CHICKEN (GALLUS GALLUS DOMESTICUS)

Chicken (Gallus Gallus Domesticus)



Chicken (Gallus Gallus Domesticus)

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, 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. 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. 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.

The chicken is believed to have descended from both the Red Junglefowl (Gallus gallus) and the Grey Junglefowl (G. sonneratii), though hybrids of both wild types usually tend to be sterile. Recent genetic work has revealed that the genotype for yellow skin present in the domestic fowl is not present in what is otherwise its closest kin, the Red Junglefowl. It is most likely that the yellow skin trait in domestic birds originated in the Grey Junglefowl.

Formerly, phenotypic diversity of modern chickens led to a belief of polyphyletic origins. According to genetic researchers, all modern chicken genes can be derived from the subspecies of Gallus found in northeast Thailand. This is supported by archaeological findings. Researchers have found chickens' bones in unusual amounts and out of natural jungle range, thus denoting a breeding place. Bones of domestic chickens have been found about 6000-4000 BC in Yangshao and Peiligan, China, while the Holocene climate was not naturally suitable for the Gallus species. Archaeological data is lacking for Thailand and southeast Asia.

Later traces are found about 3000-2000 BC in Harappa and Mohenjo-Daro, Pakistan, and -according to linguistic researchers- in Austronesian populations traveling across southeast Asia and Oceania. A northern road spread chicken to the Tarim basin of central Asia, modern day Iran. The chicken reached Europe (Romania, Turkey, Greece, Urkraine) about 3000BC, and the Indus Valley about 2500 BC. Introduction into Western Europe came far later, about the 1st millennium BC. Phoenicians spread chickens along the Mediterranean coasts, to Iberia. Breeding increased under the Roman Empire, and was reduced in the Middle Ages. Middle East traces of chicken go back to a little earlier than 2000 BC, in Syria; chicken went southward only in the 1st millennium BC. The chicken reached Egypt for purposes of cock fighting about 1400BC, and became widely bred only in Ptolemaic Egypt (about 300 BC).

Little is known about the chicken's introduction into Africa. Three possible ways of introduction in about the early first millennium AD could have been through the Egyptian Nile Valley, the East Africa Roman-Greek ...