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The vertebral column of Australopithecus sediba.
Scott A Williams1, Kelly R Ostrofsky, Nakita Frater
1Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY 10003, USA. sawilliams@nyu.edu
Science (New York, N.Y.)
|April 13, 2013
Summary
Australopithecus sediba had a flexible spine with a longer lower back, similar to Homo erectus. This finding offers new insights into early hominin spinal evolution and posture.
Area of Science:
- Paleoanthropology
- Primatology
- Human Evolution
Background:
- Understanding early hominin spinal anatomy is crucial for reconstructing locomotion and behavior.
- Previous interpretations of Australopithecus vertebral formulas have varied.
Purpose of the Study:
- To analyze the vertebral columns of Australopithecus sediba to determine spinal mobility, lumbar curvature, and vertebral formula.
- To compare the vertebral anatomy of Au. sediba with other hominins, including modern humans and Homo erectus.
Main Methods:
- Examination of two partial vertebral columns attributed to Australopithecus sediba.
- Analysis of vertebral morphology to infer lumbar curvature, vertebral formula, and transitional vertebra position.
Main Results:
- Au. sediba likely had five lumbar and five sacral vertebrae, matching the modal human configuration.
- A distinct transitional vertebra above the last rib-bearing vertebra suggests a functionally longer lower back.
- Evidence of lordotic posture and a wedged lumbar vertebra indicate a highly flexible spine.
Conclusions:
- The vertebral anatomy of Au. sediba indicates a derived, highly flexible spine, distinct from earlier Australopithecus species.
- This spinal configuration is more similar to that of Homo erectus, suggesting convergent evolution or shared ancestry.
- The findings challenge previous interpretations of early hominin vertebral numbers and spinal evolution.
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