QUANTITATIVE COMPLETE TOOTH VARIATION AMONG EAST ASIANS AND NATIVE-AMERICANS - DEVELOPMENTAL BIOLOGY AS A TOOL FOR THE ASSESSMENT OF HUMAN DIVERGENCE

The quantification of total tooth structure derived from X-rays of Vie tnamese, Southern Chinese, Mongolians, Western Eskimos, and Peruvian p re-Inca (Huari Empire) populations was used to examine dental divergen ce and the morphogenetics of-change, Multivariate derived distances be tween the samples helped identify a quasicontinuous web of ethnic grou ps with two binary clusters ensconced within the web. One cluster was composed of Mongolians, Western Eskimos, and pre-Inca, and the other g roup consisted of the Southern Chinese and Vietnamese. Mongolians ente red the quasicontinuum from a divergent angle (externally influenced) from that of the Southeast Asians. The Chinese and pre-Inca formed the polar samples of the distance superstructure. The pre-Inca sample was the most isolated, its closest neighbor being the Western Eskimos. Un ivariate and multivariate analyses suggested that the pre-Inca, whose ancestors arrived in America perhaps similar to 30,000 years ago, was the least derived sample. Clearly, microevolutionary change occurred a mong the samples, but the dental phenotype was resistant to environmen tal developmental perturbations. An assessment of dental divergence an d developmental biology suggested that the overall dental phenotype is a complex multigenic morphological character, and that the observed v ariation evolved through total genomic drift. The quantified dental ph enotype is greater than its highly multigenic algorithm and its develo pment homeostasis is tightly controlled, or canalized, by the determin istic organization of a complex nonlinear epigenetic milieu. The overa ll dental phenotype quantified here was selectively neutral and a good character to help reconstruct the sequence of human evolution, but if the outlying homeostatic threshold was or will be exceeded in anteced ents and descendants, respectively, evolutionary saltation occurs.