Christianity’s ban on eating four-legged animals during fasting season may have boosted the stock of chickens as food.
Humans started raising chickens some 6,000 years ago, but it only became common in Europe around 800 A.D. Christianity is also spreading during those times, which led to speculations that chicken meat served as alternative food for Medieval Catholics when they observed fasting.
The study also found that the gene changes that made modern chicken farming possible came out of Medieval Europe.
It was also around 800 A.D. when new variant of the gene TSHR were found in European chickens. It was responsible for making chickens lay eggs all year round and at a younger age while reducing their fear of humans.
But it isn’t clear whether the Catholics were responsible for shaping chicken genetics as urbanization could also be the reason that ultimately allowed chickens to live in small spaces and stop pecking each other.
“We cannot say which one of these was most important,” said author Anders Eriksson in a press statement. “But most likely a combination of all these factors affected selective pressures on European chickens and consequently their evolution.”