Stone Tools and the Evolution of Human Cognition

1: Introduction and Overview

 Stone tools are among the most distinctive features of the lives and evolution of hominins and, through them, material culture came to play an increasingly important role in the behavior of our ancestors. As a result, material culture and stone tools in particular have given archaeologists a window onto behaviors and lifeways that have long since disappeared. Although stone tools were initially studied primarily as indicators of cultural achievements and then of technology and subsistence strategies, our understanding of the kinds of information that can be inferred from stone tools has expanded significantly in recent years. This broadening of analysis is linked to the development of cognitive archaeology. In this volume, we focus on the multiple ways in which stone tools can inform archaeologists about the evolution of hominin cognitive abilities. THE EARLIEST STONE TOOLS In the 1960s Mary and Louis Leakey uncovered 1.8 million-year-old stone tools at the site of Olduvai Gorge in Tanzania. These tools, which archaeologists called the Oldowan industry, were later associated with Homo habilis, the first member O N E IaIn DavIDson anD aprIl nowell UNIVERSITY OF NEW ENGLAND, UNIVERSITY OF VICTORIA Introduction and Overview  I a I n D a v I D s o n a n D a p r I l n o w e l l of the genus Homo. This was a significant discovery because relative to older hominin species that were not thought to be tool users, H. habilis had a larger brain size and possessed anatomical features reminiscent of later species (e.g., reduced molar size, flatter face). Increasing cranial capacity, tool use, and more modern-looking features fit together in the story of what made humans unique. In fact, for the first time the use of material culture was included in the official definition of a species (Leakey, Tobias, and Napier 1964)—and thus the phrase “Man the Tool Maker” was coined (Oakley 1952). Since that time, our knowledge of the relationship between stone tools and the evolving human brain has grown and the resulting picture is predictably more complex. The earliest known stone tools now date to approximately 2.7 to 2.5 million years ago (mya) (Semaw 2000) whereas hominin evolution can be traced back using the fossil record to between 7.0 and 6.0 mya (see Wood 2002). Researchers question whether the “sudden” appearance of the Oldowan is the result of a dramatic change in cognitive abilities or the transition to a more archaeologically visible medium. One way to think about this is to consider the niche that was opened by the use of stone tools. Davidson and McGrew (2005; see also Davidson, Chapter 9) have suggested that the permanence of stone tools and the products of knapping on the landscape made a distinctive difference to the pattern of cognitive evolution. It also seems likely that H. habilis was not the only stone tool maker and user. Depending on how many species one recognizes between 2.5 and 1.5 mya, up to as many as eight hominin species have been found in direct or indirect association with stone tools (Toth and Schick, 2005). In addition, there is now good evidence that early hominins were using bone tools (Backwell and d’Errico 2001, 2008). Thus, it is clear that tool use was a important behavioral adaptation of our hominin ancestors—but not only of our hominin ancestors, as there is considerable evidence that nonhuman primates also use a wide variety of tools for subsistence and display purposes (see, e.g., Boesch and Boesch 1984; Boesch et al. 1994; Goodall 1964; Whiten et al. 1999) (there is an extensive discussion of ape tools by de la Torre in Chapter 3), and that they reuse stone hammers from one year to the next, apparently remembering where they left hammers the previous season (Boesch and Boesch 1984). The key question is what are the similarities and differences in cognition that underlie human and nonhuman primate tool behavior? The search for answers to this question has led to new research directions, including teaching nonhuman primates how to knap stone (Schick et al. 1999; Toth et al. 1993); studies of the cognitive aspects of nonhuman primate tool use in the wild (Byrne 2005); archaeological excavations of nonhuman primate “sites” to see what behaviors leave archaeologically visible residue  Introduction and Overview (Carvalho et al. 2008; Mercader et al. 2007; Mercader, Panger, and Boesch...