工藤 雄一郎

The impact of the 4.2 ka event on the subsistence of Jomon hunter-gatherers was studied at the Denotame site in central Japan with pollen, plant macrofossils, and wood remains. From 6,250 cal bp, the middle phase of the early Jomon period, to 3,750 cal bp, the late Jomon period, there were deciduous forests dominated by Quercus on the higher land between the river valleys. In the lower land in the valleys or at their edges Alnus japonica grew at 6,250-5,900 cal bp, Juglans mandshurica at 6,100-3,750 cal bp, and Aesculus turbinata at 4,500-3,750 cal bp. While maintaining their settlements and making pottery from 5,300 to 3,600 cal bp, Jomon people managed Castanea crenata and Toxicodendron vernicifluum and used their timber and other resources and the nuts of Juglans through these periods and of Aesculus in later periods. Abundant occurrences of other plants from archaeological remains indicated the use of plants with edible fruits such as Morus, Quercus, Phellodendron amurense, Actinidia, Vitis, Rubus, and Broussonetia, and those with other uses such as Styrax, Sapindus mukorossi, and Sambucus racemosa. In contrast to many instances of social disturbance through the 4.2 ka event on the Asian continent, the event did not affect the life of the Jomon hunter-gatherers at Denotame. The stable temperature of the warm Kuroshio current during this period probably supported an unchanged environment and the undisturbed life of the Jomon people in central Japan.

Little is known about the spatiotemporal dynamics of gray wolves in the Pleistocene across low-latitude regions of Eurasia. In Japan, a small-bodied endemic subspecies of Japanese wolves existed and went extinct in the early 1900s. The fossil record indicates that a giant wolf, which reached 70 cm in body height, inhabited Japan during the Pleistocene, but its evolutionary relationship, if any, with the Japanese wolf remains uncertain. Here, to reveal the genetic origin of the Japanese wolf, we analyzed ancient DNA from remains (recovered in Japan) of one Pleistocene wolf that lived 35,000 years ago and one Holocene wolf from 5,000 years ago. The analysis of the mitochondrial DNA revealed that the Pleistocene wolf was not part of the Japanese wolf clade but rather an earlier-diverging lineage. The analysis of the nuclear DNA of the Holocene Japanese wolf revealed that it was an admixture of the Japanese Pleistocene wolf and continental wolf lineages. These findings suggest that the Japanese wolf originated via waves of colonization of multiple Pleistocene wolf populations at 57-35 and 37-14 ka, respectively, followed by interpopulation hybridization.