Cultural macroevolution in the Pacific Northwest: a phylogenetic test of the diversification and decimation model

Abstract A number of scholars have proposed models of cultural evolution whereby entities defined by socio-economic variables held at group levels evolve in a branching or cladogenetic process. The Diversification and Decimation model seeks to explain temporally short-lived patterns of cladogenetic diversification and subsequent decline in the range of such cultural variants during the Middle Holocene of North America's Pacific Northwest region. This paper uses cladistic and network techniques to examine core predictions of the model – that cultural entities evolved in a branching process, not significantly impacted by tokogenetic processes; and that the pattern of evolution was as predicted by the model. Outcomes suggest that while major tenets of the model are supported, some aspects require minor refinement. Implications are considered for future studies of this nature.