Hokkaido Jomon people, but subsequently underwent considerable admixture with adjacent populations. The present study strongly recommends revision of the widely accepted dual-structure model for the population history of the Japanese, in which the Ainu are assumed to be the direct descendants of the Jomon people." Autosomal DNA A 2004 reevaluation of cranial traits suggests that the Ainu resemble the Okhotsk more than they do the Jōmon but there are large variations. This agrees with the references to the Ainu as a merger of Okhotsk and Satsumon referenced above. Similarly more recent studies link the Ainu to the local Hokkaido Jōmon period samples, such as the 3,800 year old Rebun sample. Genetic analyses of HLA I and HLA II genes as well as HLA-A, -B, and -DRB1 gene frequencies links the Ainu to Indigenous peoples of the Americas. The genetics of a variety Asian groups show Ainu and of Native Americans are place relatively close can be traced back to Paleolithic groups in Siberia. Hideo Matsumoto (2009) suggested, based on immunoglobulin analyses, that the Ainu (and Jōmon) have a Siberian origin. Compared with other East Asian populations, the Ainu have the highest amount of Siberian (immunoglobulin) components, higher than mainland Japanese people. A 2012 genetic study has revealed that the closest genetic relatives of the Ainu are the Ryukyuan people, followed by the Yamato people and Nivkh. A genetic analysis in 2016 showed that although the Ainu have some genetic relations to the Japanese people and Eastern Siberians (especially Itelmens and Chukchis), they are not directly related to any modern ethnic group. Further, the study detected genetic contribution from the Ainu to populations around the Sea of Okhotsk but no genetic influence on the Ainu themselves. According to the study, the Ainu-like genetic contribution in the Ulch people is about 17.8% or 13.5% and about 27.2% in the Nivkhs. The study also disproved the idea about a relation to Andamanese or Tibetans; instead, it presented evidence of gene flow between the Ainu and "lowland East Asian farmer populations" (represented in the study by the Ami and Atayal in Taiwan, and the Dai and Lahu in Mainland East Asia). A genetic study in 2016 about historical Ainu samples from southern Sakhalin (8) and northern Hokkaido (4), found that these samples were closely related to the ancient Okhotsk people followed by Ainu samples from southern Hokkaido, pointing to some substructure among the ancient