Archaeomalocological methods, forager decision-making, and intertidal ecosystems: Two millennia of mollusc exploitation on a remote Pacific atoll

Abstract

Marine mollusc shells are excellent proxy records for human behaviour and environmental archives as they are ubiquitous in coastal archaeological deposits and preserve well compared with other marine fauna. Archaeomalacology, the study of molluscs from archaeological sites, has generated new data on the role of coastal environments in the human story, elucidating patterns of forager behaviour, human impacts to the environment, the role of marine foods in coastal palaeo-economies, and responses to changes in climate and environments both within and outside the Pacific Islands. Molluscs are also critical to the functioning of coral reefs and intertidal ecosystems, and as such, can be useful in tracking long-term trajectories of change in marine environments. This thesis presents the first high-resolution study of the archaeomalacological record of Ebon Atoll, Republic of the Marshall Islands, eastern Micronesia, demonstrating that molluscs had been a stable component of the diet for two millennia.Atolls, consisting primarily of unconsolidated biogenic sediments atop a narrow reef platform that surrounds a lagoon, have long been considered marginal environments for human habitation. A lack of standing fresh water, poor soils for agriculture, and exposure to storms and extreme weather due to low elevation present considerable challenges for inhabitants in the past as they do today. The relatively small land area is, however, bounded by an expansive reef platform which hosts a rich and diverse range of mollusc species, offering an easily accessible source of protein and other minerals not available in terrestrial foods.Nevertheless, mollusc remains from Marshall Islands archaeological sites have been assessed only in broad terms as part of synthetic works on settlement and subsistence patterns in the archipelago. This thesis presents a detailed analysis of mollusc remains from a number of archaeological sites on Ebon Atoll, using a newly developed quantification protocol that incorporates a greater number of non-repetitive shell elements, and a new method for tracking forager decision-making in tropical intertidal settings. In addition, a review of the archaeological literature pertaining to human impacts to molluscs during the prehistoric period of the Pacific Islands facilitated investigation of these processes on Ebon Atoll. No discernible human impacts were noted, and mollusc assemblages from Ebon Atoll spanning two millennia of occupation were consistently rich, even, and diverse, incorporating a broad range of taxa from different habitats. Variation in assemblage composition is likely related to the configuration of intertidal habitats on windward and leeward exposed islets, rather than site function or alterations to marine environments. These results indicate that this generalised foraging strategy, low human populations and a productive marine environment produced sustained yields of molluscs by spreading impact across trophic levels and functional groups. These data contest traditional perceptions of atolls, and are in line with current discourses that challenge traditional notions of small islands, and especially atolls as remote, isolated and marginal settings for human habitation.