341 15 Grades, gradients, and geography: a dental morphometric approach to the population history of South Asia Brian E. Hemphill Anthropological Perspectives on Tooth Morphology: Genetics, Evolution, Variation, eds. G. Richard Scott and Joel D. Irish. Published by Cambridge University Press. © Cambridge University Press 2013. 15.1 Introduction The purposes of this chapter are threefold. First, it will be demonstrated that dental observations from archaeologically derived and modern samples can be combined without introducing systemic bias that compromises attempts to reconstruct population history. Second, it is shown that dental morphological trait frequencies yield similar, but distinct patterns of intersample phenetic afinities compared to those obtained with dental metrics. Third, it will be tested whether South Asians evidence long-standing local continuity, or whether they, and Pakistanis in particular, experienced signiicant gene low from outside populations. 15.1.1 Relative proportionality, tooth size gradients, allocation of permanent tooth size In recent years, largely as a consequence of the inluential work of Christy Turner II, researchers interested in understanding patterns of human microevo- lution in the post-Pleistocene era have focused their attention on the assessment of variation in dental morphological trait frequencies. Odontometric data have been used far less commonly for the same purpose (T. Hanihara 2008; Harris 1998; Harris and Harris 2007; Harris and Rathbun 1989, 1991; Hemphill 1991, 2008, 2009b; Hemphill et al. 1992, in press). Multivariate studies consistently demonstrate that isometric scaling accounts for a large proportion of the size variation across populations (Harris 1998; 9781107011458c15_p341-387.indd 341 9781107011458c15_p341-387.indd 341 10/30/2012 5:07:15 PM 10/30/2012 5:07:15 PM