Facial Width-To-Height Ratio (fWHR) Is Not Associated with Adolescent Testosterone Levels
Facial width-to-height ratio (fWHR) has been proposed as a sexually dimorphic signal in
humans that develops under the influence of pubertal testosterone (T); however, no studies
have examined the association between fWHR and T during the phase in which facial
growth is canalized—adolescence. In a sample of adolescent Tsimane males, we evaluate
the relationship between T, known T-derived traits (i.e. strength and voice pitch), and craniofacial
measurements. If fWHR variation derives from T’s effect on craniofacial growth
during adolescence, several predictions should be supported: 1) fWHR should increase
with age as T increases, 2) fWHR should reflect adolescent T (rather than adult T per se), 3)
fWHR should exhibit velocity changes during adolescence in parallel with the pubertal spurt
in T, 4) fWHR should correlate with T after controlling for age and other potential confounds,
and 5) fWHR should show strong associations with other T-derived traits. Only prediction 4
was observed. Additionally, we examined three alternative facial masculinity ratios: facial
width/lower face height, cheekbone prominence, and facial width/full face height. In contrast
to fWHR, all three alternative measures show a strong age-related trend and are associated
with both T and T-dependent traits. Overall, our results question the status of fWHR as a
sexually-selected signal of pubertal T and T-linked traits.