Post by Admin on Dec 4, 2021 22:18:03 GMT
Anthropologists have long been challenged to determine the place of the Ainu in the broad web of human history. Their teeth defy simple or obvious classification. The Jomon present the same conundrum: they have elements of mainland Asia, Southeast Asia, Austral-Melanesia, and American Arctic. The only element they both lack is the hyper-Sinodont dental pattern displayed by the Native Americans of mid-latitude North America and South America (i.e., outside the Arctic) (Scott et al. 2018b). The dental morphological data suggest that the biological contribution of the Jomon to the settlement of the Americas is negligible or nonexistent.
4. Human genetics
Human genetics provides an even more direct measure of biological relationships among present and past populations than teeth, but until recently it was possible only to examine the genetics of the Ainu and other living groups, including living Native Americans. The development of techniques for recovering and analyzing ancient DNA (aDNA) in human skeletal remains dating to tens of thousands of years ago transformed paleoanthropology and made it possible to test the hypothesis that Native Americans are derived from the people who made stemmed points in Japan 16,000–15,000 cal yr BP with genetic data. We are limited only by the recovery of pertinent skeletal remains with adequate preservation of aDNA.
4.1. Native American paleogenomics
The ancestry of the First Peoples of the Americas lies in two major sources. The first source derives from a population that separated from the ancestors of East Asians (represented by present-day Han) approximately 30,000 cal yr BP (95% CI 26.8–36.4 ka) (Moreno-Mayar et al. 2018; Sikora et al. 2019). This population subsequently diverged into an “Ancient Palaeo-Siberian” lineage and an “Ancient Beringian” lineage around 24,000 cal yr BP (95% CI 20.9–27.9 ka), with the latter represented by Upward Sun River 1 (USR1) (Moreno-Mayar et al. 2018).8
About 20,000 cal yr BP, gene flow from a second population with west Eurasian roots that currently is best represented by the 24,000-year-old Mal'ta child contributed ancestry representing 18.3% (95% CI 9.8–20.3%) of the USR1 genome (Raghavan et al. 2014; Sikora et al. 2019). It is this combination of ancestral Mal'ta and ancestral East Asian that comprises the majority of the Native American gene pool, although where and how these demographic scenarios played out during and after the last glacial maximum (LGM) is a matter of ongoing debate (Moreno-Mayar et al. 2018; Ning et al. 2020; Sikora et al. 2019; Yu et al. 2020).
To test the hypothesis that post-LGM Japan is the source population for Native Americans (e.g., Davis et al. 2019), it is essential to focus our analysis on the people who occupied Japan before 2300 cal yr BP, rather than the contemporary mainland Japanese population, which is derived from the admixture of early Jomon peoples and Yayoi migrants from mainland Asia approximately 2300 cal yr BP. While the Jomon made a limited genetic contribution to the modern Japanese population (i.e., < 20%; Kanzawa-Kiriyama et al. 2017), they share more ancestry with living Ainu people of northern Japan and Ryukyuans of the southern Okinawan Islands (e.g., Yuasa et al. 2015).
4.2. Maternal lineages (mtDNA)
Published Jomon mitochondrial DNA sequences are predominantly from Hokkaido, the northernmost island and the environment most amenable to ancient DNA preservation. These individuals, spanning a range of nearly 6000 years (Adachi, Shinoda, and Izuho 2015, 413; Adachi et al. 2011), indicate that the Jomon were represented by a set of maternal lineages that are not found in contemporary or ancient Native Americans, nor are direct ancestral or descendant clades to Native American lineages (Adachi et al. 2011, 2013; Horai et al. 1989; Kanzawa-Kiriyama et al. 2013; Perego et al. 2009, 2010).
The most common mitochondrial haplogroup identified from Hokkaido Jomon remains is N9b (at ∼65%), present in contemporary Siberian populations but rare in East or Southeast Asia. Haplogroups M7a, G1b, and D4h2 have also been identified (Adachi, Shinoda, and Izuho 2015, table 28.3; Kanzawa-Kiriyama et al. 2013, appendix 1). Limited sampling of a small number of human remains from Honshu further expands this list to D4b2, as well as additional haplotypes of N9b and M7a (Adachi et al. 2013; Kanzawa-Kiriyama et al. 2013; Mizuno et al. 2020; Takahashi et al. 2019). Of particular interest for this discussion is macro-haplogroup D4, which is widely distributed and diversified across Asia.
