Metric characteristics of human limb bones in Asian and Japanese populations

Abstract

Twelve metric variables of the humerus, radius, femur, and tibia were investigated in 11 male samples from northeastern and eastern Asian populations. Variations among regions and correlations between latitude and respective measurements and indices were calculated and a principal component analysis was conducted to elucidate human limb bone characteristics. Significant correlation and marginally significant correlation were found for the maximum subtrochanteric diameter (r = 0.662, P = 0.027) and the platymeric index (r = −0.583, P = 0.060) with latitude, respectively, suggesting that the femur of northern Asians had a wide and flat subtrochanteric shape. The second principal component of the principal component analysis shows that the northeastern samples with comparatively long shaft length and thin and flat shaft diameters were discriminated from the southern samples; the second principal component was significantly correlated with latitude (r = −0.743, P = 0.009). The estimated F_st value of 0.432–0.336 shows that the variation in limb bone measurements across regions is rather large, at approximately two or three times the low levels of interregional variation (0.078–0.180) in analyses of cranial and dental data. Limb bone morphology has been repeatedly proposed to be more strongly influenced by environmental and nutritional factors than cranial and dental traits, but this study is the first to confirm it on the basis of statistical analysis.

Introduction

Evolutionary and phylogenetic changes in hominid limb skeletons, especially changes between Neanderthals and modern humans, have been investigated for a long time (Trinkaus, 1981; Ruff, 2002; Weaver and Steudel-Numbers, 2005; Young et al., 2010). Until the 1990s, morphological differences, including those in body proportions, between Neanderthals and anatomically modern humans (Homo sapiens) had been explained as one line of evidence for the replacement model in Europe (Holliday, 1997a, b).

Geographic variation of human cranial and postcranial forms has been investigated as reflecting genetic diversity in association with worldwide migration of anatomically modern humans from Africa (Relethford, 1994, 2002; Jorde et al., 2000; Holliday and Ruff, 2001; Manica et al., 2007). Cranial and dental traits usually show approximately 10–15% of their total variation among regions and are therefore suggested to be neutral genetic markers (Relethford, 2002; Hanihara, 2008).

On the other hand, limb bone morphology is considered also to have substantial relationships with climatic, nutritional, and other environmental conditions (Trinkaus, 1981; Ruff, 1994, 2002). For example, it is well known that people living in cold climates tend to have low tibiofemoral (crural) index values (tibial length relative to femur length), while the opposite is true for those in warm climates.

In Japan, plenty of basic information about limb bone metrics of Jomon people, and of other prehistoric and historic populations, has been reported over the last 100 years (e.g. Koganei, 1893; Kiyono and Hirai, 1928a, b). First, we would like to provide a brief outline of the population history of Japan. The Jomon people were prehistoric hunter-gatherer inhabitants of the Japanese Islands from 10000 to 2300 BP (Hanihara, 1991; Habu, 2004). The people of the Yayoi cultural period, identified as having lived in the northern Kyushu and Yamaguchi areas of Japan from 300 BP to 300 AD, were thought to have been significantly influenced by immigrants from the Asian mainland or their descendants. The basic concept of the ‘dual’ structure model for Japanese population history, or the Ainu–Ryukyu common origin theory, is as follows (Hanihara, 1991): the genetic composition of the modern mainland Japanese is mainly derived from the Yayoi people, whereas both the Ainu people in the northern part and the Ryukyuans on the southernmost islands of Japan are descendants of the Jomon people. Recent genetic studies based on substantial single-nucleotide polymorphism data have corroborated the Ainu–Ryukyu common origin theory (Koganebuchi et al., 2012; Japanese Archipelago Human Population Genetics Consortium, 2012).

Yamaguchi (1982) revealed that both the Jomon and the Ainu populations had relatively high radiohumeral and tibiofemoral index values, whereas the Yayoi people and modern mainland Japanese had low values, thus supporting the dual-structure model. On the other hand, the Ainu people had a hypercnemic index value of the femur, or flat subtrochanteric shape, while the Jomon people had a high pilaster index value instead (Yamaguchi, 1982).

