Journal of Archaeological Science 1981, 8, 109-l 20 A Model of Prehistoric Collecting on the Rocky Shore A. J. Anderson0 Selectiveresource. exploitation patterns in prehistory are often explained in terms of cultural preference, but this paper argues that a non-cultural explanation based upon zoological models of consumer choicemay be equally valid. A modelof shell- fishing behaviour concerningthe relationshipof abundance and yield is developed and used to predict that rocky shore collectors should ignore all factors other than the individual size of shellfishand that, in doing so, they would become progressively selective in their collecting patterns. Data from prehistoric rocky shore shell middens in Pall&r Bay, New Zealand, indicates several phases of progressivelyselectivecollecting over a period of 600 years and these patterns appearbestexplicable in terms of the model. Keywords: MOLLUSCA, NEW ZEALAND, PALLISER BAY, SHELLFISH, SHELL MIDDEN. Introduction Fundamental to the archaeological understanding of subsistence economics is the question of why people seldom consume the edible plants or animals available to them in the proportions in which these occur. Selective consumption patterns have been variously attributed to cultural choice (Bigalke, 1973; Voight, 1973; Jones, 1977) the intervention of other limiting resources (Lee, 1969) or, more generally, to the broader nutritional adaptations of humankind (Yudkin, 1969; Cohen, 1977). This paper argues that such selective, specialized or “coarse-grained” (MacArthur & Levins, 1964), con- sumption patterns, as reflected in the analysis of shell middens, may be also widely explicable in terms of an essentially non-cultural exploitation strategy. A model of shellfish collecting behaviour showing progressively selective exploitation is developed, and examined in conjunction with the evidence from shell middens excavated in Palliser Bay, New Zealand. Background Assumptions to a Model of Shellfishiig Shellfishing in many areas, including New Zealand, was frequently a subsistence activity of soft shore microenvironments and this has led some archaeologists, such as Shawcross (1970), to believe that rocky shores were comparatively unimportant resource zones. Since the present model is based upon the exploitation of rocky shores it is thus pertinent briefly to consider the matter. In New Zealand it is generally the case that rocky shores support a wider variety of edible species (Morton and Miller, 1973, p. 444) and many which provide mature individuals of substantially greater meat weight than any soft aAnthropology Department, University of Otago,New Zealand. 109 0305-403/81/020109 + 12$02.00/O 0 1981 Academic Press Inc. (London) Limited