<P> The deliberate exploitation of selective breeding to produce desired results has become very common in agriculture and experimental biology . </P> <P> Selective breeding can be unintentional, e.g., resulting from the process of human cultivation; and it may also produce unintended--desirable or undesirable--results . For example, in some grains, an increase in seed size may have resulted from certain ploughing practices rather than from the intentional selection of larger seeds . Most likely, there has been an interdependence between natural and artificial factors that have resulted in plant domestication . </P> <P> Selective breeding of both plants and animals has been practiced since early prehistory; key species such as wheat, rice, and dogs have been significantly different from their wild ancestors for millennia, and maize, which required especially large changes from teosinte, its wild form, was selectively bred in Mesoamerica . Selective breeding was practiced by the Romans . Treatises as much as 2,000 years old give advice on selecting animals for different purposes, and these ancient works cite still older authorities, such as Mago the Carthaginian . The notion of selective breeding was later expressed by the Persian Muslim polymath Abu Rayhan Biruni in the 11th century . He noted the idea in his book titled India, which included various examples . </P> <P> The agriculturist selects his corn, letting grow as much as he requires, and tearing out the remainder . The forester leaves those branches which he perceives to be excellent, whilst he cuts away all others . The bees kill those of their kind who only eat, but do not work in their beehive . </P>

Which process is a common practice that has been used by farmers for hundreds of years