Population structure drives cultural diversity in finite populations: A hypothesis for localized community patterns on Rapa Nui (Easter Island, Chile)

Forgotten books: The application of unseen species models to the survival of culture

The study of ancient cultures is hindered by the incomplete survival of material artifacts, so we commonly underestimate the diversity of cultural production in historic societies. To correct this survivorship bias, we applied unseen species models from ecology to gauge the loss of narratives from medieval Europe, such as the romances about King Arthur. The estimates obtained are compatible with the scant historic evidence. In addition to events such as library fires, we identified the original evenness of cultural populations as an overlooked factor in these assemblages' stability in the face of immaterial loss. We link the elevated evenness in island literatures to analogous accounts of ecological and cultural diversity in insular communities. These analyses call for a wider application of these methods across the heritage sciences.

Thermal Imaging Shows Submarine Groundwater Discharge Plumes Associated with Ancient Settlements on Rapa Nui (Easter Island, Chile)

Submarine groundwater discharge (SGD) is an important component of many coastal environments and hydrologic processes, providing sources of nutrients to marine ecosystems, and potentially, an important source of fresh water for human populations. Here, we use a combination of unpiloted aerial systems (UAS) thermal infrared (TIR) imaging and salinity measurements to characterize SGD on the remote East Polynesian island of Rapa Nui (Easter Island, Chile). Previous research has shown that coastal freshwater seeps are abundant on Rapa Nui and strongly associated with the locations of ancient settlement sites. We currently lack, however, information on the differential magnitude or quality of these sources of fresh water. Our UAS-based TIR results from four locations on Rapa Nui suggest that locations of variably-sized SGD plumes are associated with many ancient settlement sites on the island and that these water sources are resilient to drought events. These findings support previous work indicating that ancient Rapa Nui communities responded to the inherent and climate-induced hydrological challenges of the island by focusing on these abundant and resilient freshwater sources. Our results highlight the efficacy of using UAS-based TIR for detecting relatively small SGD locations and provide key insights on the potential uses of these water sources for past and current Rapa Nui communities.