The mechanical interaction of the humerus and ulna during articulation has been examined in skeletal material from African and European populations.It was found that the presence or absence of perforation of the humeral septum and the thickness of the septum when unperforated can be predicted with considerable accuracy when two factors are known: the length of the coronoid and olecranon processes of the ulna relative to the minimum diameter of the trochlea humeri, and the total angle of movement at the elbow from full extension to full flexion. The influences which control either or both of these factors also determine the thickness of the septum of the humerus. These influences are not well known and there is opportunity for both genetic and environmental effects.The coefficients of correlation between septum thickness, flexion angle, humeral robusticity, minimum circumference of the humerus, trochlea diameter and brachial index are given. Septum thickness is correlated more highly with trochlea diameter than with robusticity or minimum circumference of the humerus.The higher frequency of perforation of the septum in the African sample (47%) compared with the European (6%) is associated with a greater range of movement at the elbow in the Africans. Bilateral, sexual and population differences in the frequency of perforation of the humeral septum may be associated with differences in the extent of movement at the elbow joint. Variation in this feature, in turn, may be associated with muscularity and somatotype.

No abstract

No abstract

The association between nasal shape, prognathism and the shape of the maxillary dental arch has been examined within samples of Negro and European skulls. Prognathism tends to be accompanied by an increasingly broad and short nose. Particularly high correlations exist between nasal height and the length of the cranial base and between nasal breadth and the distance which separates the upper canine teeth. Regression analysis has yielded quantitative estimates of the effect on a given dimension of variation in one or more of the others.It seems probable that both nasal shape and the maxillary dental arch-prognathism complex may be subject to direct selection by environmental stress. The morphological association between these complexes suggests that a part of the interpopulation variation in prognathism may be a secondary effect of selection acting on the nose. Similarly, selection acting on the dental arch or maxilla could produce secondary changes in the nasal index (i.e. a non-adaptive component of nasal variation).

No abstract