These pictures come from psychologist Steven Pinker’s book The Better Angels of Our Nature. The left picture—the one with the obvious clusters—is actually the one that is truly random. The right picture—the one that intuitively seems more random—is not; it is a depiction of the positions of glowworms on the ceiling of a cave in Waitomo, New Zealand. The glowworms intentionally space themselves apart from one another in the competition for food.
