- Email: [email protected]
ON THE ORIGIN OF THE RYUKYU ISLANDERS: THE INTEGRATION OF CRANIOMETRIC AND CRANIAL NONMETRIC DATA
ARCHAEOLOGY, ETHNOLOGY & ANTHROPOLOGY OF EURASIA Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152 E-mail: [email protected]
146
ANTHROPOLOGY
V.G. Moiseyev Museum of Anthropology and Ethnography, Russian Academy of Sciences, Universitetskaya Nab. 3, St. Petersburg, 199034, Russia E-mail: [email protected]
ON THE ORIGIN OF THE RYUKYU ISLANDERS: THE INTEGRATION OF CRANIOMETRIC AND CRANIAL NONMETRIC DATA
To test various hypotheses concerning the origin of the Ryukyu Islanders, data on two systems of traits – craniometric and cranial non-metric – were integrated using multivariate statistical methods. The results indicate that the Ryukyuans are a hybrid group which formed from at least three components. The ¿rst two, associated with the Jomon and Yayoi cultures, are also ancestral for other modern Japanese groups. The speci¿city of Ryukyuans may be due to Southern Mongoloid admixture. Keywords: Japan, Ryukyu, Jomon, Yayoi, craniometry, cranial nonmetrics.
Introduction The Ryukyu archipelago is a chain of small islands stretching from Kyushu in the southwestern direction. Before the early 17th century, an independent state had existed on these islands, which ¿nally became part of Japan only in 1879. A long period of independent development brought about numerous peculiarities in the material and spiritual culture of the Ryukyuan natives. Many of these features have persisted up to the present day despite the cultural and political impact of the Japanese state. Until recently, the population history of Ryukyu appeared rather well understood. As early as 1911, E. Baelz suggested that modern Ryukyuans were related to the Ainu (Baelz, 1911), based on the analysis of somatic traits. The traits which, in his view indicated the Ryukyuans’ closer relationship with the Ainu than with the Japanese, include thick facial hair, comparatively dark pigmentation, lesser development of Mongoloid features of the eye region, low face, and low stature. This view predominated in Japanese physical anthropology until the end of the 20th century. It agrees well with the consensus opinion concerning the dual structure of the population of Japan (Hanihara, 1991).
The dual model states that the population diversity of Japan results from the admixture of two ancient components. The ¿rst one presumably derives from the Upper Paleolithic population which migrated to Japan ca 35–30 thousand years ago along the land bridge which at that time connected Japan with mainland Southeast Asia. The Ryukyu archipelago is a remnant of this land bridge. It is here, at the Minatogawa site on Okinawa that the most representative Upper Paleolithic human remains were found. The remains, which were dated to 18–16 thousand years ago, belonged to three individuals. The male skeleton (Minatogawa 1) which is the best preserved one is central for understanding Japan’s early population history. Cranially, it resembles the presumably Upper Paleolithic individual from Liukiang, south China, possibly indicating the route of migration to Japan. Also, the Minatogawa 1 cranium is similar to the skulls of the Neolithic Jomon people; the cultural continuity between the Jomon and the Upper Paleolithic, too is traceable (Baba, Narasaki, 1991; Suzuki, Hanihara, 1982). Populations which represented the second ancestral component differing from the Jomon people in origin
Copyright © 2010, Siberian Branch of Russian Academy of Sciences, Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.aeae.2010.02.016
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
began to immigrate to Japan, speci¿cally to Kyushu from North China and the Korean peninsula around 300 BC. The immigrants introduced a new culture – Yayoi. The Yayoi economy was based on rice cultivation; the Jomon people by contrast were hunters and gatherers. Physically, both populations were quite different: the Yayoi people, unlike the Jomon people were Mongoloids. The Yayoi farmers are believed to have assimilated certain Jomon groups, eventually resulting in the formation of the Japanese people. The Ainu, by contrast are evidently descendants of those Jomon groups which were pushed to the north by the advancing proto-Japanese and were the least affected by Japanese inÀuence. Under the dual model, Ryukyuans are regarded as descendants of the Jomon natives, and their difference from the Ainu is caused by a lesser share of Mongoloid genes. The dual model was supported by the analysis of various systems of traits and genetic markers (Levin, 1961; Kozintsev, 1992a; Higo et al., 2003). However, in the late 20th century it was challenged by a number of specialists who denied the presence of the Jomon component in the Ryukyuan population (Dodo, Doi, Kondo, 1998, 2000; Manabe et al., 1999; Pietrusewsky, 1999; Hatta et al., 1999). The objective of the present article is to test various hypotheses concerning the origin of the Rykyuans by integrating data on two virtually independent systems of cranial traits – craniometric and cranial non-metric.
147
Hokkaido Ainu; Sakhalin Ainu; Chinese (mostly northern); and Indonesians (Moluccans excluded). Non-metric observations on all the series were taken by A.G. Kozintsev according to the program suggested by him (Kozintsev, 1992a). Five traits were included in the analysis: spheno-maxillary suture (SMS); transverse zygomatic suture posterior trace (TZST); infraorbital pattern type II (IOP II); supraorbital foramina (SOF); and transverse palatine suture index (TPSI). The occipital Wormian index (OI) was not used since a pilot analysis indicated that this trait does not contribute to any of the three ¿rst principal components in which the most important information on group relationships is condensed. This con¿rms the previous conclusion that OI does not display meaningful patterns of variation in North Asia (Kozintsev, 1988). Also, fourteen cranial measurements were used: length; breadth; and height of the braincase; facial breadth and height; minimal frontal breadth; orbital and nasal breadth and height; naso-malar and zygo-maxillary angles; simotic index; and nasal protrusion angle. The measurements were conducted by various authors. In the case of missing relevant data or an uncertain measurement technique, my own measurements were used (Table 1). Information on both systems of traits was integrated by means of multivariate statistical analysis. The integration method was described in my previous publications (Moiseyev, 2001, 2004).
