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1,604 cards. Each one is a 40-second story with a five-minute read behind it. Page 19 of 27.

1081. Until the 1800s, a fossil meant anything dug from the ground, gems includedBefore the 19th century a fossil could be a bone, a pebble or a gemstone; the word simply meant something dug up. Many scholars thought fossils grew inside rock the way crystals d…
1082. Family trees of species now help hunt for new drugs and solve court casesA drug for severe pain, Prialt, comes from animal venom. To find more venoms worth testing, researchers consult evolutionary family trees: if one fish is venomous, its close relat…
1083. A Hungarian noble wrote laws of heredity decades before Mendel's peasIn 1819 Imre Festetics, a nobleman in Kőszeg, published rules of inheritance that anticipated one of Mendel's laws and noticed that traits could skip generations. Mendel's own wor…
1084. For billions of years, Earth's most advanced life was a slimy microbial matEarth is about 4.54 billion years old, and clear signs of life appear by 3.7 billion. Yet animals with left and right sides only show up around 555 million years ago. Most of life…
1085. Only one or two percent of human DNA actually spells out proteinsYour genome runs to about 3.1 billion letters per set of chromosomes, yet the parts that code for proteins fill just one to two percent. Half is repeats, a big share comes from an…
1086. Wheat, wolfdogs and even modern humans owe something to hybridizationThe liger kicked off a naming habit in the 1920s, and since then we have had wholphins, pumapards and the sturddlefish. Mixing species is far from a zoo curiosity. About a quarter…
1087. Linnaeus sorted rocks into a kingdom of their own alongside plants and animalsHow many kingdoms of life are there? Ask a textbook in the United States and it says six; one in Britain or India says five; one biologist's scheme says seven. When Carl Linnaeus …
1088. Scientists have collected at least 123 different definitions of lifeEveryone recognises a living thing, yet nobody agrees on what life is. More than 123 definitions exist. NASA's favourite, based on a suggestion by Carl Sagan, has an awkward flaw:…
1089. Fewer than one percent of microbes around us will grow in a lab dishFor two centuries microbiologists learned about germs by growing them in culture. The catch is that fewer than one in a hundred microbes from ordinary soil or water will grow alon…
1090. A Roman farmer warned against building near swamps because of invisible creaturesIn the 1st century BC Marcus Terentius Varro advised against siting a farmhouse near a swamp, where tiny unseen creatures drifted through the air and entered through the mouth and…
1091. Why fruit flies, mice and baker's yeast keep showing up in labsA fly that breeds in days, a bacterium from the human gut and a humble weed called Arabidopsis have taught biology more than almost any other creatures. Because all life shares an…
1092. A stop codon called amber got its name from a friend's German surnameLife's instruction manual fits in a 64-entry table. Each three-letter word of DNA or RNA names one amino acid or says stop, and nearly every organism reads the same table. Crackin…
1093. Evolution can happen by pure luck, no survival advantage requiredImagine four bacteria surviving a shrinking drop of water, drawn at random from a colony split evenly between two gene versions. The odds that those four still carry an even split…
1094. CPR forced doctors to rethink the moment of deathFor most of history, a person was dead when breathing and heartbeat stopped. Then cardiopulmonary resuscitation and prompt defibrillation showed that both could sometimes be resta…
1095. Casper's Law: air speeds decay eightfold compared with burialA rough rule of thumb called Casper's Law captures how much surroundings matter. All else being equal, remains left in open air break down twice as fast as those under water and e…
1096. In 1977 Carl Woese found life had three great branches, not twoScientists long split living things into two camps: cells with a nucleus and cells without. Then Carl Woese compared sequences of a molecule found in every ribosome and discovered…
1097. A neuron and a muscle cell share the same DNA but read it differentlyEvery cell in your body descends from one fertilised egg and carries the same genetic text. Yet a neuron, a muscle fibre and the lining of a blood vessel look and behave nothing a…
1098. Your colour vision and night vision grew from one ancient geneThe human eye senses light with four genes: three handle colour and one handles dim light at night. All four descend from a single ancestral gene that was copied, and the copies d…
1099. Fossil elephant skulls may explain the one-eyed Cyclopes of Greek mythSkulls of Deinotherium giganteum, an elephant relative found in Crete and Greece, have a large opening at the front that looks like a single eye socket. It is really the gap for t…
1100. One mammalian messenger RNA gets read into roughly 2,800 proteinsA gene does nothing on its own. Its instructions must be copied into RNA and, for most genes, translated into protein. The copying is surprisingly efficient: in mammals, each mess…
