1Anthropology, Boston University, 2Evolutionary Anthropology, Duke University, 3Sociology and Anthropology, Illinois State University, 4Anthropology, University of Colorado - Boulder
April 16, 2020 3:45PM, Diamond 5
Recent fossil discoveries, especially of partial foot skeletons, have brought about a gradual recognition that there were probably at least two hominin species coexisting in East Africa around 3.5 My ago. Yet most analyses continue to assume that all, or nearly all, of the East African material from this period represents a single species, Australopithecus afarensis. We suggest that we no longer have any conclusive reasons for thinking that A.L. 288-1 “Lucy” (3.18 My), the Dikika infant (3.32 My), KSD/VP/1-1 “Kadanuumuu” (3.6 My), and the LH 4 type specimen of A. afarensis (3.6 My) all sample the same species, or for assuming that parts of the skeleton known for one tell us much about unknown parts of any other. It is unclear in the present state of our knowledge how many species are represented in the “A. afarensis” congeries, or where the boundaries are between them. We nevertheless contend that if we free ourselves from the presumption that all evolutionary analysis must start with a fully resolved phylogenetic hypothesis, it is possible to say interesting and important things about early hominin evolution in terms of a fuzzy phylogeny.