Soichiro Kusaka of School of Humanities and his research group at Associate Professor have found that the Naumann elephant, which lived in the Japanese archipelago, was dated to extinction about 35,000 to 33,000 years ago, about 10,000 years older than previously thought. A paper on this subject was published in the British scientific journal Scientific Reports on May 26.
This research is a project led by Kazuki Morisaki Associate Professor of the Graduate School of Humanities and Sociology, University of Tokyo, Graduate School with participation from Associate Professor Kusaka, Atsushi Kimura Professor from the Tokai University Department, Yuichiro Nishioka Associate Professor from the Fujinokuni Global Environmental History Museum, and Akira Iwase Assistant Professor from Tokyo Metropolitan University. Until now, the Naumann elephant in the Japanese archipelago was thought to have gone extinct about 24,000 years ago, but the gelatinization method, which extracts collagen from bones for dating, has been pointed out as insufficient to remove trace amounts of new carbon mixed into fossils, potentially resulting in a more recent age than the actual one. The research group remeasured radiocarbon age using ultrafiltration methods, which extract only long-chain collagen with good preservation and high molecular weight from the collagen found in fossil bones. This enables highly accurate analysis that suppresses the impact of impurities. Furthermore, after investigating fossil specimens found around Imabari City in Ehime Prefecture, including the Seto Inland Sea and other parts of the Japanese archipelago, it was determined that the Naumann elephant went extinct about 35,000~33,000 years ago, which is about 10,000 years older than the previous theory.
While it is believed that present-day humans arrived in the Japanese archipelago about 38,000 years ago, it has become clear that the period of coexistence with the Naumann elephant was approximately 4,000 to 6,000 years, much shorter than the previously assumed period of about 14,000 years. Furthermore, since it is suggested that the human activity area and the habitat of the Naumann elephant may not have overlapped chronologically and spatially, the research group concluded that climate change and habitat change, rather than hunting pressure by humans, were more likely to be the main factors in the Naumann elephant's extinction. Kusaka Associate Professor, who played a central role in the study, said, "Fossils record information about the past, even for Paleolithic events that occurred tens of thousands of years ago. In this study, by accumulating data using the latest research methods, we were able to bring new insights into the coexistence relationship between humans and the Naumann elephant," he explained. We hope to conduct similar analyses of fossils of large mammals other than the Naumann elephant in the future to further clarify the extinction process of large mammals and human history in the Japanese archipelago," he said.