Materials and methods Results The cranial series representing the following groups were used in the present study: Jomon; Yayoi; Kofun; 18th-century Edo; modern Japanese; Ryukyuans;
As a ¿rst step, apart from data concerning the ancient and modern groups of Japan and the Sakhalin Ainu,
Table 1. Sources of data No.
Series
Craniometry
Cranial nonmetrics
1
Jomon
Own unpublished data
2
Yayoi
Masafumi, 1988
3
Kofun
Same
»
4
Japanese, Edo
Own unpublished data
»
5
Modern Japanese
Same
»
6
Ryukyuans*
Fukumine et al., 2001
»
7
Hokkaido Ainu
Own unpublished data
»
8
Sakhalin Ainu
Debetz, 1951
»
9
Northern Chinese
Cheboksarov, 1982
»
10
Indonesians
Alekseyev, 1984
»
*Supplemented by my measurements of facial height and nasal protrusion angle.
Kozintsev, 1992a Same
148
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
information on the northern Chinese series was used because North China (and Korea) are regarded as territories from where the ancestors of the Yayoi people had migrated to Japan. Results concerning the non-metric and metric traits turned out to be rather similar. Both the ¿rst canonical vector (CV I), based on the analysis of measurements and the ¿rst principal component (PC I), based on the analysis of non-metric traits reveal the basic contrast between the Jomon people and the northern Chinese (Fig. 1). The former are quite unique on a world scale in terms of both non-metric and metric characters. Non-metrically, Jomon people are characterized by a combination of extremely high TZST frequency combined with low frequencies of IOP II, SOF and SMS (Table 2). Craniometrically, they reveal a frontal breadth that is large by Asian standards, combined with a broad face, low nasal aperture, and
Table 3. Loadings of craniometric traits on the ¿rst three canonical vectors No. (Martin etc.)
CV I
CV II
CV III
1
–0.53
0.69*
0.28
8
–0.29
0.68*
–0.42
17
–0.09
–0.40
0.61
9
–0.83*
0.38
–0.21
45
–0.81*
0.40
0.16
48
0.57
0.57
0.57
55
0.84*
0.30
0.40
54
–0.10
0.52
–0.80*
51
–0.51
0.63
0.29
52
–0.10
0.36
0.78*
77
0.13
0.04
–0.42
zm
0.24
0.40
–0.74*
SS:SC
–0.52
–0.57
0.40
75 (1)
–0.78*
0.53
0.11
*p<0.05.
Fig. 1. Position of groups on PC I based on cranial nonmetric traits and CV I based on craniometric traits. Northern Chinese model.
Table 2. Loadings of cranial nonmetric traits on the ¿rst two principal components Traits
PC I
PC II
SMS
0.83*
–0.41
TZST
–0.98*
0.03
IOP II
0.97*
0.05
TPSI
–0.22
–0.96*
SOF
0.96*
0.11
Eigenvalue
3.56
1.10
Percent of variance
0.71
0.22
*p<0.05.
protruding nasal bones (Table 3). The correlation between the ¿rst vectors, PC I and CV I is high and signi¿cant (r=–0,70, p<0,05), attesting to a marked peculiarity of the Jomon trait combination and, apparently to its considerable antiquity. Correlations between other PCs and CVs are insigni¿cant (Table 4). The northern Chinese series occupies an opposite extreme on both CV I and PC I and most ancient and modern groups of Japan are intermediate on both vectors. This arrangement agrees with the dual hypothesis stating that Jomon aborigines and migrants from North China and the Korean peninsula were the two basic components in the origin of the populations of Japan. Regrettably, no information on either ancient or modern groups of Korea is available to me. The least distant from the Jomon people are the Ainu, which yet again supports the widespread view concerning a direct genetic continuity between these two groups. However, the gap between the Jomon series and the Ainu group closest to it, which is the one from Hokkaido is considerable in both trait systems. The Ainu deviate toward the Mongoloids, speci¿cally the northern Chinese. Incidentally, the Ainu may have received Mongoloid genes not only from the Japanese but also from other populations, for instance from the early medieval Okhotsk people of southern Sakhalin and Hokkaido (Moiseyev, 2008). Also, the difference
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
149
Table 4. Spearman’s coef¿cients of rank correlation between the ¿rst three principal components and canonical vectors Vectors
PC I
PC II
PC III
CV I
PC I
1.00
PC II
0.00
1.00
PC III
0.00
0.00
1.00
CV I
0.70*
–0.08
–0.12
1.00
CV II
PC II
–0.37
0.12
0.62
0.00
1.00
PC III
0.47
0.27
0.52
0.00
0.00
CV III
1.00
*p<0.05.
