As an aside from the Neandertal theme, I ran across a paper from earlier this year by Ichim, Swain, an Kieser, where they apply a mechanical model to mandibles with and without chins:
The development of the chin, a feature unique to humans, suggests a close functional linkage between jaw biomechanics and symphyseal architecture. The present study tests the hypothesis that the presence of a chin changes strain patterns in the loaded mandible. Using an anatomically correct 3-D model of a dentate mandible derived from a CT scan image, we analyzed strain patterns during incisal and molar biting. We then constructed a second mandible, without a chin, by 'defeaturing' the first model. Strain patterns of the second model were then compared and contrasted to the first. Our main finding was that chinned and non-chinned mandibles follow closely concordant patterns of strain distribution. The results suggest that the development of the human chin is unrelated to the demands placed on the mandible during function.
There's a long literature on chin biomechanics (notably, including Tim White's dissertation!), and if you're interested you probably already know it. (If you're interested and don't already know it, there's still hope for you!)
So I really have no comments; just a note to point this one out.
Ichim I, Swain M, Kieser JA. 2006. Mandibular biomechanics and development of the human chin. J Dent Res 85:638-642. Abstract