Transformation models contend that genetic variation in modern Japanese populations derives solely from Jomon ancestors and does not reflect Yayoi admixture (Suzuki 1981 Mizoguchi 1986). The first model involves complete replacement of Jomon genetic lineages by those of the Yayoi (Howells 1966 Turner 1976). Like many debates on human evolution, current hypotheses on the origins of the mainland Japanese can be classified into three groups: replacement, hybridization, and transformation (Suzuki 1981).

The Ryukyuans and Ainu are generally recognized as remnant populations descended from the Jomon, with the Ainu surviving in Hokkaido in relative isolation from post-Jomon influences until the end of the last century (Howells 1966 Omoto and Misawa 1976 Turner 1976 Ossenberg 1986 Hanihara 1991). These are the Ainu, inhabiting the northern island of Hokkaido, and the Ryukyuans living on the southernmost islands, including Okinawa.

There are two contemporary ethnic groups that are distinct from Japanese populations living on the centrally located islands of Honshu, Shikoku and Kyushu (Fig. However, the relative genetic contribution each of these populations made to mainland Japanese, and the geographic regions from where they originated on continental Asia are still in dispute. It is generally accepted that modern Japanese are descendants of the two populations who produced the Jomon and the Yayoi cultures. Yayoi culture completed its expansion, resulting in the alteration of all local cultures south of Hokkaido.

The effects of this new culture are first seen in Kyushu, and then spread northeastward. Entering from the Korean Peninsula around 2,300В years ago, the Yayoi migration brought wet rice agriculture, weaving, and metalworking to Japan (Chard 1974). The Jomon people lived a hunter-gatherer lifestyle and made some of the worldвЂ™s earliest pottery for several thousand years in isolation before a second major wave of migration began. 2002 Takamiya 2002), and gave rise to the Jomon culture в‰Ґ12,000В years ago (Chard 1974). An early wave of migration brought people to Japan more than 30,000В years ago (Ono et al. Abundant archaeological evidence documents at least two major migration processes that brought people from the Asian continent to the Japanese archipelago. A number of contrasting models attempt to explain the fairly large range of morphological, cultural, and genetic variation represented in modern Japanese populations and recognized in the archaeological and fossil records. The results also support the hypothesis of a Central Asian origin of Jomonese ancestors, and a Southeast Asian origin of the ancestors of the Yayoi, contra previous models based on morphological and genetic evidence.ДЄfter more than 100В years of intense investigation (Mizoguchi 1986), the origin of the Japanese population still remains controversial. We infer that these patterns result from separate and distinct genetic contributions from both the Jomon and the Yayoi cultures to modern Japanese, with varying levels of admixture between these two populations across the archipelago. Coalescent analyses of Y chromosome short tandem repeat diversity indicated that haplogroups D and C began their expansions in Japan ~20,000 and ~12,000В years ago, respectively, while haplogroup O-47z began its expansion only ~4,000В years ago. In contrast, haplogroup O lineages (51.8%) were distributed in an inverted U-shaped pattern with a maximum frequency on Kyushu. Haplogroup D chromosomes were present at 34.7% and were distributed in a U-shaped pattern with the highest frequency in the northern Ainu and southern Ryukyuans. Japanese populations were characterized by the presence of two major (D and O) and two minor (C and N) clades of Y chromosomes, each with several sub-lineages.

Our global sample consisted of >2,500 males from 39 Asian populations, including six populations sampled from across the Japanese archipelago. A set of 81 Y chromosome single nucleotide polymorphisms (SNPs) was used to trace the origins of Paleolithic and Neolithic components of the Japanese paternal gene pool, and to determine the relative contribution of Jomon and Yayoi Y chromosome lineages to modern Japanese. Hunter-gatherers arrived before land bridges were submerged after the last glacial maximum (>12,000В years ago) and gave rise to the Jomon culture, and the Yayoi migration brought wet rice agriculture from Korea beginning ~2,300В years ago. Historic Japanese culture evolved from at least two distinct migrations that originated on the Asian continent.

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