Handedness and lower face variability: Findings in three national surveys.

Lower face variability in modern humans has been associated with a series of phenotypic characteristics including body architecture and handedness. The aim of this study was to provide a systematic review of lower face variability and handedness in national health surveys conducted in the United States. Three informative surveys with a total of 13,663 participants were identified. Lower face variability was described as one of six facial phenotypes and related to handedness using logistic regression models while adjusting for sex, ancestry, geography, and income. The results on 13,536 participants with complete information showed that bilateral retrognathism-a marker for a lower face phenotype characterized by a convex facial profile and slender jaws-was associated with a 25% increased odds for non-right-handedness (odds ratio, 1.250; 95% confidence interval: 1.076-1.453, p-value < .004). This association between non-right-handedness and a convex facial profile may unexpectedly find its origin in the genetic polymorphisms which determine tuberculosis susceptibility.