Associations in the hominoid facial skeleton.

A comparative study has been made of the correlations between numerous linear and angular dimensions of the facial skeleton of man and the three great apes. The Varimax (rotated orthogonal) factor analysis was found to be an essential aid in analysing the very large correlation matrices obtained. It indicated that three groups of association can be identified in the hominoid skull. The first reflects co-ordonated variation in total skull size; the second, co-ordinated variation within common anatomical regions; the third, co-ordination between the jaws and dentition. A broadly similar pattern was found in each group for all four genera. The principal contrasts between man, on the one hand, and the apes, on the other, were found in groups 1 and 2. The most prominent of these was a generally much tighter degree of association between the size and position of upper and lower jaws in the apes, and a consequently reduced tendency for disruption of the occlusal relationship of the teeth.