Single Nucleotide Polymorphisms of the Oxytocin Receptor (OXTR) and CD38 Genes Impact Perception of Facial Aging in Humans
- Susan Blauth, Associate Professor of Biology, University of Redlands
- Thomas F. Gross, Professor of Psychology, University of Redlands
Facial morphology in human beings is a complex and multi-factored characteristic capable of displaying incredible subtlety. Conversely, human beings possess intensively developed cognitive faculties capable of discerning socially relevant features from faces. One socially salient feature—facial age—is considered here. Although the discrimination of facial age by humans is likely subject to behavioral phenomena such as learning, such contextual and experiential factors fail to account for all individual differences in the ability to discern facial cues related to age. As found by McCall and Kennedy (1980), differences in the ability to perceive facial age emerge within the first year of life in normally developing children. Even noting the critical role of early environment alone in affecting varied outcomes related to social cognition, this rapid rate of early differentiation in the absence of extensive social experience poses the possibility of innate, genetic mechanisms of facial perception. To evaluate this possibility, I amplified and sequenced participants' DNA at two poymorphic regions within the oxytocin receptor (OXTR) and CD38 genes, respectively, known to contain single nucleotide polymorphisms (SNPs) functionally related to proficiency in other social behaviors (Bakermans-Kranenburg & Van Ljzendoorn, 2008; Sauer, Montag, Wörner, Kirsch, & Reuter, 2012). Participants additionally completed a computerized facial age sorting task to evaluate their accuracy in perceiving facial age. Although data analysis is still pending with respect to the CD38 polymorphic locus, I have demonstrated that those homozygous for guanine at the OXTR SNP (i.e., G/G) make consistently more accurate judgments of facial age compared to those with at least one adenine nucleotide at the same locus (i.e., A/-) at a rate that approached significance, p = .07. As such, the findings of the present study lend support to a model of facial perception substantially informed by the physiology of the neurohormone oxytocin within the central nervous system.