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Am J Phys Anthropol. 2018 Feb;165(2):327-342. doi: 10.1002/ajpa.23356. Epub 2017 Nov 27.

Body size and allometric variation in facial shape in children.

Author information

1
Department of Cell Biology & Anatomy, Cumming School of Medicine, University of Calgary, Calgary, Canada.
2
Division of Medical Education, Weill Cornell Medicine - Qatar, Doha, Qatar.
3
Department of Anatomy, Catholic University of Health and Allied Science, Mwanza, Tanzania.
4
Broad Institute of MIT and Harvard, Cambridge, Massachusetts.
5
Human Medical Genetics and Genomics Program and Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado.
6
Department of Anthropology, University of La Plata, La Plata, Argentina.
7
Department of Anthropology, Stony Brook University, Stony Brook, New York, USA.
8
National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland.
9
School of Pharmacy, University of Alberta, Edmonton, Canada.
10
Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
11
McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada.
12
Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, USA.
13
Department of Animal Biology, College of Liberal Arts and Science, University of Illinois, Urbana-Champaign, Urbana, Illinois.
14
Departments of Orofacial Sciences and Pediatrics, and Program in Craniofacial Biology, University of California San Francisco, San Francisco, California.
15
Department of Physiology & Pharmacology and the Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
16
Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada.

Abstract

OBJECTIVES:

Morphological integration, or the tendency for covariation, is commonly seen in complex traits such as the human face. The effects of growth on shape, or allometry, represent a ubiquitous but poorly understood axis of integration. We address the question of to what extent age and measures of size converge on a single pattern of allometry for human facial shape.

METHODS:

Our study is based on two large cross-sectional cohorts of children, one from Tanzania and the other from the United States (Nā€‰=ā€‰7,173). We employ 3D facial imaging and geometric morphometrics to relate facial shape to age and anthropometric measures.

RESULTS:

The two populations differ significantly in facial shape, but the magnitude of this difference is small relative to the variation within each group. Allometric variation for facial shape is similar in both populations, representing a small but significant proportion of total variation in facial shape. Different measures of size are associated with overlapping but statistically distinct aspects of shape variation. Only half of the size-related variation in facial shape can be explained by the first principal component of four size measures and age while the remainder associates distinctly with individual measures.

CONCLUSIONS:

Allometric variation in the human face is complex and should not be regarded as a singular effect. This finding has important implications for how size is treated in studies of human facial shape and for the developmental basis for allometric variation more generally.

KEYWORDS:

3D facial imaging; allometry; face shape; growth; human; morphometrics

PMID:
29178597
PMCID:
PMC5777898
DOI:
10.1002/ajpa.23356
[Indexed for MEDLINE]
Free PMC Article

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