USING DISTANCE MATRICES TO CHOOSE BETWEEN COMPETING THEORIES AND AN APPLICATION TO THE ORIGIN OF MODERN HUMANS

This paper examines competing theories for cases in which both the dat a and the hypotheses can be represented as distance matrices. A test d ue to Dow & Cheverud has been used for such comparisons in anthropolog y, but when data are spatially, temporally. or phylogenetically autoco rrelated, this test may be far too liberal. We examine a classificatio n procedure based on ratios of probabilities obtained from Mantel test , of the competing hypotheses and find that design matrices describing only lag-one connections and those eliminating common connections of competing hypotheses are the most informative. We apply this method to simulated gene-frequency data in a 7 x 7 chessboard representing a st epping-stone model and discriminate between alternative theories with a 7% misclassification rate. We also apply these techniques io the cur rent controversy concerning the origin of anatomically modern humans b y testing design matrices representing regional continuity and single African origins. The outcome for lag-one matrices and those shelving o nly unique lag-one differences indicate that the single African origin of anatomically modern humans fits the distance matrix based on 165 c haracters of 83 fossil crania better than the competing theory. Howeve r, we also rested a design matrix describing single origin cut of sout hwest Asia. This design matrix was clearly most similar to the data in all tested cases. These results make the regional-continuity theory a less likely explanation for the observed cranial differences than the two single-origin theories. Of these, single southwest Asian origins seems the more likely interpretation of the data. (C) 1997 Academic Pr ess Limited.