New research gains insight into how the barnyard chicken came to be.
Researchers looked at 200 to 2,300-year-old chicken bones discovered in Europe to make their findings, a National Evolutionary Synthesis Center (NESCent) news release reported.
The team found that only a few hundred years ago chickens may have been almost unrecognizable.
"It's a blink of an eye from an evolutionary perspective," co-author Greger Larson at Durham University in the United Kingdom, said in the news release.
Chickens are descendants of a wild bird called the Red Junglefowl that was domesticated between 4,000 and 5,000 years ago in South Asia. The researchers focused on two genes that were believed to have differed between domestic chickens and the Junglefowl. These were "a gene associated with yellow skin color, called BCDO2, and a gene involved in thyroid hormone production, called TSHR," the news release reported.
Researchers are unsure of the exact function of TSHR, but believe it could have something to do with the ability to lay eggs year-round. Wild birds such as the red junglefowl only lay eggs at certain times of the year.
The team also found that only one sequence of DNA would have given the chicken yellow skin, as is seen today; only half the ancient chickens had the TSHR gene.
The finding suggests these traits only became popular within the past 500 years; thousands of years after the chicken was first domesticated.
"Just because a plant or animal trait is common today doesn't mean that it was bred into them from the beginning," Larson said.
"It demonstrates that the pets and livestock we know today -- dogs, chickens, horses, cows -- are probably radically different from the ones our great-great-grandparents knew," he said. "They are subjected to the whim of human fancy and control, [so] radical change in the way they look can be achieved in very few generations."
