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1,604 cards. Each one is a 40-second story with a five-minute read behind it. Page 13 of 27.

721. When many simple software agents cooperate, no one needs to be in chargeA flock of birds has no leader, yet it turns as one. Engineers build computer systems on the same principle: many independent agents, each seeing only part of the picture, none in…
722. Pluto crosses Neptune's path yet never gets close, thanks to rhythmPluto's orbit cuts inside Neptune's, and yet the two can never collide. Pluto goes around the Sun twice for every three Neptune laps, and that fixed rhythm guarantees Neptune is a…
723. How engineers crash a car thousands of times without building oneThe equations describing how metal bends, heat spreads or air flows around a wing are usually impossible to solve exactly for a real, awkward shape. The finite element method side…
724. The pharynx is a shared tube where food always gets right of wayEvery breath and every swallow pass through the same short stretch of throat. The pharynx channels air towards the lungs and food towards the stomach, and a flap of cartilage call…
725. The Paleocene was the ten million years when mammals inherited an emptied planetAn asteroid ended the age of dinosaurs about 66 million years ago, and a vast burst of carbon closed the next chapter ten million years later. Between those two catastrophes lay t…
726. A river split our two closest relatives into warlike chimps and peaceful bonobosChimpanzees live north of the Congo River, bonobos to its south, and the two were treated as one species until 1928. They parted ways only about a million years ago, yet chimp gro…
727. Four lentil-sized glands in your neck keep your blood calcium on a knife edgeTucked behind the thyroid sit usually four tiny glands, each about 6 millimetres long and weighing roughly 30 milligrams. Despite the similar name, they have nothing to do with th…
728. Peptides are the short protein chains doing much of your cells' talkingString a few amino acids together and you get a peptide; keep going past a certain size and it becomes a protein. These short chains act as hormones, antibiotics and venoms, and b…
729. Cats, ducks and ants were humanity's first pest controllers, long before DDTEgyptians were setting cats loose in grain stores around 3000 BC, and Chinese farmers placed colonies of weaver ants in citrus orchards to eat beetles and caterpillars. Pest contr…
730. Your immune cells defend you by literally eating invaders wholeWhen bacteria slip into a wound, some of the first responders simply swallow them. The cell wraps its membrane around the intruder, seals it inside a bubble and digests it. This c…
731. Why your thumb has one bone fewer than your fingers, and whales have many moreCount the bones in your fingers and toes and you reach 56, fourteen per hand and foot. Each finger has three, the thumb only two. That same pattern holds for most land mammals, ye…
732. The Orang Asli descend from several migrations spanning 60,000 yearsThe oldest inhabitants of Peninsular Malaysia are not one people but many. The Orang Asli, just 0.7 per cent of the peninsula's population in 2017, include descendants of the firs…
733. Ovarian cancer risk tracks how many times a woman has ovulatedEvery ovulation prompts cells in and around the ovary to divide, and each round of division is a small chance for something to go wrong. That is why ovarian cancer risk rises with…
734. The moment of human ovulation was first filmed by accident in 2008Nobody had ever filmed a human egg leaving its follicle until 2008, when a gynaecologist performing a routine hysterectomy happened to catch it on camera. The egg emerged and was …
735. Oxygen damage to DNA may explain why complex cells, and sex, evolvedWhen cyanobacteria began filling Earth's air with oxygen about 2.45 billion years ago, the gas was probably poisonous to much surrounding life. One hypothesis holds that the press…
736. Elephants carry 20 copies of the gene nicknamed the guardian of the genomeElephants have huge bodies and trillions of dividing cells, yet they rarely get cancer. Part of the explanation may be that they carry 20 copies of TP53, the gene for a protein ca…
737. Why paywalls hit scientific papers harder than novels, and the colours of escapeA literature class can swap a modern bestseller for a free classic without much loss. An emergency doctor treating severe poison ivy cannot swap today's paywalled review for a 90-…
738. Opioid, opiate and narcotic mean different things, and tolerance is unevenYour own body makes opioids: endorphins are one family of them. The word covers anything, natural or lab-made, that binds the brain's opioid receptors, from poppy-derived morphine…
739. The surgical specialty that counts as dentistry in one country, medicine in anotherIn the United States, the surgeons who rebuild shattered jaws, repair cleft palates and remove head and neck cancers are formally dental specialists; a medical degree is optional.…
740. DNA's double helix has a wide groove where proteins read the codeTwist two strands of DNA around each other and the gaps between them form grooves of unequal size, 22 and 12 ångströms across. The wider one leaves the edges of the bases exposed,…
