Divergent demographic responses to the Kikai-Akahoya volcanic catastrophe in mid-Holocene Japan.

We examine human demographic responses to one of the Holocene's largest volcanic eruptions, which devastated East Asia 7300 years ago. Archaeologists have intensively debated the impacts of massive environmental shocks, highlighting either societal collapse or cultural continuity, although few studies situate such catastrophic events within longer-term demographic trajectories. We address this gap in knowledge by using statistical models to infer the demographic and environmental impacts of the Kikai-Akahoya (K-Ah) eruption on Jomon foraging communities occupying the Japanese archipelago. Traditionally framed as an apocalyptic "forcing" mechanism that changed the direction of Japanese prehistory, our results identify a more complex and contingent suite of demographic outcomes. Although we do find evidence of major population collapse in immediately adjacent regions to the volcano, some proximal populations actually increased after the catastrophe, whereas some distal communities were affected by environmental consequences that have hitherto been overlooked. Demographic perspectives on ancient disasters are useful in generating a deeper understanding of the contingent ways in which cultures and societies cope with sudden shocks and catastrophes.