Daughter clades of haplogroup D4 are represented in Native American populations. These are Holocene-aged haplogroups D2a and D4b1a2a1a, limited to Arctic populations of North America and Chukotka (Tackney et al. 2019), and the rare Native American founding haplogroup D4h3a (Perego et al. 2009). While the first two haplogroups are only distantly related to the Jomon types, haplogroup D4h3a is more intriguing. This haplogroup has been typed at low frequency along the Pacific coast of North and South America in ancient and contemporary individuals, though occasionally is found farther inland, most notably in the Clovis-associated Anzick-1 child (Perego et al. 2009; Posth et al. 2018; Rasmussen et al. 2014). The most closely related haplotype to D4h3a is a single D4h3b lineage from the Shandong province of China (Perego et al. 2009), followed by D4h2, which is present not just in the Jomon, but the Ulchi of Khabarovsk Krai (Kanzawa-Kiriyama et al. 2019). Both, however, are multiple mutational steps away from D4h3a and therefore temporally quite divergent.
4.3. ABO blood groups
Sato et al. (2010) characterized the molecular diversity of the ABO blood group system in Jomon/Epi-Jomon and Okhotsk people from Hokkaido. These molecular markers of the ABO system showed slight differences between the Jomon/Epi-Jomon and either the Okhotsk or modern Japanese. In addition, the Jomon/Epi-Jomon showed some similarity to populations in eastern Siberia, but whether this was the result of ancestral-descendant relationships or gene flow could not be determined in these samples.
4.4. Paternal lineages (Y-DNA)
Although information on Jomon paternal lineages is scarce, Y-DNA haplogroup D-M174 (which contains the YAP polymorphism) dominates among the Ainu. Y-DNA D-M174 sub-clade D1b2b has been identified from Jomon skeletal remains at the mid-Holocene site Funadomari in Hokkaido (Kanzawa-Kiriyama 2016; Kanzawa-Kiriyama et al. 2019).
In a larger study of Japanese Y-chromosome diversity in contemporary Japan, Watanabe et al. (2019) identify the D1b Y-lineage as deriving from early Jomon because it is at high frequency in Japan, but effectively absent from the rest of East Asian populations, except Tibetans. This paternal lineage represents ∼35% of Y-lineages in Japan (Jinam, Kanzawa-Kiriyama, and Saitou 2015; Kanzawa-Kiriyama et al. 2017). Watanabe et al. (2019) also identify a significant Jomon population decrease near the end of the Jomon period coincident with a climatic change, as well as the introduction of Yayoi migrants. This population bottleneck, inferred from Y-chromosome variation, was also detected by Karmin et al. (2015) in a global analysis of Y-lineage diversity.
4. Human genetics
Human genetics provides an even more direct measure of biological relationships among present and past populations than teeth, but until recently it was possible only to examine the genetics of the Ainu and other living groups, including living Native Americans. The development of techniques for recovering and analyzing ancient DNA (aDNA) in human skeletal remains dating to tens of thousands of years ago transformed paleoanthropology and made it possible to test the hypothesis that Native Americans are derived from the people who made stemmed points in Japan 16,000–15,000 cal yr BP with genetic data. We are limited only by the recovery of pertinent skeletal remains with adequate preservation of aDNA.
4.1. Native American paleogenomics
The ancestry of the First Peoples of the Americas lies in two major sources. The first source derives from a population that separated from the ancestors of East Asians (represented by present-day Han) approximately 30,000 cal yr BP (95% CI 26.8–36.4 ka) (Moreno-Mayar et al. 2018; Sikora et al. 2019). This population subsequently diverged into an “Ancient Palaeo-Siberian” lineage and an “Ancient Beringian” lineage around 24,000 cal yr BP (95% CI 20.9–27.9 ka), with the latter represented by Upward Sun River 1 (USR1) (Moreno-Mayar et al. 2018).8
About 20,000 cal yr BP, gene flow from a second population with west Eurasian roots that currently is best represented by the 24,000-year-old Mal'ta child contributed ancestry representing 18.3% (95% CI 9.8–20.3%) of the USR1 genome (Raghavan et al. 2014; Sikora et al. 2019). It is this combination of ancestral Mal'ta and ancestral East Asian that comprises the majority of the Native American gene pool, although where and how these demographic scenarios played out during and after the last glacial maximum (LGM) is a matter of ongoing debate (Moreno-Mayar et al. 2018; Ning et al. 2020; Sikora et al. 2019; Yu et al. 2020).
