J.Anthrop. Soc. Nippon 人 類 誌 97(1):493-512 (1989) Geographical Variation of Dental Measurements in the Jomon Population Hirofumi MATSUMURA Department of Anatomy, Sapporo Medical College Abstract Mesiodistal and buccolingual crown measurements were taken from the permanent tooth remains of the five Middle to Latest Jomon population samples from the Hokkaido, Tohoku, Kanto, Tokai and San'yo districts of Japan. The metrical data were compared with each other through multi- variate statistical methods. The analysis of variance for these crown meas- urements suggested that most of the variables showing significant geogra- phical difference were buccolingual diameters. The distance analysis based on the crown measurements revealed that the Hokkaido Jomon was isolated from the Jomon in Honshu, the main island of Japan. The Honshu Jomon groups were closely related to each other, although the male Tohoku Jomon was slightly closer to the Hokkaido Jomon. The principal factor analysis revealed that the overall dental proportion of the Hokkaido Jomon was dif- ferent from those of the Honshu Jomon groups, and the Tohoku Jomon carried the smallest overall tooth size among the five Jomon population samples com- pared. From the comparisons with recent groups, it was indicated that 1) the diversity in dental morphology between the Hokkaido and Honshu Jomon was smaller than that between the recent Kanto Japanese and the Jomon as a whole ; 2) the dentition of the Jomon population was characterized by relatively small canines, premolars and second molars as compared with the first molars; 3) these dental characteristics could also be seen in the dentition of the Ainu. These facts suggested a close affinity between the Ainu and Jomon in the posterior tooth characteristics. However, with regard to the anterior teeth, both the relative and absolute dimensions of the incisors were larger in the Jomon than in the Ainu. Thus, the size reduction of the incisors may have proceeded from the prehistoric Jomon to the recent Ainu. Keywords Jomon, Permanent dentition, Crown diameter, Geographical varia- tion, Multivariate statistical analysis Article No 8916 Received July 15, 1989 494 H. MATSUMURA and ETOH, 1989). However, most of the Introduction studies on the geographical variations of The Jomon people were prehistoric hunter- the Jomon population have been based on gatherers in Japan, ranging in time from ca. cranial morphology, and studies based on 10,000 B. P. to ca, 2,000 B. P. Numerous metri- dental morphology have been very scarce. cal and nonmetrical studies have been pre- In the present study, first, geographical sented on the Jomon skeletal and dental variations of dental crown measurements morphology (KOGANEI,1893, 1894; HOWELLS, in the five Jomon population samples from 1966; SUZVKI, 1969, 1981; TURNER, 1976, Honshu and Hokkaido were examined 1979, 1987, 1989; BRACE and NAGAI, 1982; through multivariate statistical analyses; YAMAGUCHI, 1979, 1982; HANIHARA, 1984, secondly, the dental crown measurements 1985a,1985b ; DODO, 1986; MIZOGUCHI,1986; obtained from the pooled-Jomon population OSSENBERG, 1986; HANIHARA, 1989; and were compared with those of the Ainu and others). In most of these studies, some recent Kanto Japanese ; lastly, metrical morphological similarities between the Jomon characteristics of the Jomon dentition were and Ainu have been pointed out, and at the elucidated. present time not a few of the scholars consider that the Jomon were the direct Materials ancestor of the recent Ainu. The materials in the present study were Recently, in accordance with the accumula- the teeth of male and female Jomon skeletal tion of Jomon skeletal remains from various remains from the Hokkaido, Tohoku, Kanto, parts of the Japanese archipelago, geogra- Tokai and San'yo districts of Japan, as phical variations in morphology have been shown in Table 1 and Fig. 1. These noted for the Jomon population (OGATA, samples were from the collection in the 1981; DOD0,1982 ; YAMAGUCHI,1982; IKEDA, Department of Anatomy of Sapporo Medical 1984; HANIHARA and UCHIDA, 1985; MOURI, College, the Department of Anthropology 1988; BABA and ETON, 1989; SHIGEHARA and Prehistory of the University Museum Table 1. The Middle to Latest Jomon dental series used in the present study Geographical Variation in Jomon Population 495 the right side of the jaws. However, when the right side was inappropriate for meas- urements because of obvious dental ab- normality, heavy wear, caries, and so on, then the tooth from the left side of the jaw was substituted. To these mesiodistal and buccolingual measurements, several sta- tistical analyses were applied. The analysis of variance was used in order to examine the intergroup differences of a variable. For estimating biological distances between groups, the PENROSE'S shape distance and the MAHALANOBIS' generalized distance were computed. The standard deviations Fig, 1. Geographical provenances of the Jomon for calculating the PENROSE's shape distance, and recent populations. and the