The morphology of the gluteus maximus during human evolution: Prerequisite or consequence of the upright bipedal posture?
The human gluteus maximus differs from that of the other hominoids because of its size and bony attachments. These differences raise questions concerning their sequence of appearance in human evolution. Given that humans practice a unique locomotor style, one wonders if the human gluteus maximus morphology is a prerequisite or a consequence of upright bipedal locomotion. This question is addressed using a computer model that evaluates muscle leverage in a variety of locomotor postures. In this model, the human-like, or ape-like, muscular pattern is imposed upon a representative hindlimb of each of the five extant hominoids. Shapes of the skeletal elements (i.e. ilium and ischium lengths) are adjusted in the computer to simulate an evolutionary progression from an ape to a human skeletal morphology. Changes in the leverage of different parts of the gluteus maximus (measured as moment arms) are monitored during this transition. The results show how the mechanical leverages of the gluteus maximus would have changed in a variety of hypothetical evolutionary sequences that describe an ape to human transition.
Although the hominoid models exhibit minor differences in these simulations, they all show that the postural and locomotor functions of the gluteus maximus would become more difficult if musculoskeletal morphology changed to the human-like pattern before erect bipedal posture was adopted. Conversely, small adjustments in the ape-like musculoskeletal condition support an erect bipedal posture. These results suggest that a human like posture would have preceded the appearance of the human-like musculoskeletal morphology. Human gluteal morphology, therefore, is a consequence and not a prerequisite of the upright bipedal posture.
Key wordsGluteus Maximus Bipedalism Locomotion Ilium Ischium Moment Arms Biomechanics
Unable to display preview. Download preview PDF.
- Aiello, L. C. & Dean, C. (1990). An introduction to human evolutionary anatomy. San Diego, Academic Press.Google Scholar
- Basmajian, J. V. & DeLuca, C. J. (1985) Muscles alive: their function revealed by electromyography. 5th edition. Baltimore: Williams & Wilkins.Google Scholar
- Greiner, T. M. (1991). The muscular mechanics of the primate hindlimb. (Abstract). Am. J. Phys. Anthropol. Supplement 12, 83.Google Scholar
- Greiner, T. M. (1994). Biomechanics of the Primate Hindlimb and the Evolution of Human Locomotion. Ph.D. Dissertation. State University of New York at Binghamton (Binghamton).Google Scholar
- Hildebrand, M. (1988) Analysis of vertebrate structure. 3rd edition, New York: John Wiley & Sons, Inc.Google Scholar
- Ishida, H., Kumakura, H. & Kondo, S. (1985). Primate bipedalism and quadrupedalism: comparative electromyography. In (S. Kondo, Ed) Primate morphophysiology, locomotor analyses and human bipedalism, pp. 59–80, Tokyo: Tokyo University Press.Google Scholar
- Jenkins, F. A. (1972). Chimpanzee bipedalism: cineradiographic analysis and applications. Science 178, 877–879.Google Scholar
- Kummer, B. K. F. (1972). Functional adaptation to posture in the pelvis of man and other primates. In (R. H. Tuttle, Ed) Primate functional morphology and evolution, pp. 281–290. The Hague: Mouton Publishers.Google Scholar
- O’Connell, A. L. & Gardner, E. B. (1972). Understanding the scientific bases of human movement. Baltimore: The Williams and Wilkins Co.Google Scholar
- Sigmon, B. A. (1975). Functions and evolution of hominid hip and thigh musculature. In (R. H. Tuttle, Ed) Primate functional morphology and evolution, pp. 235–252, The Hague: Mouton Publishers.Google Scholar
- Sigmon, B. A. & Farslow, D. L. (1986). The primate hindlimb. In (D. R. Swindler & J. Erwin, Eds) Comparative primate biology, Vol. 1: Systematics, evolution, and anatomy, pp. 671–718, New York: Alan R. Liss.Google Scholar
- Tuttle, R. H., Basmajian, J. V. & Ischida, H. (1975). Electromyography of the gluteus maximus muscle inGorilla and the evolution of hominid bipedalism. In (R. H. Tuttle, Ed) Primate functional morphology and evolution, pp. 251–269. The Hague: Mouton Publishers.Google Scholar
- Williams, P. L., Warwick, R., Dyson, M. & Bannister, L. H. (1989). Gray’s anatomy. 37th Ed. Edinburgh: Churchill Livingstone.Google Scholar