Anthropol. Sci. 103(3), 291-308, 1995

Differences in Mandibular Morphology of the Jomon People from

Kanto and the Yayoi People from Northern Kyushu and Yamaguchi

YOUSUKE KAIFU

Department of , National Science Museum, 3-23-1, Hyakunin-cho, Shinjuku-ku, Tokyo 169, Japan

Received October 31, 1994

•ôGH•ô Abstract•ôGS•ô Differences in mandibular morphology were investigated among three Japanese populations, the Neolithic Jomon from the Kanto region and two Aeneolithic Yayoi series from the northern Kyushu region and Yamaguchi Prefecture. The Jomon and Yayoi are considered to represent two major ancestral

populations of the modern Japanese. Differences between the two male Yayoi samples were so small that they could be considered as having nearly identical mandibular morphology. Considerable differences were detected between the males of the Yayoi populations and the Jomon. In comparison to the Jomon males, mandibles of the male Yayoi populations are characterized by having (1) a larger overall size, (2) a higher symphyseal height, (3) corpus heights consistently decreasing posteriorly, (4) a relatively lower least coronial height, (5) a deeper

sigmoid notch, (6) a thicker angular region, and (7) a larger mandibular angle. In contrast, corpus heights at the premolar region of the Jomon mandibles were approximately equivalent to the symphyseal height. A similar tendency was recognized in the females with minor exceptions.

•ôGH•ô Key Words•ôGS•ô: mandible, morphometry, Jomon, Yayoi

INTRODUCTION

Investigation of differences in skeletal morphology between populations is a

fundamental step in studies of skeletal anthropology. There are two major possible

ancestral populations of the modern Japanese. One is the original Holocene

inhabitants of Japan, the Neolithic Jomon people. The other is represented by a series

of skeletons from the Aeneolithic Yayoi period unearthed in the northern Kyushu

region and Yamaguchi Prefecture (Fig. 1). The latter is morphologically different

from the former, and has thus been regarded as immigrants from the Asian continent

or their offspring. Therefore, establishing in advance the morphological differences

between these two populations is fundamental to most studies utilizing Japanese

skeletal material.

While there are a certain number of studies concerning the morphological

differences between the Jomon and the Yayoi series in the cranium, teeth and

postcranial limb (Brace and Nagai,1982; Dodo and Ishida, 1988, 1990; Dodo et al., 1992; Hanihara et al., 1988; Kanaseki et al., 1960; Matsumura, 1991, 1994;

Naito,1981; Nakahashi, 1993; Nakahashi et al., 1985; Nakahashi and Nagai, 1989; 292 Y. KAIFU

Fig. 1. Map of Japan showing the geographical derivation of the samples used. District names are in italic. K-Jomon=The Jomon from the Kanto region; NK-Yayoi=The Yayoi from the northern Kyushu region; Y-Yayoi=The Yayoi from Yamaguchi Prefecture.

Tagaya, 1987; Ushijima, 1954; Yamaguchi, 1989; Zaitsu, 1956), differences in mandibular morphology have never been comprehensively investigated. Ohori (1958) made a comparative study of the mandibles of the Yayoi material unearthed at the Doigahama site in Yamaguchi Prefecture and data from several published reports including Jomon data. However, he did not take the effect of interobserver measurement error into consideration, and the selection criteria for the materials were not presented. Moreover, numerous additional Yayoi specimens have been unearthed in the last three decades. The majority of the sample used in this study is comprised of these new specimens. The paucity of studies on the mandible may be partly because mandibular morphology is considered to have a great degree of plasticity resulting from Mandiblesof the Jomon and Yayoi People 293

environmental influences. However, plasticity is something which must be taken into consideration whenever genealogical relationships between populations are examined by means of skeletal morphology, no matter what part of the skeleton is utilized. With proper considerations, analyses of mandibular morphology should provide valuable information to studies of population history. The purpose of the present study is to assess metric morphological differences between the mandibles of the Jomon from the Kanto region and the Yayoi from the northern Kyushu region and Yamaguchi Prefecture.

