Domestic sheep (Ovis aries) have long been important to humans for their milk, meat, and wool. In 2000, the United Nations Food and Argiculture Organization (FAO) compiled a list of recognized breeds of domesticated mammals which included 1495 breeds of sheep (Scherf 2000 cited in Groves and Leslie 2011). The origins of domestic sheep are not well known. It is generally believed that sheep domestication occurred shortly after goat domestication (probably 7000-10000 years ago) and in the same region, the Fertile Crescent http://en.wikipedia.org/wiki/Fertile_Crescent of the Middle East. Genetic studies have not yet provided a clear indication of the wild ancestors of modern domestic shape, although progress has made in addressing this question.
In some areas, such as parts of Australia and the United States, overgrazing by domestic sheep has caused great ecological damage and transmission of diseases to wild relatives such as the Bighorn Sheep (Ovis canadensis) of North America have resulted in significant mortality.