Phenotypic evolution of human craniofacial morphology after admixture: A geometric morphometrics approach

Authors

  • Neus Martínez-Abadías,

    Corresponding author
    1. Unitat d'Antropologia, Departament de Biologia Animal, Facultat de Biologia,Universitat de Barcelona, Barcelona 08028, Spain
    • Unitat d'Antropologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 645, Barcelona 08028, Spain
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  • Rolando González-José,

    1. Unitat d'Antropologia, Departament de Biologia Animal, Facultat de Biologia,Universitat de Barcelona, Barcelona 08028, Spain
    2. Centro Nacional Patagónico, Consejo Nacional de Investigaciones Científicas y Técnicas,CONICET, Puerto Madryn U9120ACV, Argentina
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  • Antonio González-Martín,

    1. Área Académica de Historia y Antropología, Universidad Autónoma del Estado de Hidalgo,Pachuca 42080, Mexico
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  • Silvina Van der Molen,

    1. Centro Nacional Patagónico, Consejo Nacional de Investigaciones Científicas y Técnicas,CONICET, Puerto Madryn U9120ACV, Argentina
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  • Arturo Talavera,

    1. Dirección de Antropología Física, Mexico D.F. 11560, Mexico
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  • Patricia Hernández,

    1. Escuela Nacional de Antropología e Historia, Mexico D.F. 04030, Mexico
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  • Miquel Hernández

    1. Unitat d'Antropologia, Departament de Biologia Animal, Facultat de Biologia,Universitat de Barcelona, Barcelona 08028, Spain
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Abstract

An evolutionary, diachronic approach to the phenotypic craniofacial pattern arisen in a human population after high levels of admixture and gene flow was achieved by means of geometric morphometrics. Admixture has long been studied after molecular data. Nevertheless, few efforts have been made to explain the morphological outcome in human craniofacial samples. The Spanish-Amerindian contact can be considered a good scenario for such an analysis. Here we present a comparative analysis of craniofacial shape changes observed between two putative ancestor groups, Spanish and precontact Aztecs, and two diachronic admixed groups, corresponding to early and late colonial periods from the Mexico's Central Valley. Quantitative shape comparisons of Amerindian, Spanish, and admixed groups were used to test the expectations of quantitative genetics for admixture events. In its simplest form, this prediction states that an admixed group will present phenotypic values falling between those of both parental groups. Results show that, in general terms, although the human skull is a complex, integrated structure, the craniofacial morphology observed fits the theoretical expectations of quantitative genetics. Thus, it is predictive of population structure and history. In fact, results obtained after the craniofacial analysis are in accordance with previous molecular and historical interpretations, providing evidence that admixture is a main microevolutionary agent influencing modern Mexican gene pool. However, expectations are not straightforward when moderate shape changes are considered. Deviations detected at localized structures, such as the upper and lower face, highlight the evolution of a craniofacial pattern exclusively inherent to the admixed groups, indicating that quantitative characters might respond to admixture in a complicated, nondirectional way. Am J Phys Anthropol, 2006 © 2005 Wiley-Liss, Inc.

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