
Pelvic Breadth and Locomotor Kinematics in Human Evolution
A broad pelvis is characteristic of most, if not all, pre‐modern hominins. In at least some early australopithecines, most notably the female Australopithecus afarensis specimen known as “Lucy,” it is very broad and coupled with very short lower limbs. In 1991,
Rak suggested that Lucy's pelvic anatomy improved locomotor efficiency by increasing stride length through rotation of the wide pelvis in the axial plane. Compared to lengthening strides by increasing flexion and extension at the hips, this mechanism could avoid potentially costly excessive
vertical oscillations of the body's center of mass (COM). Here, we test this hypothesis. We examined 3D kinematics of walking at various speeds in 26 adult subjects to address the following questions: Do individuals with wider pelves take longer strides, and do they use a smaller degree of
hip flexion and extension? Is pelvic rotation greater in individuals with shorter legs, and those with narrower pelves? Our results support Rak's hypothesis. Subjects with wider pelves do take longer strides for a given velocity, and for a given stride length they flex and extend their hips
less, suggesting a smoother pathway of the COM. Individuals with shorter legs do use more pelvic rotation when walking, but pelvic breadth was not related to pelvic rotation. These results suggest that a broad pelvis could benefit any bipedal hominin, but especially a short‐legged australopithecine
such as Lucy, by improving locomotor efficiency, particularly when carrying an infant or traveling in a foraging group with individuals of varying sizes. Anat Rec, 300:739–751, 2017. © 2017 Wiley Periodicals, Inc.
No References
No Citations
No Supplementary Data
No Article Media
No Metrics
Keywords: Australopithecus afarensis; biomechanics; body proportions; hominin; human evolution; locomotion; pelvis
Document Type: Research Article
Publication date: April 1, 2017