whatEach creature is three masses and three springs: two muscles whose rest lengths pulse, one passive bone, feet that grip. Its whole genome is four numbers -- a frequency, two amplitudes, a phase lag. Twenty-four race to the right for six seconds; the race IS the fitness test. The best quarter breed, the champion re-races unmutated (that is the gait replay), mutants fill the ranks, and the next gun fires.

whyThe claim: locomotion EVOLVES. Generation zero is random flailing -- twitching, toppling, drifting the wrong way. Within about twenty generations the lineage discovers a coordinated gait and the pack starts to lope. The chart is the lineage's own scorecard, best and mean per generation, plotting exactly the races you watched. Click to drop a hill: the score dips and the lineage adapts again. Nobody designed the gait.

howVerlet masses with constraint relaxation; muscles are distance constraints with sinusoidal rest lengths; grounded feet lose most of their slide (the grip that makes gaits possible). Selection keeps the top six genomes, each breeding three Gaussian mutants. Deterministic: one integer seeds every genome and every mutation, and races step at a fixed 120 Hz.