Pleistocene chickens (Gallus sp.)

Some of my wife’s relatives are chicken farmers.  Modern day poultry farmers raise chickens in long metal warehouses containing as many as 30,000 birds.  The warehouses smell like the inside of a toilet bowl that hasn’t been flushed or cleaned in a year.  Chicken farmers have to walk through each of their warehouses twice a day to collect and dispose of dead chicks.  This task prevents the spread of infectious diseases.  Agricultural catalogues sell Israeli gas masks for poultry farmers, so they won’t get sick from working inside their warehouses.  Wild chickens have a better quality of life than the birds that spend their entire lives inside these awful concentration camps.  At least they get to breathe fresh air and live naturally.

According to the paleobiology database, chickens formerly lived all across Eurasia.  The bones of extinct species of chickens have been unearthed at 8 sites in Europe.  These extinct species lived from the late Miocene to the early Pleistocene.  But when Ice Ages began occurring, the range of the chicken was reduced to southeast Asia.  Now, there are 4 or 5 species of chickens, but many additional species existed when earth’s overall climate was warmer.  Chickens require warm tropical/semi-tropical river valley forests where they can forage for seeds, fruits, and insects on the ground.  They can’t endure harsh temperatures.  Curiously, there are no known Pleistocene-aged fossils of chickens from their current range, though they undoubtedly abounded in the region then.  Bone preservation is uncommon in lowland tropical forests because of the acid soils.

Distribution map of the red jungle fowl, 1 of the ancestors of the domesticated chicken.

Research of the origin of chicken domestication is confused and contradictory.  Zooarchaeological and genetic evidence suggests chickens were first domesticated in northern China about 8,000 years ago.  However, some scientists re-examined the zooarchaeological evidence and determined the chicken bones were misidentified.  Instead, these supposed chicken remains are actually pheasant bones.  They also note that chickens are and were not native to northern China, a temperate zone region.  The fauna associated with the pheasant bones consisted of temperate species such as red deer, sika deer, and wild boar.  The species of mammals that co-occur with wild chickens including rhesus macaques, Asian elephants, and rhinos were absent from this region.  Northern China is just too cold for chickens, and it’s far more likely they were first domesticated in their native range of southern China.  By 3000 BP chicken farming had spread to northern China where the birds could survive winter with human help.

The modern farm-raised chicken is a hybrid cross between 2 species–the red jungle fowl (Gallus gallus) and the gray jungle fowl (G. sonneratii). Genetic evidence suggests the yellow skin pigment descends from the latter species.  Feral chickens occur locally in many towns and cities across southeastern North America including Miami, Key West, St. Augustine, Houston, New Orleans, and Fitzgerald, Georgia.  Chickens living in Fitzgerald descend from a population released along the Ocmulgee River.  The Georgia State Fish and Game Department hoped the birds would become a popular target for hunters.  Instead, the chickens abandoned the river bottomland forest and moved into suburban areas of the nearby town where they have thrived for decades.  Their preference for human-modified habitats may mirror their close ties to habitats modified by elephant foraging in their native range.  Elephants expand and maintain open areas, and they knock fruit to the ground.  Their manure attracts insects and contains undigested seeds.  Wild chickens benefit from the presence of elephants.  In suburbs humans maintain the open areas and accidentally provide food for chickens.

Feral chickens in Fitzgerald, Georgia.

Some people love suburban wild chickens, while others (the get-off-my-lawn assholes) resent the crowing and droppings.  I like free-ranging chickens better than grouchy old people.

References:

Eriksson, J; and et. al.

“Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken”

PLOS Genetics 2008

Peter, Joris; and Ophelia Librasseum, Hai Deng, and Gregor Larsh

“Holocene Cultural History of Red Jungle Fowl (Gallus gallus) and its Domestic Descendent in East Asia”

Quaternary Science Reviews   June 2016

Tags: domesticated chickens, feral chickens, Fitzgerald, origin of domestic chicken confused