1101. Darwin guessed life began in a warm little pondIn a letter to Joseph Hooker on 1 February 1871, Charles Darwin speculated that life's first spark might have struck in a warm little pond rich in ammonia and phosphoric salts, wi…
1102. Why a simple-looking liver fluke is still a masterpiece of adaptationA parasite living inside a liver can have a strikingly plain body and still be exquisitely suited to its home. That paradox captures what biologists mean by adaptation: it is a pr…
1103. Before Linnaeus, a plantain's scientific name ran to a dozen Latin wordsEarly botanists tried to make a species name double as its description, and it got out of hand. One plantain was labelled Plantago foliis ovato-lanceolatus pubescentibus, spica cy…
1104. The pioneers of cell theory got its third rule wrongIn 1838 Schleiden and Schwann championed two ideas every biology student now learns: organisms are built from cells, and each cell has all the features of life. But they rejected …
1105. In the tiniest blood vessels, red cells must squeeze through single fileEngineers usually treat blood as a smooth, uniform liquid, and for large vessels that works. Shrink the pipe to barely wider than a red blood cell and the rules shift: friction ag…
1106. The green plant you see is only half of its own life cycleThe trees, shrubs and flowers you see are just one of two generations. Botanists call this visible, double-chromosome phase the sporophyte; it alternates with a tiny single-set ge…
1107. One frog's tadpole grows to 27 centimetres, then shrinks as it maturesThe paradoxical frog earns its name. Its tadpoles can stretch to 27 centimetres, longer than any other frog larva, yet the adult that emerges measures only a few centimetres from …
1108. Cold-blooded animals are often just as warm as warm-blooded onesCalling reptiles and fish cold-blooded is misleading. Their bodies often sit in the same temperature range as mammals. The real difference, which John Hunter pinned down through m…
1109. A large oak can breathe out 150,000 litres of water a yearPlants drink far more than they need. Of all the water their roots absorb, only a sliver goes into growth and metabolism; somewhere between 97 and 99.5 percent escapes into the ai…
1110. Sex costs half your genes, so why did evolution keep it?On paper, sexual reproduction is a bad deal. An asexual population, where every individual can bear young, should grow much faster, and a sexual parent passes on only half of its …
1111. Some fungi fire their spores with an acceleration above 10,000 gMany fungi do not wait for the wind. Certain species launch single spores using a tiny water droplet, known as Buller's drop, that flings each one off at a starting acceleration t…
1112. In South Africa, some protea flowers are pollinated by miceCertain proteas hold their blooms near the ground, smell yeasty rather than sweet, and offer nectar laden with xylose that sunbirds refuse. Their customers are Cape spiny mice and…
1113. The standard 40-week pregnancy starts counting two weeks before conceptionDoctors date pregnancy from the first day of the last menstrual period, so the familiar 40 weeks includes roughly two weeks before fertilisation even happens. Measured from fertil…
1114. Boys start shorter than girls, yet end up about 13 centimetres tallerBefore puberty, boys average about 2 centimetres shorter than girls. By adulthood men are roughly 13 centimetres taller. The reason is timing: the male growth spurt starts later a…
1115. A caterpillar does not fully dissolve into soup inside its cocoonThe popular image of a larva melting into liquid inside its case is wrong. During the pupal stage, larval tissues are broken down while adult structures grow from clusters of cell…
1116. Why sex evolved at all remains one of biology's great puzzlesSexual reproduction looks like a bad bargain. Only half of a population, the females, bears young, and each parent passes on just half its genes. Biologists call this the two-fold…
1117. Each breath refreshes only a small share of the air in your lungsA resting breath brings in roughly 350 millilitres of fresh air, but it lands in about 2.5 litres of gas that never leaves the lungs between breaths. That reservoir, the functiona…
1118. Most of human seminal fluid comes from glands, not the testesSperm cells make up only part of semen. About 70 percent of the human fluid comes from the seminal vesicles, a sugary secretion rich in fructose, with more added by the prostate. …
1119. In 1702 Leeuwenhoek watched dried-out animalcules come back to lifeAntonie van Leeuwenhoek let the water around tiny rotifers evaporate, expecting them to burst. Instead they curled into ovals and waited; add water, and they swam again. He had gl…
1120. London's Royal Mews takes its name from the moulting of royal hawksIn medieval English, moulting was called mewing, from the French muer. The King's hawks were kept in the Mews while they shed their feathers, and after Tudor times the building be…
