Shifting Coastlines: Archaeomalacology of Sohoton I and Sohoton III, Basey, Western Samar

Patrick Ryan C. Castro1*, Kristine Kate A. Lim1, Patricia S. Cabrera1, Emil Robles1, and Juan C. Rofes1,4,5

Along the Basey River in Western Samar are two shell-bearing archaeological sites: Sohoton I and Sohoton III. First excavated in 1971 by the University of Hawaii and re-excavated by the UP School of Archaeology recently, Sohoton I is a cave with Early to Late Holocene dates ranging from 10,200 ± 150 BP to 385 ± 105 BP, while Sohoton III is a rockshelter with Late Holocene dates of 1280 ± 90 BP and 1560 ± 75 BP. The significant amount of shell material in both sites indicates habitation, contrasting with the numerous other burial sites along the river. Sohoton III was also initially interpreted as a stopping point for trade between lowland communities and interior populations. However, recent data on sea level changes suggest an alternative interpretation where higher sea levels would have made coastal and marine environments closer to the site, reducing the need for long-distance transport and trade of marine resources for interior populations. This is supported by an archaeomalacological analysis through taxonomic identification and quantification, which has identified an almost entirely marine-dwelling assemblage. These results contrast with preliminary analysis from the Sohoton I molluscan assemblage, which shows a more diverse assemblage of taxa from different habitats, possibly signifying substantial environmental changes throughout the Holocene. Furthermore, an informal market survey revealed that only a fraction of the species represented in the archaeological record continue to be consumed. Ultimately, these findings highlight a shift in shellfish exploitation over time, reflecting changing environments since the Early Holocene.