Evolution of P 3 morphology in Australopithecus afarensis

Bibliographic Data

ID8317290
AuthorsW R Leonard (0000-0002-6233-604X, University of Michigan), M Hegmon (0000-0002-9500-5685, University of Michigan)
Year1987
Volume73
Issue1
Pages41-63
Publication date1987-05-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueAmerican Journal of Physical Anthropology (JOURNAL)
Journal identifiersISSN: 0002-9483 • E-ISSN: 1096-8644
PublisherWiley (PUBLISHER • GB)
DOI10.1002/ajpa.1330730105
PMID3113258
OpenAlexW2025034870
LanguageEN
Citations received32
References cited59

The Australopithecus afarensis dental sample exhibits a wide range of variation, which is most notable in the morphology of the lower third premolar (P 3 ). P 3 morphology in the A. afarensis sample ranges from the primitive sectorial extreme in AL 128‐23 to the derived, bicuspid (molarized) extreme in AL 333w‐1. In this paper, the degree and patterning of variation of the 20 known A. afarensis P 3 s are examined and the evolutionary implications are discussed. Initially, a series of dental and mandibular metric criteria are evaluated to determine whether this sample may be analyzed as a single species. From the metrics, it is clear that the single species hypothesis cannot be rejected. Next, a series of morphological criteria is devised to measure P 3 molarization. Taken as a whole, the A. afarensis P 3 sample displays more variation than a sample of modern hominoids ( Pan troglodytes ) and shows a slight trend toward increased molarization through time. When separated by sex, the A. afarensis sample still displays greater variation than the chimpanzee sample; however, only the male A. afarensis specimens show a trend toward increased molarization. Additionally, the male A. afarensis P 3 s are more molarized than the female, a pattern that is seen as well (though less markedly) in the chimpanzee sample. The trend toward increased molarization over time indicates selection for grinding in A. afarensis. The sexual differences parallel those seen in the postcrania (cf. Stern and Susman: Am. J. Phys. Anthropol. 60 :279–318, 1983), as the females tend to retain the primitive condition, while the males display the derived morphology. Consequently, a model of sexual differences in niche exploitation, with the females exploiting a more arboreal environment, would seem to be supported by both the dental and postcranial evidence

Biology · Evolutionary biology · Morphology (biology) · Variation (astronomy) · Zoology · Evolution and Paleontology Studies · Primate Behavior and Ecology · Wildlife Ecology and Conservation

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