title: Prenatal sex hormones, digit ratio, and face shape in adult males.
abstract: OBJECTIVE
  Several reports have demonstrated a relationship between second to fourth digit ratio (2D:4D) and facial shape, suggesting that prenatal sex hormones play a role in the development of the craniofacial complex. Using 3D surface imaging and geometric morphometrics, we test the hypothesis that decreased digit ratio (indicative of increased prenatal androgen exposure) is associated with a more masculine facial phenotype.
  
  
  METHODS
  3D facial surface images and digit measures were collected on a sample of 151 adult males. Facial landmarks collected from the images were aligned by Procrustes superimposition and the resulting shape coordinates regressed on 2D:4D. Variations in facial shape related to 2D:4D were visualized with deformable surface warps.
  
  
  RESULTS
  A significant statistical relationship was observed between facial shape variation and 2D:4D (p = 0.0084). Lower 2D:4D ratio in adult males was associated with increased facial width relative to height, increased mandibular prognathism, greater nasal projection, and increased upper and lower lip projection.
  
  
  CONCLUSIONS
  A statistical relationship between 2D:4D and facial shape in adult males was observed. Faces tended to look more masculine as 2D:4D decreased, suggesting a biologically plausible link between prenatal androgen exposure and the development of male facial characteristics.
authors.affiliation: Center for Craniofacial and Dental Genetics, Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Department of Anthropology, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Weinberg
authors.forename: T E
authors.initials: TE
authors.lastname: Parsons
authors.forename: Z D
authors.initials: ZD
authors.lastname: Raffensperger
authors.forename: M L
authors.initials: ML
authors.lastname: Marazita
mesh_terms: D000293:Adolescent; D000328:Adult; D059925:Anatomic Landmarks / Q000033:anatomy & histology; D000728:Androgens / Q000502:physiology*; D000886:Anthropometry / Q000379:methods; D002508:Cephalometry / Q000379:methods; D002680:Chin / Q000033:anatomy & histology; D005145:Face / Q000033:anatomy & histology*; D005385:Fingers / Q000033:anatomy & histology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008046:Lip / Q000033:anatomy & histology; D008297:Male; D008334:Mandible / Q000033:anatomy & histology; D008445:Maxillofacial Development / Q000502:physiology; D009666:Nose / Q000033:anatomy & histology; D011378:Prognathism / Q000473:pathology; D055815:Young Adult
chemical_list: D000728:Androgens
keywords: digit ratio; face shape; geometric morphometrics; sex hormones