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
Cheek pouch face with food." When full, the pouches can make the hamsters' heads double, or even triple in size. The platypus feeds on annelid worms, insect larvae, freshwater shrimps, and yabbies (freshwater crayfish) that it digs out of the riverbed with its snout or catches while swimming. It uses its cheek-pouches to carry prey to the surface for eating. The cheek pouch is a specific morphological feature that is evident in particular subgroups of rodents (i.e. Heteromyidae and Geomyidae (or Gopher)), yet a common misconception is that certain families, like Muridae (including the common black and brown rats), contain this structure