between the Ainu and the Jomon people may be partly due to micro-evolutionary processes. Other groups from Japan are rather tightly clustered on both CV 1 and PC 1, and this cluster is intermediate between the Jomon people and Ainu on the one hand and northern Chinese on the other. Variations within this cluster are minor and unstable on the cross-systemic level. Thus, craniometrically the Yayoi series turns out to be closest to the northern Chinese on CV I but furthest from them in terms of non-metric traits (PC I). The position of the Ryukyans too is variable. Nonmetrically, they are closer to the Jomon group than are the Japanese or the Kofun people; measurements reveal a reverse tendency. Whatever the actual position of Ryukuans on the Jomon to northern Chinese vector, the presence of the Jomon component in this group, as well as in all modern Japanese groups and in the Yayoi and Kofun people, is beyond doubt. In my view, the only question is how large this component is in Ryukyuans as compared to other Japanese populations. When the information on metric and non-metric traits is integrated, speci¿cally by the ¿rst integral principal component (IPC I) de¿ned mostly by CV I and PC I, Ryukyuans turn out to be somewhat closer to Jomon people than are other modern Japanese and the Edo group (Table 5, Fig. 2). The difference, however is minor and can be incidental. IPC II reveals the contrast between the Ryukyuans and Sakhalin Ainu, other groups being intermediate and distant from both extremes suggesting that they are neutral on this vector. In other words, IPC II may point to certain components (different ones of course) that are present in the Sakhalin Ainu and Ryukyuans but not in other groups included in the analysis. As to the Sakhalin Ainu, their distinction from Hokkaido Ainu is evidently due to a considerable Siberian, probably Tunguso-Manchrian admixture (Kozintsev, 1992b). While the distinctness of Ryukyuans may theoretically be explained by microevolutionary processes triggered by their isolation, the
Fig. 2. Position of groups on the ¿rst and second integral principal components (IPC I and IPC II). Northern Chinese model.
Table 5. Loadings of the within-system vectors on the ¿rst two integral principal components (northern Chinese model) Vectors
IPC I
IPC II
PC I
0.97*
0.00
PC II
0.01
–0.80*
CV I
0.94*
–0.05
CV II
–0.17
–0.68*
CV III
0.16
–0.42
Eigenvalue
1.90
1.27
Percent of variance
0.38
0.25
*p<0.05.
150
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
alternative explanation worth considering is that some component which is absent in other groups is present in the Ryukyu Islanders. Vectors loading heaviest on IPC II are PC II and CV II (Table 5). Regrettably, I have no information on either Taiwanese or Philippine crania (these were the regions with which the Ryukyu Islanders apparently maintained contact). Therefore, to assess the Southern Mongoloid component in the Ryukyuans, the northern Chinese series was replaced by the Indonesian one, and the analysis was conducted again, all other groups remaining the same. The “Indonesian model” showed a somewhat poorer ¿t to the data than did the “northern Chinese model”. The coef¿cient of correlation between the new CV I and the
Fig. 3. Position of groups on PC I based on cranial nonmetric traits and CV I based on craniometric traits. Indonesian model.
new PC I equals 0.68 rather than 0.70 as before, still being signi¿cant at the 5 % level. Compared to the northern Chinese series, the Indonesian series is further from the between-group regression line (Fig. 3). As in the “northern Chinese model,” IPC I is mostly de¿ned by PC I and CV I but their loadings on IPC I are much lower (Table 6). Therefore, it does not make much sense to analyze the position of groups on the new IPS I. While the “northern Chinese model” is more suitable for explaining the source of the Mongoloid component in most population of Japan, this does not imply that the “Indonesian model” cannot be more adequate with regard to certain groups. Also, the presence of more than two components in the Ryukyuans cannot be ruled out. To evaluate this possibility, I used the method proposed by A.G. Kozintsev for assessing the two most probable parental populations for a hybrid group (Kozintsev, 1992b). The method is based on the assumption that the ratio of the sum of multivariate Euclidean distances between the hybrid group (B) and each of the presumed ancestral groups (A and C) to the distance between the latter may be a measure of ¿t of the speci¿c hybridization model. The relative difference (RD) is calculated as RD = [(AB+BC)/AC] – 1, AB, BC, and AC being the multivariate Euclidean distances between groups A, B, and C. The smaller the RD, the closer the hybrid group is to the straight line connecting the two supposed parental populations and consequently the more suitable the model. In our models, one of the presumed ancestral groups was the Jomon group, another either the northern Chinese or the Indonesians. The RD value in the Indonesian model was nearly twice smaller than in the northern Chinese model (0.23 versus 0.40, respectively). Evidently, the Mongoloid component in the Ryukyuans is closer to that represented by the Indonesian group. The result suggests
Table 6. Loadings of the within-system vectors on the ¿rst three integral principal components (Indonesian model) Vector
IPC I
IPC II
IPC III
PC I
0.858*
0.43
0.00
PC II
–0.48
0.76*
–0.00
CV I
–0.74*
–0.40
0.47
CV II
0.33
0.30
0.88*
CV III
–0.55
0.72*
–0.10
Eigenvalue
1.91
1.53
1.00
Percent of variance
0.38
0.31
0.20
*p<0.05.
Fig. 4. Position of groups on IPC II and IPC III. Indonesian model.
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
that the Southern Mongoloid admixture may be present in the Ryukyuan population. It should be repeated, however that the component in question should be related to the populations of Taiwan or the Philippines rather than to those of Indonesia. Another approach to the assessment of the Southern Mongoloid component in the Ryukyuans is to analyze IPCs II and III in the Indonesian model (Fig. 4). IPC II opposes Yayoi and Kofun to the remaining series. There is little doubt that both groups have a common origin, being descendants of the immigrants from Korea and North China. The Yayoi group in this analysis occupies an extreme position, while the Kofun series is somewhat shifted towards other groups, apparently because of a larger proportion of the genes inherited from the Jomon natives. Amongst other series, the strongest Yayoi tendency on IPC II is shown by the Ryukyuans, who are also close the Jomon group. IPC II then reveals the distinction of the two ancient groups, and Ryukyuans may have partly retained the speci¿city of the early immigrants from Korea and North China. Vectors with the highest loadings on IPC II are PC II and CV III resulting from the within-system analysis (Table 6). The principal meaning of IPC III is that it discloses the Southern Mongoloid tendency in Ryukyuans. The principal role in revealing this tendency is played by craniometric traits (Table 6). The negative extreme of IPC III is occupied by Ryukyuans and Indonesians, whereas the positive extreme is occupied by groups from Japan except Yayoi and Kofun. The Indonesian model then provides an insight into the sources of the non-Jomon admixture in the Ryukyu Islanders, whereas the northern Chinese model only points to the difference between Ryukyuans and other Japanese populations. Conclusions 1. Modern Ryukyu Islanders, like the Ainu and other Japanese groups, have retained the genetic legacy of the Neolithic Jomon population. 2. The share of the Jomon component in the Ryukyuans is close to that in other modern Japanese groups. 3. The principal Mongoloid component in the Ryukyuans is the same as in the Yayoi immigrants. 4. The unique combination of cranial traits in the Ryukyuans is apparently due to a Southern Mongoloid admixture. Acknowledgments My sincere thanks are due to Prof. T. Amano and Dr. H. Ono of Hokkaido University, and to Dr. H. Matsumura
151
of Sapporo Medical College for the permission to study the cranial collections. I express my cordial gratitude to Prof. H. Ishida of Okinawa University for granting me access to unpublished data. I am deeply thankful to Prof. A. Kozintsev for his comments and help.
References Alekseyev V.P. 1984 Materialy po kraniologii Novoy Gvinei, Zondskikh i Molukkskih ostrovov, Malaiskogo poluostrova, pt. 2. Sbornik MAE, vol. 39: 26–60. Baba H., Narasaki S. 1991 Minatogawa man, the oldest type of modern Homo sapience in East Asia. Quarter. Results, vol. 30: 221–230. Baelz E. 1911 Die Riu-Kiu-Insulaner, die Aino und andere kaukasierähnliche Reste in Ostasien. Korrespondenz-Blatt der Deutschen Gesellschaft für Anthroplogie, Ethnologie und Urgeschichte, Bd. 42: 187–191. Cheboksarov N.N. 1982 Etnicheskaya antropologiya Kitaya. Moscow: Nauka. Debetz G.F. 1951 Antropologicheskiye issledovaniya v Kamchatskoy oblasti. Moscow, Leningrad: Izd. AN SSSR, 1951. (Trudy Inst. etnogra¿i AN SSSR. N.s.; vol. 17). Dodo Y., Doi N., Kondo O. 1998 Ainu and Ryukyuan cranial nonmetric variation: Evidence which disputes the Ainu-Ryukyu common origin theory. Anthropological Science, vol. 106: 99–120. Dodo Y., Doi N., Kondo O. 2000 Facial flatness of Ryukyuans. Anthropological Science, vol. 108 (2): 183–198. Fukumine T., Doi N., Ishida H., Zukeran C., Sensui S., Saso A., Higa T. 2001 Human skeletal remains from the Yacchi-no-Gama and Kanjinbaru grave sites. Okinawa Prefectural Archaeological Center Research Report, No. 6: 345–385. Hanihara K. 1991 Dual structure model for population history of the Japanese. Japan Review, No. 2: 1–33. Hatta Y., Ohashi J., Imanishi T., Kamiyama H., Iha M., Simabukure T., Ogawa A., Tanaka H., Akaza T., Gojobori T., Juji T., Tokunaga K. 1999 HLA genes and haplotypes in Ryukyuans suggest recent gene Àow to the Okinawa Islands. Human Biology, vol. 71: 353–365. Higo T., Hanihara T., Sukawa H., Ishida H. 2003 Dental variation of Ryukyu Islanders: A comparative study among Ryukyu, Ainu, and other Asian populations. Amer. J. of Physical Anthropology, vol. 15: 127–143. Kozintsev A.G. 1988 Etnicheskaya kranioskopiya (rasovaya izmenchivost shvov cherepa). Leningrad: Nauka. Kozintsev A.G. 1992ɚ Ethnic epigenetics: A new approach. Homo, vol. 43 (3): 213–244.
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Kozintsev A.G. 1992b Prehistoric and recent populations of Japan: Multivariate analysis of cranioscopic data. Arctic Anthropology, vol. 29 (1): 104–111. Levin M.G. 1961 Nekotorye problemy etnicheskoi antropologii Yaponii. Sovetskaya etnogra¿ya, No. 2: 63–75. Manabe Y., Kitagawa Y., Oyamada J., Kato K., Ito R., Kobayashi S., Rokutanda A. 1999 Genealogical positioning of the Okinawa main islanders in East Asian populations based on nonmetric tooth crown traits. Anthropological Science, vol. 107: 85. Masafumi N. 1988 Nihon minzoku, vol. 2. Tokyo: Rokko. Moiseyev V.G. 2001 North Eurasian populations: Linguistic versus biological differentiation. Archaeology, Ethnology and Anthropology of Eurasia, No. 4: 154–159.
Moiseyev V.G. 2004 Opyt integratsii razlichnykh sistem antropologicheskikh priznakov. In Paleoantropologiya, etnicheskaya antropologiya, etnogenez. St. Petersburg: Izd. MAE RAN, pp. 186–200. Moiseyev V.G. 2008 On the origin of the Okhotsk population of Northern and Eastern Hokkaido: Cranial evidence. Archaeology, Ethnology and Anthropology of Eurasia, No. 1: 133–140. Pietrusewsky M. 1999 A multivariate craniometric study of the inhabitants of the Ryukyu Island and comparisons with cranial series from Japan, Asia, and the Paci¿c. Anthropological Science, vol. 107: 255–281. Suzuki H., Hanihara K. 1982 The Minatogawa Man: The Upper Pleistocene man from the Island of Okinawa. In University of Tokyo Bulletin, No. 19. Tokyo: University Museum, pp. 7–49. Received May 29, 2008.