variance-covariance or dispersion matrix used for computation of the MAHA- of the University of Tokyo, the Department LANOBIS' generalized distance were based of Anthropology of the National Science on all of the Jomon samples. Multidimen- Museum, Tokyo, and the Primate Research sional scaling (MDS) (TOGERSON, 1958) was Institute and the Laboratory of Physical applied to the distance matrix in order to Anthropology of Kyoto University. All of easily understand the multidimensional in- these samples were dental series of the tergroup relationships. The factor analysis Middle to Latest Jomon periods. was employed in order to find out in- The dental samples from the Hokkaido formative dental characteristics for each Ainu and recent Japanese skeletal series group. In this procedure, the varimax rota- were used for comparison. The Ainu series tion method was used to clarify the mean- were from the collection in the Department ing of each factor, and then factor scores of Anatomy of Sapporo Medical College were computed for intergroup comparisons. and from the KOGANEI'S collection in the In addition, some indices were calculated to University Museum of the University of disclose more detailed dental characteristics Tokyo. The recent Japanese series from for each population sample. These analyses the Kanto district was the one housed in were carried out for males and females the University Museum of the University of separately. Tokyo. All of the samples examined were Results permanent teeth. Tables 2 and 3 give the basic statistics for Methods the mesiodistal and buccolingual diameters Mesiodistal and buccolingual crown di- of the permanent teeth in the five Jomon ameters were measured according to FUJI- population samples as well as the Ainu and TA's system of measurement (FUJITA, 1949). recent Kanto Japanese. Measurements were taken of the teeth from 496 H. MATSUMURA Geographical Variation in Jomon Population 497 498 H. MATSUMURA Geographical variation urements in the Jomon population, five in Geographical differences in tooth size the male and eight in the female showed a were examined among the five Jomon statistically significant geographical varia- population samples. The measurements of tion at the 5% or 1% level. It is noteworthy the incisors and canines as well as the third that most of them were buccolingual di- molars of the Jomon population were ex- ameters both in males and in females. cluded in the analysis of intergroup dif- Next, distance analyses were applied to ferences because the numbers of these teeth the five Jomon population samples. Table 5 were not sufficient for statistical analyses. gives PENROSE'S shape distances between The small sample size of the anterior teeth the five Jomon groups computed on the was chiefly due to customary tooth evulsion basis of the 16 crown measurements. The among the Jomon population. Consequently, results of the MDS applied to the shape 16 measurements for the premolars and distance matrices of Table 5 are illustrated molars were used in this comparative in Fig. 2 as one dimensional expressions. analysis. In the male, the Hokkaido Jomon showed a First, the analysis of variance was at- tendency of separation from the Jomon in tempted to examine the intergroup dif- Honshu. Among the Honshu Jomon groups, ferences in each variable. The results are the Kanto, Tokai and San'yo Jomon were shown in Table 4. Of the 16 crown meas- close to one another, while the Tohoku Table 4. Analysis of variance for mesiodistal (MD) and buccolingual (BL) crown diameters in the five Jomon population samples Fig. 2. One dimensional expression of MDS applied to the PENROSE's shape distances * Significant at the 5% level . based on the 16 crown diameters in the five ** Significant at the 1% level . Jomon population samples. Geographical Variation in Jomon Population 499 Table 5. PENROSE's shape distances based on 16 crown diameters (lower left: males, upper right: females) J : Middle to Latest Jomon, R : Recent Jomon was slightly closer to the Hokkaido the Hokkaido Jomon are separated from the Jomon. In the female, the Hokkaido Jomon Honshu Jomon in the PENROSE's shape dis- was apparently isolated from the Jomon tances. MAHALANOBIS'generalized distances groups in Honshu. Consequently, it can be were also calculated based on the 16 crown postulated that both in males and females measurements. The results are shown in Table 6. Fig. 3 shows the one dimensional expressions of the MDS applied to the MAHALANOBIS' generalized distances. For both the male and female, almost the same trend as in Fig. 2 could be observed. In the third place, geographical and tem- poral variations of the 16 dental measure- ments were examined in the seven popula- tion samples including those of the Ainu and recent Kanto Japanese. In order to compare the overall tooth size, the sum of the cross-sectional areas (mesiodistal diameter buccolingual diameter) for the permanent* teeth from the first premolars to the second molars of both jaws were calculated for each population sample as shown in Fig.