Lucy and evolution of hand dexterity and tool use

The discovery of the relatively complete skeleton of “Lucy” (A.L. 288-1) in 1974 in Ethiopia revealed unprecedented information about the early hominin body form and bipedal locomotion, but with only two hand bones (a capitate and proximal phalanx) preserved, Lucy offered limited insight into Australopithecus afarensis hand morphology. Fortunately, numerous A. afarensis hand bones were recovered from other sites within the Hadar Formation between 1974–1977, providing, at the time, the earliest and most complete “composite” hominin hand skeleton. Functional inferences about Lucy’s overall dexterity focused on her species ability to carry and manipulate stones as tools, but without contemporaneous archaeological evidence of stone tools in the Pliocene, inferences about tool manufacture were not within the realm of potential A. afarensis behaviors.

Since this time, four important advancements have been made: (1) the discovery of a few hand skeletons associated to single individuals from other australopith and Homo taxa, offering a better understanding of hominin hand evolution and its complexity; (2) archaeological discoveries of tool-making and tool-use in time periods contemporaneous with A. afarensis; (3) experimental evidence; and (4) developments in primate archaeology that have expanded our knowledge of the functional and cognitive requirements of stone tool making and use. I will discuss how these advancements have changed our interpretation of Lucy’s tool-related abilities, her dexterity, and the emergence of tool behaviors in human evolution.