Milk : It is a white, nutrient-rich liquid food produced in the mammary glands of mammals. It is the primary source of nutrition for infants and newborns, before they are able to digest food. Evolution of Milk: It gives new-born animals the advantage of ideally formulated food from the mother even after birth, and therefore to continue the opportunity to continue their physical development outside womb. The rise of the ruminants: The key to the rise of the ruminants is their highly specialized, multichambered stomach, which accounts for a fifth of their body weight and houses trillions of fiber-digesting microbes, most of them in the first chamber or rumen. Their unique plumbing, together with the habit of regurgitating and rechewing partly digested food, allows ruminants to extract nourishment from high-fiber, poor quality plant material. Ruminants produce milk copiously on feed that is otherwise useless to humans and that can be stockpiled as straw or silage. Without them there