To test the hypothesis that post-LGM Japan is the source population for Native Americans (e.g., Davis et al. 2019), it is essential to focus our analysis on the people who occupied Japan before 2300 cal yr BP, rather than the contemporary mainland Japanese population, which is derived from the admixture of early Jomon peoples and Yayoi migrants from mainland Asia approximately 2300 cal yr BP. While the Jomon made a limited genetic contribution to the modern Japanese population (i.e., < 20%; Kanzawa-Kiriyama et al. 2017), they share more ancestry with living Ainu people of northern Japan and Ryukyuans of the southern Okinawan Islands (e.g., Yuasa et al. 2015).
4.2. Maternal lineages (mtDNA)
Published Jomon mitochondrial DNA sequences are predominantly from Hokkaido, the northernmost island and the environment most amenable to ancient DNA preservation. These individuals, spanning a range of nearly 6000 years (Adachi, Shinoda, and Izuho 2015, 413; Adachi et al. 2011), indicate that the Jomon were represented by a set of maternal lineages that are not found in contemporary or ancient Native Americans, nor are direct ancestral or descendant clades to Native American lineages (Adachi et al. 2011, 2013; Horai et al. 1989; Kanzawa-Kiriyama et al. 2013; Perego et al. 2009, 2010).
The most common mitochondrial haplogroup identified from Hokkaido Jomon remains is N9b (at ∼65%), present in contemporary Siberian populations but rare in East or Southeast Asia. Haplogroups M7a, G1b, and D4h2 have also been identified (Adachi, Shinoda, and Izuho 2015, table 28.3; Kanzawa-Kiriyama et al. 2013, appendix 1). Limited sampling of a small number of human remains from Honshu further expands this list to D4b2, as well as additional haplotypes of N9b and M7a (Adachi et al. 2013; Kanzawa-Kiriyama et al. 2013; Mizuno et al. 2020; Takahashi et al. 2019). Of particular interest for this discussion is macro-haplogroup D4, which is widely distributed and diversified across Asia.
Daughter clades of haplogroup D4 are represented in Native American populations. These are Holocene-aged haplogroups D2a and D4b1a2a1a, limited to Arctic populations of North America and Chukotka (Tackney et al. 2019), and the rare Native American founding haplogroup D4h3a (Perego et al. 2009). While the first two haplogroups are only distantly related to the Jomon types, haplogroup D4h3a is more intriguing. This haplogroup has been typed at low frequency along the Pacific coast of North and South America in ancient and contemporary individuals, though occasionally is found farther inland, most notably in the Clovis-associated Anzick-1 child (Perego et al. 2009; Posth et al. 2018; Rasmussen et al. 2014). The most closely related haplotype to D4h3a is a single D4h3b lineage from the Shandong province of China (Perego et al. 2009), followed by D4h2, which is present not just in the Jomon, but the Ulchi of Khabarovsk Krai (Kanzawa-Kiriyama et al. 2019). Both, however, are multiple mutational steps away from D4h3a and therefore temporally quite divergent.
4.3. ABO blood groups
Sato et al. (2010) characterized the molecular diversity of the ABO blood group system in Jomon/Epi-Jomon and Okhotsk people from Hokkaido. These molecular markers of the ABO system showed slight differences between the Jomon/Epi-Jomon and either the Okhotsk or modern Japanese. In addition, the Jomon/Epi-Jomon showed some similarity to populations in eastern Siberia, but whether this was the result of ancestral-descendant relationships or gene flow could not be determined in these samples.
4.4. Paternal lineages (Y-DNA)
Although information on Jomon paternal lineages is scarce, Y-DNA haplogroup D-M174 (which contains the YAP polymorphism) dominates among the Ainu. Y-DNA D-M174 sub-clade D1b2b has been identified from Jomon skeletal remains at the mid-Holocene site Funadomari in Hokkaido (Kanzawa-Kiriyama 2016; Kanzawa-Kiriyama et al. 2019).
In a larger study of Japanese Y-chromosome diversity in contemporary Japan, Watanabe et al. (2019) identify the D1b Y-lineage as deriving from early Jomon because it is at high frequency in Japan, but effectively absent from the rest of East Asian populations, except Tibetans. This paternal lineage represents ∼35% of Y-lineages in Japan (Jinam, Kanzawa-Kiriyama, and Saitou 2015; Kanzawa-Kiriyama et al. 2017). Watanabe et al. (2019) also identify a significant Jomon population decrease near the end of the Jomon period coincident with a climatic change, as well as the introduction of Yayoi migrants. This population bottleneck, inferred from Y-chromosome variation, was also detected by Karmin et al. (2015) in a global analysis of Y-lineage diversity.