MATERIALS AND METHODS The materials used in this study and other relevant information are presented in Table 1. The existence of some morphological differences in the metric and nonmetric cranial characteristics of the northern Kyushu region and Yamaguchi Prefecture samples in the Yayoi series has been pointed out (Dodo et al., 1992; Matsushita, 1987; Matsushita and Naito, 1989; Nakahashi and Nagai, 1989). Because of this, the samples from these two regions were handled separately in the present study. Selection criteria for the materials are: 1) The presence of a full complement of lower alveoli including that of M3. 2) Lower M3 having erupted to at least near the occlusal plane. 3) No marked abnormalities on the lower jaw and teeth (e.g., caries, periodontal disease). Specimens with unilateral alveolar resorption (due to antemortem tooth loss) were included in the present sample as long as a non -resorbed contralateral alveolus was retained without recognizable side differences of the dental arch as evaluated with the naked eye. Some broken specimens were included to increase the sample size of the K-Jomon and NK-Yayoi as far as the remaining portions met the above criteria. The number of such incomplete specimens was relatively small (6/58, 5/34 respectively for the K-Jomon males and females, and 2/46, 3/22 respectively for the NK-Yayoi males and females).

Table 1. Materialsused in this study

TUM=University Museum, Univ. of Tokyo; NSM=National Science Museum, Tokyo; St.M=St. Marianna Medical College; CCC=Cultural Properties Center of Chiba Prefecture. 294 Y. KAIFU

Frequency of congenital absence of M3 may be a population dependent trait.

However, in the case of some individuals, M3 may fail to erupt due to insufficient

development of the jaw . Alternatively, M3 agenesis may result in an

underdeveloped mandibular body. To avoid these complications, specimens without

alveoli for M3 were omitted from the present sample.

Sex was determined by the present author whenever possible on the basis of

morphological observations of the associated and cranium. The pelvis was

given priority and the cranium was used after the careful observation of individuals sexed by their associated pelvis. Using these independently sexed mandibular

samples, 5 discriminant functions were calculated with 40 male and 24 female Jomon

specimens using 2 to 4 measurements. The percentage of correct discrimination of

these functions ranged between 78 and 88. By applying these discriminant functions,

18 additional Jomon specimens without associated pelvis or cranium were evaluated

and added to the sample.

Methods of measurements are defined in Table 2 and graphically displayed in

Fig. 2.

In addition to the raw measurements, the size and size-standardized variables were

calculated, following Hagaman and Morbeck (1984). The size variable was defined

as the average of the selected raw measurements for an individual. The size

- standardized variables were defined as 100•~(raw measurement)/(size variable).

This isometric method allows a simple and straightforward comparison of shape,

preserving the original dimensional relationship of the variables while not dependent on a single variable as the denominator. The size variable was calculated as follows.

SV and M(n) (n=1,...,13) were defined as outlined in Table 3. SV/M(n) were

calculated for individual specimens and the mean of this for each population was

represented by P(n,i) (i indicates one of the three populations). S(n)=M(n)•~P(n, i)

was computed for every individual and the mean of S(1) through S(9) was expressed

as SS, the mean of S(10) through S(13) as SSS. SV was given priority as the size

variable, but SS was used if SV was missing, and SSS was used if both SV and

SS were missing.

Measurements were made by the present author with a digital sliding caliper

(Mitutoyo, Japan) to an accuracy of 0.1mm. The mean of the left and right sides was used for the analysis. If it was impossible to measure one side, the other side

alone was used. The least significant difference (LSD) was utilized for the univariate

comparisons of the measurements and the size variable since these were planned

comparisons (Sokal and Rohlf, 1981). The objective of these statistical tests is to

compare each pair among the three populations (the K-Jomon, NK-Yayoi and Y-

Yayoi). Mann-Whitney's U test was employed for the indices and size-standardized

variables since these are quotients of individual measurements, therefore, the

distributions of these are not expected to be normal (Hoel, Port and Stone, 1971). Mandibles of the Jomon and Yayoi People 295

Table 2. List of measurement names and methods

Martin's methods were referred to in Baba (1991).

