Thinking and doing in cognitive archaeology: Giving skill its due

Wynn shows that intentionally standardized artifacts (handaxes) provide evidence of the ability to conceptualize form (symmetry). However, such conceptual ability is not sufficient for the actual production of these forms. Stone knapping is a concrete skill that is acquired in the real world. Appreciation of its perceptual-motor foundations and the broader issues surrounding skill acquisition may lead to further important insights into human cognitive evolution. Wynn presents a valuable example of the way in which archaeology can contribute to our understanding of human cognitive evolution. Particularly important is his insistence that cognitive archaeologists should avoid traditional archaeological typologies in favor of psychological theories and methods. However, this still leaves the question of which psychological theories and methods should be applied. Insofar as a Grand Unified Theory of human mental life does not appear to be on the horizon, a somewhat pluralistic approach to this question is probably most appropriate (Pickering 2001). The set of theories and methods that proves to be most illuminating will largely depend on what questions are being asked. Wynn chooses to base his analysis of the archaeological record on a fairly traditional theoretical framework derived from cognitive and developmental psychology. This framework is essentially computational in that it seeks to explain diverse overt behavior in terms of underlying formal cognitive operations (e.g., “frame independence” or “coordination of shape recognition”). Because Wynn, like many cognitive archaeologists, is primarily interested in using artifacts as evidence of abstract conceptual capacities, this framework is particularly well suited to the questions he is asking. However, abstract conceptualization is not the only (nor perhaps even the most important) mental process involved in stone tool making, a fact that is reflected in some of Wynn’s previous work (e.g., 1993a; 1995). Stone knapping is, first and foremost, a concrete and practical skill that is acquired and performed in the real world. The implications of this for cognitive archaeology are best appreciated from a theoretical perspective that draws on elements of ecological psychology (Gibson 1979; Michaels & Beek 1995), cultural psychology (Bruner 1990; Vygotsky 1978), and the dynamic systems approach (Bernstein 1967; Thelen & Smith 1994). As Wynn states, “even [the] simplest of knapping actions requires directed blows” (sect. 2.1). In fact, many archaeologists have noted the perceptual-motor skill evident in the earliest stone tools (Ambrose 2001; Ludwig & Harris 1998; Semaw 2000). A great deal of experimental work is needed to describe more rigorously the skills associated with particular prehistoric technologies, but the preliminary PET research (Stout et al. 2000) cited by Wynn does suggest that even simple flake removal places significant demands on the dorsal visuomotor control system (Milner & Goodale 1995) of modern humans. Although perceptual-motor skill is often dismissed as trivial or primitive compared to abstract conceptualization, such skill is an impressive achievement requiring the discovery of dynamically stable behavioral solutions to inherently variable motor problems (Reed & Bril 1996). Huge portions of the modern human brain are involved in this process, including areas like the cerebellum, superior parietal lobule, and premotor cortices that appear to have experienced preferential expansion during human evolution. The sophisticated perceptualmotor skills that typify human sport, art, and craft can take years of dedicated practice to acquire, and are as reflective of human mental uniqueness as more “cognitive” behaviors like visualization and language. Ethnographic studies of stone knapping (Roux et al. 1995; Stout 2002) indicate that, even in sophisticated modern technologies, mastery of the elementary percussive action is the most fundamental and time-consuming aspect of skill learning. Effective flaking is a specialized form of perception-though-action that allows for the discovery and stabilization of larger scale patterns (strategies) in necessarily variable reduction processes. Less skilled knappers can readily conceptualize or describe an appropriate reduction strategy, but they do not actually comprehend it in the concrete sense required for performance. Wynn has previously pointed out (Wynn 1995) that skilled tool use is only developed through long periods of practice and observation. In modern humans, such learning occurs through guided participation in a community of practice (Lave & Wenger 1991). The social situation scaffolds (Wood et al. 1976) learning by providing opportunities for participation at appropriate levels of difficulty (i.e., within the zone of proximal development [Vygotsky 1978]) using culturally provided material and conceptual tools. Motivational and affective elements critical to learning (Damasio 1994; Greenspan 1996) derive from the culturally constructed meanings (Perret-Clermont et al. 1991; Fogel 1997) of participation. This is exemplified in the modern stone knapping craft of Langda village in Indonesian Irian Jaya (Stout 2002). Over evolutionary time, this distinctly human, cultural, mode of learning came to replace the primitive hominoid condition. Modern chimpanzee societies scaffold skill acquisition to a degree (Boesch 1991), but lack the added dimension of cultural meaning and structure. In the absence of cultural facilitation of more intensive and/or protracted learning (as seen, for example, in captive “enculturated” apes), efficient nut cracking may approximate the upper limit of skill acquisition possible in chimpanzee sociCommentary/Wynn: Archaeology and cognitive evolution BEHAVIORAL AND BRAIN SCIENCES (2002) 25:3 421 eties. Premodern hominids clearly came to exceed this limit, perhaps through some “proto-cultural” adaptation such as the mimetic culture proposed by Donald (1991). Careful attention to the level of skill indicated by premodern stone artifacts may help to chart the course and timing of this critical development in human cognitive evolution. As Wynn has shown, the conceptualization of form and symmetry is necessary to the production of standardized artifacts like later Acheulean handaxes. This is just the tip of the iceberg for cognitive archaeology, however, because such conceptualization is by no means sufficient for actual tool production. Thinking about knapping and actually knapping are closely related but diagnostically different mental behaviors (cf. Thelen & Smith 1994). Wynn has demonstrated the promise of psychologically informed research on stone tools, and it is to be hoped that he and others will continue in this vein to address the many exciting questions that remain. Natural selection of visual symmetries Peter A. van der Helm Nijmegen Institute for Cognition and Information, University of Nijmegen, 6500 HE Nijmegen, The Netherlands. [email protected] Abstract: Implicitly, Wynn’s target article starts from the transformational Implicitly, Wynn’s target article starts from the transformational definition of symmetry. Unlike his suggestion, this traditional definition and the recent holographic definition are relevant to the discussion on the cognitive evolution of visual symmetries. These definitions reveal underlying properties and, thereby, they support the natural selection hypothesis. The holographic definition even agrees with an indirect test of this hy-