The widespread alliance systems of Australian Aboriginal society had an economic and survival value in harsh environments, but in resource-rich areas such as South-east Queensland it is more a question of strategies for increasing regional carrying capacity. Recent archaeological results in the area, with evidence of increases in site numbers and artefact deposition rates and diversification of subsistence resources to include small-bodied species, show the development of new patterns of technology, economy and demography following major environmental changes in the post-Pleistocene period. Widespread changes in Australian prehistory around 4000 years ago may have been triggered in certain key areas such as South-east Queensland.
Morwood, M. J. (1987). The archaeology of social complexity in South-east Queensland. Proceedings of the Prehistoric Society (London), 53 337-350.