Stone toolmaking and the evolution of human culture and cognition

Stone toolmaking and the evolution of human culture and cognition On Fri, Aug 17, 2018 at 3:56 PM, Charles Brown wrote: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3049103/ " ABSTRACT Although many species display behavioural traditions, human culture is unique in the complexity of its technological, symbolic and social contents. Is this extraordinary complexity a product of cognitive evolution, cultural evolution or some interaction of the two? Answering this question will require a much better understanding of patterns of increasing cultural diversity, complexity and rates of change in human evolution. Palaeolithic stone tools provide a relatively abundant and continuous record of such change, but a systematic method for describing the complexity and diversity of these early technologies has yet to be developed. Here, an initial attempt at such a system is presented. Results suggest that rates of Palaeolithic culture change may have been underestimated and that there is a direct relationship between increasing technological complexity and diversity. Cognitive evolution and the greater latitude for cultural variation afforded by increasingly complex technologies may play complementary roles in explaining this pattern. Keywords: Palaeolithic, technology, hierarchical behaviour, cumulative culture, Oldowan, Acheulean 1. INTRODUCTION Humans display evolved capacities for complex technological, symbolic and social action that are unique among extant species. But what exactly has evolved to produce these capacities? A prime candidate is the human brain, long viewed as the source of our distinctive ‘mental powers’ and the sine qua non of human uniqueness [1]. However, early evolutionary theorists also recognized the importance of culture [2,3] in accounting for the complexity of modern human behaviour. More recently, it has been suggested that the full range of modern human behaviour may be explicable as a product of cumulative cultural evolution [4], and that key behavioural transitions in human prehistory reflect the dynamics of cultural, rather than biological, evolution [5]. To further dissect the complex interaction of human cognitive and cultural evolution, it will be necessary to better understand these patterns of prehistoric culture change. There is general agreement that human and animal ‘cultures’ are distinguished by the much greater diversity and complexity of the former. What remains unclear is whether this difference arises from the increased fidelity of human cultural transmission [4,6], from the greater cognitive capacity of individual humans [7] or from some complex interaction of the two [8]. This is a difficult question to address because modern humans differ from even our closest living relatives on a wide array of interdependent somatic, cognitive and cultural dimensions. The question of which trait(s) may have had evolutionary/causal priority in human evolution is a historical one regarding developments that appear simultaneous from a comparative perspective. Archaeological evidence provides a complementary data source that is better positioned to answer questions about developments since the last common ancestor with Pan. Palaeolithic stone tools offer a relatively abundant and continuous record of technological change over the past 2.5 Myr, documenting the gradual expression of new behavioural capabilities. Exploitation of this evidence will depend on the development of increasingly robust inferential links between archaeological remains, past behaviours, and the necessary cognitive and cultural mechanisms supporting these behaviours. High on the list of tools needing to be developed is a systematic method for describing the complexity and diversity of Palaeolithic technologies. It might be supposed that 150 years of Palaeolithic archaeology had already solved this problem, and that the wealth of named cultures, ‘industries’ and ‘modes’ in the literature would be sufficient for comparison. Indeed, it has been argued that the longevity of the Oldowan and Acheulean Industries reflects an absence of cumulative cultural evolution in the Lower Palaeolithic [7,9]. However, the nature of cultural variation in the Oldowan is a matter of ongoing debate [10,11] and many researchers do see evidence of progressive technological change within the Acheulean (e.g. [12–14]). One difficulty with classical archaeological approaches to technological variation has been a tendency to focus on the form of artefacts rather than on the processes that produced them. This is problematic because it conflates many potential sources of variation [15] and because it is biological capacities and cultural ‘recipes’ [16] that evolve, not artefact morphologies. Analysis of the hierarchical organization of toolmaking action sequences may provide a better foundation for inferences about culture and cognition. 2. STONE TOOLMAKING ACTION HIERARCHIES Analysis of toolmaking action sequences is not new in archaeology. For over 30 years, the châine opértoire approach has focused on describing the processes of Palaeolithic tool production, based on insights gained from the experimental replication and the ‘reading’ of production scars left on tools (e.g. [12,17]). However, this approach has yet to be fully integrated with theoretical and methodological insights from other disciplines. As the name implies, the châine opértoire approach involves the reconstruction of action ‘chains’ or sequences, commonly represented as flow charts. This sequential approach has been useful in reconstructing the details of particular past technologies, but is less suitable for generalizing comparisons or cognitive analyses. The presence of hierarchical as well as sequential structure in human action has been a cornerstone of cognitive science since the demise of behaviourism [18–20], and is especially relevant to understanding the goal-oriented flexibility [18] of behaviours like stone toolmaking, in which consistent products are generated from inherently variable raw materials and action outcomes [17]. Elements of hierarchical analysis are implicit in many technological descriptions produced by the châine opértoire approach, but the formal description of Palaeolithic technologies in these terms should help provide a more uniform framework for comparison and promote better integration with research on the hierarchical structure in motor control [21], functional neuroanatomy [22,23] and social transmission [16,24–26]. In a hierarchy, individual elements are grouped into increasingly inclusive nested categories. This is commonly depicted using tree diagrams, with multiple nodes at lower (subordinate) levels being linked to single nodes at the next higher (superordinate) level, culminating in a single node at the top of the diagram. In action hierarchies, superordinate levels correspond to more abstract goals and/or temporally extended processes, from the overall objective (e.g. ‘make coffee’) down through more particular sub-goals and operations (‘add sugar’) to highly specific motor acts (‘grasp spoon’). This multi-level organization provides flexibility by allowing context-specific adaptive variation at subordinate levels to be combined with more global stability at superordinate levels. For example, ‘turn on light’ is a coherent goal that might be accomplished by flipping a switch, twisting a knob or pulling a cord [23]. Critically, information can flow both up and down within hierarchies so that superordinate goals determine subordinate action selection (‘top-down’ influence) but are themselves driven by subordinate action outcomes (‘bottom-up’ influence). This bi-directional interaction is an important mechanism supporting the learning and adaptability of complex behaviours [21] like stone toolmaking. Hierarchical structure is interesting from a cognitive perspective because it implies the existence of superordinate representations abstracted from, and maintained over, the course of multiple subordinate events [23]. As such, it implicates processes of stimulus generalization, relational integration, temporal abstraction and goal abstraction associated with the distinctive response properties and anatomical connections of prefrontal cortex [22]. Hierarchical structure is also interesting with respect to cultural evolution because it relates to questions about the ‘level’ of copying [6] and potential biases in transmission [25]. Early hierarchical analyses of stone toolmaking action sequences were developed by Holloway [27] and Gowlett [28]. More recently, the hierarchical structure of toolmaking has been described in relation to models from cognitive neuroscience and developmental psychology [29–31]. Moore [30] presented a tree structure notation, adapted from Greenfield [32], which is further modified here to describe the organization of major Lower Palaeolithic toolmaking methods as inferred from modern experiments and the analysis of archaeological materials. Sent from my iPhone --- To unsubscribe: List help: