The Domestication History of Chickens (Gallus domesticus)

When Was the Chicken Domesticated? And Who Gets the Credit?

Red Junglefowl (Gallus gallus) in Kaziranga National park in Assam, India
Red Junglefowl (Gallus gallus) in Kaziranga National park in Assam, India. Getty Images / Hira Punjabi / Lonely Planet Images

The history of chickens (Gallus domesticus) is a bit of a puzzle. They were first domesticated from a wild form called red junglefowl (Gallus gallus), a bird that still runs wild in most of southeast Asia, likely hybridized with the gray junglefowl (G. sonneratii). That occurred probably about 8,000 years ago. Recent research suggests there may have been multiple origins in distinct areas of South and Southeast Asia, southern China, Thailand, Burma, and India.

The Evidence for Domestic Chicken Origins

Since the wild progenitor of chickens is still among us, comparisons of behavior and other differences between the wild and domestic forms are available to us. Behaviorally, domesticated chickens are less active, have fewer social interactions, are less aggressive to would-be predators, and are less likely to go looking for foreign food sources than their wild ancestors. Other changes include increased adult body weight and simplified plumage; domestic chicken egg production starts earlier, is more frequent, and produces larger eggs.

Genetic studies hint at multiple origins of domestication. The earliest archaeological evidence to date is from China about 5400 BC, in geographically widespread sites such as Cishan (Hebei province, ca 5300 BC), Beixin (Shandong province, ca 5000 BC), and Xian (Shaanxi province, ca 4300 BC). In 2014, a few studies were published supporting the identification of early chicken domestication in northern and central China (Xiang et al.).

However, their results remain controversial.

A 2016 study (Eda et al.) of 280 bird bones reported as chicken from Neolithic and Bronze age sites in northern and central China found that only a handful could securely be identified as actually chicken. Peters and colleagues (2016) looked at environmental proxies in addition to other research and concluded that the habitats conducive to jungle fowl were not present early enough.

Researchers suggest that chickens were a rare occurrence in northern and Central China, and thus probably an import from southern China or Southeast Asia where evidence of domestication is stronger. 

Chicken Dispersals

Domesticated chickens appear at Mohenjo-Daro in the Indus Valley by about 2000 BC and, from there the chicken spread into Europe and Africa. Chickens arrived in the Middle East starting with Iran at 3900 BC, followed by Turkey and Syria (2400-2000 BC) and into Jordan by 1200 BC.

The earliest firm evidence for chickens in east Africa are illustrations from several sites in New Kingdom Egypt. Chickens were introduced into western Africa multiple times, arriving at Iron Age sites such as Jenne-Jeno in Mali, Kirikongo in Burkina Faso and Daboya in Ghana by the mid-first millennium AD. Chickens arrived in the southern Levant about 2500 BC and in Iberia about 2000 BC.

Chickens were brought to the Polynesian islands from Southeast Asia by Pacific Ocean sailors during the Lapita expansion, about 3,300 years ago. While it was assumed that they had been brought to the Americas by the Spanish conquistadors, presumably pre-Columbian chickens have been identified at several sites throughout the Americas, most notably at the site of El Arenal-1 in Chile, ca 1350 AD.

Chickens in America

At El-Arenal, American archaeologist Alice Storey and colleagues have identified evidence for chickens prior to the medieval Spanish colonization. Ancient and modern DNA from chickens reported by Thomson et al. identified the likely genetic markers of authentic ancient Polynesian chickens at El Arenal-1. They assert that among Polynesian chickens, one particular cluster of mitochondrial DNA, Haplogroup D, is the signature of the founding lineage of Polynesian chickens. Haplogroup E is the key piece of genetic evidence supporting the pre-Columbian presence of Polynesian chickens on the coast of South America: Storey and colleagues pointed to the presence of haplogroup E in both chickens from Rapa Nui (Easter Island) and coastal Chile (El Arenal-1). Thomson and colleagues argue that the presence of Haplogroup E in chickens from Rapa Nui is from contamination.

In supplementary data provided with the Thomson article, the researchers indicate that Haplogroup D closely follows the distribution of cockfighting in India, Indonesia, China, and Japan, also a traditional practice in Polynesian societies. In contrast, the other haplogroups, including A, B, and E, are ubiquitous worldwide. Radiocarbon dates from el-Arenal and the other early South American sites fall as early as 1350 but are debated in the published literature. Storey et al. responded with longer database sequences; and Thomson et al. countered: the presence of pre-Columbian chickens in South America is still controversial. 

Simulations from the Thomson studies indicate that chickens were transported from New Guinea into Micronesia by about 3,850 years ago; and separately from New Guinea to the Solomon Islands, Vanuatu and eastward at a later date.