741. Frog eggs without a nucleolus revealed the cell's ribosome factoryIn 1964 John Gurdon and Donald Brown noticed that a quarter of their clawed-frog eggs had no nucleolus, and none of those eggs survived. Two years later hybridisation experiments …
742. Nucleotides build your genes, fuel your cells and even boost umamiThe same molecules that string together into DNA and RNA also power nearly everything a cell does. ATP, a nucleotide carrying three phosphates, funds protein building, movement an…
743. Five small nitrogen rings spell out every gene on EarthAdenine, cytosine, guanine, thymine and uracil are compact molecules built around rings of carbon and nitrogen. Pair a big one with a small one and the DNA ladder keeps a constant…
744. Humans need vitamin C from food while most animals simply make their ownMost animals and many plants manufacture ascorbic acid for themselves, but people must eat it. That quirk captures the idea of an essential nutrient: something the body requires y…
745. Chemists grumble that their Nobel Prize keeps going to biologistsIn the thirty years up to 2012, the Nobel Prize in Chemistry went ten times to biochemistry or molecular biology, and in the final decade of that stretch only four awards honoured…
746. The physics Nobel waits decades to be sure a discovery really mattersSubrahmanyan Chandrasekhar worked out how stars are built and evolve during the 1930s, yet received his share of the physics Nobel only in 1983. That delay is deliberate: the priz…
747. The medicine Nobel skipped Salk and Freud to reward basic discoveriesEveryone expected Jonas Salk or Albert Sabin to win a Nobel for polio vaccines. Instead the prize went to three researchers who first grew the virus in monkey cells, the step that…
748. The 'merchant of death' obituary said to inspire the Peace Prize may never have existedA popular tale says that in 1888 a French paper mistook Ludvig Nobel's death for Alfred's and damned him as a merchant of death, shaming him into endowing a peace prize. Investiga…
749. John Watson's famous 'dozen healthy infants' boast is usually quoted without its confessionThe behaviourist John B. Watson is remembered for promising that, given a dozen healthy babies, he could train any of them into a doctor, lawyer or thief. The usual quotation stop…
750. Your belly button is a one-of-a-kind scar, and birds have one tooThe navel is the scar left where the umbilical cord once attached, so no two are quite alike. Doctors sort them into innies and outies with a surprising list of sub-shapes, surgeo…
751. Scattered across living people, about a fifth of the Neanderthal genome still survivesMost people carry only a few percent of Neanderthal DNA, yet different people carry different pieces. Pooled together, roughly 20 percent of the Neanderthal genome survives in mod…
752. Your neck packs airway, gullet, glands and the brain's blood supply into four compartmentsThe neck holds up the head, lets it swivel in every direction, and shields the nerves linking brain and body. Crammed inside a surprisingly small column are the windpipe, the thro…
753. The word neoteny rests on a Greek-Latin mix-up by its own inventorJulius Kollmann coined neoteny in 1885 for the axolotl, which grows up without leaving its gilled larval body. He meant retaining youth, but seems to have confused a Greek verb me…
754. In 1879 a Scottish surgeon found a brain tumour using only the patient's symptomsWith no scanners of any kind, William Macewen pinpointed a tumour in 1879 purely from neurological signs, then removed it successfully. Five years later Rickman Godlee went a step…
755. Why do men have nipples? Because losing them offered no advantageAlmost every mammal has nipples, including males, who cannot use them to feed young. Biologists broadly agree the reason is anticlimactic: nothing was gained by getting rid of the…
756. America's giant medical research agency began as a bacteria lab on Staten IslandIn 1887 the US Marine Hospital Service set up a small laboratory to study bacteria at its hospital on Staten Island. That Hygienic Laboratory grew into the National Institutes of …
757. Seven million fish in jars: inside the world's largest natural history collectionThe Smithsonian's National Museum of Natural History in Washington holds over 148 million specimens, the largest natural history collection on Earth. Visitors see only a sliver. B…
758. A five-year fight over who controls science shaped America's research funderEveryone in 1940s Washington agreed the government should back science. They could not agree how. One camp wanted scientists in charge; the other wanted the public to own the resu…
759. Identical twins don't run in families, but fraternal twins canFraternal twins come from two separate eggs, and a gene that makes some women release extra eggs can pass down the generations. Identical twins arise when a single fertilized egg …
760. Early strength gains come mostly from the brain, not bigger musclesWhen someone starts lifting weights, they often get stronger quickly before their muscles visibly grow. Most of that early progress is the nervous system learning to recruit and c…
