties, when a fresh wave sweeps through to clear leftovers.

A knock on the elbow's so-called 'funny bone' actually jolts which nerve, left unprotected as it passes the joint?

Ulnar is the name of the largest nerve in the body that no muscle or bone shields, which is why a bump there sends a tingle down to the ring and little fingers.

People who inherit the reflex nicknamed 'ACHOO syndrome' sneeze when suddenly exposed to what?

Bright light, most often stepping out into sunshine, sets off the photic sneeze reflex. It runs in families as a dominant trait, so one affected parent gives a child a 50 per cent chance of it.

The word 'spa' comes from the name of a mineral-springs town in which European country?

Belgium's town of Spa, a health resort since the 14th century, was so famous for its waters that its name became the word for any resort built around a spring.

In the ancient Greek theory of the four humours, too much black bile was said to produce which temperament?

Melancholy is simply the Greek for 'black bile'. Old medicine blamed gloom on an excess of the fluid, which was thought to seep from the spleen.

Which operation, one of the oldest known to archaeology, involves drilling or scraping a hole into the skull?

Trepanation was survivable even in the Stone Age: Neolithic skulls show new bone grown around the rim of the hole, proof that the patient lived on after the operation.

Which Swiss Alpine town, host of the World Economic Forum since 1971, first grew famous as a resort for lung patients?

Davos drew tuberculosis sufferers such as Robert Louis Stevenson to its mountain air, and one of its sanatoriums inspired the clinic in Thomas Mann's novel The Magic Mountain.

Doctor Barry Marshall drank a broth of Helicobacter pylori in 1984 to help prove the microbe causes which condition?

Peptic ulcers had been blamed on stress, spicy food and excess acid. Marshall expected an ulcer years later; instead he felt sick within three days, and the work won a 2005 Nobel Prize.

Which Persian physician completed The Canon of Medicine in 1025, a standard textbook in Europe for centuries?

Avicenna, or Ibn Sina, filled five books with the medicine of his day. Translated into Latin in 12th-century Toledo, they were still a standard textbook in Europe into the 1700s.

The Apgar score, devised by anaesthetist Virginia Apgar in 1952, is a quick check on the condition of whom?

Newborns are scored at one and five minutes after birth on breathing, skin colour, reflexes, movement and heart rate. Apgar's surname was later turned into a memory aid for the five signs.

Which disease, caused by a lack of thiamine, was long common where people lived mostly on white rice?

Beriberi may get its name from a Sinhalese phrase meaning 'I cannot, I cannot', after the weakness it brings. It swept Japan once polished rice went from an upper-class luxury to an everyday staple.

Which hands-on therapy did magnetic healer D. D. Palmer found in Davenport, Iowa, in the 1890s?

Chiropractic rests on Palmer's hunch that adjusting the spine could cure disease. He claimed the idea was passed to him from 'the other world' by a doctor who had died 50 years earlier.

The prescription symbol 'Rx' stands for the Latin word 'recipe', which gave a pharmacist which one-word instruction?

Take was the word doctors wrote at the head of a prescription, an order to gather the ingredients listed below it. 'Recipe' did not mean cooking instructions until the 1700s.

The proverb 'An apple a day keeps the doctor away' grew from a rhyme first recorded in 1866 in which country?

Wales gave us the original, noted down in Pembrokeshire: 'Eat an apple on going to bed, and you'll keep the doctor from earning his bread.' The shorter wording came later.

Which Greek physician to Roman emperors shaped Western medicine for more than 1,300 years after his death?

Galen could not legally dissect people, so he described the body from Barbary apes. His anatomy went uncontested until 1543, when Andreas Vesalius published drawings made from human dissections.

Which woman was the unwitting source, in 1951, of the 'HeLa' cells still grown in research labs around the world?

Henrietta Lacks was being treated for cervical cancer in Baltimore when a biopsy was cultured without her knowledge. Hers were the first human cells seen to keep dividing in a lab without dying.