146
ANTHROPOLOGY
V.G. Moiseyev Museum of Anthropology and Ethnography, Russian Academy of Sciences, Universitetskaya Nab. 3, St. Petersburg, 199034, Russia E-mail: [email protected]
ON THE ORIGIN OF THE RYUKYU ISLANDERS: THE INTEGRATION OF CRANIOMETRIC AND CRANIAL NONMETRIC DATA
To test various hypotheses concerning the origin of the Ryukyu Islanders, data on two systems of traits – craniometric and cranial non-metric – were integrated using multivariate statistical methods. The results indicate that the Ryukyuans are a hybrid group which formed from at least three components. The ¿rst two, associated with the Jomon and Yayoi cultures, are also ancestral for other modern Japanese groups. The speci¿city of Ryukyuans may be due to Southern Mongoloid admixture. Keywords: Japan, Ryukyu, Jomon, Yayoi, craniometry, cranial nonmetrics.
Introduction The Ryukyu archipelago is a chain of small islands stretching from Kyushu in the southwestern direction. Before the early 17th century, an independent state had existed on these islands, which ¿nally became part of Japan only in 1879. A long period of independent development brought about numerous peculiarities in the material and spiritual culture of the Ryukyuan natives. Many of these features have persisted up to the present day despite the cultural and political impact of the Japanese state. Until recently, the population history of Ryukyu appeared rather well understood. As early as 1911, E. Baelz suggested that modern Ryukyuans were related to the Ainu (Baelz, 1911), based on the analysis of somatic traits. The traits which, in his view indicated the Ryukyuans’ closer relationship with the Ainu than with the Japanese, include thick facial hair, comparatively dark pigmentation, lesser development of Mongoloid features of the eye region, low face, and low stature. This view predominated in Japanese physical anthropology until the end of the 20th century. It agrees well with the consensus opinion concerning the dual structure of the population of Japan (Hanihara, 1991).
The dual model states that the population diversity of Japan results from the admixture of two ancient components. The ¿rst one presumably derives from the Upper Paleolithic population which migrated to Japan ca 35–30 thousand years ago along the land bridge which at that time connected Japan with mainland Southeast Asia. The Ryukyu archipelago is a remnant of this land bridge. It is here, at the Minatogawa site on Okinawa that the most representative Upper Paleolithic human remains were found. The remains, which were dated to 18–16 thousand years ago, belonged to three individuals. The male skeleton (Minatogawa 1) which is the best preserved one is central for understanding Japan’s early population history. Cranially, it resembles the presumably Upper Paleolithic individual from Liukiang, south China, possibly indicating the route of migration to Japan. Also, the Minatogawa 1 cranium is similar to the skulls of the Neolithic Jomon people; the cultural continuity between the Jomon and the Upper Paleolithic, too is traceable (Baba, Narasaki, 1991; Suzuki, Hanihara, 1982). Populations which represented the second ancestral component differing from the Jomon people in origin
Copyright © 2010, Siberian Branch of Russian Academy of Sciences, Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.aeae.2010.02.016
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
began to immigrate to Japan, speci¿cally to Kyushu from North China and the Korean peninsula around 300 BC. The immigrants introduced a new culture – Yayoi. The Yayoi economy was based on rice cultivation; the Jomon people by contrast were hunters and gatherers. Physically, both populations were quite different: the Yayoi people, unlike the Jomon people were Mongoloids. The Yayoi farmers are believed to have assimilated certain Jomon groups, eventually resulting in the formation of the Japanese people. The Ainu, by contrast are evidently descendants of those Jomon groups which were pushed to the north by the advancing proto-Japanese and were the least affected by Japanese inÀuence. Under the dual model, Ryukyuans are regarded as descendants of the Jomon natives, and their difference from the Ainu is caused by a lesser share of Mongoloid genes. The dual model was supported by the analysis of various systems of traits and genetic markers (Levin, 1961; Kozintsev, 1992a; Higo et al., 2003). However, in the late 20th century it was challenged by a number of specialists who denied the presence of the Jomon component in the Ryukyuan population (Dodo, Doi, Kondo, 1998, 2000; Manabe et al., 1999; Pietrusewsky, 1999; Hatta et al., 1999). The objective of the present article is to test various hypotheses concerning the origin of the Rykyuans by integrating data on two virtually independent systems of cranial traits – craniometric and cranial non-metric.
147
Hokkaido Ainu; Sakhalin Ainu; Chinese (mostly northern); and Indonesians (Moluccans excluded). Non-metric observations on all the series were taken by A.G. Kozintsev according to the program suggested by him (Kozintsev, 1992a). Five traits were included in the analysis: spheno-maxillary suture (SMS); transverse zygomatic suture posterior trace (TZST); infraorbital pattern type II (IOP II); supraorbital foramina (SOF); and transverse palatine suture index (TPSI). The occipital Wormian index (OI) was not used since a pilot analysis indicated that this trait does not contribute to any of the three ¿rst principal components in which the most important information on group relationships is condensed. This con¿rms the previous conclusion that OI does not display meaningful patterns of variation in North Asia (Kozintsev, 1988). Also, fourteen cranial measurements were used: length; breadth; and height of the braincase; facial breadth and height; minimal frontal breadth; orbital and nasal breadth and height; naso-malar and zygo-maxillary angles; simotic index; and nasal protrusion angle. The measurements were conducted by various authors. In the case of missing relevant data or an uncertain measurement technique, my own measurements were used (Table 1). Information on both systems of traits was integrated by means of multivariate statistical analysis. The integration method was described in my previous publications (Moiseyev, 2001, 2004).
Materials and methods Results The cranial series representing the following groups were used in the present study: Jomon; Yayoi; Kofun; 18th-century Edo; modern Japanese; Ryukyuans;
As a ¿rst step, apart from data concerning the ancient and modern groups of Japan and the Sakhalin Ainu,
Table 1. Sources of data No.
Series
Craniometry
Cranial nonmetrics
1
Jomon
Own unpublished data
2
Yayoi
Masafumi, 1988
3
Kofun
Same
»
4
Japanese, Edo
Own unpublished data
»
5
Modern Japanese
Same
»
6
Ryukyuans*
Fukumine et al., 2001
»
7
Hokkaido Ainu
Own unpublished data
»
8
Sakhalin Ainu
Debetz, 1951
»
9
Northern Chinese
Cheboksarov, 1982
»
10
Indonesians
Alekseyev, 1984
»
*Supplemented by my measurements of facial height and nasal protrusion angle.
Kozintsev, 1992a Same
148
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
information on the northern Chinese series was used because North China (and Korea) are regarded as territories from where the ancestors of the Yayoi people had migrated to Japan. Results concerning the non-metric and metric traits turned out to be rather similar. Both the ¿rst canonical vector (CV I), based on the analysis of measurements and the ¿rst principal component (PC I), based on the analysis of non-metric traits reveal the basic contrast between the Jomon people and the northern Chinese (Fig. 1). The former are quite unique on a world scale in terms of both non-metric and metric characters. Non-metrically, Jomon people are characterized by a combination of extremely high TZST frequency combined with low frequencies of IOP II, SOF and SMS (Table 2). Craniometrically, they reveal a frontal breadth that is large by Asian standards, combined with a broad face, low nasal aperture, and
Table 3. Loadings of craniometric traits on the ¿rst three canonical vectors No. (Martin etc.)
CV I
CV II
CV III
1
–0.53
0.69*
0.28
8
–0.29
0.68*
–0.42
17
–0.09
–0.40
0.61
9
–0.83*
0.38
–0.21
45
–0.81*
0.40
0.16
48
0.57
0.57
0.57
55
0.84*
0.30
0.40
54
–0.10
0.52
–0.80*
51
–0.51
0.63
0.29
52
–0.10
0.36
0.78*
77
0.13
0.04
–0.42
zm
0.24
0.40
–0.74*
SS:SC
–0.52
–0.57
0.40
75 (1)
–0.78*
0.53
0.11
*p<0.05.
Fig. 1. Position of groups on PC I based on cranial nonmetric traits and CV I based on craniometric traits. Northern Chinese model.
Table 2. Loadings of cranial nonmetric traits on the ¿rst two principal components Traits
PC I
PC II
SMS
0.83*
–0.41
TZST
–0.98*
0.03
IOP II
0.97*
0.05
TPSI
–0.22
–0.96*
SOF
0.96*
0.11
Eigenvalue
3.56
1.10
Percent of variance
0.71
0.22
*p<0.05.
protruding nasal bones (Table 3). The correlation between the ¿rst vectors, PC I and CV I is high and signi¿cant (r=–0,70, p<0,05), attesting to a marked peculiarity of the Jomon trait combination and, apparently to its considerable antiquity. Correlations between other PCs and CVs are insigni¿cant (Table 4). The northern Chinese series occupies an opposite extreme on both CV I and PC I and most ancient and modern groups of Japan are intermediate on both vectors. This arrangement agrees with the dual hypothesis stating that Jomon aborigines and migrants from North China and the Korean peninsula were the two basic components in the origin of the populations of Japan. Regrettably, no information on either ancient or modern groups of Korea is available to me. The least distant from the Jomon people are the Ainu, which yet again supports the widespread view concerning a direct genetic continuity between these two groups. However, the gap between the Jomon series and the Ainu group closest to it, which is the one from Hokkaido is considerable in both trait systems. The Ainu deviate toward the Mongoloids, speci¿cally the northern Chinese. Incidentally, the Ainu may have received Mongoloid genes not only from the Japanese but also from other populations, for instance from the early medieval Okhotsk people of southern Sakhalin and Hokkaido (Moiseyev, 2008). Also, the difference
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
149
Table 4. Spearman’s coef¿cients of rank correlation between the ¿rst three principal components and canonical vectors Vectors
PC I
PC II
PC III
CV I
PC I
1.00
PC II
0.00
1.00
PC III
0.00
0.00
1.00
CV I
0.70*
–0.08
–0.12
1.00
CV II
PC II
–0.37
0.12
0.62
0.00
1.00
PC III
0.47
0.27
0.52
0.00
0.00
CV III
1.00
*p<0.05.
