Submitted to: Encyclopedia of Global Change
Publication Type: Book / Chapter
Publication Acceptance Date: June 17, 1998
Publication Date: N/A
Technical Abstract: Animal agriculture has evolved with the growth of the human population from 4 million people 10,000 years before the present (ybp) to the 5.85 billion people that occupy the world today. Domestication of a relatively few of the available mammalian species initially occurred in conjunction with climatic, cultural and societal changes at the end of the last ice age - the Wisconsin deglaciation. Agrarian based communities developed independently around the world, and animal husbandry practices became common. Today, despite tremendous technological advances in genetics (e.g., cloning), physiological manipulations (e.g., artificial insemination) and nutritional provisions (e.g., high quality harvested forages), there are still only a few domesticated species used in animal agriculture, and traditional animal husbandry practices are still universally applied. In 1996, the world population of domesticated grazing glivestock was approximately 3.3 billion, an increase of 1.1 billion during the last 5 decades despite a relatively constant total amount of grazeable land. The bulk of this increase during the last half of the 20th century is due to a near doubling of cattle, sheep and goats on the continents of Asia and Africa. The impacts of unmanaged grazing animals have been substantial through the course of human history. The modern principles for proper management of grazing lands developed during this century in response to destructive impacts of unmanaged grazing throughout the world.