Before the Backyard
Early history of the hen, by Andy Cawthray
Chickens weren’t always chickens, at least not in the way we think of and see them today or even a couple of centuries ago. The humble chicken in the 21st Century is probably the most prolific bird on the planet. Did you know that there are more chickens around the globe than there are people? In 2002, the Food and Agriculture Organization of the United Nations estimated that there were 19bn live chickens in the world, with China having the largest population, followed by the US, Indonesia and Brazil. This means that with a world human population of just over 7bn, there are almost three times as many chickens as there are people on the Earth at any one time.
This was not always the case, however, because the chicken began its existence as a rather localised, obscure, ground dwelling pheasant in the jungles of South East Asia. In truth, they are classed with similar birds in the taxonomic order Galliformes (commonly called gamebirds or galliforms). This group includes — in addition to the chicken and its wild forerunner the jungle fowl — turkeys, pheasants, quail, partridges, guinea fowl and peafowl.
Galliforms in general are adapted to life on the ground and, as a result, tend to be heavy in the body when compared to other birds. While we don’t consider chickens to be flyers, Galliformes are not viewed as flightless, with some capable of flight,
The history of the most abundant bird on the planet may be documented from domestication onwards, but the actual origin and prehistory of the chicken remains as complex a question as to which came first — it or the egg
although none of them are particularly strong at taking to the air. In the wild, most of the species in the order use their half flight ability for the primary purpose of avoiding predators.
If, while out walking, you have ever happened upon a pheasant, you will be familiar with the sudden explosion of wing flapping as the bird takes off. This is usually accompanied by an alarmed squawk. This is a defence mechanism designed to startle a potential threat or a predator and it usually lasts for only a few moments, although it is sufficiently long enough for the bird to land and put a fair few metres of distance between itself and danger. It seems likely that it was Charles Darwin who first proposed that the chicken was evolved from galliforms, primarily the jungle fowl ( Gallus gallus) and, most probably, the red jungle fowl. The red jungle fowl, which has the broadest range of the jungle fowl, most resembles the domestic chicken in appearance and behaviour. In fact, many novice and even some experienced poultry enthusiasts can and do mistake it for a chicken, although truly wild examples of the breed are infrequently encountered. This species is among a group of four surviving and as many as 13 extinct pheasant-type species that are found from western India through the southern reaches of Asia and into the island chains of Indonesia and the Philippines. The birds generally dwell on the jungle floor and on the margins of grasslands that edge forested areas. The ranges of these closely-related species rarely intersect, however, so there is little possibility of natural hybridisation between them. This indicates that man must have influenced the evolution of the chicken at the very beginning as opposed to nature taking its course unaided.
The red jungle fowl’s cousin
The other jungle fowl species have relatively small ranges and are mostly isolated. The grey jungle fowl ( Gallus sonneratii), sometimes called Sonnerat’s jungle fowl, is found in the westernmost part of the overall range of jungle fowl, generally in peninsular India. It differs most strikingly from its red jungle fowl cousin in its comb — the small points and minimal serrations of the grey jungle fowl comb are clearly in contrast with the more chicken-like ‘single’ comb of the red jungle fowl.
The remaining two jungle fowl species can be found isolated on some of the islands that lie within the overall range of the Gallus genus. The Sri Lankan jungle fowl ( Gallus lafayetii; previously called the Ceylon jungle fowl) is found only on the island of Sri Lanka off the eastern tip of southern India, while the green or Javan jungle fowl ( Gallus varius) is found on a few islands in western Indonesia, including Java and Bali.
It is understandable how evolutionary theory would identify the red jungle fowl as being the precursor to the chicken we know and love today. However, it is not beyond belief that the chicken may have evolved down all lines of the jungle fowl. Even today the true roots of the Araucana are subject to debate, with studies continuing into its true origins. The ones seen today most certainly will be related in some way to the original jungle fowls, although there is evidence to suggest that the blue egg-laying bird that was discovered in northern Chile (later to be known as the Araucana) may, in fact, have no Asian roots at all and may not be related to any of the four foundation species of jungle fowl.
The history of the most abundant bird on the planet may be documented from domestication onwards, but the actual origin and prehistory of the chicken remains as complex a question as to which came first — it or the egg.
NEXT MONTH: The history of the chicken after early domestication.
TOP: The Sri Lankan jungle fowl is found on the island of Sri Lanka in jungle like this ABOVE: It seems likely that Charles Darwin first proposed that the chicken was evolved from Galliformes
The chicken began its existence as a ground dwelling jungle pheasant
Man must have influenced the evolution of the chicken from the very beginning
Chickens are classed in the same taxonomic order (Galliformes) as pheasants