The protruding chin is an anatomical feature unique to modern humans, but its mechanical significance is not well understood. This research used finite element analysis, a computer-based technique able to investigate the mechanics of physical systems, to test the biological function of the chin by comparing two mandible models of the modern human and the Neanderthal, a sister species without a chin. The two models were subjected to forces simulating the muscles forces during wish boning, the lateral bending of the mandible. Boundary constraints were also applied to avoid unnecessary rotation. The values of the resulting maximum principal strain, the minimum principal strain and the von Mises strain were recorded. The results show that the chin plays an important role in reducing the strains in the mandibular symphysis by redistributing the strains which were formerly concentrated in the symphysis, to both sides of the mandible. Although the redistribution will cause higher strains in the submental foramen area, the overall strains in the mandible are reduced, which suggests that the chin evolved to strengthen the mandible.