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In 1877, a South African railway guard named James Edwin Wide lost both his legs. His coworkers called him “Jumper” for his habit of leaping between moving railcars, until one jump went wrong and the wheels took his legs below the knee. Wide fashioned himself two wooden legs, proved he could still work, and got moved to a signal box job at Uitenhage station near Port Elizabeth, where the railway company appointed him signalman.

The commute was still brutal on wooden legs. So one day at the market, Wide spotted a chacma baboon leading an oxcart, and impressed by what the animal could clearly do, he bought it, named it Jack, and took it home as an assistant. Jack pushed Wide’s trolley to work, swept floors, and carried the coal shed key across the yard whenever trains needed loading. However, it quickly became clear that Jack was capable of much more.

Wide began training Jack to help him at the signal box. At those times, trains rolling toward Uitenhage would blow their whistle a set number of times to tell the signalman which track to change. By watching Wide switch the levers, and by Wide signaling him with his fingers which lever to pull, Jack picked up the pattern and started pulling on the levers himself.

Although Wide used to supervise him, he had trained Jack so well that Wide could sit inside doing other tasks while Jack, chained up outside, did the work alone.

What Jack had learned was to link a specific sound to a specific action and repeat it on his own. That’s associative learning. You’ve probably heard of Pavlov’s dog, where the sound of a bell alone made a dog expect food. Jack’s case was a bit more complex. A bell always led to the same conditioned response. Jack had to tell different whistle patterns apart and match each one to a different lever, so each whistle wasn’t pointing to just one response; it was pointing him to the right choice among several.

And it wasn’t happening in a lab with treats on the line. It was a real railway, where getting it wrong had real consequences.

This is the part where it should have fallen apart. A baboon operating railway signals is exactly the kind of thing that gets a company shut down and a man fired. And it nearly did. A startled passenger looked out her window, saw a baboon running the signals instead of a person, and complained about it. Railway officials arrived, and both Wide and Jack were fired on the spot. Wide pleaded his case, and the officials agreed to test Jack before making the decision final.

Jack passed. Not sort of passed. He passed clean. The officials were reportedly so impressed that they gave Jack an official employee number. From then on, Jack was on the books as a paid railway worker, earning twenty cents a day and half a bottle of beer a week.

A superintendent named George Howe, visiting Wide and Jack around 1890, wrote:

It was very touching to see his fondness for his master. As I drew near they were both sitting on the trolley. The baboon’s arms round his master’s neck, the other stroking Wide’s face. At my approach, Jack jumped to the ground, but his strong love could not be restrained.

Jack held the job for nine years. Multiple accounts, including a note published in the journal Nature, describe the same claim. In nine years pulling signal levers at a real train station, Jack never made a single mistake. He died of tuberculosis in 1890. His skull ended up in the collection of South Africa’s Albany Museum, where it still sits today.

Whether Jack truly understood what he was doing, or was just running a pattern he’d been trained into, a baboon did a real signalman’s job for nine years and never once got it wrong, which says something bigger than just Jack. Our distant relatives, not just primates but also all others, are often more capable than we expect. Intelligence was never really humans on one side and everyone else on the other. It’s a gradient, and we may stand near the top, but the other side isn’t just blank.

I first posted it on ScienceClock. If you liked this, you can join my newsletter, where I share stories like this every Sunday.

We have all probably messed around in the bucket or pool as kids, flipping an empty plastic jug upside down into the water just to watch it trap a pocket of air underneath. It feels like a neat little physics trick when the inside stays perfectly dry, but if you scale that exact concept up and trap a real human inside, it can literally save a life.

That’s exactly what happened with Harrison Okene. In 2013, his tugboat, the Jascon-4, was capsized by a massive wave off the Nigerian coast, sinking 100 feet to the seafloor. Harrison, the 29-year-old ship’s cook, was in the bathroom in his boxers when the water came flooding in. He tried to escape, but the watertight exit hatch wouldn’t open. As rushing water flooded the vessel, it swept him deeper into the ship, where he found himself inside another bathroom.

But the room did not fully fill up, a small pocket of air formed near the ceiling, and that tiny bubble became his lifeline.

Harrison got stuck in pitch-black freezing water. He couldn’t see anything, but he managed to find a couple of lifejackets, two torches, a can of Coke, and a tin of sardines. That was all the food and drink he had for nearly three days. To make things worse, crayfish started biting his skin in the dark. Tragically, the other 11 crew members had already drowned.

The science of his survival in that bubble isn’t so straightforward. In a space that size, you don’t run out of oxygen first. The real killer is carbon dioxide buildup.

Once CO2 hits a certain level, it starts overwhelming the body. Scientists later calculated that Harrison had about 56 hours before the air began turning toxic, and he would have slipped unconscious around hour 79.

