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Published on: December 14, 2011
Sexual dimorphism in the face of Australopithecus africanus
1Institute of Human Origins, Arizona State University, Tempe 85287-4101, USA. cal.iho@asu.edu
American Journal of Physical Anthropology
|January 23, 1999
Summary
New Australopithecus africanus fossils reveal a greater craniofacial size range than humans or chimpanzees, indicating moderate sexual dimorphism. This finding offers insights into early hominin evolution and variation.
Area of Science:
- Paleoanthropology
- Primatology
- Human Evolution
Background:
- Recent discoveries of Australopithecus africanus crania from Sterkfontein Member 4 and Makapansgat.
- Need for reappraisal of the degree and pattern of sexual dimorphism in this species.
Observation:
- Craniofacial size range of Australopithecus africanus exceeds that of chimpanzees and modern humans.
- Statistical analysis (bootstrapping) confirms a greater size range, attributed to moderate sexual dimorphism.
Findings:
- Australopithecus africanus exhibits moderate sexual dimorphism, comparable to Homo habilis but less than Australopithecus boisei.
- Craniofacial dimorphism patterns in A. africanus show similarities to modern humans in some features, but differ in others.
- Larger specimens display prominent brow ridges, while features related to canine size show less variation between sexes.
Implications:
- Suggests a complex pattern of sexual dimorphism in early hominins.
- Provides a comparative baseline for understanding variation within fossil hominin species.
- Highlights unique aspects of A. africanus craniofacial morphology in relation to extant hominines.
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