The history
Nearly 1,900 years from a squealing pig in Rome to the oxygen clip on your finger.
For most of history, people knew we must breathe but not why. Then experiments with bellows, candles and mice showed that one part of the air, oxygen, keeps us alive, and that the body burns it slowly, like a gentle fire. Scientists found the air sacs, the nerves and the brainstem centre that run each breath, and learned that carbon dioxide, not oxygen, sets the pace. Then came vaccines, medicines, machines and clean-air rules to protect the lungs, and a long fight against TB that matters most of all in India.
c. 2nd century CE
Proof that nerves control the voice
Galen, Rome
1661
Air sacs (alveoli) seen under a microscope
Marcello Malpighi, Italy
1667
Animal kept alive by pumping air into its lungs
Robert Hooke, England
1812
Breathing centre found in the brainstem
Julien Jean César Legallois, France
1846
Spirometer and 'vital capacity'
John Hutchinson, England
1921
BCG vaccine given to a baby
Calmette, Guérin, Weill-Hallé and Turpin, France
1943–1944
Antibiotic that cures TB
Schatz, Bugie and Waksman, USA
1956
Pressurised metered-dose inhaler
Riker Laboratories, USA
1975
Pulse oximeter on sale
Takuo Aoyagi and Nihon Kohden, Japan
1978
Everest climbed without bottled oxygen
Reinhold Messner and Peter Habeler
100 – 1600
Doctors and artists open bodies and draw the airways. They see that nerves control the voice and that blood passes through the lungs, but nobody knows what air does.
170
c. 160–200 CE
The Greek doctor Galen cut open a live pig in front of an audience in Rome. When he cut two thin nerves in its neck, the pig went silent, though it still struggled. He had shown that the voice is made in the larynx, the voice box at the top of the windpipe, and that nerves from the brain control it.
Why it mattered. It was one of the first experiments to show that nerves, not the heart, run the parts we breathe and speak with.
1242
c. 1242
Galen had said blood seeps through tiny holes in the wall of the heart. The Damascus-born doctor Ibn al-Nafis said that was wrong: blood travels from the right side of the heart to the lungs, mixes with air, and comes back to the left side. Europe did not know his book until a copy was found in Berlin in 1924.
Why it mattered. It is widely credited as the first correct description of blood picking up air in the lungs.
1510
c. 1508–1513
Leonardo dissected human bodies and animals and drew what he saw in careful ink drawings. His sheets show the windpipe branching again and again into the bronchi, like the branches of a tree, and the lungs sitting around the heart. Almost all of these drawings are now in the Royal Collection at Windsor Castle.
Why it mattered. They are some of the first accurate pictures of the airways, the path air takes from your throat into your lungs.
1600 – 1800
Microscopes, bellows, flames and mice show that a single part of the air keeps us alive, and that breathing is a slow, gentle fire.
1661
Looking through an early microscope, Malpighi saw that a lung is not a solid lump of flesh. It is full of tiny air-filled bubbles, like a honeycomb, wrapped in the thinnest blood vessels, the capillaries. He studied frog lungs and described them in letters called De pulmonibus.
Why it mattered. He found the alveoli, the air sacs where oxygen finally crosses into your blood.
1667
October 1667
People argued about whether the moving of the lungs or the air itself kept an animal alive. In front of the Royal Society, Hooke pumped air into a dog's opened lungs with bellows. When he kept the lungs still and just let fresh air flow through them, the dog lived, and it failed when the fresh air stopped.
Why it mattered. It showed that fresh air, not the movement, is what the body needs, an early step toward breathing machines.
1674
In his book Tractatus quinque, the young Oxford doctor Mayow argued that air holds a special part, which he called nitro-aerial spirit, that is used up by both a burning flame and a breathing animal. He also described how chest muscles and the diaphragm make the chest bigger, so the lungs fill like bellows. He guessed right a century before oxygen was named.
Why it mattered. He saw that breathing and burning use the same part of the air, and that the chest works like a pump.
1774
1 August 1774
Priestley used a big lens to focus sunlight on red mercury oxide and collected the gas it gave off. A candle burned brilliantly in it, and a mouse lived longer in it than in ordinary air. In Sweden, Carl Wilhelm Scheele had probably made the same gas a little earlier, but published later.
Why it mattered. Oxygen is the gas your whole respiratory system exists to collect.
1783
1777–1790
Lavoisier showed that animals use up oxygen and breathe out carbon dioxide, just like a burning candle. With Laplace he measured the body heat of a guinea pig by how much ice it melted, and later, with Séguin, how much oxygen a person uses resting and working. Marie-Anne Lavoisier worked in the lab and drew the experiments.
Why it mattered. It explained what breathing is for: burning food with oxygen, slowly, inside the body to release energy.
1800 – 1920
Physiologists find the breathing centre in the brainstem, measure lungs and blood gases, climb mountains to test thin air, and find the germ that causes TB.
1812
Legallois removed parts of the brain in young rabbits, one layer at a time. Taking away the big upper brain did not stop breathing, but cutting a small area of the medulla, at the base of the brain, stopped it at once. He published his results in a book in 1812.
