The evidence that pure ecological science has influenced grazing management practices employed in livestock husbandry on the North American Great Plains is tenuous at best. Those practices arose from critical technological innovations in the 19th century that modified the essential properties of grazing ecosystems when applied to livestock husbandry. Ecological research has identified many significant differences as well as similarities between natural and human—defined grazing systems, and how husbandry can lead to overgrazing. There is considerable evidence that moderate grazing can increase primary productivity and unequivocal evidence that some plants benefit from the presence of grazing animals.