761. The slow, waxy microbe behind tuberculosis hides inside the cells sent to eat itMost bacteria split every few minutes; E. coli can manage roughly every 20. The germ that causes tuberculosis takes 18 to 24 hours. What it lacks in speed it makes up for in armou…
762. Nerve signals leap between gaps in a fatty wrapping named after bone marrowMany of your nerve fibres are wrapped in myelin, a fatty insulating sheath. Unlike the plastic on a wire, it comes in segments separated by tiny bare gaps about a micrometre long.…
763. River dolphins, caribou people and backwards-footed women: folklore's almost-humansNearly every culture imagines beings that are part human or pass for human. In the Amazon, river dolphins are said to step ashore as people. Inuit tradition tells of caribou folk …
764. Mathematical models trade realism for clarity, and the trade is the pointBend a coin slightly, flip it once, then try to predict the next toss. With so little data, you have to lean on a hunch from the coin's shape. That dilemma sits at the heart of ma…
765. Messenger RNA is the short-lived working copy that turns genes into proteinsYour DNA stays locked in the cell nucleus like a reference library, so cells make disposable copies of individual genes to carry out to the protein factories. These copies, called…
766. Why cancer cells that travel keep the identity of where they startedWhen breast cancer spreads to the lungs, the new growth is made of breast cells, not lung cells, and doctors call it metastatic breast cancer. That journey from one organ to anoth…
767. Microtubules are the hollow scaffolding and railways inside your cellsInside nearly every cell with a nucleus runs a network of tiny hollow tubes, each about 25 nanometres wide yet sometimes 50 micrometres long. These microtubules hold the cell's sh…
768. The American mink escaped the fur farm and remade European riversidesA mink with no white patch on its upper lip is certainly American, because every European mink has one. That small detail matters in Europe, where American mink bred for their fur…
769. The Magdalenians painted Lascaux and hunted across an Ice Age EuropeThe first excavators of a rock shelter in France's Dordogne called the era the age of the reindeer. Today it is known as the Magdalenian, a culture of Ice Age hunters who carved s…
770. The same brain protein behind mad cow disease may also help us rememberEvery human nerve cell carries a protein called PrP, and nobody is quite sure what it is for. When it folds into the wrong shape, it drives fatal brain illnesses such as mad cow d…
771. Mary Leakey, expelled from two schools, found some of humanity's oldest tracesOne morning in July 1959, with her husband ill in camp, Mary Leakey spotted a skull fragment at Olduvai Gorge, brushed away the soil, found two big teeth in a curved jaw and drove…
772. The B in B cell comes from an organ found in birds, not from bone marrowImmunologists often assume B cells are named for bone marrow, where mammals make them. In fact the letter honours the bursa of Fabricius, a lymphoid organ in birds where Chang and…
773. Stalin's favourite agronomist declared the gene a bourgeois invention, and biology paidTrofim Lysenko promised Stalin wheat yielding 15,000 kilograms per hectare, when the best variety under ideal conditions managed about 2,000. He called genes a bourgeois invention…
774. Why ancient farmers paired beans with maize: the missing amino acid lysineMaize is short on lysine, one of the amino acids the human body cannot make for itself. Beans are rich in it. So it may be no accident that the archaeological record so often find…
775. DNA stores, proteins work, RNA does a bit of both: life's giant moleculesEvery living thing depends on three long chain molecules, each shaped for a different job. DNA is built for safekeeping, proteins for getting chemistry done, and RNA sits awkwardl…
776. LDL is not cholesterol itself but a tiny shuttle that carries fats through bloodFat does not dissolve in water, so the body ships it in particles. A low-density lipoprotein is a speck about 22 to 27.5 nanometres across, wrapped around thousands of fat molecul…
777. Lucy's skeleton showed our ancestors walked upright long before their brains grew largeOn 24 November 1974, Donald Johanson skipped updating his field notes to search a gully in Ethiopia that others had already checked twice. As he turned to leave, an arm bone caugh…
778. A three-year-old's drawing of his classmate gave the Beatles Lucy in the SkyJulian Lennon came home from nursery school with a picture of his friend Lucy Vodden and called it Lucy in the sky with diamonds. His father John turned the title into one of the …
779. Humans have more lower-back vertebrae than chimps, and that lets our spines curveBetween your ribs and pelvis sit five heavy vertebrae, the largest bones in the spinal column. Chimpanzees and gorillas have only three or four, which leaves them unable to arch t…
780. Lymph nodes slow the flow of lymph on purpose so immune cells can reactAn adult body holds about 450 lymph nodes, bean-shaped filters averaging 15 millimetres long. Lymph pours into each one through many vessels but usually leaves through a single ex…

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