Why it mattered. He found the place where the automatic rhythm of breathing starts, even while you sleep.
1846
Hutchinson built a spirometer, a bell floating in water that rises as you blow into it. He measured thousands of people and named the biggest breath you can blow out the 'vital capacity'. He found it grows with height and falls with age and illness.
Why it mattered. Blowing into a spirometer is still how doctors test lungs today.
1868
Breuer, a young doctor working in Hering's lab, found that stretching an animal's lungs made it stop breathing in for a while. The message travelled to the brain along the vagus nerve. This is now called the Hering-Breuer reflex.
Why it mattered. It showed that breathing is a loop: sensors in the lungs report back, and the brain adjusts each breath.
1878
Bert put animals and himself in steel chambers where he could lower the air pressure, as on a high mountain. In his book La pression barométrique he showed that altitude sickness comes from the low pressure of oxygen, not from low pressure itself, and that breathing extra oxygen helps. He also showed that too much oxygen can be poisonous.
Why it mattered. He is often called the father of high-altitude medicine.
1882
24 March 1882
Tuberculosis was one of the biggest killers in the world. At a meeting of the Berlin Physiological Society, Koch showed the microbe that causes it, using more than 200 slides he had prepared. The date, 24 March, is now World TB Day.
Why it mattered. Knowing the cause made it possible to find TB, stop it spreading and, later, cure it, a fight that matters most of all in India.
1904
The team measured how much oxygen blood holds at different pressures. The curve was S-shaped, and more carbon dioxide made blood hold oxygen less tightly. This is the Bohr effect. A few years later August and Marie Krogh showed that oxygen simply diffuses from the air sacs into the blood.
Why it mattered. Busy muscles make carbon dioxide, so they get more oxygen exactly when they need it.
1905
Haldane and Priestley measured the air at the very end of a breath, which comes from deep in the lungs. Whatever they did, the level of carbon dioxide there stayed almost the same, and even a small rise made people breathe much harder. They showed that the brain controls breathing mainly by watching carbon dioxide, not oxygen.
Why it mattered. It is why holding your breath gets hard so fast: carbon dioxide builds up long before oxygen runs low.
1911
Summer 1911
Four men lived for five weeks in the summit house of Pikes Peak, about 4,300 metres up, and measured how their breathing and blood changed. Mabel FitzGerald travelled alone to Colorado mining towns and measured people who lived at different heights. Together they showed how the body slowly adjusts, or acclimatises, to thin air.
Why it mattered. It explained why climbers must go up slowly, breathing more and making more red blood cells as they climb.
1920 – 1980
Vaccines, antibiotics, iron lungs, inhalers, CPR and oximeters keep people breathing, and a study in Madras changes how the world treats TB.
1921
18 July 1921
In Lille, Calmette and Guérin spent 13 years weakening a TB germ taken from cows, growing it again and again. In 1921 doctors in Paris gave the vaccine by mouth to a newborn baby whose mother had just died of TB. The baby stayed well.
Why it mattered. BCG is still given to babies in India and many other countries to protect them from severe TB.
1928
12 October 1928
Polio could paralyse the muscles used for breathing. Drinker and Shaw built a sealed metal tank that lowered and raised the air pressure around a patient's body, so air flowed in and out of the lungs. Its first patient was an eight-year-old girl at Boston Children's Hospital.
Why it mattered. It copies the pressure trick your own chest and diaphragm use every time you breathe in.
1938
1938 (work from the late 1920s)
Heymans and his father ran tricky experiments on dogs, keeping a head alive on blood from a second dog. They found that small sensors near the big arteries in the neck, above all the carotid bodies, check the blood and send signals that change breathing. Heymans won the 1938 Nobel Prize, handed over in 1939.
Why it mattered. The carotid bodies are the body's main alarm for low oxygen in the blood.
1944
1943–1944
In 1943 a student, Albert Schatz, working in Waksman's lab, found a soil microbe that made a new drug, streptomycin. It could kill the TB germ. In November 1944 it was first given to a very sick young woman with TB in Minnesota, and she recovered.
Why it mattered. For the first time, TB of the lungs could be cured with medicine instead of just rest and fresh air.
1956
March 1956
Thirteen-year-old Susie Maison had asthma and hated her clumsy squeeze-bulb nebuliser. She asked her father why her medicine could not come in a spray can, like hairspray. His company, Riker Laboratories, made the Medihaler, which was approved in the USA in March 1956.
Why it mattered. A pocket spray that sends medicine straight into the airways is still how most people treat asthma.
1958
1956–1959
A research centre opened in Madras in 1956, supported by ICMR, the Madras government, WHO and Britain's Medical Research Council. It gave 193 TB patients the same pills for a year, half at home and half in a sanatorium. Patients treated at home did almost as well, and their families were not put at extra risk.
Why it mattered. It helped close sanatoria around the world and led to treating TB at home, the basis of India's TB care today.
