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
Pouch (marsupial) Pouch (marsupial) The pouch is a distinguishing feature of female marsupials and monotremes (and rarely in the males as in the water opossum and the extinct thylacine); the name marsupial is derived from the Latin "marsupium", meaning "pouch". Marsupials give birth to a live but relatively undeveloped fetus called a joey. When the joey is born it crawls from inside the mother to the pouch. The pouch is a fold of skin with a single opening that covers the nipples. Inside the pouch, the blind offspring attaches itself to one of the mother’s nipples and remains attached for as long