Quaternary paleoenvironmental variation and its impact on initial human dispersals into the Japanese Archipelago

Abstract

To understand the Late Pleistocene human dispersals to the Japanese Archipelago, we examine the paleobathymetric changes in and around the archipelago based on the results of recent paleoclimatological study of the Japan Sea that has provided millennium-scale sea level changes, the Pleistocene mammalian faunal record (e.g., extinct proboscideans), and the Paleolithic archaeological record. Proboscideans likely migrated from continental East Asia to Paleo-Honshu (consisting of the present day Honshu, Shikoku, and Kyushu islands) and the Ryukyu islands via land bridges across the Tsushima Strait and Yonaguni Strait during the coldest periods of the Middle Pleistocene (MIS 6, 12, 16, and probably 35). However, no clear evidence of hominin arrival in the archipelago has been dated to the Middle Pleistocene. Further, land bridges connecting continental East Asia and Paleo-Honshu were not present during the period of initial major human dispersals to the Japanese Archipelago, i.e., Marine Isotope Stage (MIS) 3 and 2. Thus, initial dispersals to Paleo-Honshu and the Ryukyus were achieved by watercraft and would have involved advanced seafaring skills. The paucity of archaeological sites before the onset of late MIS 3 (prior to 40ka) and the significant increase of archaeological sites since late MIS 3 suggests that increasing population density on the East Asian mainland may have been a factor for humans to disperse into the Japanese Archipelago.