Stephen Jay Gould, the noted Harvard biologist, has made the observation that within the last generation or so we have begun to witness the realization of essentially biological or 'evolutionary' limits to human performance in certain areas. The argument for limits to performance is grounded in the recognition that people in advanced industrialized societies have already realized the potential set by evolutionary history in respect to such dimensions as average life span and average height. Further, Gould argues, we may be approaching evolutionary limits to certain dimensions of human performance; hence, male athletes, for example, like thoroughbred horses before them, appear to be approaching the natural limit represented by the time it takes to run a mile (Kentucky Derby winners averaged 2:06.4 during the 1910'S and 2:02.0 for the past ten years).