between the Ainu and the Jomon people may be partly due to micro-evolutionary processes. Other groups from Japan are rather tightly clustered on both CV 1 and PC 1, and this cluster is intermediate between the Jomon people and Ainu on the one hand and northern Chinese on the other. Variations within this cluster are minor and unstable on the cross-systemic level. Thus, craniometrically the Yayoi series turns out to be closest to the northern Chinese on CV I but furthest from them in terms of non-metric traits (PC I). The position of the Ryukyans too is variable. Nonmetrically, they are closer to the Jomon group than are the Japanese or the Kofun people; measurements reveal a reverse tendency. Whatever the actual position of Ryukuans on the Jomon to northern Chinese vector, the presence of the Jomon component in this group, as well as in all modern Japanese groups and in the Yayoi and Kofun people, is beyond doubt. In my view, the only question is how large this component is in Ryukyuans as compared to other Japanese populations. When the information on metric and non-metric traits is integrated, speci¿cally by the ¿rst integral principal component (IPC I) de¿ned mostly by CV I and PC I, Ryukyuans turn out to be somewhat closer to Jomon people than are other modern Japanese and the Edo group (Table 5, Fig. 2). The difference, however is minor and can be incidental. IPC II reveals the contrast between the Ryukyuans and Sakhalin Ainu, other groups being intermediate and distant from both extremes suggesting that they are neutral on this vector. In other words, IPC II may point to certain components (different ones of course) that are present in the Sakhalin Ainu and Ryukyuans but not in other groups included in the analysis. As to the Sakhalin Ainu, their distinction from Hokkaido Ainu is evidently due to a considerable Siberian, probably Tunguso-Manchrian admixture (Kozintsev, 1992b). While the distinctness of Ryukyuans may theoretically be explained by microevolutionary processes triggered by their isolation, the
Fig. 2. Position of groups on the ¿rst and second integral principal components (IPC I and IPC II). Northern Chinese model.
Table 5. Loadings of the within-system vectors on the ¿rst two integral principal components (northern Chinese model) Vectors
IPC I
IPC II
PC I
0.97*
0.00
PC II
0.01
–0.80*
CV I
0.94*
–0.05
CV II
–0.17
–0.68*
CV III
0.16
–0.42
Eigenvalue
1.90
1.27
Percent of variance
0.38
0.25
*p<0.05.
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alternative explanation worth considering is that some component which is absent in other groups is present in the Ryukyu Islanders. Vectors loading heaviest on IPC II are PC II and CV II (Table 5). Regrettably, I have no information on either Taiwanese or Philippine crania (these were the regions with which the Ryukyu Islanders apparently maintained contact). Therefore, to assess the Southern Mongoloid component in the Ryukyuans, the northern Chinese series was replaced by the Indonesian one, and the analysis was conducted again, all other groups remaining the same. The “Indonesian model” showed a somewhat poorer ¿t to the data than did the “northern Chinese model”. The coef¿cient of correlation between the new CV I and the
Fig. 3. Position of groups on PC I based on cranial nonmetric traits and CV I based on craniometric traits. Indonesian model.
new PC I equals 0.68 rather than 0.70 as before, still being signi¿cant at the 5 % level. Compared to the northern Chinese series, the Indonesian series is further from the between-group regression line (Fig. 3). As in the “northern Chinese model,” IPC I is mostly de¿ned by PC I and CV I but their loadings on IPC I are much lower (Table 6). Therefore, it does not make much sense to analyze the position of groups on the new IPS I. While the “northern Chinese model” is more suitable for explaining the source of the Mongoloid component in most population of Japan, this does not imply that the “Indonesian model” cannot be more adequate with regard to certain groups. Also, the presence of more than two components in the Ryukyuans cannot be ruled out. To evaluate this possibility, I used the method proposed by A.G. Kozintsev for assessing the two most probable parental populations for a hybrid group (Kozintsev, 1992b). The method is based on the assumption that the ratio of the sum of multivariate Euclidean distances between the hybrid group (B) and each of the presumed ancestral groups (A and C) to the distance between the latter may be a measure of ¿t of the speci¿c hybridization model. The relative difference (RD) is calculated as RD = [(AB+BC)/AC] – 1, AB, BC, and AC being the multivariate Euclidean distances between groups A, B, and C. The smaller the RD, the closer the hybrid group is to the straight line connecting the two supposed parental populations and consequently the more suitable the model. In our models, one of the presumed ancestral groups was the Jomon group, another either the northern Chinese or the Indonesians. The RD value in the Indonesian model was nearly twice smaller than in the northern Chinese model (0.23 versus 0.40, respectively). Evidently, the Mongoloid component in the Ryukyuans is closer to that represented by the Indonesian group. The result suggests
Table 6. Loadings of the within-system vectors on the ¿rst three integral principal components (Indonesian model) Vector
IPC I
IPC II
IPC III
PC I
0.858*
0.43
0.00
PC II
–0.48
0.76*
–0.00
CV I
–0.74*
–0.40
0.47
CV II
0.33
0.30
0.88*
CV III
–0.55
0.72*
–0.10
Eigenvalue
1.91
1.53
1.00
Percent of variance
0.38
0.31
0.20
*p<0.05.
Fig. 4. Position of groups on IPC II and IPC III. Indonesian model.
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
that the Southern Mongoloid admixture may be present in the Ryukyuan population. It should be repeated, however that the component in question should be related to the populations of Taiwan or the Philippines rather than to those of Indonesia. Another approach to the assessment of the Southern Mongoloid component in the Ryukyuans is to analyze IPCs II and III in the Indonesian model (Fig. 4). IPC II opposes Yayoi and Kofun to the remaining series. There is little doubt that both groups have a common origin, being descendants of the immigrants from Korea and North China. The Yayoi group in this analysis occupies an extreme position, while the Kofun series is somewhat shifted towards other groups, apparently because of a larger proportion of the genes inherited from the Jomon natives. Amongst other series, the strongest Yayoi tendency on IPC II is shown by the Ryukyuans, who are also close the Jomon group. IPC II then reveals the distinction of the two ancient groups, and Ryukyuans may have partly retained the speci¿city of the early immigrants from Korea and North China. Vectors with the highest loadings on IPC II are PC II and CV III resulting from the within-system analysis (Table 6). The principal meaning of IPC III is that it discloses the Southern Mongoloid tendency in Ryukyuans. The principal role in revealing this tendency is played by craniometric traits (Table 6). The negative extreme of IPC III is occupied by Ryukyuans and Indonesians, whereas the positive extreme is occupied by groups from Japan except Yayoi and Kofun. The Indonesian model then provides an insight into the sources of the non-Jomon admixture in the Ryukyu Islanders, whereas the northern Chinese model only points to the difference between Ryukyuans and other Japanese populations. Conclusions 1. Modern Ryukyu Islanders, like the Ainu and other Japanese groups, have retained the genetic legacy of the Neolithic Jomon population. 2. The share of the Jomon component in the Ryukyuans is close to that in other modern Japanese groups. 3. The principal Mongoloid component in the Ryukyuans is the same as in the Yayoi immigrants. 4. The unique combination of cranial traits in the Ryukyuans is apparently due to a Southern Mongoloid admixture. Acknowledgments My sincere thanks are due to Prof. T. Amano and Dr. H. Ono of Hokkaido University, and to Dr. H. Matsumura
151
of Sapporo Medical College for the permission to study the cranial collections. I express my cordial gratitude to Prof. H. Ishida of Okinawa University for granting me access to unpublished data. I am deeply thankful to Prof. A. Kozintsev for his comments and help.
References Alekseyev V.P. 1984 Materialy po kraniologii Novoy Gvinei, Zondskikh i Molukkskih ostrovov, Malaiskogo poluostrova, pt. 2. Sbornik MAE, vol. 39: 26–60. Baba H., Narasaki S. 1991 Minatogawa man, the oldest type of modern Homo sapience in East Asia. Quarter. Results, vol. 30: 221–230. Baelz E. 1911 Die Riu-Kiu-Insulaner, die Aino und andere kaukasierähnliche Reste in Ostasien. Korrespondenz-Blatt der Deutschen Gesellschaft für Anthroplogie, Ethnologie und Urgeschichte, Bd. 42: 187–191. Cheboksarov N.N. 1982 Etnicheskaya antropologiya Kitaya. Moscow: Nauka. Debetz G.F. 1951 Antropologicheskiye issledovaniya v Kamchatskoy oblasti. Moscow, Leningrad: Izd. AN SSSR, 1951. (Trudy Inst. etnogra¿i AN SSSR. N.s.; vol. 17). Dodo Y., Doi N., Kondo O. 1998 Ainu and Ryukyuan cranial nonmetric variation: Evidence which disputes the Ainu-Ryukyu common origin theory. Anthropological Science, vol. 106: 99–120. Dodo Y., Doi N., Kondo O. 2000 Facial flatness of Ryukyuans. Anthropological Science, vol. 108 (2): 183–198. Fukumine T., Doi N., Ishida H., Zukeran C., Sensui S., Saso A., Higa T. 2001 Human skeletal remains from the Yacchi-no-Gama and Kanjinbaru grave sites. Okinawa Prefectural Archaeological Center Research Report, No. 6: 345–385. Hanihara K. 1991 Dual structure model for population history of the Japanese. Japan Review, No. 2: 1–33. Hatta Y., Ohashi J., Imanishi T., Kamiyama H., Iha M., Simabukure T., Ogawa A., Tanaka H., Akaza T., Gojobori T., Juji T., Tokunaga K. 1999 HLA genes and haplotypes in Ryukyuans suggest recent gene Àow to the Okinawa Islands. Human Biology, vol. 71: 353–365. Higo T., Hanihara T., Sukawa H., Ishida H. 2003 Dental variation of Ryukyu Islanders: A comparative study among Ryukyu, Ainu, and other Asian populations. Amer. J. of Physical Anthropology, vol. 15: 127–143. Kozintsev A.G. 1988 Etnicheskaya kranioskopiya (rasovaya izmenchivost shvov cherepa). Leningrad: Nauka. Kozintsev A.G. 1992ɚ Ethnic epigenetics: A new approach. Homo, vol. 43 (3): 213–244.
152
V.G. Moiseyev / Archaeology Ethnology & Anthropology of Eurasia 37/4 (2009) 146–152
Kozintsev A.G. 1992b Prehistoric and recent populations of Japan: Multivariate analysis of cranioscopic data. Arctic Anthropology, vol. 29 (1): 104–111. Levin M.G. 1961 Nekotorye problemy etnicheskoi antropologii Yaponii. Sovetskaya etnogra¿ya, No. 2: 63–75. Manabe Y., Kitagawa Y., Oyamada J., Kato K., Ito R., Kobayashi S., Rokutanda A. 1999 Genealogical positioning of the Okinawa main islanders in East Asian populations based on nonmetric tooth crown traits. Anthropological Science, vol. 107: 85. Masafumi N. 1988 Nihon minzoku, vol. 2. Tokyo: Rokko. Moiseyev V.G. 2001 North Eurasian populations: Linguistic versus biological differentiation. Archaeology, Ethnology and Anthropology of Eurasia, No. 4: 154–159.
Moiseyev V.G. 2004 Opyt integratsii razlichnykh sistem antropologicheskikh priznakov. In Paleoantropologiya, etnicheskaya antropologiya, etnogenez. St. Petersburg: Izd. MAE RAN, pp. 186–200. Moiseyev V.G. 2008 On the origin of the Okhotsk population of Northern and Eastern Hokkaido: Cranial evidence. Archaeology, Ethnology and Anthropology of Eurasia, No. 1: 133–140. Pietrusewsky M. 1999 A multivariate craniometric study of the inhabitants of the Ryukyu Island and comparisons with cranial series from Japan, Asia, and the Paci¿c. Anthropological Science, vol. 107: 255–281. Suzuki H., Hanihara K. 1982 The Minatogawa Man: The Upper Pleistocene man from the Island of Okinawa. In University of Tokyo Bulletin, No. 19. Tokyo: University Museum, pp. 7–49. Received May 29, 2008.