Introduced into Europe during the Bronze-and Iron Ages as an exotic, non-native species, very little is 8 currently understood about the origins and spread of early domestic fowl, Gallus gallus domesticus. Ecological niche 9 modelling of extant Red Junglefowl, Gallus gallus, presents a unique opportunity to examine historical ecological 10 implications associated with its descendant, the chicken, in early stages of domestication. We model the 11 environmental conditions associated with Red Junglefowl populations both in south-east Asia, where the bird 12 originates, and populations transported further afield as a consequence of human interaction. This allows us to 13 establish the full extent of the ecological tolerance of the ancestor bird. We show that potential for suitable sets of 14 environmental conditions for Red Junglefowl in Europe ranges from poor to limited, based on both current climate 15 and when projecting to mid-Holocene (ca. 4000BC) climate simulations. This suggests that human intervention played 16 a vital contribution during early domestication to ensure the future widespread success of the chicken. These 17 conclusions offer new insights into the archaeological evidence. We identify areas in the native range as the probable 18 location of first domestication, and not China as has been suggested. We suggest that a dispersal route into Europe via

Xiang et al. (1) assert that chickens were domesticated on the North China plain 10,000 y ago. Although a great deal remains unknown about the temporal and geographic origins of poultry husbandry, this claim is extraordinary. We welcome the increasing application of modern bioarcheological techniques to questions pertaining to animal domestication in China, but we are skeptical about these conclusions for several reasons. Firstly, their claim that chickens were domesticated on the North China plain is problematic because this region is currently climatically unsuitable for their wild ancestor (the red jungle fowl). In support of this assertion, they point to the abundance of tropical animals at the sites of Nanzhuangtou and Cishan. High-resolution paleoclimatic records (2) suggest, however, that before the mid-Holocene, cooler temperate conditions prevailed between 35°N and 40°N (hence the dominance of Palaearctic species at Nanzhuangtou). Although higher (+2-4°C) average temperatures in the mid-Holocene supported the presence of an Indomalayan mammalian complex, the species identified are present today above 30°N. In contrast, red jungle fowl populations in China do not exist north of 23°N. This evidence suggests that an environment suitable for thermophile red jungle fowl did not exist at the sites of Cishan or Wangyin. In addition, although cooler temperatures would allow for enhanced DNA preservation, the predicted (thermal-age.eu) mean fragment lengths of 23 bp and 31 bp for Nanzhuangtou and Cishan, respectively, appear at odds with the described looped PCR protocol. Secondly, identifying Galliform bones to genus on the basis of their morphology is straightforward (3). In fact, studies of phasianid remains from across China (4) have revealed that although pheasants were identified at Neolithic Cishan and Wangyin, Gallus was only present in the Warring States Period tomb (476−221 B.C.) at Jiuliandun.

Little is known about the early history of the chicken (Gallus gallus domesticus), including the timing and circumstances of its introduction into new cultural environments. To evaluate its spatio-temporal spread across Eurasia and north-west Africa, the authors radiocarbon dated 23 chicken bones from presumed early contexts. Three-quarters returned dates later than those suggested by stratigraphy, indicating the importance of direct dating. The results indicate that chickens did not arrive in Europe until the first millennium BC. Moreover, a consistent time-lag between the introduction of chickens and their consumption by humans suggests that these animals were initially regarded as exotica and only several centuries later recognised as a source of ‘food’.

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