Holy chick! Fasting by medieval Christians more than 1,000 years ago led to the evolution of domestic HENS

Monks banned meat at fasting but allowed chicken and eggs in Medieval times

As a result chickens evolved to be less aggressive and lay eggs at a faster rate

These traits began to appear during the High Middle Ages, around 1,000 AD 

A new study of discarded medieval chicken bones and their DNA found modern traits began to appear during the High Middle Ages, around 1,000 AD 

MODERN CHICKENS

Benedictine monks banned meat during fasting but allowed chicken and eggs in Medieval Europe. 

Chickens evolved a number of traits valuable to humans, including reduced aggression and faster egg-laying.

Researchers looked at discarded medieval chicken bones and their DNA, and found these traits began to appear during the High Middle Ages, around 1,000 AD.

Research shows that people were increasingly eating chicken around that time. 

They developed a variant of this gene that has been shown to enable faster egg-laying, and result in reduced aggression and decreased fear of humans. 

Benedictine monks banned meat during fasting but allowed chicken and eggs in Medieval Europe. At this time chickens evolved a number of traits valuable to humans (stock image)



GENETIC VARIANTS

The new study analysed ancient and modern chicken DNA using a statistical method they developed to pinpoint when selection starts and how strong it is.

Scientists pinpointed genetic variants in the thyroid-stimulating hormone receptor (TSHR) and the beta-carotene dioxygenase 2 (BCD02). 

In chickens, a variant of the TSHR gene has been shown to enable faster egg-laying, and result in reduced aggression and decreased fear of humans.

Selection of this gene began around 920AD, which coincides with increased chicken consumption across the whole of Northern Europe.

BCD02 has an effect on skin pigmentation in birds but they lacked the right statistical methods to quantify the timing or strength of natural selection.