Standing in the center of a crowded bus on your way to class, you might think: “why don’t these people just move? It’s hot and I can’t breathe!” Male penguins huddling to keep their eggs warm in the Antarctic winter have the opposite problem – no penguin wants to be at the cold edge of the huddle. A penguin in the huddle wants to stay in the warm center, since the outside temperature can reach -45 oC. However, penguins on the edge of the huddle are trying to push through the crowd to reach the center. Through the independent motion of each penguin, the huddle stays tight enough for the center to remain warm but loose enough to keep moving.