For further data summary and discussion, principal component and discriminant function analyses were undertaken on selected variable subsets. Remarks on these analyses are described in their respective sections. All statistical procedures were performed using SYSTAT Macintosh 5.2.1 (SYSTAT Inc., 1992) but in the case of Mann-Whitney's U test, Table J of the appendix in Siegel (1956, translation by 296 Y. KAIFU

Fig. 2. Measurements used in this study.

Fujimoto (1983)) was used if the sample sizes were less than 20 in both the populations under comparison. Mandibles of the Jomon and Yayoi People 297

Table 3. Equations for calculating the size variable

UMLm=distance from infradentale to kondylion laterale; LMLm=distance from gnathion to gonion.

RESULTS Tables 4 and 5 show the descriptive statistics and results of statistical tests for the measurements, indices, size variable and size-standardized measurements. The female size-standardized measurements are not considered here since the sample size was considerably small. Overall Size: In males, 5 out of 9 items which represent breadth of the mandible (#1-5 and 8-11 in Table 4), are significantly broader in the NK-Yayoi and 3 in the Y-Yayoi compared to the K-Jomon. The remainder of the 9 variables, although not significant, exhibit greater mean values in the Yayoi samples than in the K-Jomon. The trend observed in females is similar although the female sample size is relatively small. Within the two Yayoi populations, the NK-Yayoi male seems slightly larger in mandibular breadth than the Y-Yayoi male as a whole. In females, although there are 4 measurements showing a significant difference between the NK-Yayoi and the Y-Yayoi, the tendency is not consistent, and thus, it is difficult to judge which population has a broader mandible. Of the 3 measurements representing the length of the mandible or dental arch (#6,7, 12 in Table 4), in males, 1 is significantly longer in the two Yayoi populations than in the K-Jomon. Trends seen in the females are similar to those seen in the males. Both the NK-Yayoi male and female and the Y-Yayoi female have higher corpus heights (#21-26 in Table 4) than the K-Jomon. The mean values of the Y-Yayoi male, although not statistically significant, are also higher than those of the K-Jomon male. There are no significant differences between the NK-Yayoi and Y-Yayoi in the above items. The differences seen in ramal dimensions (#13-15 in 298 Y. KAIFU

Table 4. a) Comparisons of the mandibular measurements, indices and size variable (male)

Descriptive statistics and the results of comparisons using LSD (measurements and size variable), and Mann-Whitney's U test (indices). In the last three columns, a blank indicates P>0.10. An asterisk on the shoulder of a probability indicates that the mean of the population on the right side is larger than that of the left. A probability without an asterisk indicates the opposite. If the sample size is less than 20 in both populations under comparison, Table J of the appendix in Siegel (1956, translation by Fujimoto (1983)) was used. KJ=K-Jomon; NKY=NK-Yayoi; YY=Y-Yayoi. Mandibles of the Jomon and Yayoi People 299

Table 4. b) Comparisons of the mandibular measurements, indices and size variable (female)

See Table 4. a) for notes.

Table 4) are not significant among the three groups. In summary, the Yayoi mandibles are obviously larger than the K-Jomon ones in breadth and corpus heights, although the differences of corpus heights between 300 Y. KAIFU

Table 5. Results of Mann-Whitney's U test for the size-standardized measurements (male)

In the last three columns, a blank indicates P>0.10. An asterisk on the shoulder of a probability indicates that the mean of the population on the right side is larger than that of the left. A probability without an asterisk indicates the opposite. If the sample size is less than 20 in both populations under comparison, Table J of the appendix in Siegel (1956, translation by Fujimoto (1983)) was used. KJ=K-Jomon; NKY=NK-Yayoi; YY=Y-Yayoi.