About 20 years before his 1982 publication, Yamaguchi also investigated the limb bone morphology of people from the Okhotsk area (Mitsuhashi and Yamaguchi, 1962a, b), whose culture spread from southern Sakhalin Island to northeastern Hokkaido Island and the Kuril Islands from the 5th to 12th centuries AD (Amano, 2003). The Okhotsk culture developed a considerable maritime infrastructure that was different from that of the native population in Hokkaido (Hudson, 2004; Naito et al., 2010; Shimoda et al., 2012). Ancient DNA and morphological analyses have revealed that the Okhotsk people were closely related to their neighboring northeast Asians (Komesu et al., 2008; Sato et al., 2009, 2010; Kazuta et al., 2011). Similar to the northeastern Asians, the Okhotsk people had much lower tibiofemoral index values than other Japanese populations (Mitsuhashi and Yamaguchi, 1962a, b).

In 1988–1989, the last author (H.I.) had an opportunity to investigate the limb bone morphology of northeast Asian groups from a collection in Russia. In addition, the authors had an opportunity to examine approximately 260 Okhotsk skeletal remains in Hokkaido University Museum from 2003. Metric and nonmetric data of cranial and dental traits in the Okhotsk area and northeast Asian samples were reported elsewhere (Ishida, 1990, 1992, 1993, 1994, 1995, 1996, 1997; Ishida and Dodo, 1996; Ishida and Kondo, 1999). Recently, Hirofumi Matsumura of Sapporo Medical University, one of the authors, reported metric features of the femur in the Okhotsk people (Matsumura et al., 2010).

In this study, we would like to present new metric data of the limb bones from the prehistoric Neolithic Baikalian, Iron-aged Ekven, and Okhotsk peoples, and recent Buryats. Using long-bone measurements of the Northeast Asian samples and other available samples from Japan and Micronesia, we investigated the regional variations and evaluated the correlational relationships with latitude. Principal component analysis was also performed to elucidate human limb bone characteristics.

Materials and Methods

Table 1 lists the 11 population samples used in this study, with their home latitudes and other information, including the institutions where they are housed. Figure 1 shows the location of the samples.

Table 1 Limb bones from Asians and Japanese used in this study

	Sample size	Period	Latitude	Information	Institution	Source
Ekven	65	2000 BP	66°N	Ancient Eskimo cemetery, Russia	MSU	Present study
Neolithic Baikal	38	c. 8000–4000 BP	52°N	East and west coasts of Lake Baikal	MAE	Present study
Buryats	20	Recent	51°N	East coast of Lake Baikal	MAE	Present study
Okhotsk	79	400–1200 AD	46°N	Sakhalin, Rebun, Hokkaido	HU, SMU, KU	Present study, Ohba (1934), Ishida (1994), Mitsuhashi and Yamaguchi (1962a, b)
Ainu	47	Early modern	42°N	Hokkaido	UT	Koganei (1893)
Modern mainland Japan	29	Recent	35°N	Kinai	KU	Miyamoto (1925), Hirai and Tabata (1928)
Jomon Yoshigo	80	4000–2300 BP	34°N	Aichi	KU	Ohba (1935), Ishizawa (1931)
Jomon Tsukumo	24	3000–2300 BP	34°N	Okayama	KU	Kiyono and Hirai (1928a, b)
Yayoi	128	2300–1700 BP	33°N	Northern Kyushu, Shimane, Yamaguchi	KY	Department of Anatomy of Kyushu University (1988)
Ryukyu Islander	84	1600–1900 AD	26°N	Early-modern Kumejima, Okinawa	OPAC	Fukumine et al. (2001)
Micronesia	42	Early modern	13°N	Guam	BM	Ishida (1993)

MSU: Moscow State University, Moscow, Russia.

MAE: Museum of Anthropology and Ethnography, St. Petersburg, Russia.

HU: Hokkaido University, Sapporo, Japan.

SMU: Sapporo Medical University, Sapporo, Japan.

KU: Kyoto University, Kyoto, Japan.

UT: University of Tokyo, Tokyo, Japan.

KY: Kyushu University, Fukuoka, Japan.

OPAC: Okinawa Prefectural Archaeological Center, Nishihara, Japan.

BM: B. P. Bishop Museum, Honolulu, Hawaii, USA.

Figure 1

Location of the samples used in this study.

The Ekven skeletal materials are from an ancient cemetery of Arctic people (Arutyunov and Sergeyev, 1975). The Neolithic Baikal samples are from both the east and the west coasts of Lake Baikal. The recent Buryat series was collected from the east coast of Lake Baikal. Seven sets of skeletal materials consisting of the Okhotsk, Hokkaido Ainu, Jomon Yoshigo, Jomon Tsukumo, modern mainland Japanese, Yayoi, and Ryukyu peoples are from the Japanese Islands. The Micronesian series is a sample of Chamorro skeletons from the Mariana Islands.

