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The chicken (''Gallus gallus domesticus'') is a domesticated fowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003,according to Firefly Encyclopedia of Birds, Ed. Perrins, Christopher. Buffalo, N.Y.: Firefly Books, Ltd., 2003. there are more chickens in the world than any other bird. Humans keep chickens primarily as a source of food, consuming both their meat and their eggs. Conventional wisdom has held that the chicken was domesticated in India, but recent evidence suggests that domestication of the chicken was already under way in Vietnam over 10,000 years ago.Sherman, David M. (2002). ''Tending Animals in the Global Village''. Blackwell Publishing. 46. ISBN 0683180517. From India the domesticated fowl made its way to the Persianized kingdom of Lydia in western Asia Minor, domestic fowl were imported to Greece by the fifth century BC.Maguelonne Toussaint-Samat, (Anthea Bell, translator) ''The History of Food'', Ch. 11 "The History of Poultry", revised ed. 2009, p. 306. Fowl had been known in Egypt since the 18th Dynasty, with the "bird that lays every day" having come to Egypt from the land between Syria and Shinar, Babylonia, according to the annals of Tutmose III.Howard Carter, "An Ostracon Depicting a Red Jungle-Fowl (The Earliest Known Drawing of the Domestic Cock)" ''The Journal of Egyptian Archaeology'', 9.1/2 (April 1923), pp. 1-4. The domestic chicken is descended primarily from the Red Junglefowl (''Gallus gallus'') and is scientifically classified as the same species.. International Chicken Polymorphism Map Consortium (GK Wong et. al.) 2004. Nature 432, 717-722| doi:10.1038/nature03156 As such it can and does freely interbreed with populations of red jungle fowl. Recent genetic analysis, has revealed that at least the gene for yellow skin, was incorporated into domestic birds through hybridization with the Grey Junglefowl (''G. sonneratii'').Eriksson J, Larson G, Gunnarsson U, Bed'hom B, Tixier-Boichard M, et al. (2008) ''Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken.'' PLoS Genet January 23, 2008 .

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