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
Birds of the Danube Delta territory. As far as the habitats are concerned, the species of the aquatic ones almost exclusivity feed from the aquatic millennium, while those living in the terrestrial habitat hardly have 50 per cent terrestrial food, the remainder having a mixed and aquatic origin. Many species owe their presence or existence in the delta – in rather high densities as compared to the rest of the area – just to this food richness. The contrast created between the great food abundance available as compared to the existence for some species of plenty of sites for nest location resulted in the simple