“In a biological context, when two rather similar species (i.e. energy transduction mechanisms) compete for the same source of energy (e.g. food), the one with even slightly more effective mechanisms (e.g. claws, teeth, feet, etc.) captures more than the other,” Annila explained to PhysOrg.com. “Gradually, the population of the more effective species will increase at the expense of the other. The overall process is pictured as flows of energy that gradually and naturally select the more effective, steeper paths. In biology, this physical consequence, which can be deduced from Lyapunov stability criterion, is known as the competitive exclusion principle.