Exploring the Possibility of Successive Breeding of Chickens in the Yayoi Culture, Japan

ABSTRACT Chickens are domestic animals whose main ancestor is the red junglefowl ( Gallus gallus ), and their natural habitat is Southeast Asia and Southern China. Domestic chickens were brought to the Japanese archipelago by the middle of the Yayoi period (4th–3rd bce ). Research on chicken sexual dimorphism shows that Yayoi‐era (10th bce –3rd ce ) birds were mostly male, hindering widespread breeding across Japan. In the 2011 research area at the Karakami site in Iki City, Nagasaki Prefecture, 18 Phasianidae bones were identified in a large ditch estimated to have been buried in the late Yayoi period. Although the tarsometatarsus and tibiotarsus were found to belong to chickens based on their morphological characteristics, it was impossible to determine whether the other bones, including the four juvenile bones, were derived from chickens. In our previous study, we established a method to distinguish between the bones of Japanese wild pheasants and chickens by using collagen peptide fingerprinting (ZooMS). In this study, we conducted ZooMS species identification of zooarchaeological bird remains and determined the sex of chicken remains in Karakami. We found six mature Phasianidae remains belonging to chickens, five of which were assumed to be males based on their sexual dimorphism. However, all five immature bird bones, including the three previously identified Phasianidae bones, were not derived from either chickens or Galliformes. These results do not support successful breeding of chickens at the Karakami site. Chickens were thought to have been brought to the Japanese archipelago from the Korean Peninsula through Iki Island. Further studies must determine when chickens were introduced to Iki Island and whether they included both males and females during their earliest introduction to Iki Island and the Japanese archipelago.