Growth and Development of the Cranial Complex and Its Implications for Sex Estimation

Background/Objectives: The incorporation of the human growth and development literature, an ontogenetic framework, a large virtual sample of individuals across the entire growth period, and a contemporary sample of adult individuals provides a unique opportunity to explore the cranial complex across the entire life cycle. This study (1) assesses cranial variation in postnatal ontogeny to determine the life history stage during which subadult crania can reach comparable levels of phenotypic expression to adult crania and (2) exposes when biological sex can be estimated using craniometric data from immature individuals with accuracy levels comparable to adults. Methods: Contemporary individuals between birth and 102 years of age from one virtual (Subadult Virtual Anthropology Database; SVAD) and one skeletal (Forensic Data Bank; FDB) collection were used in the analyses (n = 2152). Results: Discriminant analysis reveals a clear ontogenetic trajectory across the life history stages, with adolescents, SVAD adults, and FDB adults exhibiting similar cranial dimensions. The analysis also revealed a shift from the growth energetic period into the reproductive energetic period during adolescence. This transition is reflected in the divergence of male and female craniometrics in adolescence, which is also when sex estimation accuracy is comparable to SVAD and FDB adults. Conclusions: The current study argues that skeletal and/or dental maturity is not necessary to estimate sex using the cranium and urges the field to reconsider methodological divisions between subadults and adults.