Medieval fasting ’linked with genetic changes in domesticated chickens?

A team of international scientists led by the University of Oxford has combined ancient DNA analyses with statistical modelling to pinpoint the timing of the selection for traits associated with modern chickens. They found that medieval Christians who fasted may have played a part in producing less aggressive farm birds. The team found that traits linked with reduced aggression and an ability to live in confined, smaller spaces with other birds emerged about 1000 AD in the European Middle Ages. These strong selection pressures coincided with an era in which Christians had widespread influence on what people should eat, including edicts that enforced fasting and the exclusion of four-legged animals from the menu. The paper published in the journal, Molecular Biology and Evolution , suggests religious edicts that allowed people to eat chickens and eggs during fasts, coupled with increasing urbanisation may have driven the evolution of modern domesticated chickens. The researchers say chickens genetically able to cope with more cramped accommodation and reproduce could be associated with the following three developments: Christian fasting, increased urbanisation, and more efficient farming practices that produced more food, such as the invention of the heavy plough, that allowed populations to work in towns and cities rather than rely on subsistence farming. Lead author Liisa Loog, from the Palaeogenomics and Bio-Archaeology Research Network at the University of Oxford, said: 'We tend to think that there were wild animals, and then there were domestic animals rather than thinking about the selection pressures on domestic plants and animals that varied through time.