The Weasel Program is a demonstration of the power of evolutionary algorithms with an appropriate fitness function (i.e. survival rule). These algorithms find the solution much more efficiently than non-directed random mutation. See here for more information and an alternate simulator.
Pressing "Go" below will run 200 simulations, plot the distribution of the number of generations required to evolve the requested string, and display one simulation generation-by-generation.Text to evolve toward: