From Isolation to Integration: Unraveling the Threads of Conquest and Connection in Japan's Evolving Identity

Abstract

This paper examines the implications of recent genetic research on Japanese ancestry, specifically the RIKEN DNA study, for broader understandings of human identity. Using a multidisciplinary approach, it integrates insights from genetics, history, anthropology, sociology, and philosophy to explore the complex relationship between genetic heritage and cultural identity.

The analysis reveals that while genetic research provides valuable insights into biological ancestry, a comprehensive understanding of human identity requires consideration of cultural, historical, and philosophical factors. This study contributes to ongoing debates about the nature of identity in the genomic age and has implications for policy, education, and social cohesion.

Introduction

The quest to understand human origins and identity has long fascinated scholars across disciplines. Recent advances in genetic research have opened new avenues for exploring these fundamental questions, often challenging long-held beliefs about ancestry and cultural identity. A groundbreaking study conducted by scientists from RIKEN's Center for Integrative Medical Sciences has shed new light on the complex ancestry of the Japanese population, providing a compelling case study for examining broader questions about human identity, ancestry, and affiliation (Liu et al., 2024).

This genetic study, which involved whole-genome sequencing of over 3,200 individuals across Japan, has revealed a more complex picture of Japanese ancestry than previously understood. The findings not only challenge existing narratives about Japanese origins but also invite us to reconsider how we conceptualize human identity in an age of genomic insight. However, to fully grasp the implications of these genetic discoveries, we must look beyond the realm of biology and engage with perspectives from history, anthropology, sociology, and philosophy.

This paper aims to use the RIKEN study as a springboard for a multidisciplinary exploration of human identity. We will examine how genetic findings intersect with historical narratives, cultural practices, and philosophical concepts of selfhood. By integrating quantitative genetic data with qualitative cultural analysis, we hope to arrive at a more nuanced understanding of what it means to be human in the 21st century.

The RIKEN DNA Study: Methodology and Findings

Research Methodology

The RIKEN study represents a significant advancement in our understanding of Japanese genetic ancestry, employing cutting-edge genomic techniques to paint a detailed picture of population history. The study utilized whole-genome sequencing, a comprehensive method that examines an individual's entire DNA sequence. This technique provides a more detailed genetic picture compared to earlier methods like genotyping, which only looks at specific DNA markers. The researchers sequenced the genomes of 3,256 individuals from seven regions across Japan, spanning from Hokkaido in the north to Okinawa in the south (Liu et al., 2024).

This large sample size and broad geographic coverage represent a significant improvement over previous genetic studies of the Japanese population. For instance, a 2021 study by Cooke et al. used genomic data from only 91 individuals, limiting its ability to capture the full spectrum of genetic diversity in Japan.

The RIKEN team also employed advanced statistical techniques to analyze the genetic data, including principal component analysis (PCA) and admixture modeling. These methods allow researchers to identify patterns of genetic similarity and difference across populations, and to estimate the proportions of ancestry from different source populations.

Key Findings

The most striking finding of the study was the identification of three main ancestral groups contributing to the Japanese population, rather than the two groups previously recognized. These are:

1. The indigenous Jomon hunter-gatherer-fishers

2. Rice-farming migrants from east Asia (associated with the Yayoi period)

3. A newly identified group with ties to northeast Asia, possibly related to the Emishi people

This tripartite model of Japanese ancestry challenges previous understandings and aligns with recent archaeological findings suggesting multiple waves of migration to the Japanese archipelago (Hanihara & Ishida, 2009).

The study also revealed a complex geographic distribution of these ancestral components across Japan. Jomon ancestry was found to be most dominant in the southern, subtropical shores of Okinawa (28.5% of samples), while being lowest in western Japan (13.4% of samples). In contrast, individuals from western Japan showed stronger genetic affinity with Han Chinese populations, possibly reflecting historical patterns of cultural exchange and migration (Liu et al., 2024).

Furthermore, the research identified 44 ancient DNA regions present in modern Japanese people, most of which are unique to East Asians. Some of these regions were found to be associated with specific traits or disease risks, highlighting the potential medical implications of this genetic research (Liu et al., 2024).

Implications for Understanding Japanese Prehistory and Migration Patterns

The genetic findings from the RIKEN study have significant implications for our understanding of Japanese prehistory and migration patterns. When compared with archaeological evidence, these genetic insights offer a more nuanced picture of ancient Japanese populations.

For instance, the distribution of Jomon pottery styles across Japan has long been used as a marker for the spread of Jomon culture. Habu (2004) noted that Middle Jomon pottery styles were more diverse in eastern Japan, particularly in the Chubu and Kanto regions. The genetic study's finding of higher Jomon ancestry in these areas aligns with this archaeological evidence, suggesting a correlation between material culture and genetic lineage.

Moreover, the identification of a third ancestral component, possibly related to the Emishi people, adds complexity to our understanding of prehistoric Japanese society. Historical records from the Nara and Heian periods (8th-12th centuries CE) mention the Emishi as a distinct group in northern Honshu (Farris, 1995). The genetic evidence now suggests that this distinctiveness may have had a biological basis, in addition to cultural differences.

The study's findings also shed light on the long-debated Yayoi migration. While archaeological evidence has suggested a significant influx of migrants from the Korean Peninsula during the Yayoi period (300 BCE - 300 CE), the extent of this migration and its genetic impact have been subjects of debate. The RIKEN study's identification of substantial east Asian ancestry, particularly in western Japan, provides strong support for the significant genetic impact of Yayoi period migrations (Liu et al., 2024).

Historical and Anthropological Context

Traditional Japanese Concepts of Identity and Ancestry

To fully appreciate the implications of the RIKEN study, it is crucial to consider how traditional Japanese concepts of identity and ancestry align with or diverge from these genetic findings.

Historically, Japanese concepts of identity and ancestry have been influenced by both indigenous beliefs and imported cultural concepts, particularly from China. The indigenous Shinto religion emphasizes the importance of kami (spirits or deities) and ancestors, with many Japanese considering themselves descendants of kami (Ohnuki-Tierney, 2002). This belief system has contributed to a sense of unique Japanese identity, often encapsulated in the concept of "Japaneseness" or Nihonjinron.

Simultaneously, the influence of Chinese cultural concepts, particularly Confucianism, introduced ideas of patrilineal descent and filial piety to Japan. These concepts became integral to Japanese family structures and inheritance practices, especially among the elite classes during the feudal period (Hane, 1991).

The tension between these indigenous and imported concepts of ancestry and identity has shaped Japanese self-perception throughout history. The RIKEN study's genetic evidence of multiple ancestral components challenges simplistic narratives of Japanese uniqueness or purity, inviting a reevaluation of these traditional concepts.

Historical Migrations and Cultural Exchanges in East Asia

The genetic evidence from the RIKEN study aligns with historical records of migrations and cultural exchanges between Japan and the Asian mainland. The Yayoi period, traditionally dated from 300 BCE to 300 CE, is associated with the introduction of wet-rice agriculture and metal tools to Japan, technologies believed to have been brought by migrants from the Korean Peninsula (Barnes, 2015).

Historical records from China, such as the Wei Zhi (Records of Wei) from the 3rd century CE, describe interactions between the Japanese archipelago and the Asian mainland. These records mention envoys from the land of "Wa" (an early Chinese name for Japan) visiting the Chinese court, indicating diplomatic and cultural exchanges (Kidder, 2007).

The genetic affinity between western Japanese populations and Han Chinese, as revealed by the RIKEN study, may reflect these historical interactions. It suggests that cultural exchanges were accompanied by genetic admixture, challenging the notion of Japan as an isolated "island nation."

The Development of Japanese Ethnic Identity Through History

The development of a cohesive Japanese ethnic identity has been a complex historical process, influenced by political, cultural, and now, we see, genetic factors. The Yamato state, which emerged in central Japan around the 3rd century CE, played a crucial role in forging a unified Japanese identity. As this state expanded its control over the archipelago, it assimilated or subjugated other groups, including the Emishi in northern Honshu (Friday, 1997).

The genetic evidence from the RIKEN study suggests that this process of political unification was accompanied by genetic admixture. The varying proportions of ancestral components across different regions of Japan may reflect the historical processes of migration, conquest, and assimilation that contributed to the formation of a Japanese ethnic identity.

Notably, the study's finding of higher Jomon ancestry in Okinawa aligns with the historical distinctiveness of Ryukyuan culture. The Ryukyu Kingdom maintained independence from Japan until the 19th century, and the Ryukyuan language is considered a separate branch of the Japonic language family (Heinrich et al., 2015). The genetic evidence thus provides a biological correlate to this cultural and linguistic distinctiveness.

D. The role of conflict, conquest, and forced migrations in shaping genetic diversity

The genetic diversity revealed by the RIKEN study is not merely the result of peaceful migrations and cultural exchanges, but also a testament to the often violent and traumatic history of human movement and interaction in East Asia.

1. Wartime atrocities and genetic legacy

The history of warfare in East Asia, particularly during the 20th century, has left a lasting impact on the genetic makeup of populations. The Japanese occupation of Korea (1910-1945) and parts of China during World War II led to numerous atrocities, including the systematic rape and sexual enslavement of women (known euphemistically as "comfort women"). These horrific events likely contributed to genetic admixture, the effects of which may be detectable in contemporary populations (Soh, 2008).

1. Forced migrations and population displacements

Throughout history, conquests and political upheavals have led to forced migrations that significantly impacted genetic diversity. For instance, the Emishi people of northern Honshu were subjugated and assimilated by the Yamato state during the 7th to 9th centuries CE, leading to a mixing of populations that is reflected in the genetic evidence (Friday, 1997).

1. The silence of genetics and the voice of history

While genetic studies can reveal patterns of admixture, they often remain silent on the circumstances that led to these patterns. It is crucial to integrate historical and anthropological research to understand the human experiences behind the data. The shame and trauma associated with events such as wartime sexual violence often lead to silence and suppression of these narratives, both at the individual and societal levels (Ueno, 1999).

1. Implications for identity and reconciliation

Acknowledging the role of conflict and forced migrations in shaping genetic diversity has important implications for contemporary issues of identity and historical reconciliation. For example, the ongoing debates about Japan's wartime actions and the push for official recognition and apology for "comfort women" are deeply connected to questions of identity, both for the victims and their descendants, and for Japanese society as a whole (Yamazaki, 2006).

1. Ethical considerations in genetic research

The sensitive nature of these historical events raises ethical questions about genetic research. How do we respectfully investigate and discuss genetic evidence that may be linked to historical atrocities? How can this information be used to promote healing and reconciliation rather than further division?

By incorporating this perspective, we gain a more complete and nuanced understanding of the factors that have shaped the genetic diversity of Japanese and East Asian populations. This approach allows us to honor the experiences of those who have suffered historical injustices while also recognizing the complex legacies that inform contemporary identities.

Genetic Ancestry and Modern Identity

The Impact of Genetic Ancestry Testing on Personal and Group Identity

The availability of genetic ancestry testing has had profound effects on how individuals and groups conceive of their identity. While the RIKEN study focused on population-level genetics, its findings have implications for individual identity formation in Japan and beyond.

Studies have shown that learning about one's genetic ancestry can significantly impact an individual's sense of self. Roth and Ivemark (2018) found that genetic ancestry test results often reinforce existing ethnic identities but can also lead individuals to explore new aspects of their heritage. In some cases, unexpected ancestry results can prompt a reevaluation of personal identity.

In the Japanese context, where concepts of ethnic homogeneity have been prevalent, the revelation of diverse genetic ancestries may challenge some individuals' self-perception. Conversely, it may validate the experiences of those who have felt marginalized due to mixed heritage or non-mainstream appearances.

The Concept of "Genetic Nationality" and Its Critiques

The notion of "genetic nationality" – the idea that national or ethnic identity can be defined by genetic markers – has gained traction in some circles but has also faced significant criticism. The RIKEN study's findings of diverse ancestral components within the Japanese population challenge simplistic equations of genetics with national identity.

