Jack Stern
Distinguished Teaching Professor
and Chair
Ph.D., University of Chicago,
1969

jack.stern@stonybrook.edu

The evolution of postcranial adaptations in primates, with emphasis on the origins of bipedalism; muscle function in nonhuman primates and humans; biomechanics

Reconstructing the pathways of nonhuman primate and human evolution often depends on knowing the functional significance of (1) osteological features characterizing fossil primates, (2) musculoskeletal similarities between living species, and (3) postcranial anatomical traits unique to humans. All three instances require a knowledge of muscle function and the ways in which bony changes might influence such function. Such knowledge is obtainable only by in vivo physiological techniques. Dr. Stern, in collaboration with colleagues at Stony Brook, has devoted the last 20 years to conducting telemetered electromyographic experiments on monkeys, apes, and humans in order to identify the functions of specific muscles and explain how structure has evolved to promote such functions. The technique of electromyography using fine-wire electrodes allows precise determination of when muscles, or portions thereof, are recruited during normal behaviors. By combining this technique with telemetry and video recording, data on unfettered animals engaging in their total range of behaviors can be garnered.

Although Dr. Stern is interested broadly in primate locomotor evolution, he has a specific interest in the origin of bipedalism among hominids. To this end, he has joined with Stony Brook colleagues in analyzing fossil hominid postcranial material from Ethiopia, Kenya, and Tanzania. From their work has emerged the finding that the locomotor adaptations of the earliest known hominids were truly intermediate between apes and humans.

Finally, Dr. Stern has recently joined certain colleagues, both in the Department of Anatomical Sciences and in the Department of Orthopaedics, to initiate studies on the relationship between the shapes of primate long bones and the stresses to which these bones are subjected during locomotion. Such stresses are measured by the application of miniature strain gages around the periphery of the bone. Problems to be investigated concern the morphologic response to functional differentiation in the limbs of primates, and the affect of facultative bipedalism on bones of the hind limb.

Selected Publications:

Demes B, Yi-Xian Q, Stern JT Jr, Larson SG, Rubin CT (2001) Patterns of strain in the macaque tibia during functional activity. Am. J. Phys. Anthrop., 116: 257-265.

Stern JT Jr, Larson SG (2001) Telemetered electromyography of the supinators and pronators of the forearm in gibbons and chimpanzees: implications for the fundamental positional adaptation of hominoids. Am. J. Phys. Anthrop., 115: 253-268.

Stern JT Jr (2000) Climbing to the top: a personal memoir of Australopithecus afarensis. Evol. Anthrop., 9: 113-133.

Stern JT Jr (1999) The cost of bent-knee, bent-hip bipedal gait. A reply to Crompton et al. J. Human Evol. 36:567-570.

Jouffroy FK, Stern JT Jr, Medina M, Larson SG (1999) Function and cytochemical characteristics of postural limb muscles in the rhesus monkey (Macaca mulatta). A telemetered EMG and immunofluorescence study. Folia Primatol. 70 :235 - 253.

Stern, JT Jr, Jungers WL, Susman RL (1995) Quantifying phalangeal curvature: an empirical comparison of alternative methods. Am. J. Phys. Anthrop., 97:1-10.

Stern JT Jr, Larson SG (1993) Electromyographic study of the obturator muscles in nonhuman primates: implications for interpreting the obturator externus groove of the femur. J Human Evol., 24:403-427.

Stern JT Jr, Susman RL (1983) Locomotor anatomy of Australopithecus afarensis. Am. J. Phys. Anthrop., 60:279-317.

Stern JT Jr, Susman, RL (1981). Electromyography of gluteal muscles in Hylobates, Pongo, and Pan: Implications for the evolution of hominid bipedality. Am. J. Phys. Anthropol., 55:153-166.

Stern JT Jr (1970). Functional Myology of the Hip and Thigh of Cebid Monkeys and Its Implications for the Evolution of Erect Posture. Bibliotheca Primatologica, No. 14. Karger, Basel.

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