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Sutural growth restriction and modern human facial evolution: an experimental study in a pig model
Journal article   Open access   Peer reviewed

Sutural growth restriction and modern human facial evolution: an experimental study in a pig model

Nathan E Holton, Robert G Franciscus, Mary Ann Nieves, Steven D Marshall, Steven B Reimer, Thomas E Southard, John C Keller and Scott D Maddux
Journal of anatomy, Vol.216(1), pp.48-61
01/2010
DOI: 10.1111/j.1469-7580.2009.01162.x
PMCID: PMC2807975
PMID: 19929910
url
https://doi.org/10.1111/j.1469-7580.2009.01162.xView
Published (Version of record) Open Access

Abstract

Facial size reduction and facial retraction are key features that distinguish modern humans from archaic Homo. In order to more fully understand the emergence of modern human craniofacial form, it is necessary to understand the underlying evolutionary basis for these defining characteristics. Although it is well established that the cranial base exerts considerable influence on the evolutionary and ontogenetic development of facial form, less emphasis has been placed on developmental factors intrinsic to the facial skeleton proper. The present analysis was designed to assess anteroposterior facial reduction in a pig model and to examine the potential role that this dynamic has played in the evolution of modern human facial form. Ten female sibship cohorts, each consisting of three individuals, were allocated to one of three groups. In the experimental group (n = 10), microplates were affixed bilaterally across the zygomaticomaxillary and frontonasomaxillary sutures at 2 months of age. The sham group (n = 10) received only screw implantation and the controls (n = 10) underwent no surgery. Following 4 months of post-surgical growth, we assessed variation in facial form using linear measurements and principal components analysis of Procrustes scaled landmarks. There were no differences between the control and sham groups; however, the experimental group exhibited a highly significant reduction in facial projection and overall size. These changes were associated with significant differences in the infraorbital region of the experimental group including the presence of an infraorbital depression and an inferiorly and coronally oriented infraorbital plane in contrast to a flat, superiorly and sagittally infraorbital plane in the control and sham groups. These altered configurations are markedly similar to important additional facial features that differentiate modern humans from archaic Homo, and suggest that facial length restriction via rigid plate fixation is a potentially useful model to assess the developmental factors that underlie changing patterns in craniofacial form associated with the emergence of modern humans.
Cephalometry - methods Humans Mandible - growth & development Bone Plates Aging - pathology Biological Evolution Animals Cranial Sutures - growth & development Maxillofacial Development - physiology Facial Bones - growth & development Models, Animal Sus scrofa Skull - growth & development

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