Chicken

Each flock of chickens develops a social hierarchy that determines access to food, nesting sites, mates, and other resources. At about six months, males produce viable sperm, and females produce viable eggs. Despite the chicken’s close relationship with the red jungle fowl, there is evidence that the gray jungle fowl (G. sonneratii) of southern India and other jungle fowl species, also members of Gallus, may have contributed to the bird’s ancestry. The chicken is a sacred animal in many cultures and deeply embedded in belief systems and religious practices.Roosters are sometimes used for divination, a practice called alectryomancy.

Farming

It is estimated that chickens share between 71 and 79% of their genome with red junglefowl. Domesticated chickens freely interbreed with populations of red junglefowl. Strongly inbred Langshan chickens display obvious inbreeding depression in reproduction, particularly for traits such as age when the first egg is laid and egg number. Only hens that could no longer produce enough eggs were killed and sold for meat. Only in the early 20th century, however, did chicken meat and eggs become mass-production commodities. Although many taxonomists and ornithologists consider it as a domesticated form of the wild red jungle fowl, some classify it as a subspecies of the red jungle fowl (i.e., G. gallus domesticus), whereas others, including the U.S.

A flock thus uses only a few preferred locations, rather than having a different nest for every bird. Reproduction declines with age, thought to be due to a decline in GnRH-I-N. If the female is unreceptive, she runs off; otherwise, she crouches, and the male mounts, treading with both feet on her back. Mating typically involves a sequence in which the male approaches the female and performs a waltzing display.

Analysis of the most popular commercial breed shows that the White Leghorn breed possesses a mosaic of divergent ancestries inherited from different subspecies of red junglefowl. Archaeological evidence appeared to support domestic chickens in Southeast Asia well before 6000 BC, China by 6000 BC and India by 2000 BC. Exactly when and where the chicken was domesticated was controversial. Inbreeding of White Leghorn chickens tends to cause inbreeding depression expressed as reduced egg number and delayed sexual maturity. When eggs are placed in a hypoxic environment, chicken embryos from these populations express much more hemoglobin than embryos from other chicken populations. Under natural conditions, most birds lay only until a clutch is complete; they then incubate all the eggs.

Africa

Adult chickens of both sexes have a fleshy crest on their heads called a comb or cockscomb, and hanging flaps of skin on either side under their beaks called wattles; combs and wattles are more prominent in males. In older sources, and still often in trade and scientific contexts, chickens as a species are described as common fowl or domestic fowl. Many immature males (cockerels) are castrated (usually chemically, with hormones that cause atrophying of the testicles) to become meat birds (capons).

• It was first domesticated around 8,000 years ago and is one of the most common and widespread domesticated animals in the world.
• An early study proposed that a single domestication event of the red junglefowl in present-day Thailand gave rise to the modern chicken.
• To initiate courting, some roosters may dance in a circle around or near a hen (a circle dance), often lowering the wing which is closest to the hen.
• The pseudo-riddle «Why did the chicken cross the road?» dates to 1847, or earlier.
• Genomic studies estimated that the chicken was domesticated 8,000 years ago in Southeast Asia and spread to China and India 2,000 to 3,000 years later.
• Adult chickens of both sexes have a fleshy crest on their heads called a comb or cockscomb, and hanging flaps of skin on either side under their beaks called wattles; combs and wattles are more prominent in males.

Chickens have been thought of primarily as providers of food, but their cognition, emotions, and sociality are comparable with other birds and mammals. Chickens are gregarious, living in flocks, and incubate eggs and raise young communally. The body is round, the legs are unfeathered in most breeds, and the wings are short. Chicken can mean a chick, and this was historically the meaning of the word chicken, as in William Shakespeare’s play Macbeth, where Macduff laments the death of «all my pretty chickens and their dam».

Large numbers of embryos can be provided commercially; fertilized eggs can easily be opened and used to observe the developing embryo. Keeping chickens as pets became increasingly popular in the 2000s among urban খেলাঘর গেম and suburban residents. The first pictures of chickens in Europe are found on Corinthian pottery of the 7th century BC.