It’s a universal fact that as any 3D object, from a Platonic sphere to a cell to an elephant, grows outward in all directions, its total surface area will increase more slowly than the space it occupies (its volume). If the object’s geometry and shape remain the same as it gets bigger, then its surface area will increase roughly as fast as its volume to the two-thirds power. For centuries, biologists have wondered if life forms, too, follow this two-thirds scaling law, even though they come in a stunning variety of shapes and sizes. If so, it would suggest that there are underlying constraints fundamental to evolution that might influence how life interacts with the world around it.