Depletion of a resource? The impact of prehistoric human foraging on intertidal mollusc communities and its significance for human settlement, mobility and dispersal

Ethnoecological studies have demonstrated the impacts that even relatively small-scale human foraging has on targeted species of shellfish and the structure of biological communities in intertidal zones. There is compelling archaeological evidence that people in various parts of the world often had a depleting effect on shellfish populations. Shellfish and other marine resources have sometimes been perceived as lowly ranked foods and coastal archaeological sites have often been interpreted as temporary (possibly seasonal) sites for the exploitation of these 'inferior' food resources. This model has been challenged by studies of mid-Holocene Mesolithic hunter-gatherer sites in Atlantic Europe, which have shown that marine foods were the main component of the total diet and that human foraging can deplete shellfish resources. Although subsistence systems based on coastal resources might have been both viable and acceptable in dietary terms, regular mobility would have been necessary for them to be sustainable. On longer time scales, such coastal mobility might result in population dispersal. Sites associated with early anatomically modern humans show the antiquity of coastal adaptations, including the consumption of shellfish, and the dispersal of early modern humans out of Africa into south-east Asia and 'Greater Australia' could have been through coastal environments. This coastal dispersal could have been driven, at least in part, by the impact of early human foragers on intertidal food resources. Resource depletion in coastal zones was probably among the first significant, but small-scale, 'ecological impacts' of human beings.