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The present paper provides an integrative theory of actions and motor programs for skill in tool use, construction, and language. We analyze preconditions for action as well as making their effects (postconditions) explicit, emphasizing the “how” of action details as well as the “what” of motor programs, aided by conceptual analysis of several brain modeling efforts. The theory is exemplified by analysis of the subtractive construction involved in percussive tooling by capuchin monkeys and Oldowan and Acheulean stone tool by protohumans making before turning to the additive construction of hafted tools. A complementary analysis focused on the construction of bird nests explores the notion of “image” and “stage” in construction. We offer a brief comparison with birdsong before arguing for a very different relation between communication and construction in humans. Pantomime lifts manipulation from practical to communicative action in protohumans, and we consider the role of pedagogy before offering hypotheses on the emergence of human language that suggest how language may have evolved from manual skills. We note that language provides an open-ended means for devising innovations in tool use and construction, but reiterate the importance of this framework for diverse future studies in ethology and comparative psychology. Publisher PDF

Homo sapiens’ capacity for the inter-generational accumulation of complex technologies, practices, and beliefs is central to contemporary accounts of human distinctiveness. However, the actual antiquity and evolutionary origins of cumulative culture are not known. Here we propose and exemplify a research program for studying the origins of cumulative culture using archaeological evidence. Our step-wise approach disentangles assessment of the observed fidelity of behavior reproduction from inferences regarding required learning mechanisms (e.g. teaching, imitation) and the explanation of larger-scale patterns of change. It is empirically grounded in technological analysis of artifact assemblages using well-validated experimental models. We demonstrate with a case study using a tool-making replication experiment to assess evidence of behavior copying across three 2.6 million-year-old Oldowan sites from Gona, Ethiopia. Results fail to reveal any effects of raw material size, shape, quality, or reduction intensity that could explain the observed details of inter-site technological variation in terms of individual learning across different local conditions. This supports the view that relatively detailed copying of tool-making methods was already a feature of Oldowan technological reproduction ~2.6 mya. We conclude with a discussion of prospects and implications for further research on the evolution of human cumulative culture.

Investments in stone tool skill learning constitute an oft-neglected cost in the evaluation of alternative adaptive strategies. Studies show that the most salient neural and cognitive demands of stone tool-making should occur during learning rather than expert performance. However, the behavioral complexity and extensive learning requirements that make stone knapping skill acquisition an interesting object of study are the very features that make it so challenging to reconstruct. Here we present results from a new study of Late Acheulean handaxe-making skill acquisition involving twenty-six naïve subjects and up to 90 hours training over several months, accompanied by psychometric testing and regular behavioral assessments. Our study’s main objectives were to derive a robust quantitative skill metric for the experimental handaxes using machine learning algorithms, to reconstruct a handaxe-making learning curve, and to explore sources of variation in handaxe making and learning outcomes. The objective, artifact-based model performed well in predicting handaxe making skill levels, in forecasting future performance and rating out-of-sample expert handaxes. The overall learning curve for subjects follows a characteristic power law showing that with training practice performance generally improves. Extrapolations of our individual learning curves suggest that experimental studies of such refined technologies should plan for at least 200 hrs. of training to achieve archaeological validity. We also find that performance in early stages of training correlates with differences in executive function (as tracked by widely-used psychometric measures) whereas performance during subsequent learning was associated with practice density. Our results highlight the significance of technologically focused teaching for achieving high-level skill in handaxe production, the importance of motivation, persistence, and self-control in knapping skill acquisition, and how these processes can be reliably reconstructed from archaeological evidence.

Paleolithic stone tools provide concrete evidence of major developments in human behavioural and cognitive evolution. Of particular interest are evolving cognitive mechanisms implied by the cultural transmission of increasingly complex prehistoric technologies, hypothetically including motor resonance, causal reasoning and mentalizing. To test the relevance of these mechanisms to specific Paleolithic technologies, we conducted a functional magnetic resonance imaging study of Naı¨ve, Trained and Expert subjects observing two toolmaking methods of differing complexity and antiquity: the simple ‘Oldowan’ method documented by the earliest tools 2.5 million years ago; and the more complex ‘Acheulean’ method used to produce refined tools 0.5 million years ago. Subjects observed 20-s video clips of an expert demonstrator, followed by behavioural tasks designed to maintain attention. Results show that observational understanding of Acheulean toolmaking involves increased demands for the recognition of abstract technological intentions. Across subject groups, Acheulean compared with Oldowan toolmaking was associated with activation of left anterior intraparietal and inferior frontal sulci, indicating the relevance of resonance mechanisms. Between groups, Naïve subjects relied on bottom-up kinematic simulation in the premotor cortex to reconstruct unfamiliar intentions, and Experts employed a combination of familiarity-based sensorimotor matching in the posterior parietal cortex and top-down mentalizing involving the medial prefrontal cortex. While no specific differences between toolmaking technologies were found for Trained subjects, both produced frontal activation relative to Control, suggesting focused engagement with toolmaking stimuli. These findings support motor resonance hypotheses for the evolutionary origins of human social cognition and cumulative culture, directly linking these hypotheses with archaeologically observable behaviours in prehistory.

International audience; Inter-site technological variation in the archaeological record is one of the richest potential sources of information about Plio-Pleistocene hominid behavior and evolution. However, appropriate methods for describing and comparing Oldowan assemblages have yet to be agreed upon, and interpretation of the early record remains highly controversial. Particularly salient is disagreement over whether the Oldowan is a single technological phenomenon or is more accurately divided into multiple regional and/or chronological traditions, perhaps including a less developed Pre-Oldowan phase in the late Pliocene. Some of this disagreement reflects theoretical and methodological differences between research traditions and some is more directly evidential. Here we present a framework for describing and interpreting Oldowan variation and apply it to three Pliocene assemblages (EG-10, EG-12, and OGS-7) from Gona, all dated to c. 2.6 million years (Ma). Results indicate proficient knapping and a full range of Oldowan reduction strategies in these earliest known occurrences, consistent with the idea of an Oldowan "technological stasis" from 2.6-1.6Ma. Patterns of variation in raw material selection and predominant reduction strategy at each site clearly indicate the importance of cultural transmission in the Oldowan, but confounding ecological and economic variation continue to render interpretation in terms of multiple tool making traditions or species inappropriate. We propose that cultural transmission and ecological adaptation should be recognized as complementary, rather than mutually exclusive, mechanisms in future attempts to explain Oldowan technological variation.

The capacity of Homo sapiens for the intergenerational accumulation of complex technologies, practices, and beliefs is central to contemporary accounts of human distinctiveness. However, the actual...