Animal genetic resources for food and agriculture crop and livestock species in the early neolithic time period changed our human evolution and lifestyles. This ability to control food production led to major demographic, technological, political and military changes. Consecutively, thousands of years of natural and human selection, genetic drift, inbreeding, and crossbreeding have contributed to the diversification of animal genetic resources and increased the variety of environments and production systems that livestock keeping takes place. Relatively few species have been domesticated; out of the world's 148 non-carnivorous species weighing more than 45 kg, only 15 have been successfully domesticated. The proportion of domesticated birds used for food
The Life of Birds kind of dance to flush out the aquatic inhabitants. Skimmers have different-sized mandibles, the lower one being used to skim the water's surface for small fish. Ducks have developed an assortment of angling skills. Some dabble, like the mallard, while others are of a more streamlined design and are at home underwater, such as the merganser. Waders, which specialise in feeding on mud flats at low tide, include avocets, godwits, dowitchers and sanderlings. The pelican feeds in groups, their pouch-like bills being more successful when used collectively. Boobies fish in the open ocean and are shown dive-bombing shoals "en masse".