Darwin in a Box is an article about the work of Torsten Reil, who created a convincingly natural walking animation by constructing a virtual joint system with a neural network to control the muscles, and let a genetic algorithm find the "best" neural network parameters. In 20 generations, he went from random flailing to a smoothly striding figure.

Genetic algorithms have long fascinated me as a practical application of Darwin's Theory of Evolution. That they can work so well is delightful, as is their subversive creativity (just as in nature): Reil had to modify the fitness function from "distance from the origin" to "distance from the origin while keeping the center of mass above a certain height", because the algorithm discovered weird crawling techniques that were doing pretty well otherwise.

Reil's company naturalmotion has a cool video of the evolution.