1121. Walking downstairs, your thigh muscles contract while getting longerA contracting muscle need not shorten. Grip a heavy bag and your forearm works hard without moving at all; lower yourself down a staircase and your muscles lengthen while resistin…
1122. Ernst Haeckel claimed embryos replay evolution; a marine biologist turned it aroundIn 1866 Ernst Haeckel proposed that an embryo's growth briefly re-runs its species' evolutionary history, a slogan summed up as ontogeny recapitulates phylogeny. It did not hold u…
1123. Photosynthesis captures about eight times the power human civilisation usesGlobally, photosynthesis traps energy at roughly 130 terawatts and turns around 100 billion tons of carbon into living matter each year. It also filled the air with oxygen, making…
1124. A 19th-century physiologist modelled the body on Adam Smith's factoryIn the 1820s Henri Milne-Edwards borrowed economics to explain life. Organs, he wrote, are like workers in a factory, each labouring nonstop at its own task. That notion of a phys…
1125. Dandelions make seeds without fertilisation, cloning themselves through apomixisA dandelion clock looks like the product of sex, but many of those seeds are clones. Through apomixis, dandelions, hawkweeds, some citrus and Kentucky bluegrass form seeds without…
1126. Strictly speaking, a tree itself is neither male nor femaleEvery plant alternates between two generations. The big visible plant, whether oak or daisy, is a sporophyte that makes spores, not sex cells, so technically it has no sex. The tr…
1127. Each pollen grain is a tiny organism in its own right, not a spermPollen is often described as plant sperm, but each grain is really a miniature male plant, a gametophyte that produces sperm cells. Its armour, sporopollenin, is so tough that pol…
1128. Every plant lives two lives, and in mosses the hidden generation is the one you seePlants alternate between two separate multicellular bodies: one carrying a single set of chromosomes, one carrying two. In trees and flowers the double-set generation dominates an…
1129. Larvae are not ancestral throwbacks; many evolved later than the adultsIt is tempting to see a caterpillar or tadpole as a glimpse of its group's distant past. Often that is wrong. In insects the larval stage evolved secondarily, so a larva can diffe…
1130. Genes explain only about a quarter of how long people liveIt is easy to credit long-lived relatives for your own prospects, but twin studies suggest genetics accounts for only about 20 to 30 percent of the variation in human lifespan. Th…
1131. Separate sexes evolved many times over, and nobody knows when males first appearedMales and females did not arise once in some ancient ancestor. The split into two kinds of sex cell evolved independently in different lineages, a textbook case of convergent evol…
1132. Menopause strips about 30 percent of skin collagen within five yearsMenopause is officially diagnosed only in hindsight, after a full year without a period. Its effects reach far beyond the reproductive system. Falling hormone levels bring hot flu…
1133. A period is triggered not by a hormone rising but by one crashingThe monthly cycle is orchestrated from the brain, which releases hormones in pulses that tell the ovaries when to ripen and release an egg. If no embryo implants, a temporary glan…
1134. E. coli and elephants run their cells on the same chemical cycleA single-celled gut bacterium and a huge elephant look like they have nothing in common, yet deep inside their cells the same set of chemical reactions is turning over. The citric…
1135. One hormone keeps caterpillars young; when it vanishes, the butterfly emergesWhether an insect moults into a bigger larva, a pupa or an adult comes down to a single chemical, juvenile hormone. Plenty of it during a moult keeps the insect juvenile; a little…
1136. The human egg is one of the few cells you can see without a microscopeAt roughly 120 micrometres across, the human egg cell is among the largest cells in the body, just visible to the naked eye. For more than a century biologists taught that females…
1137. Every organ in your body traces back to one of three cell layersSkin and brain, muscle and bone, gut and lungs: every tissue in an adult human can be traced to one of three sheets of cells that formed when you were an early embryo. The process…
1138. Birds excrete a paste instead of watery urine, trading energy for waterHow an animal disposes of nitrogen waste depends on how much water it can spare. Aquatic animals simply release toxic ammonia into the surrounding water. Land animals convert it i…
1139. Female and male share a spelling but not an originIn biology, being female comes down to one thing: producing the larger sex cell, the egg. The English word, meanwhile, has a quirky history. It descends from a Latin word for a li…
1140. Flowering plants fertilise twice, and a burst of oxygen chemistry releases the spermMost plant sperm cannot swim. Instead, a pollen grain grows a tube that tunnels through the flower to the ovule, where a chemical signal from the female tissue makes the tube burs…

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