At first the robots just flashed their lights at random. But over time things changed. In the trials with relatives undergoing colony selection, twelve out of the twenty lines began to turn on the blue light when they reached the food. The light attracted the other robots, bringing them quickly to the food. The other eight lines evolved the opposite strategy. They turned blue when they hit the poison, and the other robots responded to the light by heading away.

Two separate communication systems had evolved, each benefiting the entire colony. By communicating, the robots also raised their score by 14%. Here’s a movie showing six of these chit-chatting robots finding a meal.