Biology

15 breaks

Cells, bodies, evolution and everything that grows.

AllBiologyComputingEarth & SpaceEconomicsEngineeringFood ScienceHistoryLanguageMathsMindMusic & SoundPhysics
Why nearly every species makes sons and daughters in equal numbers: Fisher's grandchildren argument Boys and girls are born in nearly equal numbers, about 105 boys for every 100 girls worldwide, even though one male could father far more children than one… Biology5 min read Why an elephant doesn't eat 200,000 times more than a mouse: Kleiber's three-quarter law A mouse is 200,000 times lighter than an elephant, yet the elephant burns only about 9,000 times more energy. In 1932 Max Kleiber found that resting metabolic… Biology5 min read Why a nerve spike is always the same size: the all-or-nothing action potential Every nerve signal in your body is the same size. A feather touch and a hammer blow send identical electrical spikes, so how does the brain tell them apart?… Biology4 min read Why predators boom after the prey do: Lotka–Volterra and the Adriatic fish puzzle After the First World War, an Italian biologist noticed something odd in Adriatic fish catches: with less fishing, the share of predators had gone up, not… Biology4 min read Why a smooth embryo grows spots and stripes: Turing's two-chemical patterns A leopard's spots and a zebra's stripes start from a smooth, featureless ball of cells. In 1952 Alan Turing showed how two chemicals that spread at different… Biology4 min read Why cells stay tiny: skin grows with the square, the cell with the cube Double a cell's width and its skin grows 4 times, but the cytoplasm it must feed grows 8 times. Add diffusion, where time grows with the square of the… Biology5 min read Why a gene can vanish by pure luck: genetic drift Two versions of a gene start at 50% each. Neither is better, yet in a small population one will vanish by pure chance and the other will take over. This is… Biology5 min read How thousands of fireflies flash in time with no leader: pulse-coupled oscillators On riverbank trees in Southeast Asia, thousands of male fireflies flash together, with no leader and no shared clock. Each insect is just a small timer that… Biology4 min read Why fishing less gave the Adriatic more sharks: foxes, rabbits and a loop When fishing slowed during the First World War, the Adriatic catch held a bigger share of sharks and rays, not a smaller one. Mathematician Vito Volterra… Biology3 min read How a leopard gets its spots: Turing's two-chemical pattern machine A leopard's spots and a zebra's stripes start out as a smooth sheet of near-identical cells. In 1952 Alan Turing showed that two interacting chemicals, one… Biology3 min read How honeybees give directions by dancing in the dark A honeybee that finds good flowers can tell her sisters where they are, inside a pitch-black hive, by dancing. She runs in a straight line while shaking her… Biology5 min read How a Venus flytrap counts to five without a brain A Venus flytrap ignores the first touch. Brush one of its trigger hairs and nothing happens; brush a second within about half a minute and the jaws slam shut… Biology5 min read