Religious dogma in the Middle Ages helped create the modern domestic chicken, new research suggests.
Scientists at Oxford University studying DNA from archaeological chicken bones found reduced aggression, faster egg-laying and an ability to live in close proximity to other birds emerged about 1000 AD, during a time of intensified chicken production.
Christians subject to fasting edicts at that time were banned from eating meat from four-legged animals, but they could eat chickens and eggs.
The study, published in the journal Molecular Biology and Evolution, said natural selection favoured chickens with the domestication DNA variants.
Chickens were domesticated from Asian jungle fowl about 6000 years ago.