At hour 60, South African rescue divers finally reached the wreck. They were looking for bodies, not survivors. In the pitch black, a diver saw what he thought was a corpse, but when he went to touch it, Harrison’s hand reached out and grabbed him. The video of this rescue went viral, as it looked like a horror movie scene when that hand emerged from the darkness.

Even after they found him, they couldn’t just swim him to the surface. Because he had spent nearly 60 hours in a pressurized air pocket 100 feet underwater, nitrogen had dissolved into his body tissues. Bringing him up too quickly could have caused dangerous nitrogen bubbles to form throughout his body, a condition known as decompression sickness. That’s why rescuers transferred him to a diving bell and then kept him in a decompression chamber for another three days before he could finally return home.

Later, instead of letting the trauma ruin his life, Harrison went back to school, trained as a professional diver, and now works offshore installing oil and gas facilities. He says, “If I have the money, I am going to buy a house beside the ocean.”

I first posted it on ScienceClock. If you liked this, you can join my newsletter, where I share stories like this every Sunday.

Smallpox was one of humanity’s deadliest diseases, killing around 30% of the people it infected. Even in the 1950s, it still infected roughly 50 million people every year. Today, it is gone. The only human disease ever eradicated completely.

That achievement is usually credited to “modern medicine” in the abstract. But in many ways, it began with a proposal made in 1958 by a Soviet virologist named Viktor Zhdanov.

Standing before the World Health Assembly, Zhdanov argued for something most countries considered unrealistic: a global campaign to eliminate smallpox entirely.

The vaccine already existed. Edward Jenner had developed it back in 1796. But a vaccine sitting in a laboratory is not the same thing as vaccinating the planet.

Zhdanov believed smallpox could actually be eradicated because humans were the virus’s only host. There were no animals continuously spreading it back into the population. New freeze-drying methods also meant vaccines could survive long journeys into remote regions.

He didn’t just argue for the campaign. The Soviet Union also pledged 25 million vaccine doses and logistical support. The assembly approved the proposal unanimously.

Over the next two decades, health workers crossed forests, deserts, villages, and war zones tracking outbreaks and vaccinating communities across Africa, Asia, and South America. The campaign even pushed the Soviet Union and the United States into cooperation at the height of the Cold War.

Then, in 1980, the World Health Organization officially declared smallpox eradicated.

According to the WHO and UNICEF, the effort has since saved 200 million lives and continues to save billions of dollars every year. Philosopher William MacAskill once argued that Zhdanov may have done more good for humanity than anyone else in history.

Yet almost nobody knows his name.

I first posted it on ScienceClock. If you liked this, you can join my newsletter, where I share stories like this every Sunday.

On August 14, 2005, a Helios Airways Boeing 737 departed Cyprus for Athens with a fatal configuration error. Earlier that morning, an engineer had set the pressurization mode selector to “manual” for a ground leak test but failed to flip it back to “auto.” As the plane climbed, the cabin did not pressurize, and the air became dangerously thin.

The flight crew misinterpreted a cabin altitude warning horn for a takeoff configuration alarm, a confusion caused by the two alerts sounding identical on that aircraft model. Distracted by the alarm and suffering the early effects of hypoxia (oxygen starvation), the pilots failed to realize they were losing oxygen. They eventually fell unconscious, leaving the plane to fly on autopilot toward Greece.

As the aircraft flew aimlessly over Athens, two Greek F-16 fighter jets intercepted the “ghost flight” and observed a haunting scene: the captain’s seat was empty, the co-pilot was slumped over the controls, and passengers appeared motionless with oxygen masks dangling in their cabin.

Meanwhile, flight attendant Andreas Prodromou, who used portable oxygen bottles to stay conscious, managed to enter the cockpit in a desperate, final attempt to save the plane.

But there was little he could do. The aircraft ran out of fuel, causing both engines to flame out. Though Prodromou had a pilot’s license, he was not qualified to fly the Boeing 737. Still, he managed to bank the plane away from Athens toward a rural area.

The plane spiraled down and crashed into a hillside near Grammatiko, Greece, killing all 121 people on board. The disaster led to major changes in pilot training and prompted Boeing to change the distinct sounds of cockpit warning alarms.

I first posted it on ScienceClock. If you liked this, you can join my newsletter, where I share stories like this every Sunday.

Clair Patterson was an American geochemist who set out to calculate the age of the Earth and ended up accidentally uncovering one of the most serious public health crises of the 20th century.

Working with lead isotope data from the Canyon Diablo meteorite, he calculated Earth’s age as 4.55 billion years — a figure that had been wildly underestimated before him and has remained largely unchallenged since.

While taking measurements of the meteorite, he kept finding huge amounts of lead everywhere, distorting his data. To get clean data, Patterson built one of the first laboratory clean rooms, acid-cleaning all his equipment and distilling every chemical that came in, essentially sealing his workspace against lead contamination from the outside world.

What he didn’t yet realize was that the contamination wasn’t a lab problem. It was a civilization-scale problem.

