Morphometric analyses of Batissa violacea shells from Emo (OAC), Gulf Province, Papua New Guinea

Morphometric analyses of Batissa violacea shells from Emo (OAC), Gulf Province, Papua New Guinea

Archaeological investigations of human predation pressures on shellfish usually rely on measurements of complete shell
specimens. However, most archaeological shell assemblages
consist predominantly of broken shells, limiting measurable
sample sizes, and thus potentially biasing results in cases where shell fragmentation is biased towards particular size classes (due to shell size-fragility correspondences). This paper presents a recent application of morphometric analyses on the Batissa violacea assemblage from Emo, an early ceramic site from the Gulf Province, Papua New Guinea. Our method enabled most shell valves, fragmented or not, to be accurately and comparably measured for size. The results reveal a close match between the commencement of occupation and maximum shell sizes in a sequence of occupational phases, each separated by many decades to hundreds of years of site abandonment. While each occupational phase begins with peak mean shell sizes, the later peaks never again attain the mean shell size of the initial phase. As each phase progresses, shell sizes diminish until abandonment, and then the same pattern starts again with the next phase. Identical trends were
obtained from two separate excavation squares. We interpret these results to indicate that while people may have abandoned the site of Emo between the occupational phases, they did not abandon the region, continuing to exploit local shellfish beds, albeit less frequently than during the site’s occupation. These results highlight the ability of local (site-specific) archaeological shell data to shed
light on regional demographic and occupational trends.

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