The Utility of Cladistic Analysis of Nonmetric Skeletal Traits for Biodistance Analysis

James Christopher Reed

PhD Thesis 2006

A significant focus of bioarchaeology is biodistance analysis, which seeks to determine the biological affinities of human groups and to support arguments about prehistoric and historic cultural topics, such as migration, marriage, and residential patterns. Although genetic comparisons are becoming more common, metric and nonmetric skeletal traits remain the primary source of information on human populations.

Biodistance analysis is grounded theoretically and methodologically in phenetics, which is an approach developed by systematists to group organisms on the basis of overall similarity. However, while phenetics was adopted by physical anthropologists and bioarchaeologists as the foundation of biodistance analysis, systematists have long since moved away from phenetic approaches for determining relatedness to hypothetico-deductively based cladistic analyses. It is time for physical anthropologists and bioarchaeologists engaged in biodistance analysis do so as well.

It is perhaps an irony that biodistance analysis, which seeks to delineate the biological relationships of group, begins by defining the groups (samples) on the basis of archaeological, cultural, or linguistic information prior to any morphological/biological comparison. However, the delineation and comparison of groups should be based from the beginning on the biology (morphology) of individuals and then of groups and, more specifically, on unique biological features, not cultural or linguistic criteria. A cladistic analysis can provide a biologically based delineation of groups.

In this study I investigate whether unique, nonmetric characters can be delineated for small groups such as those traditionally the focus of biodistance analysis and, thus, whether cladistic analysis is an appropriate substitute for the phenetic approach in biodistance analysis. Four samples of skeletal material were examined. One, the Spitalfields collection, consists of burials of individuals whose familial relationships are well documented. The other samples are undocumented and compared to the Spitalfields sample in an attempt to delineate unique characters that might define groups.

The result was that no unique characters could be delineated, which means that cladistic analysis, while perhaps applicable to study of higher-level groups within the species, fails at the population level. Consequently, while unsatisfactory, biodistance analysis must continue to rely on abiological criteria for defining populations.