1960
1958–1960
Safar and Elam showed that a rescuer's breath, blown mouth-to-mouth, can fill another person's lungs. In 1960 Kouwenhoven, Jude and Knickerbocker showed that pressing on the chest keeps blood moving. That year the two ideas were joined into CPR.
Why it mattered. Anyone can learn it, and it can keep oxygen reaching the brain until help arrives.
1962
India started a national programme to fight TB in every district. It used BCG vaccination, chest X-rays to find patients and medicines such as streptomycin and isoniazid, often given at home, as the Madras study had shown was possible.
Why it mattered. It was India's first attempt to fight its biggest lung disease across the whole country.
1975
1972–1975
In 1972 the engineer Aoyagi was annoyed by a 'noise' in his light signals that rose and fell with each heartbeat. He realised that pulsing red and infrared light could show how much oxygen the blood was carrying. He presented the idea in 1974, and in 1975 Nihon Kohden sold the first ear oximeter.
Why it mattered. Every clip-on finger oximeter, used by millions in the COVID-19 pandemic, works on his idea.
1978
8 May 1978
At the top of Everest the air holds only about a third as much oxygen as at sea level. Many experts thought a person could not survive there without bottled oxygen. Messner and Habeler climbed to the summit breathing only the thin air.
Why it mattered. It showed how far a well-acclimatised body can push its breathing and blood.
1980 – today
Treatments for tiny babies, watched TB treatment across India and stricter clean-air rules put healthy lungs at the heart of public health.
1980
12 January 1980
Premature babies often lack surfactant, the soapy liquid that stops air sacs from collapsing. Fujiwara's team made surfactant from cow lungs and gave it through a tube to ten very sick newborns. Their oxygen levels rose quickly, and the results were published in The Lancet.
Why it mattered. It turned a discovery about the air sacs into a treatment used in newborn units around the world.
1997
1993 (pilot), 1997 (national)
Many patients stopped their TB pills too early, and the germ came back stronger. India's Revised National TB Control Programme, tested from 1993 and launched nationally in 1997, used the WHO DOTS plan: a health worker watches the patient take each dose. By 2006 it covered the whole country, and in 2020 it was renamed the National TB Elimination Programme.
Why it mattered. Free tests and watched treatment became the backbone of TB care in India.
2018
1 April 2018
Poor food makes TB more likely and harder to beat. Under the Nikshay Poshan Yojana, every notified TB patient in India gets money for food each month while on treatment, first ₹500 and, from November 2024, ₹1,000. It is paid straight into their bank accounts.
Why it mattered. It treats hunger as part of treating the lungs.
2021
22 September 2021
WHO halved its guideline for fine PM2.5 dust to a yearly average of 5 micrograms per cubic metre. These tiny particles slip past the nose and deep into the air sacs. India's own national limit, set in 2009, is 40, and cities such as Delhi are often far above even that.
Why it mattered. Clean air is one of the biggest things that keeps lungs healthy for life.
By the numbers
WHO estimates of tuberculosis incidence in India from the Global TB Report 2025: a 21% fall in nine years, though India still has more TB cases than any other country.
Did you know?
Your lungs hold about 480 million tiny air sacs, according to careful counts of adult lungs.
The urge to breathe comes mostly from rising carbon dioxide, not falling oxygen, which is why holding your breath gets hard so quickly.
Galen proved the voice comes from the larynx by cutting two thin nerves in a live pig's neck: the pig went silent.
The first puffer inhaler began with a 13-year-old girl asking why her asthma medicine could not come in a spray can, like hairspray.
The pulse oximeter was born from a nuisance: a heartbeat 'noise' in a light signal that Takuo Aoyagi was trying to cancel out.
The people
129 – c. 216 · Physician · Pergamon (today Türkiye)
Silenced a squealing pig by cutting two neck nerves, showing that the voice comes from the larynx.
1452 – 1519 · Artist and anatomist · Italy
Drew the windpipe branching into the bronchial tree from his own dissections.
1628 – 1694 · Physician and microscopist · Italy
First to see the air sacs and the capillaries around them.
1635 – 1703 · Natural philosopher · England
Kept a dog alive with bellows, showing that fresh air is what matters.
1641 – 1679 · Physician · England
Said breathing and burning use the same part of the air, and explained the chest as a pump.
1758 – 1836 · Scientist, translator and illustrator · France
Worked in the lab and drew the famous experiments on breathing.
1743 – 1794 · Chemist · France
Named oxygen and showed that breathing is a slow burning.
1770 – 1814 · Physician and physiologist · France
Found that the rhythm of breathing starts in the medulla of the brainstem.
1833 – 1886 · Physiologist · France
Showed that altitude sickness comes from too little oxygen pressure.
1860 – 1936 · Physiologist · Scotland
Showed that carbon dioxide is the main signal that controls breathing.
1872 – 1973 · Physiologist · England
Measured the breathing of people living at different heights in Colorado in 1911.
1936 – 2020 · Engineer · Japan
Invented pulse oximetry, measuring blood oxygen with light.
Where it happened
Sources
Dates marked “c.” are approximate, and historians sometimes disagree about who was first. If you spot a mistake, tell us.
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