Title

Sexual Dimorphism in Australopithecus afarensis Was Similar to That of Modern Humans

Publication Title

Proceedings of the National Academy of Sciences of the United States of America

Publication Date

8-5-2003

Document Type

Conference Proceeding

DOI

10.1073/pnas.1133180100

Keywords

sexual dimorphism, Australopithecus afarensis, modern humans

Disciplines

Anthropology

Abstract

The substantial fossil record for Australopithecus afarensis includes both an adult partial skeleton [Afar Locality (A.L.) 288-1, “Lucy”] and a large simultaneous death assemblage (A.L. 333). Here we optimize data derived from both to more accurately estimate skeletal size dimorphism. Postcranial ratios derived from A.L. 288-1 enable a significant increase in sample size compared with previous studies. Extensive simulations using modern humans, chimpanzees, and gorillas confirm that this technique is accurate and that skeletal size dimorphism in A. afarensis was most similar to that of contemporary Homo sapiens. These data eliminate some apparent discrepancies between the canine and skeletal size dimorphism in hominoids, imply that the species was not characterized by substantial sexual bimaturation, and greatly increase the probability that the reproductive strategy of A. afarensis was principally monogamy