Human Adaptation to the High-Altitude Permafrost Zone at Daisetsuzan National Park, Japan

We investigated the formation processes of surface artifact scatters at the open-air site of Hakuundake-Koizumidake (H-K), located above the forest line (> 2000 masl) in Daisetsuzan National Park, within the Daisetsu Mountains of Hokkaido, Japanese northernmost island. Our survey data suggest that the sorting of artifact sizes results from a two-stage post-depositional process: an initial upward movement of artifacts due to freeze-thaw cycles, followed by downslope displacement, primarily driven by frost creep along the southern-facing slope. Analysis of museum collections from H-K reveals that the artifacts are predominantly lithics, with a high frequency of flakes and formal tools, including armatures (notably arrowheads) and processing tools (e.g., burins and scrapers). Geochemical and hydration analyses of the obsidian samples suggest that prehistoric hunter-gatherers, equipped with minimal tools for bow and arrow technology, likely exploited mobile game in high-altitude regions. These groups are thought to have migrated from lower elevations at least 3000 years ago.