REGIONAL VARIATIONS IN THE RYUKYU ISLANDERS ON TOOTH CROWN TRAITS

利用牙冠的格律和17个非格律特征对东亚和日本的冲绳本土种群、宫古岛种群和石垣岛种群进行了家谱定位。牙科石膏模型是从冲绳本土、琉球群岛的宫古岛和石垣岛的现代青少年居民身上收集的。对琉球岛民的牙列进行了岛屿间变异和生物种群亲和力的计量检验。测量了宫古岛和石垣岛居民的牙冠直径，并与其他地区的居民进行了比较。宫古岛和石垣岛所有前牙的中远端和阴唇舌冠直径均小于冲绳。石垣岛的牙冠直径均小于宫古岛。在中远端牙冠直径和牙冠面积上，上第一磨牙和下第一磨牙是最大和最稳定的牙齿，而上第二前磨牙和下第一前磨牙是最小的。上、下第二前臼齿按比例是冠指数中最大的牙齿。男性颊舌冠直径和冠面积均大于女性，宫古岛人群的前磨牙和除上第二磨牙外的磨牙，石垣岛人群的上第一前磨牙、上第二磨牙、下第一磨牙和第二磨牙均存在显著的性别差异。在琉球群岛，牙齿大小与地理位置相关。但当比较后区大小时，宫古岛和石垣岛具有地理相关性，而另一个则没有。将宫古岛和石垣岛人群的牙齿特征与其他人群进行了比较。宫古岛种群与种子岛种群和弥生种群有密切的亲缘关系，石垣岛种群与阿伊努种群和绳纹种群相似。研究了冲绳本土和琉球石垣岛现代青少年居民的牙石膏模型中17种非公制牙冠特征的发生率。将冲绳本土和石垣岛的发病率与其他11个日本人口和35个亚洲人口的发病率进行了比较。在东亚人群中，冲绳大陆和石垣岛具有介于东北亚（中国）和东南亚（中国）之间的中间特征。在日本人口中，琉球的三个岛屿绝大多数与移民群体相似（九州北部的弥生时代，绳纹时代和现代北海道阿伊努人）。然而，弥生时代种子岛的日籍人等星期天东渡人的居住表明，星期天东渡人在过去的琉球群岛上居住，中东渡人迁移到琉球群岛的后期。在现代琉球人口中，石垣人和冲绳主岛居民与九州北部的弥生时代和现代种子岛人口有密切关系，与现代北海道爱努人、绳纹时代和种子岛的弥生时代有很大不同。琉球群岛从北到南有一定数量的变异，这可能表明中国人的基因是从北而来的。本研究显示的牙齿证据可能有助于建立宫古岛和石垣岛人群之间的生物学关系。少

A genealogical positioning of the Okinawa main land, Miyakojima and Ishigakijima populations in East Asia and Japan was carried out by using metrical and 17 nonmetric tooth crown traits. Dental plaster casts were collected from teen-aged modern inhabitants of the Okinawa main land, Miyakojima and Ishigakijima of the Ryukyu islands.The dentition of the Ryukyu islanders were metrically examined in terms of inter island variation and biological population affinity. Measurements were taken of the tooth crown diameter of the inhabitants in Miyakojima and Ishigakijima and compared with those of another region. Mesiodistal and labio(bucco)lingual crown diameters of all anterior teeth in Miyakojima and Ishigakijima were smaller than in Okinawa. The crown diameters of all teeth in Ishigakijima were smaller than in Miyakojima.The upper and lower first molars are the largest and the most stable teeth in the mesiodistal and bucculingual crown diameters and crown area, while the upper second premol … More ar and the lower first premolar the smallest on the Miyakojima and the Ishigakijima populations. The upper and lower second premolars are proportionately the largest teeth in the crown index. The buccolingual crown diameter and crown area were larger for male than female, showing significant sex difference, premolars and molars except upper second molar, on the Miyakojima, and upper first premolar, upper second molar, lower first and second molars on the Ishigakijima populations.In Ryukyu islands, tooth sizes were correlated with geographical locations. But when compared with posterior region the sizes of Miyakojima and Ishigakijima were geographically correlated, and another not. Metrical dental characters of the Miyakojima and Ishigakijima populations were compared with these from the others. The Miyakojima populations show close affinities to the Tanegashima and Yayoi populations, and the Ishigakijima similar to the Ainu and Jomon populations.Incidences of 17 nonmetric tooth crown traits were investigated on dental plaster casts which collected from teen-age modern inhabitants of the Okinawa main land and Ishigaki island of the Ryukyu islands. The incidences of the Okinawa main land and Ishigaki islands were compared with other 11 Japanese populations and other 35 Asian-derived populations. In East Asian populations, Okinawa main land and Ishigakiisland had intermediate characters between the northeast Asian(Sinodonty)and the Southeast Asian(Sundadonty). In the Japanese populations, three Ryukyu islands were overwhelmingly similar to the migrant group(Yayoi period in north Kyusyu, the Jomon period, and the modern Hokkaido Ainu). However, the residence of Sundadonty such as Jomonese in Tanegashima on of the Yayoi period suggests a residence of Sundadonty in past Ryukyu islands and late migration on Sinodonty to Ryukyu islands. In modern Ryukyu poppulations, the Ishigaki and the Okinawa main islanders show affinities to the Yayoi period in north Kyusyu and the modern Tanegashima populations, and largely differ from the modern Hokkaido Ainu, the Jomon period and the Yayoi period in Tanegasima.Some amount of cline from north to south in the Ryukyu islands might indicate the gene flow of Sinodonty from the northward. The dental evidences shown in this study may contribute to the establishment of biological relationships between Miyakojima and Ishigakijima populations. Less