By analyzing ice core samples from Greenland and Antarctica, Patterson found that atmospheric lead levels had begun rising sharply after tetraethyl lead (TEL) was introduced as a gasoline additive to reduce engine knock.

The lead wasn’t naturally occurring, it was being pumped into the air by millions of cars. He compared lead in 1600-year-old Peruvian skeletons with modern human bones and found a 700- to 1200-fold increase, with no comparable rise in other metals like barium or calcium.

Then came the fight. The lead industry, represented by powerful figures like Robert Kehoe of the Ethyl Corporation, pushed back hard. Patterson was refused contracts by several research organizations, and in 1971 was excluded from a National Research Council panel on atmospheric lead contamination, even though he was the foremost expert on the subject at that time.

The industry’s line was that observed lead levels were “normal.” Patterson’s counter was precise: normal just means common. It doesn’t mean safe.

His activism contributed to the accelerated phaseout of leaded gasoline in the US by 1986, and by the late 1990s, blood lead levels in Americans had dropped by up to 80%. He died in 1995, just before leaded automotive fuel was fully banned in the US in 1996 and in most major countries in the years that followed.

He never became a household name, but the air everyone breathes today is measurably cleaner because of him.

I first posted it on ScienceClock. If you liked this, you can join my newsletter, where I share stories like this every week.

Ibn al-Haytham, also known as Alhazen, was born around 965 AD in Basra, Iraq. A mathematician, astronomer, and physicist of the Islamic Golden Age, he became famous across the region for his knowledge of applied mathematics — and his towering ambition.

That ambition nearly got him killed. He boasted to Egypt’s caliph Al-Hakim — a ruler notorious for cruelty and erratic behavior — that he could build a dam to control the Nile’s floods. When he arrived and saw the scale of the river, he realized that, with current technology, it was impossible. Al-Hakim’s wrath was certain.

To avoid execution, he pretended to have lost his mind. It worked convincingly enough that Al-Hakim spared his life and placed him under house arrest instead — a sentence he endured for nearly a decade, until the caliph’s death in 1021. The mad ruler had no idea he’d just given science its most productive prisoner.

It was during this house arrest that he wrote the Book of Optics — seven volumes that would reshape how humanity understood light and vision. He was the first to correctly explain that vision works because light reflects off objects and enters the eye, overturning a belief held since Euclid that eyes emit rays outward.

His work was later cited by Galileo, Descartes, and Kepler. Today, he is called the “father of modern optics” and sometimes described as the world’s “first true scientist” — a man who pioneered the scientific method five centuries before the Renaissance.

I first posted it on ScienceClock.

On the night of February 8–9, 1855, after a heavy snowfall around the Exe Estuary in Devon, England, trails of hoof-like marks appeared overnight in the snow, covering a total distance of somewhere between 60 and 160 kilometres.

The footprints — mostly about 4 inches long and 3 inches wide, spaced 8 to 16 inches apart in a single-file line — were reported from over 30 locations. But the strangest part was — they didn’t go around obstacles. They went over them. Footprints appeared on rooftops, over high walls, and even leading into and out of drainpipes as narrow as 4 inches in diameter.

Trails across 30 locations. Single file. For a hundred miles. The religious panic was immediate. The superstitious believed they were the marks of Satan himself, and the subject was even preached about from pulpits. The impressions closely resembled a donkey’s shoe, but here and there they appeared as if cloven, which only fed the devil theory.

Here’s where it gets interesting — or, if you were hoping for the devil, disappointing.

There is little direct evidence of the event. It wasn’t until 1950, when an article was published asking if anyone had information about the event, that the only known evidence surfaced — a handful of personal letters and rough tracings of the footprints, found inside a local vicar’s papers.

In 1994, researcher Mike Dash collected and published the available primary and secondary source material. He concluded there was no single source for the hoofmarks; some tracks were probably hoaxes, some made by common animals like donkeys, and some possibly by wood mice — whose hopping gait leaves a cloven-hoof-shaped impression in snow.

Though he later admitted these cannot explain all the reported marks, and “the mystery remains.”

One of the wildest theories, sourced from a local man, suggested that an experimental balloon accidentally released from Devonport Dockyard, trailing shackles on its mooring ropes, dragged across Devon before finally coming down at Honiton — leaving those devil tracks behind. The man claimed the incident was hushed up because it also destroyed several conservatories and greenhouses along the way.

But if that balloon rope is the cause, I think that itself is more mysterious than the devil — what a deadly coincidence that would be!

Sceptics note that eyewitness descriptions of the footprints varied significantly from person to person, and nobody could realistically have tracked the full 160-kilometre course in a single day — raising questions about whether the claim was an exaggeration or folklore layering on top of a real but smaller event.

I first posted it on ScienceClock. If you liked this, you can join my newsletter, where I share stories like this every week.