Masticatory function and histogenesis of the middle and upper face in chimpanzees (Pan troglodytes).

Evidence has been offered suggesting that masticatory function is an important factor governing development of the supraorbital region. Data have also been provided showing that a mechanism which enables rapid skeletal growth to occur is present in the supraorbital region in the form of fine cancellous woven bone tissue. That Browridge morphogenesis is linked with masticatory function is not a novel interpretation. On the contrary, numerous investigators have offered a variety of evidence in support or refutation of this notion [Toldt, 1914; Weidenreich, 1941, 1946; Endo, 1966, 1970; Moss and Young, 1960]. This study differs from most previous efforts, however, in that it specifically identifies some of the factors and mechanisms; i.e., bite forces and bone tissues involved in growth and development of the upper facial skeleton and the masticatory system. The nature of the relationships among these developmental and functional phenomena remains to be experimentally demonstrated.