The most common biomechanical explanation for the chin is that
it acts as a buttress against masticatory stress. However,
recent evidence suggests that this hypothesis is unlikely [...]
More recently Ichim et al. (2007) have suggested that speech
production is associated with mechanical stresses acting on the
mandibular symphysis due to tongue and orofacial muscle
activity. Thus, they argue that the chin is an adaptive response
to resist stresses caused by oblique contractions of the
genioglossus muscles during speech. Computer simulations provide
results that are consistent with the orofacial stress hypothesis
(Ichim et al., 2007), but this hypothesis has yet to be fully
tested. A less well-established adaptive hypothesis, but one
worth considering, is that chin shape variation is a consequence
of sexual selection (e.g., Hershkovitz, 1970). Psychological
studies of facial attractiveness suggest that a ‘‘broad chin’’
in males is correlated with social dominance, which some females
may prefer in a potential ma