The prominence of sport in the American secondary school curriculum owes much to 19th-century child development theories, the most prominent of which (Von Baer's Law) originated in embryology, the forerunner of modern psychology. Von Baer's Law held that embryonic development formed a condensed record of human development, that the embryo in the womb represented in miniature the overall organic evolution of man. The "law" held that youth passed through the same developmental gradations ontogenetically that the human race passed through phylogenetically; that youth repeated in their development approximately the development, from barbarity to civilization, of the human race. Indeed, they stood at a primitive developmental level and simply passed through a stage the human race had passed through thousands of years earlier. Von Baer's Law became a scientific rationale for sport in American schools, most particularly, football, which was believed to be spirited enough to "satisfy the racial claim" and mitigate against antisocial aggressiveness.