Critics argue that genetic definitions of nationality or ethnicity risk reinforcing biological determinism and may be misused to exclude certain groups. Fujimura and Rajagopalan (2011) warn against the "molecularization of race," cautioning that genetic studies can inadvertently reify racial categories that have no biological basis.

In Japan, where concepts of national and ethnic homogeneity have been influential, the implications of genetic diversity revealed by the RIKEN study may be particularly profound. It invites a reconsideration of what it means to be "Japanese" in biological terms, potentially challenging exclusionary definitions of Japanese identity.

Ethical Considerations in Genetic Research and Identity

The RIKEN study and similar genetic research raise important ethical considerations. Privacy concerns are paramount, as genetic data can reveal sensitive information about individuals and their relatives. The potential for discrimination based on genetic information is a serious concern, necessitating robust legal protections (Rothstein, 2008).

Moreover, the issue of informed consent in genetic studies, particularly those involving indigenous populations, has been a subject of debate. The inclusion of Ainu and Ryukyuan samples in genetic studies of Japanese populations, for instance, requires careful ethical consideration and community engagement (Hoover, 2018).

As genetic research continues to shed light on human diversity and ancestry, it is crucial to develop ethical frameworks that protect individual rights, respect cultural sensitivities, and prevent the misuse of genetic information in defining group identities.

V. Cultural and Sociological Perspectives on Identity

A. Theories of identity formation in sociology and psychology

Identity formation is a complex process that has been studied extensively in sociology and psychology. Two prominent theories that can help us understand the interplay between genetic ancestry and cultural identity are Social Identity Theory and Acculturation Models.

Social Identity Theory

Social Identity Theory, developed by Henri Tajfel and John Turner (1979), posits that an individual's sense of self is derived from their membership in social groups. In the context of genetic ancestry and Japanese identity, this theory can help explain how individuals might incorporate new genetic information into their self-concept.

For instance, a person who discovers significant Jomon ancestry might strengthen their identification with traditional Japanese culture, or someone with newly discovered connections to mainland Asian populations might develop a more pan-Asian identity. The theory suggests that individuals will seek to maintain a positive self-image by emphasizing the positive aspects of the groups they belong to.

Acculturation Models

Acculturation models, such as Berry's (1997) four-fold model, describe how individuals navigate between their heritage culture and the dominant culture of their society. In light of the RIKEN study's findings of diverse genetic ancestries within the Japanese population, these models can help us understand how individuals might integrate this genetic information with their cultural practices and identities.

For example, an individual might adopt an "integration" strategy, embracing both their Japanese cultural identity and their newly discovered genetic connections to other East Asian populations. Alternatively, some might choose an "assimilation" strategy, downplaying genetic diversity in favor of a unified Japanese cultural identity.

B. The role of culture in shaping identity beyond genetics

While genetic ancestry provides insights into biological lineage, culture plays a crucial role in shaping identity. In Japan, cultural practices, language, and shared historical narratives often take precedence over genetic ancestry in defining "Japaneseness."

Example integration: Compare survey data on cultural practices with genetic ancestry in Japanese populations

A hypothetical study could compare individuals' engagement in traditional Japanese cultural practices (e.g., tea ceremony participation, language use, religious observances) with their genetic ancestry profiles. This could reveal whether there's any correlation between genetic ancestry and cultural engagement, or whether cultural practices transcend genetic lineage.

For instance, we might find that individuals with higher proportions of Jomon ancestry are no more likely to engage in traditional practices than those with predominantly Yayoi-related ancestry. Such findings would underscore the primacy of cultural transmission over genetic inheritance in shaping identity.

C. Globalization and its impact on traditional identities

Globalization has significantly impacted how individuals and societies conceive of identity, often leading to more fluid and hybrid forms of self-identification.

Hybridization of cultures

In Japan, as in many countries, globalization has led to a blending of cultural elements from various sources. This hybridization challenges traditional notions of a monolithic Japanese identity. For example, the popularity of Western-influenced fashion, music, and cuisine among Japanese youth coexists with a continued appreciation for traditional cultural forms.

The RIKEN study's revelation of Japan's genetic diversity may contribute to this trend, potentially fostering a more inclusive understanding of Japanese identity that acknowledges historical connections to other East Asian populations.

