Comparative and functional morphology of hominoid fingers
Article first published online: 2 JUN 2005
Copyright © 1979 Wiley-Liss, Inc., A Wiley Company
American Journal of Physical Anthropology
Volume 50, Issue 2, pages 215–236, February 1979
How to Cite
Susman, R. L. (1979), Comparative and functional morphology of hominoid fingers. Am. J. Phys. Anthropol., 50: 215–236. doi: 10.1002/ajpa.1330500211
- Issue published online: 2 JUN 2005
- Article first published online: 2 JUN 2005
- Ape hands;
- Hominoid morphology;
- Ape locomotion;
Comparisons of hominoid metacarpals and phalanges reveal differences, many of which are closely linked to locomotor hand postures. The African apes display features of the metacarpals and phalanges which distinguish them from the other Hominoidea. These features are most evident in digits III and IV. The orangutan hand is demonstrably less well adapted to knuckle-walking and is distinctive in its adaptation to power and hook grasping of vertical and horizontal supports, respectively. Orangutan fingers possess a “double-locking” mechanism (Napier, '60), and a slight ulnad shift in the axis of the hand which results in lengthened phalanges of ray IV. Hylobatid apes are more like orangutans in their finger morphology than any of the other Hominoidea, but exhibit unique features of their own. These include elongate phalanges of fingers II-V. Human metacarpals II-V form two sets composed of II-III, and IV-V. The heads of both metacarpals II and III are characterized by axial torsion. This reflects the enhanced manipulatory role of the third finger in humans. Human distal phalanges are unique in the development of pronounced apical tufts.
Multivariate analysis of metacarpal III and proximal III yields variables that array the extant apes along an arboreal-terrestrial axis, from hylobatid apes to male gorillas. The positions of taxa on this discriminant concur with observations on the locomotion of free-ranging apes.