Antitrust agencies are concerned that the autonomous pricing algorithms increasingly used by online vendors may learn to collude. This column uses experiments with pricing algorithms powered by AI in a controlled environment to demonstrate that even relatively simple algorithms systematically learn to play sophisticated collusive strategies. Most worrying is that they learn to collude by trial and error, with no prior knowledge of the environment in which they operate, without communicating with one another, and without being specifically designed or instructed to collude.