East Eurasian Dispersals to the Americas: A Spatiotemporal Perspective from Paleogenomics

The dispersal of modern humans from East Eurasia to the Americas involved multiple migration routes, repeated admixture, and long-term adaptation. Recent paleogenomic studies have provided direct insights into these processes by reconstructing population histories. In this review, we summarize genome-wide data from Upper Paleolithic to early Holocene individuals to examine the spatiotemporal dynamics of these dispersals, with particular attention to the Pacific Rim of Northeast Asia. We discuss the genetic structure and interactions of key ancestral lineages, including Ancient North Siberians (ANS), Ancient North Eurasians (ANE), and Ancient Paleo-Siberians (APS), and their roles in the formation of ancestral Native American populations. Genomic evidence indicates that Native American ancestry emerged through admixture between East Asian–related and ANS-related lineages, likely during or before a period of population standstill, followed by rapid expansion into the Americas via coastal and/or interior pathways. Within this framework, we examine the position of the Japanese Archipelago and Jomon-related populations along the western Pacific Rim. Although Jomon people are not considered direct ancestors of Native Americans, paleogenomic studies demonstrate that Jomon-related genetic affinities or ancestry components have been detected in several populations around the northern Pacific Rim. Taken together, these results argue for viewing the Japanese Archipelago as potential refugium and interaction zone within the Pacific Rim, rather than as an isolated endpoint. We also consider genetic evidence for cold and coastal adaptation, and outline future directions, emphasizing the need for high-coverage ancient genomes, broader sampling in the Japan–Pacific Rim region, and integrative approaches to visualize complex migration scenarios.