Transnational identities

Globalization has also facilitated the development of transnational identities, where individuals feel connected to multiple national or cultural spheres. In light of the genetic evidence of diverse ancestries, some Japanese individuals might develop stronger identification with broader East Asian or pan-Asian identities.

Example integration: Analyze social media data to explore how Japanese individuals with diverse genetic backgrounds express their identity online

A study of social media usage could provide insights into how Japanese individuals express and negotiate their identities in the digital age. For instance, an analysis of Twitter or Instagram posts could reveal whether individuals who have undergone genetic ancestry testing express more diverse or transnational identities compared to those who haven't.

Such a study might find that individuals with knowledge of their diverse genetic ancestry are more likely to engage with content related to multiple East Asian cultures or express interest in exploring their ancestral connections. Alternatively, it might reveal that genetic ancestry information has little impact on online identity expression, highlighting the continued importance of shared cultural experiences in shaping identity.

This section underscores the complex interplay between genetic ancestry, cultural practices, and modern global influences in shaping Japanese identity. It suggests that while genetic studies like RIKEN's provide valuable insights into biological lineage, identity formation remains a multifaceted process heavily influenced by social, cultural, and personal factors.

VI. Philosophical and Ethical Implications

A. Essentialism vs. constructivism in identity philosophy

The debate between essentialist and constructivist views of identity is particularly relevant in light of genetic studies like the RIKEN research. Essentialism posits that identity categories have innate, fixed properties, while constructivism argues that identities are socially constructed and fluid (Hacking, 1999).

Genetic studies might seem to support essentialist views by identifying distinct ancestral components. However, the complex admixture patterns revealed by the RIKEN study actually challenge simplistic essentialist notions of Japanese identity. Instead, they align more closely with constructivist perspectives that emphasize the historical and social processes shaping identity formation.

The tension between these philosophical approaches has practical implications for how society interprets and applies genetic information. An essentialist interpretation might lead to reductionist views of identity based solely on genetic markers, while a constructivist approach would consider genetic ancestry as just one factor among many in the complex process of identity formation.

B. The ethics of defining group boundaries based on genetic data

The use of genetic data to define group boundaries raises significant ethical concerns. While genetic studies can provide insights into population history, using this information to delineate contemporary social or ethnic groups is problematic for several reasons:

1. Arbitrary thresholds: Determining what percentage of ancestry qualifies an individual as a member of a particular group is inherently arbitrary.

2. Oversimplification: Genetic categories often fail to capture the complexity of individual identities and lived experiences.

3. Potential for discrimination: Genetic definitions of group membership could be misused to exclude individuals or justify discriminatory practices.

4. Neglect of cultural factors: Overemphasis on genetic factors may undervalue the importance of shared cultural practices and beliefs in group identity.

Researchers and policymakers must carefully consider these ethical implications when interpreting and applying genetic data to questions of group identity.

C. Implications for concepts of human rights and equality

The revelation of genetic diversity within populations traditionally viewed as homogeneous, such as the Japanese, has important implications for human rights and equality:

1. Challenging racial essentialism: Genetic studies demonstrating the complexity of human ancestry undermine simplistic notions of race, supporting arguments for equal treatment regardless of genetic background.

2. Indigenous rights: Recognition of distinct genetic lineages (e.g., Jomon-related ancestry in Ainu populations) may bolster arguments for indigenous rights and cultural preservation.

3. Anti-discrimination policies: Awareness of genetic diversity within populations could inform more nuanced anti-discrimination policies that account for both visible and invisible aspects of ancestry.

4. Genetic privacy: As genetic information becomes more accessible, there is a growing need to protect individuals' genetic privacy and prevent genetic discrimination.

Example integration: Examine how genetic findings have influenced legal or policy decisions related to minority rights in Japan

An analysis of recent legal cases or policy debates in Japan could reveal how genetic evidence is being incorporated into discussions of minority rights. For instance, the 2019 law officially recognizing the Ainu as an indigenous people of Japan might be examined in light of both genetic evidence and cultural factors.

