A Non-Phylogenetic Conceptual Network Architecture for Organizing Classes of Material Artifacts into Cultural Lineages

A Non-Phylogenetic Conceptual Network Architecture for Organizing Classes of Material Artifacts into Cultural Lineages Liane Gabora (liane.gabora@ubc.ca), Stefan Leijnen, Tomas Veloz (tomas.veloz@ubc.ca) and Department of Psychology, University of British Columbia Okanagan campus, 3333 University Way Kelowna BC, V1V 1V7, Canada Carl Lipo (clipo@csulb.edu) Department of Anthropology and IIRMES, California State University, Long Beach 1250 Bellflower Boulevard Long Beach, CA 90840, USA Abstract Phylogenetic Approaches The application of phylogenetic techniques to the documentation of cultural history can present a distorted picture due to horizontal transmission and blending. Moreover, the units of cultural transmission must be communicable concepts, rather than conveniently measurable attributes, and relatedness between elements of culture often resides at the conceptual level, something not captured by phylogenetic methods, which focus on measurable attributes. (For example, mortars and pestles are as related as two artifacts could be, despite little similarity at the attribute level.) This paper introduces a new, cognitively inspired framework for chronicling material cultural history, building on Lipo’s (2005) network-based computational approach. We show that by incorporating not just superficial attributes of artifact samples (e.g. fluting) but also conceptual knowledge (e.g. information about function), a different pattern of cultural ancestry emerges. Keywords: archaeology; artifacts; cladistics; cultural evolution; material culture; network model; phylogeny Introduction The efforts of biologists, phylogeneticists, and others, have culminated in an impressively detailed understanding of how the living things of today evolved. We can trace the ancestral origins of our eyes and fingers, and even certain behavioral traits such as mating preferences. However, we lack comprehensive knowledge of patterns of relatedness of elements of culture, even restricting ourselves just to material artifacts. The paper discusses difficulties that have arisen attempting to chronicle material cultural history using phylogenetic and network based approaches. We then describe our new conceptual network approach. The insight that guides this approach is: since artifacts are the product of minds that encode representations of them not just at the attribute level but also at an abstract, conceptual level, to reconstruct material cultural evolution it is necessary to incorporate how artifacts are conceived, and how these conceptions interact in a human mind. We introduce a computer program that is able to construct such networks from both attribute data and conceptual information. Since artifacts undergo ‘descent with modification’, the theory of natural selection appears to offer a means for explaining cultural history. Accordingly, phylogenetic methods such as cladistics are routinely borrowed from biology and applied in an archaeological context (O’Brien & Lyman 2003; O’Brien, Darwent & Lyman, 2001). In cladistic representations of archaeological data, the measured attributes of a ‘taxon’ of artifact are listed as a number string. The position in the string is loosely analogous to the concept of gene, and the number at that position is loosely analogous to the concept of allele. Thus if a taxon is represented by 132 then the first attribute is in state one, the second is in state three, and the third is in state two. For example, consider the representation of early projectile points from the Southeastern United States shown in Figure 1 (O’Brien et al., 2001). The data consist of metric and morphological measurements with respect to eight attributes, each of which can take from two to six possible states. Thus for example if fluting is absent in a particular artifact it has a 1 in position VII, and if fluting is present it has a 2. Seventeen ‘taxa’ are identified, and the pattern is such that one common ancestor (identified as KDR) gave rise to sequential branchings that culminated in 16 different taxa. This technique provides an intuitively meaningful (although potentially misleading) means of capturing structural change. The ‘root taxon’ at the far left is the most primitive, and early branch points represent changes that provided the structural constraints that shaped more recent changes. For example, much as evolution of the backbone paved the way for limbs, evolution of containers paved the way for spouts and handles. Phylogenetic approaches have also been applied to culture in more complex ways. For example, relationships amongst different elements of culture have been analyzed by comparing their phylogenetic trees (Holden & Mace, 2003). The procedure involves running a series of forward models, one in which the phenomena are assumed to evolve completely independently, another in which one kind of correlation is assumed (e.g. matriliny with cattle), another in which a different correlation is assumed (e.g. patriliny with