Phase 1: Cultural diversification: Project 015|
Do new cultural assemblages arise primarily through phylogenesis or ethnogenesis?
Stephen Shennan (Institute of Archaeology, University College London)
Mark Collard (Department of Archaeology, Simon Fraser University)
PROJECT FUNDING: PI
Neutral evolution and pottery
Some aspects of artefacts are subject to selection in terms of how well they perform their function; others such as decoration on pottery are much more free to vary, and are adaptively neutral. In 1995, Fraser Neiman predicted the amount of variation expected for neutral traits, and found that seven successive phases of Woodland-period pottery decorations (American Mid-West) matched these expectations.
Shennan and Wilkinson (2001) extended Neiman's methods in a study of patterns of decorative motifs on pottery from two early Neolithic settlements in western Germany. Shennan and Wilkinson showed that the amount of variation coincided with the neutral model for the earlier phases but not for the later ones, when novel decoration types may have been deliberately selected. Other evidence (Bentley and Shennan 2003, see Project 9) suggests that the potters may been trying to establish their own local identity and distinguish themselves from neighbouring groups.
Cultural origins: branching or blending?
In phylogenesis, a new cultural entity results from descent with modification from an ancestral assemblage (branching). In ethnogenesis, a new cultural assemblage arises through the blending of contemporaneous elements. Collard and Shennan (2000) suggested that distinguishing phylogenesis from ethnogenesis is very similar to estimating the descent of species in biology, as both divide similarities into those resulting from shared ancestry and resulting from other mechanisms, such as diffusion. Biologists generate trees to link species in a way that minimises the number of hypotheses of change required to account for the observed distribution of similarities. Similarities compatible with the tree should have shared ancestry while those that conflict with the tree should not.
Collard and Shennan analyzed the pottery data from all seven of the early Neolithic settlements mentioned above. Results from the four settlements occupied throughout the whole of the ten-phase period indicated that pottery decorations were generated both by phylogenesis and by ethnogenesis. In contrast, the three newly founded assemblages in the ten-phase period appear to derive from a single ancestral assemblage through descent with modification, I.e., phylogenesis.
Our results are consistent with colonization and group fission having driven the early Neolithic expansion into central Europe, which clearly involved cultural differentiation and branching even at the local scale of settlements that would have communicated frequently.
|•||Lipo, C.P., M.J. O'Brien, M. Collard and S.J. Shennan (2005).|
Cultural phylogenies and explanation: why historical methods matter. In: Lipo, C.P., M.J. O'Brien, M. Collard & S.J. Shennan (eds.) (ed\s) Mapping Our Ancestors: Phylogenetic Methods in Anthropology and Prehistory. Aldine Transaction: Hawthorne, NY. 3-18.