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General biology and habitat
Chickens may live for five to ten years, depending on the breed. Roosters can usually be differentiated from hens by their striking plumage of long flowing tails and shiny, pointed feathers on their necks and backs which are typically of brighter, bolder colors than those of females of the same species. The identification must be made by looking at the comb, or eventually from the development of spurs on the male’s leg. In 2006, scientists researching the ancestry of birds “turned on” a chicken recessive gene, talpid2, and found that the embryo jaws initiated formation of teeth, like those found in ancient bird fossils.