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
Human uses of birds down are used for bedding, insulation, and other purposes. Birds were among the wild animals hunted for food before the Neolithic revolution and the development of agriculture. For example, in the Epipaleolithic of the Levant, between c. 14,500 and 11,500 BP, both waterfowl and migratory birds were eaten. Archaeologists have studied the return in terms of energy from captured food compared to the energy expended to capture it; birds provide a smaller return than larger game such as deer, but better than many plant materials. For example, waterfowl captured in a drive can yield a return of around 2,000 kcal/hour,