Hundreds of years ago, American Indians were hunting wild, free-ranging bison and using all the body parts to keep them alive. However, the majority of bison alive today are experiencing a shift towards domestication. Today, there are approximately 30,000 wild bison living in conservation herds where managers strive to restore the ecological role of bison as a keystone herbivore in grassland ecosystems. At the same time, there are also roughly 500,000 bison living in private and commercial herds that are managed for meat production and other purposes. It is important to realize that human intervention and the domestication of animals can have consequences. With wild bison in conservation herds, intervention is limited, but with domesticated bison, animal husbandry methods have heavily influenced their reproduction and survival. Indeed, much of the differences between wild bison and domesticated bison are because of two different types of selection: artificial and natural.