Why a smooth embryo grows spots and stripes: Turing's two-chemical patterns
30seconds
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 speeds can write a pattern onto a blank sheet.
Play with a reaction-diffusion sandbox: drag to drop in a seed and watch spots, stripes and mazes grow from nothing, then see how the idea held up in angelfish skin and mouse digits.
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