the Y-Yayoi and the K-Jomon are not significant. Mandibular lengths are approximately the same or slightly longer in the Yayoi groups than in the K-Jomon. There is no significant difference in ramal size among the three populations. In addition, looking at mandibular breadth and corpus heights within the two Yayoi populations, the NK - Yayoi seems slightly larger than the Y-Yayoi in males, although this was not statistically significant. The above interpretation is strengthened by a comparison of the size variable. In males, it is significantly larger in the NK-Yayoi than in the K-Jomon. The Y-Yayoi mean is only slightly larger than that of the K-Jomon, probably owing to the fact that items such as LPRB or BGoB, which are significantly larger in the Y-Yayoi than in the K-Jomon, were excluded from the definition of the size variable to avoid a decrease in sample size. Mandiblesof the Jomon and Yayoi People 301

From the above comparisons, it is evident that the NK-Yayoi and Y-Yayoi are larger in overall mandibular size than the K-Jomon. Within the Yayoi populations, the NK-Yayoi male seems to have a slightly larger mandible than the Y-Yayoi. However, this was not statistically significant. Such a trend in females is not clear. Proportions between Longitudinal and Transverse Dimensions: Differences in size-standardized longitudinal (#6-7 and 12 in Table 5) and transverse dimensions (#1-5 and 8-11 in Table 5), and proportions of longitudinal to transverse dimensions (UML/BCoB, LML/BGoB and DAL/BM2B in Table 4) in males among the three populations are relatively small and show no consistent trends. A similar situation occurs in the females. Ramus Heights: In males, size-standardized LCrH (s-LCrH in Table 5) is significantly smaller in the NK-Yayoi and Y-Yayoi than in the K-Jomon, although LCrH shows no significant difference. LCrH/CoH shows the same relationship between the Y-Yayoi and the K-Jomon. It can be said that the NK-Yayoi and Y- Yayoi males (especially the latter) have lower relative LCrH to the whole mandibular size or CoH. Moreover, in regard to absolute measurements, several Yayoi specimens show considerably low LCrH. Three of 28 specimens from the NK-Yayoi and 3 of 16 from the Y-Yayoi have LCrH of lower than 60mm (the lowest limit of the K-Jomon). Females show no significant differences in the above variables although LRB/CoH in the Y-Yayoi may show a similar trend to that seen in the males. Sigmoid Notch: In males, there is no significant difference in breadth (SnB), but sigmoid notch depth (SnD) is significantly deeper in the NK-Yayoi and Y-Yayoi than in the K-Jomon. Females show a similar trend, although the differences are not significant. No specimen from the Yayoi populations has a notch shallower than 10mm, but 5 of 37 males and 9 of 26 females from the K-Jomon do. SnD/SnB is larger in the Yayoi groups, which is consistent with the above results. Thickness: In both males and females, the NK-Yayoi and Y-Yayoi have a thicker mandibular angular region (TAng) than the K-Jomon. There is no marked difference in thickness of the coronoid process (TCor). According to the present author's observation, thickness of the mandibular base below the posterior teeth is noticeably greater in the Yayoi groups, although this was not quantified in the present study. Mandibular Angle: The mandibular angle (MA) is larger in the Yayoi groups than in the K-Jomon, although some of the Jomon-Yayoi comparisons did not exhibit significant differences. Corpus Heights: Symphyseal height (SH) is consistently higher in the NK-Yayoi and Y-Yayoi than in the K-Jomon in both males and females. There was little difference in minimum value among the three groups. However, in males, 8 out of 37 individuals in the NK-Yayoi, and 1 of 15 in the Y-Yayoi were beyond the maximum value of the K-Jomon (37mm), and in females, 4 of 15 in the NK-Yayoi 302 Y. KAIFU and 2 of 6 in the Y-Yayoi exceed the maximum value of the K-Jomon (30mm). Corpus height means at all the other landmarks (CCH to M2CH) are greater in both Yayoi groups than in the K-Jomon, so that the corpus of the NK-Yayoi and Y-Yayoi are higher on the whole. Size-standardized variables, however, show that a high SH is the most characteristic feature of the Yayoi populations. Corpus height indices (CCH/SH to M2CH/SH) indicate that SH is relatively high compared to the posterior corpus heights in the NK-Yayoi and Y-Yayoi. Comparisons of these indices within each group show that the CCH/SH, P3CH/SH and P4CH/ SH in the K-Jomon are relatively constant and near 100, contrasting with the trend seen in the Yayoi groups (except the Y-Yayoi female) in which CCH/SH is the maximum (considerably less than 100) and the index values decrease posteriorly. This tendency is summarized in Table 6 which shows the positions of the maximum corpus heights for each population. While about half of the K-Jomon specimens are highest at P3 or P4, the symphysis is the highest in most specimens of the Yayoi groups, although the frequency falls a little in the Y-Yayoi female. The results of the above univariate comparisons were also confirmed by the following multivariate analysis. Table 7 and Fig. 3 show the results of a principal component analysis using the six corpus heights as variables and that of Mann- Whitney's U test of the component scores. Taking side differences of corpus heights into consideration, specimens with no missing data for the six corpus heights (from SH through M2CH) on either side were selected. If both sides were complete, the mean of the both sides was utilized. If one side was incomplete, the other side alone was used. Since the objective here is to compare the proportion of corpus heights, the first factor which represents overall size in corpus heights is not considered. The second factor gives positive scores for those cases having relatively higher anterior corpus heights (SH to CCH) and lower posterior ones (M1CH to M2CH). In both males and females, the NK-Yayoi tends to exhibit positive scores, the K-Jomon negative scores. The Y-Yayoi falls in between the two. The third factor gives positive scores if P3CH and P4CH are relatively high and SH and M2CH are relatively low. The component scores show significant differences between the

