〇Masami IZUHO (Tokyo Metropolitan University), Kazuki MORISAKI (The University of Tokyo), Akira IWASE (Tokyo Metropolitan University), Jun OHASHI (The University of Tokyo), Hitoshi HASEGAWA (Kochi University), Nagayoshi KATSUTA (Gifu University), Koji SHICHI (Organization Forestry and Forest Products Research Institute)
１．Research goals and plans of Project Team B01
Modern human groups during the Initial Upper Paleolithic (Initial UP) made the early dispersal across Eurasia approximately 46,000 to 40,000 years ago are likely to be interpret the so-called 'ghost populations' in western Eurasia that are not genetically related to the subsequent Early UP (40,000 to 30,000 years ago) and later populations. Did the first modern human groups appear in the Japanese archipelago about 38,000 years ago have genetic and cultural relationships with those ghost populations? How did the fluctuating natural environment and repeated rapid changes affect the spread and adaptation of modern humans to the Japanese archipelago? Cultural evidence, paleoenvironmental evidence, and ancient DNA evidence are all currently fragmentary, preventing us from a precise understanding of the phenomena.
The main research questions of Project Team B01 are (1) when and how did the ghost populations of Initial UP dispersed to eastern Eurasia about 46,000 years ago? (2) Were first modern human group appeared in Japanese archipelago about 38,000 years ago, if any, maintain the genetic and cultural relationships from those ghost populations? (3) How did the fluctuated natural environment in eastern Eurasia affect the emergence and development of the Early UP society in the Japanese archipelago?
Project Team B01 investigates the empirical data primarily based on cultural, paleoenvironmental, and ancient DNA evidence to better understand the dispersals, colonization, migrations, evacuations, and disappearances of modern humans in the Japanese Archipelago at the mid latitude of East Eurasia. The research encompasses three distinct areas, each shaped by different climatic mechanisms: Inner Asia, the Circum-Japan Sea region, and the Pacific slope of the Japanese Archipelago. By integrating evidence from each area to reconstruct a comprehensive model, we aim to elucidate the sociological and genetic changes in modern human groups which occurred but not always alongside with the natural environmental changes in East Eurasia during the late Pleistocene.
２．Report on activities in fiscal year 2023
Since this research project is in its inaugural year, online meetings and email correspondence were conducted as necessary to facilitate coordination among all team members for the smooth progression of future research endeavors. The following presents a brief overview of the major research activities undertaken by Project Team B01 during fiscal year 2023, categorized into four main areas: archaeology, ancient DNA, paleoenvironment/paleoecology, and comparison/ integration of each evidence.
(1) Archaeology: Research activities outside Japan included excavations at the Tarbagataiin Am (T-Am) site in Mongolia conducted by Izuho, Morisaki, and other colleagues, with subsequent organization and analysis of excavated materials. Additionally, research information in China, Korea, and Mongolia was collected. Otani, a research collaborator, alongside Izuho, conducted obsidian chemical compositional analysis and landscape analysis for Upper Paleolithic (UP) sites in Korea. Among the several research activities in Japan, Iwase conducted excavations at the Okubo-Minami site (early UP) in Nagano Prefecture, while Izuho, Morisaki, Otani, and Yamada excavated the Akita 10 site (early UP) in Hokkaido. Radiocarbon dating for UP sites in the Japanese archipelago was compiled, and a chronological distribution of dates using the KDE model was developed, with Izuho and Otani responsible for Hokkaido, and Morisaki and Iwase responsible for Honshu and Ryukyu regions.
(2) Ancient DNA: Ohashi conducted a literature survey to collect previous study data from East Eurasia and constructed a model of admixture in the Japanese archipelago after the Yayoi period.
(3) Paleoenvironment and Paleoecology: Hasegawa, Katsuta, and Shichi conducted fieldwork and laboratory work in Japan and abroad. Research activities outside Japan included the collection of sediment cores from Lake Buil in Mongolia, although this was postponed to the next fiscal year due to an unusually warm winter. Katsuta conducted Pb dating and reconstructed paleoenvironmental changes over the past 100 years using surface sediment cores from Lake Buil and analyzed paleoenvironmental changes since the middle Holocene using sediment cores from Lake Jingpo in northeastern China. Shichi also conducted vegetation reconstruction based on pollen data from Lake Baikal sediments. In Japan, a 5-meter-long sediment core was collected from Kashiwazaki City, Niigata Prefecture, with subsequent stratigraphic description and sampling.
(4) Correlation and Integration of Each Research evidence: Shichi, Izuho, and other colleagues revealed that moderate warming occurred in the Baikal area approximately 45,000 to 40,000 years ago, resulting in open forest expansion mixed with steppe, which led to the dispersal of the earliest modern humans in the Baikal area (Shichi et al., 2023, Science Advances). In addition to this published project, collaborative research was initiated with Project Team A02 on sediment DNA samples collected from archaeological sites in Japan.
３．2024 Activity Plan
(1) Archaeology: Outside of Japan, we will continue excavations in Mongolia and collect various samples. Additionally, data collection in China and Korea will be ongoing. In Japan, we will continue excavations at the Okubo-Minami site in Nagano Prefecture and the Akita 10 site in Hokkaido. Establishing a chronological distribution (KDE model) of archaeological sites in the Japanese archipelago is crucial for accurate comparison of ancient DNA with the results of paleoenvironmental and paleoecological research. We will prioritize completing this task and also gather information for creating KDE models for China and Korea.
(2) Ancient DNA: We will continue collecting previous studies and constructing a population movement model in eastern Eurasia.
(3) Paleoenvironment and paleoecology: Outside Japan, we will collect sediment cores from Lake Buil, Mongolia. We will conduct Pb dating of Lake Buil surface sediment cores and reconstruct paleoenvironmental changes over the past 100 years. Additionally, we will summarize our research on paleoenvironmental change analysis since the middle Holocene using sediment cores from Lake Jingpo in northeastern China. In Japan, we will conduct 14C dating, chemical composition analysis, stable isotope composition analysis, and pollen analysis of sediment samples collected from Kashiwazaki City, Niigata Prefecture, to reconstruct vegetation change. Furthermore, we will collect pollen data from eastern Eurasia to Japan during marine oxygen isotope stage (MIS) 3 for reconstructing the vegetation and climate in each region.
(4) Correlation and integration of each research evidence: Once the KDE model of the archaeological sites on the Japanese archipelago is completed, we plan to correlate the pattern observed in the ancient DNA, with paleoenvironmental and paleoecological data and attempt to find directions for better integrating research results.
(modified from Shichi et al. 2023, Science Advances)