The error of twentieth-century archaeology was to assume that the history of human behaviour was structured by some form of ultimate reality. The New Archaeology claimed that the ultimate reality of causation comprised the environments, to which human communities had to adapt by employing the technologies available to them. Social Archaeology then extended this approach by claiming that the adaptive procedures had also to satisfy the demands of various forms of social organisation, and Interpretive Archaeology proposed that all human practices had utilised a semiotic logic that made sense to those social beings who were involved. Living things exist in the ways that non-living things do not simply because living things are able to identify those aspects of the world around them that are necessary for them to grow and to develop. The processes of growing and developing as a person have always involved the interpretation of some aspects of the assemblages within which that person lives.