Table 6. Position of the maximumcorpus height

The absolute frequency and percentage for each row. When an individual shows the maximum height on two positions (e.g., C and P3), each position was counted as 0.5. Mandibles of the Jomon and Yayoi People 303

Table 7. Results of the principal component analysis of corpus heights

Component loadings (upper), percentage of dispersion (upper middle), means of the component scores (lower middle) and probabilities of Mann-Whitney's U test of component scores (lower). In the last three columns, a blank indicates P>0.10. An asterisk on the shoulder of a probability indicates that the mean of the population on the right side is larger than that of the left. A probability without an asterisk indicates the opposite. If the sample size is less than 20 in both populations under comparison, Table J of the appendix in Siegel (1956, translation by Fujimoto (1983)) was used. KJ=K-Jomon; NKY=NK-Yayoi; YY=Y-Yayoi.

Fig. 3. Principal component analysis of mandibular corpus heights. The scatter plot of the second and third component scores. Squares denote the K-Jomon sample; circles, NK-Yayoi; triangles, Y-Yayoi. 304 Y. KAIFU

Yayoi (negative) and the K-Jomon (positive) males. The female scores among the three populations are relatively similar. From the above results of univariate and multivariate analyses, it can be said that most members of the NK-Yayoi and Y-Yayoi populations have high corpus heights (especially at the symphysis), which consistently decrease posteriorly (except for the Y-Yayoi female). In contrast, most members of the K-Jomon have lower SH and, especially in males, corpus heights at the premolar region are approximately equivalent to that at the symphysis. In addition it seems from Table 7 and Fig. 3 that in both males and females the NK-Yayoi is more different from the K-Jomon than is the Y-Yayoi. Therefore, compared to the NK-Yayoi, the Y-Yayoi may have been closer to the K-Jomon in corpus height proportions.

