The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Covariance patterns in the human skull: a phylogenetic approach to the structure of human cranial variation


1Laboratório de Estudos Evolutivos Humanos, Instituto de Biociências, Universidade de São Paulo, 2Unidade de Genética Médica, Faculdade de Medicina da Universidade de São Paulo

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Although being a recent field of evolutionary biology, the study of the genetic variance/covariance (V/CV) matrix (G-matrix) is a promising approach to the investigation of the evolution of complex traits, like the human skull. Assuming the expressive correspondence among G-matrix and their phenotypic counterpart, the phenotypic (V/CV) matrix (P-matrix), we can infer the evolutionary history by means of the quantification of the similarities between P-matrices. In this work our objective is access the structure of the human cranial variation through the investigation of the patterns of covariance of P-matrices inferred from a sample represented by 9,287 skulls from 161 autochthones populations. Each skull was represented for 24 measurements taken in accordance with the Howell's protocol. The P-matrices were constructed for different association groups, following different associative criteria, as location and chronology of the samples. The similarities of P-matrices in each analytical level were inferred through random skewers method, assuming a distribution of 1,000 vectors. Only similarities with statistical significance (p<0,05) were considered. Our results show that P-matrices were not constant among human populations, although the expressivity of the divergence observed between them was generally low. These results are in accordance with similar investigations carried out for another anthropoids and suggests that P-matrices remained relatively similar along the human evolutionary history. Notwithstanding, lower amounts of similarity were observed within minor grouping levels, suggesting that in despite of the general stasis detected in the global pattern, specific evolutionary conditions at population levels played important role in the diversification of the human skull.

Grant: FAPESP 2008/58729-8

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