We only examined male samples for comparison due to the lack of a female Buryat collection. Sex was estimated by morphological examination of whole skeletons (White, 2000). In this study, the first author (M.K.) measured the Okhotsk samples and the last author (H.I.) collected the data of the Ekven, Neolithic Baikalian, and Buryat samples. Limb bones consisting of the humerus, radius, femur, and tibia (12 metric variables) were measured mainly following Martin’s methods, as listed in Appendices 1 and 2 (Knussmann, 1988). However, for subtrochanteric diameters of the femur, we employed not the sagittal and transverse diameters, but maximum and minimum ones (Koganei, 1893). Transverse diameters of the tibial shaft were taken at the position of the nutrient foramen, following the definition given by Vallois (Olivier, 1960). In principle, we measured the bones on the right side. However, in the cases in which the maximum bone length was unavailable on the right side, the left side was instead used for measurement. Other sample data were quoted from the literature as listed in Table 1. However, the sagittal and transverse sub-trochanteric diameters of the femur were adopted in the Yayoi and Ryukyu samples. Therefore, to match comparative data, maximum and minimum diameters were estimated from multiple regression methods using the available sagittal and transverse subtrochanteric diameters.

We calculated basic statistics for each sample. Next, an analysis of variance was conducted to evaluate group differences (Snedecor and Cochran, 1980). When significant differences were found among the samples, Student’s t-test was performed to determine if each group differed significantly from the average of all other groups after Bonferroni correction. Spearman’s rank correlation coefficients between the measurements and latitudes were then computed for evaluation of the association between skeletal limb morphology and climatic conditions. Principal component analysis was performed with the 12 variables to characterize the pattern of the limb bones. The Z-scores of individual datasets were used for the analysis to mitigate size-related effects (Howells, 1989; Brace and Hunt, 1990) Additionally, Spearman’s rank correlation coefficients were computed between the principal component scores and latitudes.

Finally, to compare variances within and among geographical groups, a modification of Wright’s F_st statistic developed by Relethford and Blangero (1990), Relethford (1994), and Relethford and Harpending (1994) was used.

Results

Basic statistics of limb bone measurements among the 11 population samples are listed in Appendices 1 and 2. The analysis of variance showed all measurements and indices to be significantly different among the samples. Figure 2 shows graphs of the respective measurements in which the populations are arranged from north (left) to south (right). The average of the group marked with an asterisk (*) is significantly higher than the total average of all other groups, while the hash mark (#) indicates a significantly lower value than the others, on the basis of respective t-tests after Bonferroni correction.

Figure 2

Comparisons of limb bone measurements among the 11 groups. Asterisks (*P < 0.05, **P < 0.01) indicate higher significance than the total average of all other groups, while hash marks (#P < 0.05, ##P < 0.01) indicate a lower significance than the others, on the basis of respective t-tests after Bonferroni correction. The upper and lower margins of the box plots represent the 75th and 25th percentiles, respectively. The median is the line bisecting the box. Baikal: Neolithic Baikal people; Japan: modern mainland Japanese; Tsukumo: Jomon Tsukumo people; Yoshigo: Jomon Yoshigo people; Ryukyu: Ryukyu Islanders.

Figure 2 (continued)

Comparisons of limb bone measurements among the 11 groups. Asterisks (*P < 0.05, **P < 0.01) indicate higher significance than the total average of all other groups, while hash marks (#P < 0.05, ##P < 0.01) indicate a lower significance than the others, on the basis of respective t-tests after Bonferroni correction. The upper and lower margins of the box plots represent the 75th and 25th percentiles, respectively. The median is the line bisecting the box. Baikal: Neolithic Baikal people; Japan: modern mainland Japanese; Tsukumo: Jomon Tsukumo people; Yoshigo: Jomon Yoshigo people; Ryukyu: Ryukyu Islanders.

Figure 2 (continued)

Comparisons of limb bone measurements among the 11 groups. Asterisks (*P < 0.05, **P < 0.01) indicate higher significance than the total average of all other groups, while hash marks (#P < 0.05, ##P < 0.01) indicate a lower significance than the others, on the basis of respective t-tests after Bonferroni correction. The upper and lower margins of the box plots represent the 75th and 25th percentiles, respectively. The median is the line bisecting the box. Baikal: Neolithic Baikal people; Japan: modern mainland Japanese; Tsukumo: Jomon Tsukumo people; Yoshigo: Jomon Yoshigo people; Ryukyu: Ryukyu Islanders.