DISCUSSION The mandible continues to grow well into adult life (Behrents, 1990). Therefore, the above results may not be an exact reflection of populational differences, but rather a reflection of morphological change related to aging. This factor, however, is considered to have influenced the present results in only a minor way since the materials were basically restricted to those without antemortem tooth loss. Thus, the range of age at death in the present samples are limited to a certain extent, and age distributions may not differ greatly among the three samples. According to Turner (1990), agenesis or degeneration of the lower M3 is correlated with that of the upper M3, whose frequency is high in the Sinodonts (frequency of the Jomon in central Japan is 14.1%, the mean frequency of the Sinodont populations is 32.4%). The Yayoi populations in the present study have been shown to exhibit Turner's Sinodonty (Matsumura, 1994). Some of the Yayoi specimens with relatively strong Sinodont features may have been omitted in the course of material selection. However, judging from the above frequencies, it is likely that this has not affected the results of the present study. Many differences were detected between the K-Jomon male and the two male Yayoi populations. They are summarized below. Compared with the K-Jomon, the mandible of the Yayoi populations can be characterized as follows: (1) an overall size is larger, (2) a symphyseal height is higher, (3) corpus heights decrease consistently posteriorly, (4) a least coronial height is relatively lower, (5) a sigmoid notch is deeper, (6) a mandibular angular region (and perhaps the mandibular base below the posterior teeth) is thicker, and (7) a mandibular angle is larger. In contrast to feature (3), the K-Jomon corpus heights at the premolar region are approximately equivalent to the symphyseal height. No significant differences were detected between the NK-Yayoi and Y-Yayoi males. However, it seemed that the degree of difference with the K-Jomon male was slightly larger in the NK-Yayoi, with the Y-Yayoi being a little closer to the K-Jomon in features (1) and (3). Mandibles of the Jomon and Yayoi People 305

A similar tendency was recognized in females except for (4), although Y-Yayoi female showed features rather closer to the K-Jomon for (3). However, as female sample sizes are small, larger samples will be necessary for further discussion. To evaluate the degree of differences in mandibular morphology observed between the Kanto Jomon and the Yayoi groups, several measurements or indices of the cranium and postcranial skeleton which show relatively marked Jomon-Yayoi differences were compared to those of the mandible (Fig. 4). Although there may be some problem in comparisons of indices using standard deviations, several are represented here for approximate comparisons. It is apparent from Fig. 4 that the degree of differences in several mandibular measurements or indices are equivalent to those of the cranium and limb bones. Thus it can be said that these features of the mandible are potentially as useful as the cranial measurements or limb proportions in discriminating between the Jomon and the Yayoi. In addition, it was revealed that discriminant analysis of the mandibular meas urementswas fairly useful in separating the Jomon and Yayoi specimens. Table 8 shows the results of a discriminant analysis between the K-Jomon and the pooled Yayoi males using 13 variables. These variables were selected so as to represent the overall properties of the mandible while maintaining reasonably large sample sizes. Corpus heights were arranged as in the case of the foregoing principal

Fig. 4. Deviation graphs of (a) cranial and postcranial, and (b) mandibular measurements and indices of Jomon (Kanto region and Fukushima Prefecture) standardized by pooled Yayoi (northern Kyushu region and Yamaguchi Prefecture) statistics. Cranial data from Kondo (1993, Jomon Ubayama and Kasori site), Uchida and Hanihara (1988, Jomon Sanganji site), Yamaguchi (1980, Jomon simotic subtense and index) and Nakahashi and Nagai (1989, Yayoi northern Kyushu and Yamaguchi). Postcranial data from Yamaguchi (1989). 306 Y. KAIFU

Table 8. Results of the discriminant analysis between the K-Jomon and the pooled Yayoi (male)

Thirteen variables (BSnB, BMeB, BCP3B, BM1B, BM2B, DAL, LRB, SH, CCH, P3CH, P4CH, M1CH and M2CH) were used.

component analysis. The percentage of accurately discriminated cases was more than 90%. Two more analyses were performed using different sets of variables (BSnB, BMeB, BM2B, LRB, and SH to M2CH; BMeB, LRB, and SH to M2CH) and similar results were obtained (the percentage of correct discrimination were 83.9% and 84.1% respectively). Following Nakahashi and Nagai (1989), the degree of divergence from the K- Jomon was compared. Table 8 shows that the Y-Yayoi is closer to the Jomon than the NK-Yayoi in terms of both the number of incorrectly discriminated cases and the mean discriminant scores. The results of the above-mentioned analyses on different sets of variables were also similar. These results are consistent with those of the foregoing univariate analyses, leading to the conclusion that, as far as the male is concerned, the Y-Yayoi is slightly closer in mandibular morphology to the Jomon than is the NK-Yayoi. It is noteworthy that this view is consistent with that drawn from studies based on cranial metric and nonmetric traits (Nakahashi and Nagai, 1989; Dodo et al., 1992). However, the differences in individual mandibular measurements and indices between the NK-Yayoi and the Y-Yayoi were not large enough to be statistically significant. Finally, several restrictions may apply to the present results. The Neolithic Jomon materials handled in the present study are limited to those unearthed in the Kanto region and Fukushima Prefecture. Therefore, it is not clear whether the morphological characters detected are universal throughout the Jomon inhabitants of Japan. Moreover, the differences detected in the present study are based purely on morphological comparisons. Therefore, it does not necessarily follow that these differences are genetically based. Such morphologies, in part, may only be reflections of environmental influences imposed on these populations.

