Central place foraging and shellfish processing on California's Northern Channel Islands

We use a central place forager model for shellfish processing to understand Middle Holocene (7550-3600 cal BP) human settlement patterns on California's Northern Channel Islands. This period was associated with increasing sedentism and special purpose sites. We examine the processing and transport costs of two high-ranked shellfish species collected during the Middle Holocene, red abalone (Haliotis rufescens) and California mussel (Mytilus californianus), and how these costs influence archaeological assemblages at coastal and interior settlements. Experimental data and the biology of these species suggest that red abalones are less likely than mussels to be transported long distances (∼2 km) without field processing. Consistent with these expectations, coastal red abalone midden sites (CA-SRI-109 and -338) are dominated by large red abalone shells and California mussels are most abundant at contemporaneous inland sites (e.g., CA-SRI-50). Large coastal settlement sites (CA-SRI-5, -19, -116, and -821) had the highest overall shellfish diversity. A stable oxygen isotope study suggests that special purpose sites were occupied seasonally and large coastal settlements were more likely to be inhabited year-round. Our study suggests that transportation and processing costs of food resources were important variables in the development of early hunter-gatherer settlement patterns.