12,000 years away from the sea: Long-term circulation of Pacific shells in the Semiarid North of Chile (South America)

Marine resources provide a baseline for understanding the sociohistorical trajectories of Andean societies using Pacific coastal environments. This study examines seashell distributions in northern Chile's semiarid region, revealing inland circulation patterns established over twelve thousand years. This included an extensive review of published information and new data assessed through GIS and least-cost paths. Sorting 950 specimens from 32 sites into 32 taxa, we identified consistent mobility patterns across time periods. In addition to the primary west-east trajectory from the sea to the interior, a secondary north-south inland vector was in use since the early Holocene. This study also revealed intensified shell transport during the middle Holocene, and a shift toward down-the-line exchange with reduced shell frequency at interior sites by the late Holocene, particularly in the Limarí Valley. Additionally, shell artifacts - ornaments and tools - were found more consistently in interior contexts. Together, these findings shed light on long-term human adaptation strategies in semiarid mountainous environments. •We examined the distribution of 950 marine shell fragments from the Pacific Ocean in 32 archaeological sites.•These 12000-year-old circulation patterns follow a main west-east mobility axis.•Shells 50-70 km away from the coast suggest a secondary mobility circuit connecting the sites in a north-south axis.•During the late Holocene, sites with shell farther and closer to the coast suggest a down-the-line exchange pattern.•Shell artifacts – ornaments and tools – appear consistently throughout the sequence.