History of the chicken
From Asian jungles to garden pet
While watching our little flocks potter around in the garden we might get to thinking about the origin of our feathery pets, so here we have some information about the history of the chicken. Chickens belong in the order Galliformes which evolved from partridge type birds that survived the extinction event that killed all tree dwelling birds and the dinosaurs.
Gallus gallus domesticus better known as the chicken, is a sub species of the red jungle fowl, they are classified as the same species and domesticated chickens and red jungle fowl can and do interbreed. DNA evidence shows that there are four different jungle fowl in chickens’ ancestry but the red jungle fowl is considered the main ancestor of the domestic chicken.
Originating in south east Asia and the Indian subcontinent chickens have been domesticated for 8000 years and were originally raised for cock fighting, this sport was instrumental in the domestication of the chicken and it’s subsequent distribution throughout the world but curiously chickens were not routinely kept for food until the 4th– 2nd centuries BC.
There are records of chickens in Greece in the 5th century BC and in Egypt in the 15th century BC the anals of Tutmose III mentions “a bird that gives birth every day”. Chickens reached Europe around 800BC.
Augury is the practice from ancient Rome of interpreting omens from the behaviour of chickens. When the individual, known as the augur, interpreted these signs, it is referred to as “taking the auspices”. ‘Auspices’ is from the Latin auspicium and auspex, literally “one who looks at birds.”
Nothing of any significance took place in the armies or the Senate without the sacred chickens being consulted first. The method used to draw these omens was observing how the chickens dealt with grain that was presented to them, if they ate it enthusiastically while scratching the ground the augury was favourable. If they refused to eat, the omen was bad and whatever the undertaking was that being consulted on would be abandoned. When the priests wanted to guarantee a favourable omen they would keep the chickens locked away without any food!
These days chickens are mainly kept as a source of food via their eggs or meat and also as pets and show birds. There are a lot of chickens on the planet, in fact there are more chickens than any other bird, nearly 24 billion in 2018!
Centuries of selective breeding has produced a myriad of different shapes and sizes, colours and feather types as well as traits which have made the chicken so popular all over the planet such as all year egg laying and birds who go from hatching to slaughter weight in just 6 to 8 weeks.
In 2004 the chicken made history as the first bird and domesticated animal to have a complete genome map produced by geneticists. The researchers used this knowledge to see what changes the centuries of selective breeding had had on the modern chicken compared to it’s red jungle fowl ancestor.
The research identified mutations in a gene in broilers (meat chickens) which regulates glucose metabolism, mutations in this gene in humans has been associated with obesity but in a bird destined for the dinner table it is considered a positive trait!
Another gene mutation was identified in modern laying chickens in the thyroid-stimulating hormone receptor. In wild birds this gene coordinates day length and reproduction which confines breeding to specific seasons. Through selective breeding birds have been produced with this gene ‘switched off’ enabling modern chickens to lay and breed all year long.
For better or worse this little dinosaur descendant has gone from its jungle home to spanning the globe and outnumbering human beings by nearly three to one!