In terms of the longitudinal dimensions of the upper limb, the inhabitants of the Japanese Islands tend to be shorter. The Ryukyu Islanders show exceptionally small values of humeral and radial lengths. However, the Okhotsk people had rather large upper limb bones, like the Neolithic Baikalian people and the Buryats. The radiohumeral indices (R1:H1) of the Jomon people were found to be markedly high, exceeding 80 (‘dolichokerisch’ in German), as previously reported (Yamaguchi, 1989; Temple et al., 2008). The Micronesian samples were found to have a long and thick humerus.

The Micronesian samples also had long lower limb bones, while the lower limbs of the Ryukyu Islanders were the shortest. The tibiofemoral indices (T1:F1) in the Jomon and Hokkaido Ainu populations were found to be higher, exceeding 82. The Buryats only showed flatter mid-shaft morphology (F6:F7) in the femur. On the other hand, the femora of the Neolithic Baikal and Okhotsk people had flat sub-trochanteric shapes (F10′:F9′) due to a large maximum sub-trochanteric diameter in general, while the femur of the Micronesian series was found to be rounded. As for the tibia, those of the Neolithic Baikalian, Hokkaido Ainu, and Jomon peoples had flat shafts (T9a′:T8a).

Next, we calculated the correlation coefficients between latitude and the averages of the limb bone measurements or indices. Significant correlation was found only for the maximum subtrochanteric diameter (r = 0.662, P = 0.027) and marginally significant correlation was also found for the platymeric index (r = −0.583, P = 0.060), as shown in Figure 3. This indicated that the femur of the northern Asians tended to possess a wide and flat subtrochanteric shape.

Figure 3

Correlation with latitude. Among the measurements and indices, significant correlation was observed only in the maximum subtrochanteric diameter (F9′) (r = 0.662, P = 0.027), but marginally significant correlation was found for the platymeric index (F10′:F9′) (r = −0.583, P = 0.0597).

The results of the principal component analysis of the 12 metric variables are shown in Table 2 and Figure 4. The first and second principal components accounted for 55.83% and 10.64% of the total variance, respectively. The first principal component can be interpreted as a size component, especially in terms of length. The second principal component can be interpreted as representing the relative size of general shaft diameters against general longitudinal lengths, maximum subtrochanteric diameter, and transverse shaft diameter of the femur. The comparatively long-limbed Micronesian and Buryat samples exhibited greater first principal component scores, resulting in the right position on the graph of Figure 4. This strongly contrasts with the short-limbed Ryukyu Islanders shown in the leftmost position. The second principal component axis in the graph also shows that the northeastern samples with a comparatively long, thin, and flat shaft are roughly positioned around the lower area, while the southern samples are located at the upper area. Only the second principal component was significantly correlated with latitude (Figure 5) and the correlation coefficient (r = −0.743, P = 0.009) was larger than those of the two femoral variables.

Table 2 Principal component analysis of the limb bone measurements

	PC1	PC2	PC3	PC4
H1. Humeral maximum length	0.783	−0.403	−0.190	−0.208
H5. Humeral maximum mid-shaft diameter	0.730	0.398	0.161	0.023
H6. Humeral minimum mid-shaft diameter	0.710	0.398	0.091	−0.206
R1. Radial maximum length	0.750	−0.345	−0.249	−0.049
F1. Femoral maximum length	0.833	−0.252	−0.329	−0.030
F6. Femoral sagittal mid-shaft diameter	0.737	0.172	−0.092	0.596
F7. Femoral transverse mid-shaft diameter	0.701	−0.153	0.586	−0.072
F9′. Femoral maximum subtrochanteric diameter	0.649	−0.294	0.595	−0.103
F10′. Femoral minimum subtrochanteric diameter	0.820	0.145	0.124	0.248
T1. Tibial lateral condyle-malleolar length	0.830	−0.318	−0.225	0.053
T8a. Tibial sagittal diameter at nutrient foramen	0.790	0.270	−0.087	0.014
T9a′. Tibial transverse diameter at nutrient foramen	0.595	0.530	−0.247	−0.381
Eigenvalue	6.700	1.277	1.081	0.669
%VAR	55.83%	10.64%	9.01%	5.58%

The principal component analysis was conducted with a correlation matrix derived from standardized (Z-score) values.

Figure 4

Results of principal component analysis based on the 12 metric variables. Top: Two-dimensional relationships between the first and second principal components. Bottom: Eigen vectors in the first and second principal components. Abbreviations are those referred to Figure 2 and Appendices 1 and 2. Solid bar: shaft diameter; open bar: shaft length.