ACKNOWLEDGEMENTS I would like to express my gratitude to the following persons for their permission to investigate the materials in their care and for their generous hospitality during Mandiblesof the Jomonand YayoiPeople 307 my investigation: Dr. Takeru Akazawa, Department of Physical Anthropology and Prehistory, University Museum, The University of Tokyo, Dr. Yosaburo Shibata, Department of Anatomy, Kyushu University, Dr. Takahiro Nakahashi, Graduate School of Social and Cultural Studies, Kyushu University, Dr. Bin Yamaguchi, Department of Anthropology, National Science Museum, Tokyo, Dr. Iwataro Morimoto, Department of Nursing, Japanese Red Cross College of Nursing, Dr. Kazuaki Hirata, Department of Anatomy, St. Marianna University School of Medicine, Messrs. Hiroshi Okuno and Hiroshi Takada, Cultural Properties Center of Chiba Prefecture. I am greatly indebted to Dr. Gen Suwa, Department of Anthropology, The University of Tokyo, for invaluable suggestions. Thanks are also due to Dr. Yuji Mizoguchi, Department of Anthropology, National Science Museum, Tokyo, and Ms. Lise Hodgkinson, Department of Archaeology, Kyushu University, for their helpful comments.

REFERENCES Baba, H, (1991)Osteometry. In Jintaikeisokuhou,Jinruigaku Koza, Suppl. 1, (Eto, M., ed.), Yuzankaku-shuppan,Tokyo. (In Japanese) Behrents,R.G. (1990)Adult facial growth. In Facial Growth3rd Ed. (Enlow,D.H., ed.), W.B. SaundersCo., Philadelphia. Brace,C.L., and Nagai, M. (1982)Japanese tooth size: Past and present. Am. J. Phys.Anthropol. 59, 399-411. Dodo,Y., and Ishida, H. (1988)Nonmetric analyses of theDoigahama crania of theAeneolithic Yayoi periodin westernJapan. In TheGenesis of theJapanese Population and Culture,Rokko-shuppan, Tokyo,pp. 127-142.(In Japanesewith Englishsummary) Dodo,Y., and Ishida, H. (1990) Population history of Japan as viewed from cranial nonmetric variation. J. Anthrop.Soc. Nippon 98, 269-287. Dodo,Y., Ishida, H., and Saito,N. (1992)Population history of Japan:A cranialnonmetric approach. In TheEvolution and Dispersalof Modern Human in Asia(Akazawa, T., Aoki,K., and Kimura, T., eds.),Hokusen-sha, Tokyo, pp. 479-492. Fujimoto,H. (1983)Nonparametric Statistics: For theBehavioral Sciences, McGraw-Hill Book Co., Tokyo.(Japanese translation of Siegel,S. (1956),McGraw-Hill Book Co.) Hagaman,R.M., and Morbeck,M.E. (1984)Data transformationsin multivariatemorphometric analysis.J. Hum.Evol. 13, 225-245. Hanihara,K., Mizoguchi,Y., Wakebe,T., Yamada,T., and Ueda,H. (1988)Comparisons of tooth attritionin the Japanesepopulations from the prehistoricto modernage. In TheGenesis of the JapanesePopulation and Culture,Rokko-shuppan, Tokyo, pp. 47-53. Hoel,P.G., Port, S.C., and Stone,C.J. (1971) Introduction to ProbabilityTheory, Houghton Mifflin Co., Boston. Kanaseki,T., Nagai,M., and Sano, H. (1960)Craniological studies of the Yayoi-periodancients, excavatedat the Doigahamasite, Yamaguchi prefecture. Jinruigaku Kenkyu 7 (Suppl.),1-36. (In Japanesewith Englishsummary) Kondo, O.(1993) of Ubayamashell-mounds. I. Morphologicaldescription and univariate comparison.Anthropol. Sci. 101,307-331. Matsumura,H. (1991)Deciduous tooth size in theprehistoric Jomon and Yayoipeople of Japan.Bull. Natn.Sci. Mus.,Tokyo, Ser. D 17, 21-29. 308 Y. KAIFU

