人種という生物学的概念の興隆と破綻

This essay briefly analyzes how the concept of race changed in physical anthropology during the later half of the 20th century. Since Johann Blumenbach divided modern humans into five varieties in 1806, racial classification was an essential part of physical anthropology until about the 1950\u27s. Race was considered to be strictly a biological concept, which must be distinguished from the "ethnic group" as a cultural concept. However, the difficulties of defining race as a biological concept and of obtaining consistent racial classification, together with the consideration of issues on racism, led most physical anthropologists to retreat from "racial" studies during the 1960\u27s. Thus, the chapter on race disappeared quickly in textbooks of physical anthropology in the 1960\u27s. At the same time, rapid development in human population genetics opened a new way for studying human geographical diversity, indicating that phylogenetic relationships and "origins" of ethnic groups can be studied much more objectively than the precious "racial" classifications. In this paper, I try to show that the biological concept of human race has now completely collapsed, and propose that race be dealt with as a "social" concept like gender, as contrasted to sex. However, this does not mean that the geographical diversity of humans is not worth studying in biological anthropology. On the contrary, I emphasize that for the integrated understanding of humans as a biological system, the studies of individual as well as geographical diversities are of crucial importance. Some perspectives for future studies are discussed

Unique characteristics of the Ainu population in Northern Japan

Various genetic data (classic markers, mitochondrial DNAs, Y chromosomes and genome-wide single-nucleotide polymorphisms (SNPs)) have confirmed the coexistence of three major human populations on the Japanese Archipelago: Ainu in Hokkaido, Ryukyuans in the Southern Islands and Mainland Japanese. We compared genome-wide SNP data of the Ainu, Ryukyuans and Mainland Japanese, and found the following results: (1) the Ainu are genetically different from Mainland Japanese living in Tohoku, the northern part of Honshu Island; (2) using Ainu as descendants of the Jomon people and continental Asians (Han Chinese, Koreans) as descendants of Yayoi people, the proportion of Jomon genetic component in Mainland Japanese was ~ 18% and ~ 28% in Ryukyuans; (3) the time since admixture for Mainland Japanese ranged from 55 to 58 generations ago, and 43 to 44 generations ago for the Ryukyuans, depending on the number of Ainu individuals with varying rates of recent admixture with Mainland Japanese; (4) estimated haplotypes of some Ainu individuals suggested relatively long-term admixture with Mainland Japanese; and (5) highly differentiated genomic regions between Ainu and Mainland Japanese included EDAR and COL7A1 gene regions, which were shown to influence macroscopic phenotypes. These results clearly demonstrate the unique status of the Ainu and Ryukyuan people within East Asia

Discerning the origins of the Negritos, First Sundaland People : deep divergence and archaic admixture

Human presence in Southeast Asia dates back to at least40,000 years ago, when the current islands for meda continental shelf called Sundaland. In the Philippine Islands, Peninsular Malaysia, and Andaman Islands, there exist indigenous groups collectively called Negritos whose ancestry can be traced to the “First Sundaland People.” To understand the relationship between these Negrito groupsand theirdemographic histories, wegeneratedgenome-wide single nucleotide polymorphism datain the Philippine Negritos and compared them with existing data from other populations. Phylogenetic tree analyses show that Negritos are basal to other East and Southeast Asians, and that they diverged from West Eurasians at least 38,000 years ago. We also found relatively high traces of Denisovan admixture in the Philippine Negritos, but not in the Malaysian and Andamanese groups, suggesting independent introgression and/or parallel losses involving Denisovan introgressed regions. Shared genetic loci between all three Negrito groups could be related to skin pigmentation, height, facial morphology and malarial resistance. These results show the unique status of Negrito groups as descended from the First Sundaland People

The history of human populations in the Japanese Archipelago inferred from genome-wide SNP data with a special reference to the Ainu and the Ryukyuan populations

The Japanese Archipelago stretches over 4000 km from north to south, and is the homeland of the three human populations; the Ainu, the Mainland Japanese and the Ryukyuan. The archeological evidence of human residence on this Archipelago goes back to 430 000 years, and various migration routes and root populations have been proposed. Here, we determined close to one million single-nucleotide polymorphisms (SNPs) for the Ainu and the Ryukyuan, and compared these with existing data sets. This is the first report of these genome-wide SNP data. Major findings are: (1) Recent admixture with the Mainland Japanese was observed for more than one third of the Ainu individuals from principal component analysis and frappe analyses; (2) The Ainu population seems to have experienced admixture with another population, and a combination of two types of admixtures is the unique characteristics of this population; (3) The Ainu and the Ryukyuan are tightly clustered with 100% bootstrap probability followed by the Mainland Japanese in the phylogenetic trees of East Eurasian populations. These results clearly support the dual structure model on the Japanese Archipelago populations, though the origins of the Jomon and the Yayoi people still remain to be solved