Figure 5

Significant correlation was found for the second principal component with latitude (r = −0.743, P = 0.009).

Assuming that the samples used in this study had the same effective population size, interregional variation was estimated using F_st values. Table 3 shows the estimated F_st (h² = 0.4–0.6) for limb bone measurements and other F_st values. The result of the estimated F_st of 0.432–0.336 shows that the variation of limb bone measurements across regions is rather large, at approximately two or three times the low levels of interregional variation (0.078–0.180) in analyses of cranial and dental data (Haneji et al., 2007; Toma et al., 2007; Komesu et al., 2008; Ishida et al., 2009).

Table 3 Comparison of F_st values obtained from metric and nonmetric skeletal traits

Data	Fst	Sample	Reference
Limb bone measurements	0.336–0.432	Northeast Asia, East Asia, Micronesia	Present study, Heritability 0.4–0.6
Craniometrics	0.153	Northeast Asia, East Asia	Ishida et al. (2009), Heritability 0.55
Nonmetric cranial traits	0.078	Northeast Asia, East Asia, Eastern Europe	Komesu et al. (2008), Heritability 0.50
Dental measurements	0.180	Northeast Asia, East Asia, Southeast Asia, Pacific Islands	Toma et al. (2007), Heritability 0.55
Nonmetric dental variation	0.163	East Asia, West Asia	Haneji et al. (2007), Heritability 0.55

Discussion

Subtrochanteric shape

In this study, we found a novel correlation between the subtrochanteric shape of the femur (especially, F9′) and the latitude among the samples used. This means that the populations living in more northern areas have flatter subtrochanteric femora. However, are these differences caused by genetic or epigenetic (i.e. environmental) factors or both?

Peoples of East Asian origin possess a flatter subtrochanteric shape of the femur than Europeans and Africans (Gill, 2001; Wescott, 2005). This study also revealed that the Asians other than the Micronesians have lower platymeric index values (under 80), thus supporting previous results and suggesting that some population difference (or genetic contribution) related to subtrochanteric shape.

Recently, Kesterke (2008) reported that the estimated heritability (h²) of the subtrochanteric shape of the femur was 0.47 ± 0.24 in Papio hamadryas samples, thus indicating almost equal contributions of genetic and non-genetic factors to the total variance.

In this light, the flatter subtrochanteric shape in the northeast Asian peoples may also be explained not only by genetic, but also non-genetic factors. The results of the principal component analysis showed that the northern peoples had a relatively long shaft with a flat subtrochanteric region (Figure 5). The northern peoples are supposed to have had a large body trunk in general accordance with ecogeographic rules (Ruff, 2002). This could cause a large mediolateral bending force on the upper femoral shaft (Ruff, 2002), perhaps resulting in the comparatively flat subtrochanteric shaft. However, because the bi-iliac breadth and femoral head diameter were not measured in this study, we cannot evaluate this hypothesis further.

The northern Asian peoples tended to have a lower platycnemic index (T9a′:T8a), or flatter tibial shaft, though there were no significant correlations between the platycnemic index and latitude (r = −0.464, P = 0.150). Because diaphyseal robustness is supposed to correspond to terrestrial mobility (Stock, 2006), the flat shaft of femur and tibia may reflect this.

The results of this study could also contribute to the longstanding issue that the Ainu people in Hokkaido had a flat subtrochanteric shape of the femur (74.2), while the Jomon people in Honshu (76.1–78.9) had a less flat subtrochanteric shape (Yamaguchi, 1982). In addition, we previously investigated indices of the upper femoral shaft among the Jomon populations from Hokkaido and Tohoku, northern Japan. Results showed the platymeric index to be 74.8 in Hokkaido Jomon people (Ishida et al., 1987, 1992) and 80.8–80.9 in Tohoku Jomon people (Yamaguchi, 1983; Baba, 1988). This regional difference raises the possibility that the flat sub-trochanteric shape of the femur in Hokkaido Ainu people reflects retention of a trait of Hokkaido Jomon people.

Intra-limb proportion

As mentioned above, the crural index tends to be higher in areas with a cold climate or a high latitude (Holliday and Hilton, 2010). Although analysis of variance revealed a significant difference between the samples compared in this study, the crural index (T1:F1) was not significantly correlated with latitude, partly because the Jomon and Ainu peoples were included in this study (Figure 2c). The Jomon and Ainu peoples have very high crural indices among the East Asians, while such indices are low in the Yayoi people, modern mainland Japanese, and Ryukyu Islanders from the same Japanese islands (Yamaguchi, 1989; Temple et al., 2008; Fukase et al., 2012). However, even when the Jomon series was excluded from the analysis, the correlation was not significant.