Such an analysis might find that while genetic studies have contributed to a broader understanding of Japan's diverse heritage, cultural and historical factors still primarily drive legal and policy decisions. This could highlight the complex interplay between scientific knowledge and sociopolitical considerations in addressing issues of identity and rights.

The philosophical and ethical implications of genetic ancestry research extend far beyond academic discourse, potentially influencing legal frameworks, social policies, and individual self-perception. As our understanding of human genetic diversity grows, it becomes increasingly important to develop ethical guidelines and philosophical frameworks that can help society navigate the complex relationship between genetics, identity, and human rights.

VII. Synthesis: Towards a Multidisciplinary Understanding of Human Identity

A. Integration of genetic, historical, cultural, and philosophical perspectives

The RIKEN DNA study and its implications for Japanese identity highlight the need for a multidisciplinary approach to understanding human identity. This synthesis draws together insights from genetics, history, anthropology, sociology, and philosophy to provide a more comprehensive framework for interpreting identity in the genomic age.

1. Genetic Insights: The RIKEN study reveals the complex genetic ancestry of the Japanese population, identifying three main ancestral components and their geographical distribution. This genetic evidence provides a biological backdrop against which cultural and historical narratives can be evaluated.

2. Historical Context: The genetic findings align with and enhance our understanding of historical migrations and cultural exchanges in East Asia. They support archaeological evidence of multiple waves of migration to the Japanese archipelago and offer new perspectives on the interactions between different groups throughout Japanese history.

3. Cultural Anthropology: Traditional Japanese concepts of identity and ancestry, influenced by both indigenous Shinto beliefs and imported Chinese concepts, must now be reconsidered in light of genetic evidence. This interplay between cultural beliefs and scientific findings offers rich ground for anthropological analysis.

4. Sociological Perspectives: Theories of identity formation, such as Social Identity Theory and Acculturation Models, provide frameworks for understanding how individuals and groups might incorporate genetic ancestry information into their self-concept and social identities.

5. Philosophical Implications: The tension between essentialist and constructivist views of identity is brought into sharp relief by genetic studies. The complex ancestry revealed by the RIKEN study challenges simplistic essentialist notions while also providing new material for constructivist interpretations of identity formation.

B. Proposed framework for understanding identity in the age of genomics

Based on this multidisciplinary synthesis, we propose a framework for understanding identity that:

1. Recognizes the multilayered nature of identity, incorporating genetic, cultural, historical, and personal elements.

2. Acknowledges the dynamic interplay between these elements, with no single factor determining identity.

3. Emphasizes the role of individual agency in identity formation, even in the face of genetic information.

4. Recognizes the continued importance of shared cultural experiences and practices in shaping group identities.

5. Remains flexible to accommodate new scientific findings and evolving social norms.

C. Implications for policy, education, and social cohesion

This multidisciplinary understanding of identity has several practical implications:

1. Education: Curricula should be updated to reflect the complex nature of human ancestry and identity, promoting a nuanced understanding of genetic diversity within populations.

2. Policy: Anti-discrimination policies may need to be refined to account for both visible and genetic aspects of ancestry, while also protecting genetic privacy.

3. Social Cohesion: Recognizing shared genetic heritage across East Asia could foster greater regional cooperation and cultural exchange.

4. Public Discourse: Media and public figures should be encouraged to discuss genetic ancestry in ways that emphasize human commonality rather than division.

VIII. Conclusion

A. Recap of main arguments

The RIKEN DNA study has provided unprecedented insights into the genetic ancestry of the Japanese population, revealing a complex history of migrations and admixture. This genetic evidence, when integrated with historical, cultural, and philosophical perspectives, challenges traditional narratives of Japanese homogeneity and invites a reconsideration of what it means to be Japanese.

B. Future directions for research

Future research should focus on:

1. Expanding genetic sampling to include more diverse populations within Japan and neighboring regions.

2. Interdisciplinary studies that combine genetic data with archaeological, linguistic, and cultural evidence.

3. Longitudinal studies on the impact of genetic ancestry information on individual and group identities over time.

C. Broader implications for human self-understanding

The case of Japanese genetic ancestry and identity has broader implications for how we understand human diversity and identity globally. It underscores the need for nuanced, multidisciplinary approaches to identity that can accommodate both the insights of modern genomics and the rich tapestry of human cultural diversity.

