Using the 3D Facial Norms Database to investigate craniofacial sexual dimorphism in healthy children, adolescents, and adults.
BACKGROUND
Although craniofacial sex differences have been extensively studied in humans, relatively little is known about when various dimorphic features manifest during postnatal life. Using cross-sectional data derived from the 3D Facial Norms data repository, we tested for sexual dimorphism of craniofacial soft-tissue morphology at different ages.


METHODS
One thousand five hundred fifty-five individuals, pre-screened for craniofacial conditions, between 3 and 25 years of age were placed in to one of six age-defined categories: early childhood, late childhood, puberty, adolescence, young adult, and adult. At each age group, sex differences were tested by ANCOVA for 29 traditional soft-tissue anthropometric measurements collected from 3D facial scans. Additionally, sex differences in shape were tested using a geometric morphometric analysis of 24 3D facial landmarks.


RESULTS
Significant (p < 0.05) sex differences were observed in every age group for measurements covering multiple aspects of the craniofacial complex. The magnitude of the dimorphism generally increased with age, with large spikes in the nasal, cranial, and facial measurements observed after puberty. Significant facial shape differences (p < 0.05) were also seen at each age, with some dimorphic features already present in young children (eye fissure inclination) and others emerging only after puberty (mandibular position).


CONCLUSIONS
Several craniofacial soft-tissue sex differences were already present in the youngest age group studied, indicating that these differences emerged prior to 3 years of age. The results paint a complex and heterogeneous picture, with different groups of traits exhibiting distinct patterns of dimorphism during ontogeny. The definitive adult male and female facial shape was present following puberty, but arose from numerous distinct changes taking place at earlier stages.
Department of Anthropology, University of Pittsburgh, Pittsburgh, PA USA.
Matthew J
MJ
Kesterke
Center for Craniofacial and Dental Genetics, Department of Oral Biology, University of Pittsburgh, 100 Technology Drive, Suite 500, Pittsburgh, PA 15219 USA.
Zachary D
ZD
Raffensperger
Department of Pediatrics, University of Washington, Seattle, WA USA.
Carrie L
CL
Heike
Department of Pediatrics, University of Washington, Seattle, WA USA ; Department of Biological Structure, University of Washington, Seattle, WA USA ; Department of Oral Biology, University of Washington, Seattle, WA USA ; Department of Pediatric Dentistry, University of Washington, Seattle, WA USA.
Michael L
ML
Cunningham
Department of Pediatrics, University of Texas Health Science Center, Houston, TX USA.
Jacqueline T
JT
Hecht
Department of Orthodontics, University of Alabama, Birmingham, AL USA.
Chung How
CH
Kau
Department of Pediatrics, University of Iowa, Iowa City, IA USA.
Nichole L
NL
Nidey
Department of Orthodontics, University of Iowa, Iowa City, IA USA ; Dows Institute for Dental Research, University of Iowa, Iowa City, IA USA.
Lina M
LM
Moreno
Department of Health Management and Policy, University of Iowa, Iowa City, IA USA.
George L
GL
Wehby
Center for Craniofacial and Dental Genetics, Department of Oral Biology, University of Pittsburgh, 100 Technology Drive, Suite 500, Pittsburgh, PA 15219 USA ; Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA USA ; Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, PA USA ; Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA USA.
Mary L
ML
Marazita
Department of Anthropology, University of Pittsburgh, Pittsburgh, PA USA ; Center for Craniofacial and Dental Genetics, Department of Oral Biology, University of Pittsburgh, 100 Technology Drive, Suite 500, Pittsburgh, PA 15219 USA.
Seth M
SM
Weinberg
Anthropometry; Facial shape; Geometric morphometrics; Sexual dimorphism; Stereophotogrammetry