Analysis of variance showed a significant difference in the brachial index (R1:H1) between the groups, but it also showed no correlation with latitude (Figure 2a). As already reported by Yamaguchi (1982), the Jomon people have an exceptionally long radius relative to the humerus (81.1–81.5). While the northeastern peoples have lower brachial indices, those in the modern mainland Japanese and Ryukyu Islanders are also low compared with the other groups, as with the crural index.

The reasons why these two indices have no correlations with latitude in this study may be as follows. First, the complex population history in the Japanese Islands, namely, the ‘dual-structure model’ (Hanihara, 1991), may have weakened the correlation of intralimb proportion with latitude. That is, the intralimb proportions among the Japanese peoples were complicated by the recent migration (c. 2000 BP) of the Yayoi people (Yamaguchi, 1982; Temple et al., 2008). The second reason is the peculiarity of the Jomon people. Although this is only one part of the ‘dual-structure model,’ it is very important. A southern or northern origin hypothesis of the Jomon people has been discussed on the basis of morphological and genetic studies (Turner, 1987, 1989, 1990; Matsumura and Hudson, 2005; Cavalli-Sforza et al., 1988; Kozintsev, 1990; Omoto and Saitou, 1997; Ishida and Kondo, 1999; Bannai et al., 1999; Tokunaga et al., 2001; Tajima et al., 2004; Tanaka et al., 2004; Fukumine et al., 2006; Hammer et al., 2006; Komesu et al., 2008; Hanihara and Ishida, 2009; Adachi et al., 2011), but this issue remains unresolved. However, because the long distal segments in the intralimb proportions of the Jomon people are stable from northern Hokkaido to the southern Ryukyu Islands (Fukase et al., 2012), the stability might decrease with the north–south cline of the intralimb proportions in this study. As a last reason, the recent Ryukyu Islanders show very low brachial and crural indices (76.0 and 79.9, respectively), which are comparable to those in northeast Asians. Because they have very short limb bones, this phenomenon could be partly explained by allometry (Holliday and Ruff, 2001; Sylvester et al., 2008; Auerbach and Sylvester, 2011).

F_st

The estimated F_st value of 0.432–0.336 shows that the variation of limb bone measurements across regions is rather large. This shows that the limb bone measurement traits are not neutral, but subject to selection before or after birth. This contrasts with the cranial and dental traits, which show low interregional variations (0.078–0.180) and are viewed as neutral genetic markers (Relethford, 1991, 1994, 2002; Relethford and Harpending, 1994, 1995; Relethford et al., 1997; Powell and Neves, 1999; Hanihara and Ishida, 2005; Hanihara, 2006; Haneji et al., 2007).

On the other hand, Relethford (2002) reported that skin color showed very high variation among regions (0.88), suggesting a natural selection pattern. Thus, the interregional variation of the limb bone measurements (0.336–0.432) is intermediate between that of skin color (0.88) and those of craniodental traits (0.078–0.180). In addition, because the level of skin reflectance is strongly correlated with latitude (r² = 0.85, from Relethford, 1997), it is reasonable that only the second principal component (Table 2, Figure 4) or the subtrochanteric shape of the femur could be correlated with the latitude in this study (r² = 0.44–0.55). The limb bone morphology has been repeatedly proposed to be more strongly subjected to influence by environmental and nutritional factors than cranial and dental traits (Trinkaus, 1981; Ruff, 1994, 2002), but this study is the first to confirm it on the basis of statistical analysis.

Acknowledgments

We wish to thank the following individuals for their permission to study skeletal materials under their care: I.I. Gokhman and A.G. Kozintsev, the Institute of Ethnography—St. Petersburg Branch, St. Petersburg; the late Academician V.P. Alekseev, the Institute of Archaeology, Moscow; and T.I. Alekseeva, Moscow State University, Moscow, Russia. B. Yamaguchi, National Museum of Nature and Science, Tokyo, kindly provided individual data of limb bones from the Omisaki site, Japan.

This study was supported in part by a Grant-in-aid for Scientific Research (No. 22370087) from the Japan Society for the Promotion of Science. We are deeply grateful to two anonymous reviewers for their valuable comments.

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