itself remained limited to the publication of species lists.

In the 1960s, archaeologists became interested in past behavior as represented in archaeological evidence. Radiocarbon dating, introduced in the late 1950s, enabled the independent dating of cultural deposits and a shifting of emphasis away from establishing culture histories to questions about how people utilized resources in the past. The effect of this shift to an economic prehistory in Europe or “new archaeology” in North America (Trigger 1989) is reflected in the large number of journal articles in the 1970s that were devoted to coastal archaeology. In these, midden analysis was central to investigating marine economies or adaptations, and central to this focus on adaptive behavior was the development of explanatory models for the patterning of archaeological evidence using ethnographic data and actualistic or experimental studies.

The economic approach is perhaps most clearly represented in the work of English archaeologist G.N. Bailey. In one work (Bailey 1975), he describes his investigation of the importance of shellfish in the precontact diet of aboriginal groups using midden excavations on the north coast of New South Wales. He used present-day yields and distribution of shellfish species, the estimated daily energy needs of modern aboriginal people, and historic demographic data to interpret the excavated shell assemblages. Bailey concluded that although the frequency and size of shell middens suggest that they are a major food resource, shellfish made up only a small percentage of dietary intake and midden sites represent only seasonal or short-term occupation.

In the 1960s and 1970s, archaeologists recognized the potential for paleoenvironmental reconstruction through midden analysis. Shellfish species are associated with discrete marine habitats, and therefore shellfish populations are susceptible to small environmental changes. As a consequence, species present in dated midden deposits reflect the coastal morphology at the time of their collection (Shackleton 1983). Judith Shackleton interpreted the changes in shell species through time from stratified midden deposits in southern greece in order to reconstruct the paleo-shoreline adjacent to the cave (Shackleton and van Andel 1980). Variability in the midden deposits reflected the changes in the shoreline that resulted from rising sea levels at the end of the Pleistocene period.

Oxygen isotope analysis of midden shells became popular in the 1970s in order to measure paleo-temperature change and to establish midden chronology through radiocarbon dating of shells (Shackleton 1971, 411). Oxygen isotope analysis was also useful in determining the season of death of the shellfish and therefore whether or not the use of midden sites was seasonal (Deith 1983; Godrey 1988).

An environmental determinism underpinned the economic approaches of the 1960s and 1970s. Human behavior was viewed as being shaped more or less exclusively by nonhuman constraints, and middens were interpreted as reflecting shell species availability rather than choice. Countering these economic approaches, social explanations for temporal and spatial variability became a popular form of archaeological analysis in the late 1970s (Lourandos 1977, 1983), and the strength of the social explanations owed much to ethnographic data. Betty Meehan (1982) observed that the Anbarra people on the northern Australian coast targeted particular shellfish species rather than randomly collecting all available species; Sandra Bowdler (1976) argued for a gendered approach to shellfish analysis using ethnographic data to show that traditional shellfish collection was women’s work.

In the early 1980s, competing social and environmental explanations were offered for the pattern of increased site density and the intensity of coastal resource use in the late Holocene record of North America and Australia. Australian archaeologist Harry Lourandos argued that an intensification of economy and settlement evident in sites in southeastern Australia could be explained as increasingly complex social networks, possibly in response to population increase, possibly owing to rising sea levels in the early Holocene period. In contrast, S. Perlman (1980) used the environmental determinism of the optimal foraging theory to argue