DNA sheds light on mysterious Okhotsk people
BY NOBUYUKI WATANABE, THE ASAHI SHIMBUN
Scholars using DNA testing hope to unravel age-old mysteries
surrounding the Okhotsk people, who suddenly disappeared around the 10th century in northern parts of Hokkaido.
And their research could shatter theories on the evolution of the indigenous Ainu people.
The Okhotsk culture is believed to have originated on Sakhalin and spread south to northern Hokkaido around the fifth century, when Japan was in the kofun period of tumulus mounds.
The culture eventually spread to eastern Hokkaido and reached the Chishima archipelago, before disappearing in the 10th century.
Researchers in such various fields as archaeology, history and
ethnology have tried to figure out just who the Okhotsk people were.
Some scholars believe the Okhotsk people were the northern race
referred to as Ashihase in the ancient chronicle Nihon Shoki, compiled in the eighth century.
Studies have also led researchers to small ethnic groups scattered around Sakhalin, Siberia and the islands in the northern parts beyond Hokkaido.
Still, no definitive answer has been found.
However, Ryuichi Masuda, an associate professor of molecular
phylogenetics at Hokkaido University, and Takehiro Sato, a graduate student, have shed more light on the Okhotsk people.
They extracted DNA samples from 37 human remains that were discovered from ruins of the Okhotsk culture and kept at Hokkaido University Museum. Analyses of the characteristics of the mitochondrial DNA led Masuda and Sato to conclude that the Okhotsk people are closest to the Nivkhis, who now live in northern Sakhalin and near the mouth of the Amur river in Siberia.
The two also concluded that the Okhotsk people shared a common
ancestor with the Ulchis, who live downstream of the Amur river.
The Nivkhis and Ulchis are small ethnic groups with only a few
thousand survivors remaining.
Little is known about the Okhotsk people, who lived along the coast and caught fish and whales while raising dogs and pigs.
But studies of the Okhotsk could also help scholars trace the
evolution of the Ainu.
Rice cultivation did not spread in Hokkaido even during the Yayoi Pottery Culture (300 B.C.-A.D. 300). But a unique culture developed, described as a procession beginning with a Jomon Pottery Culture, followed by a Later Jomon Pottery Culture and a Satsumon Pottery Culture.
Although the Ainu are believed to have inherited aspects of Hokkaido culture, they also have cultural factors not found in the Jomon strain, for example their ceremonies involving bears.
Moreover, scholars have said that similar habits with bears were found in the Okhotsk culture.
Masuda and his associates have confirmed that some Okhotsk people had genetic types similar to those of the Ainu, but these types were not found among the Jomon strain.
Tetsuya Amano, an archaeology professor at Hokkaido University,
believes the analytic results opened new doors.
“It has now become clear that the Ainu are not simply the direct descendants of the Jomon people, but emerged after going through a very complicated process,” Amano said.
So if the closest people to the Okhotsk were the Nivkhis, what kind of people are they?
According to Hidetoshi Shiraishi, an associate professor of
linguistics at Sapporo Gakuin University, the Nivkhi language is independent in that it is not structurally related to other languages in the vicinity. The origins of the Nivkhi people are also unclear.
While the Nivkhis are believed to have navigated sail boats and led a life centered on fishing, their unique culture has been encroached upon in recent years with gradual integration into Russian culture.
“There has been a number of waves of immigrants to Japan, such as the arrival of the Yayoi people, but the southern advance by the Okhotsk people is likely the most recent of those waves,” said Naruya Saito, a professor of population genetics at the National Institute of Genetics.
However, scholars still do not know what brought those Okhotsk people to Hokkaido.
Hiroshi Ushiro, a curator specializing in archaeology at the
Historical Museum of Hokkaido, said climate change, or more
specifically global warming, may have enabled the Okhotsk people to enter Hokkaido.
The latter part of the kofun period when the Okhotsk culture reached northern Hokkaido was relatively warm. Sea levels were about 1 meter higher than they are now.
In the early part of the Heian Period (794-1185), when the culture spread across Hokkaido, the average annual temperatures were about 2 to 3 degrees higher than they are today.
At that time, on the opposite side of the Eurasia continent, another northern people, the vikings, increased their population due to the warmer weather. The Vikings ventured out to sea, conquered various lands in Europe and spread their reach to as far away as Greenland.
A similar tale of cultural expansion may have taken place around the same time in the northern parts of the Japanese archipelago.(IHT/
Asahi: February 24,2009)
Sato T, et al, Origins and genetic features of the Okhotsk people, revealed by ancient mitochondrial DNA analysis.
J Hum Genet. 2007;52(7):618-27. Epub 2007 Jun 14.
In order to investigate the phylogenetic status of the Okhotsk people that were distributed in northern and eastern Hokkaido as well as southern Sakhalin during the fifth to the thirteenth centuries, DNA was carefully extracted from human bone and tooth remains excavated from archaeological sites. The hypervariable region 1 sequences of the mitochondrial DNA (mtDNA) control region were successfully amplified and 16 mtDNA haplotypes were identified from 37 individuals of the Okhotsk people. Of the 16 haplotypes found, 6 were unique to the Okhotsk people, whereas the other 10 were shared by northeastern Asian people that are currently distributed around Sakhalin and downstream of the Amur River. The phylogenetic relationships inferred from mtDNA sequences showed that the Okhotsk people were more closely related to the Nivkhi and Ulchi people among populations of northeastern Asia. In addition, the Okhotsk people had a relatively closer genetic affinity with the Ainu people of Hokkaido, and were likely intermediates of gene flow from the northeastern Asian people to the Ainu people. These findings support the hypothesis that the Okhotsk culture joined the Satsumon culture (direct descendants of the Jomon people) resulting in the Ainu culture, as suggested by previous archaeological and anthropological studies.
Genetic origins of the Ainu inferred from combined DNA analyses of maternal and paternal lineages.
Tajima A1, et al., J Hum Genet. 2004;49(4):187-93. Epub 2004 Mar 2.
The Ainu, a minority ethnic group from the northernmost island of Japan, was investigated for DNA polymorphisms both from maternal (mitochondrial DNA) and paternal (Y chromosome) lineages extensively. Other Asian populations inhabiting North, East, and Southeast Asia were also examined for detailed phylogeographic analyses at the mtDNA sequence type as well as Y-haplogroup levels. The maternal and paternal gene pools of the Ainu contained 25 mtDNA sequence types and three Y-haplogroups, respectively. Eleven of the 25 mtDNA sequence types were unique to the Ainu and accounted for over 50% of the population, whereas 14 were widely distributed among other Asian populations. Of the 14 shared types, the most frequently shared type was found in common among the Ainu, Nivkhi in northern Sakhalin, and Koryaks in the Kamchatka Peninsula. Moreover, analysis of genetic distances calculated from the mtDNA data revealed that the Ainu seemed to be related to both the Nivkhi and other Japanese populations (such as mainland Japanese and Okinawans) at the population level. On the paternal side, the vast majority (87.5%) of the Ainu exhibited the Asian-specific YAP+ lineages (Y-haplogroups D-M55* and D-M125), which were distributed only in the Japanese Archipelago in this analysis. On the other hand, the Ainu exhibited no other Y-haplogroups (C-M8, O-M175*, and O-M122*) common in mainland Japanese and Okinawans. It is noteworthy that the rest of the Ainu gene pool was occupied by the paternal lineage (Y-haplogroup C-M217*) from North Asia including Sakhalin. Thus, the present findings suggest that the Ainu retain a certain degree of their own genetic uniqueness, while having higher genetic affinities with other regional populations in Japan and the Nivkhi among Asian populations.