Matsumura, H. (1994) A microevolutional history of the Japanese people from a dental characteristics perspective. Anthropol. Sci. 102, 93-118. Matsushita, T. (1987) The regional variation of the Yayoi people. Kikan Jinruigaku 18, 219-232. (In Japanese) Matsushita, T., and Naito, M. (1989) The regional differences of the Yayoi people. In Yayoi-bunka no Kenkyu 1, Yuzankaku-shuppan, Tokyo, pp. 65-75. (In Japanese) Morant, G.M. (1936) A biometric study of the human mandible. Biometrica 28, 84-122. Naito, Y. (1981) Skeleton of the Yayoi period. In Nihonjin 1, Jinruigaku-Koza, vol. 5., Yuzankaku -shuppan, Tokyo, pp. 57-99. (In Japanese) Nakahashi, T. (1993) Temporal craniometric changes from the Jomon to Modern period in western Japan. Am. J. Phys. Anthropol. 90, 409-425. Nakahashi, T., Doi, N., and Nagai, M. (1985) Human skeletal remains of the Yayoi period from the Kanenokuma site. In The Kanenokuma Site, Fukuoka City Board of Education, Fukuoka, pp. 43-145. (In Japanese) Nakahashi, T., and Nagai, M. (1989) The physical features of the Yayoi people. In Yayoi-bunka no Kenkyu 1, Yuzankaku-shuppan, Tokyo, pp. 23-51. (In Japanese) Ohori, M. (1958) On the human mandibles of Yayoi-period ancients, excavated at Doigahama site, Yamaguchi Prefecture. Jinruigaku Kenkyu 5, 87-151. (In Japanese with English summary) Ushijima, Y. (1954) The human skeletal remains from the Mitsu site, Saga Prefecture, a site associated with the "Yayoishiki" period of prehistoric Japan. Jinruigaku Kenkyu 1, 273-303. (In Japanese with English summary) Sokal, R.R., and Rohlf, F.J. (1981) Biometry, W.H. Freeman and Co., New York. Tagaya, A. (1987) Interpopulation variation of sex differences: An analysis of the extremity long bone measurements of Japanese. J. Anthrop. Soc. Nippon 95, 45-76. (In Japanese with English summary) Turner, C.G., II (1990) Major features of Sundadonty and Sinodonty, including suggestions about East Asian micro evolution, population history, and late Pleistocene relationships with Australian aboriginals. Am J. Phys. Anthropol. 82, 295-317. Uchida, A., and Hanihara, K. (1988) Cranial measurements. In: Sanganji Shell-Mound, Bull. Fukushima Prefecture Mus. 78, 427-434. (In Japanese with English tables) Yamaguchi, B. (1980) A study on the facial flatness of the Jomon crania. Bull. Natn. Sci. Mus., Tokyo, Ser.D 6, 21-28. Yamaguchi, B. (1989) Limb segment proportions in human skeletal remains of Jomon period. Bull. Natn. Sci. Mus., Tokyo, Ser. D 15, 41-48. Zaitsu, H. (1956) On the limb bones of certain Yayoi-period ancients, excavated at the Doigahama site, Yamaguchi Prefecture. Jinruigaku Kenkyu 3-4, 320-349. (In Japanese with English summary)