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
Handbook of the Birds of the World are large, measuring , and weighing between ; it has been commented in a review that "fork-lift truck book" would be a more appropriate title. As a complement to the "Handbook of the Birds of the World" and with the ultimate goal of disseminating knowledge about the world's avifauna, in 2002 Lynx Edicions started the Internet Bird Collection (IBC). It is a free-access, but not free-licensed, on-line audiovisual library of the world's birds with the aim of posting videos, photos and sound recordings showing a variety of biological aspects (e.g. subspecies, plumages, feeding, breeding, etc.) for every species. It is