Deciduous teeth morphology in the Hokkaido Jomon population: data on the population history of the Japanese archipelago

The article discusses morphology of deciduous key teeth (upper central incisors, upper and lower second molars) in the population of Hokkaido in the Jomon period, predominantly of its later part. The examined series included dental evidence from the sites of Irie, Bibi 4, Funadomari, Takasaga Abuto, Higashi Kushiro, Midorigaoka, and Mitsuya 3, 4, analyzed with the help of extended protocol which included the standard traits of the Russian odontological program, archaic markers, and features of the Neanderthal complex. Based on the frequencies of non-metric characteristics, it was concluded that the series was distinguished by weak representation of eastern traits and sharply increased frequency of mid-trigonid crest on deciduous lower second molars. Comparison of the series from Hokkaido with data from the western part of the Japanese archipelago has revealed that the Jomon population as a whole had at least two components, and population of Honshu and Kyushu had a Mongoloid component in its composition, which was absent in Hokkaido. An analysis of distribution of the mid-trigonid crest frequency in chronologically later series (Yayoi, Kofun, and Edo periods, Okhotsk culture, the Ainu of Hokkaido) has shown that direct population continuity with the Jomon groups in Honshu and Kyushu could only be traced up to the Yayoi period, while in Hokkaido it persisted from the Jomon period to the Ainu of Hokkaido close to modern times. Comparison of the examined series with characteristics of deciduous teeth from the archaeological sites of Siberia and Russian Far East has shown that mid-trigonid crest was absent in most of these finds. An exception was the series of the Bolsherechenskaya culture of the Early Iron Age from the burial grounds of Bystrovka 1, 2, and 3 in Western Siberia. Unfortunately the lack of comparative data does not make it possible to establish the reasons for the similarities with the population of Hokkaido.