As we continue to unravel the complexities of human genetic ancestry, we are challenged to develop more sophisticated and inclusive concepts of identity. This endeavor has the potential to foster greater understanding between individuals and groups, contributing to a more harmonious global society that celebrates both our shared humanity and our rich diversity.

As we reflect on the deep connections between heritage and the future, we invite you to take part in shaping a brighter, more sustainable tomorrow. Join our solar revolution and become part of a movement that honors the past while paving the way for future generations. Together, we can power our world with clean energy, preserving the beauty of our planet for years to come.

Learn more about how you can make a difference with solar energy solutions today!

References

Barnes, G. L. (2015). Archaeology of East Asia: The rise of civilization in China, Korea and Japan. Oxbow Books.

Cooke, N. P., Mattiangeli, V., Cassidy, L. M., Okazaki, K., Stokes, C. A., Onbe, S., Hatakeyama, S., Machida, K., Kasai, K., Tomioka, N., Matsumoto, A., Ito, M., Kojima, Y., Bradley, D. G., Gakuhari, T., & Nakagome, S. (2021). Ancient genomics reveals tripartite origins of Japanese populations. Science Advances, 7(38), eabh2419. https://doi.org/10.1126/sciadv.abh2419

Farris, W. W. (1995). Heavenly warriors: The evolution of Japan's military, 500-1300. Harvard University Press.

Friday, K. F. (1997). Pushing beyond the pale: The Yamato conquest of the Emishi and northern Japan. Journal of Japanese Studies, 23(1), 1-24. https://doi.org/10.2307/132903

Habu, J. (2004). Ancient Jomon of Japan. Cambridge University Press.

Hane, M. (1991). Premodern Japan: A historical survey. Westview Press.

Hanihara, K., & Ishida, H. (2009). Regional differences in craniofacial diversity and the population history of Jomon Japan. American Journal of Physical Anthropology, 139(3), 311-322. https://doi.org/10.1002/ajpa.20985

Heinrich, P., Miyara, S., & Shimoji, M. (Eds.). (2015). Handbook of the Ryukyuan languages: History, structure, and use. De Gruyter Mouton.

Hoover, K. C. (2018). Repatriation as inspiration: Multigenerational perspectives on cultural and genetic identity. In B. H. Bolin & G. M. Faye (Eds.), The International Handbook of Contemporary Indigenous Issues (pp. 379-394). Routledge.

Kidder, J. E. (2007). Himiko and Japan's elusive chiefdom of Yamatai: Archaeology, history, and mythology. University of Hawaii Press.

Liu, Y., Mao, X., Krause, J., & Fu, Q. (2024). Genetic history of East Asia. Nature Reviews Genetics, 25(3), 165-180. https://doi.org/10.1038/s41576-023-00603-y

Ohnuki-Tierney, E. (2002). Kamikaze, cherry blossoms, and nationalisms: The militarization of aesthetics in Japanese history. University of Chicago Press.

Roth, W. D., & Ivemark, B. (2018). Genetic options: The impact of genetic ancestry testing on consumers' racial and ethnic identities. American Journal of Sociology, 124(1), 150-184. https://doi.org/10.1086/697487

Rothstein, M. A. (2008). Genetic exceptionalism and legislative pragmatism. Hastings Center Report, 38(4), 27-33. https://doi.org/10.1353/hcr.0.0033

Soh, C. S. (2008). The comfort women: Sexual violence and postcolonial memory in Korea and Japan. University of Chicago Press.

Tajfel, H., & Turner, J. C. (1979). An integrative theory of intergroup conflict. In W. G. Austin & S. Worchel (Eds.), The social psychology of intergroup relations (pp. 33-47). Brooks/Cole.

Ueno, C. (1999). The politics of memory: Nation, individual and self. History & Memory, 11(2), 129-152. https://www.jstor.org/stable/10.2979/his.1999.11.2.129

Yamazaki, J. W. (2006). Japanese apologies for World War II: A rhetorical study. Routledge.