Steak tournedos or beef Wellington: an attempt to understand the meaning of Stone Age transformative techniques

The paper addresses longstanding debates about human uniqueness and the timing and nature of behavioural modernity in prehistory. Earlier models posited a late onset of behavioural modernity relative to anatomical modernity, while subsequent research argued for a gradual emergence across the African Middle Stone Age. These debates often define modernity via specific artefactual traits (e.g., ornaments, engravings, compound tools), yet the concept has faced criticism for inconsistency, methodological issues, and limited ability to distinguish among hominins. Alternative frameworks such as behavioural variability, metaplasticity, and complex cognition offer interpretive lenses but lack quantitative means to compare behaviours. The paper focuses on fire-based transformative techniques—processes that alter material properties rather than shape (e.g., heat treatment of stone, reddening of ochre, distillation of plant exudates into adhesives)—as potential markers of human uniqueness. It asks whether such techniques are more cognitively demanding, how they could have been invented (purposefully versus discovered accidentally), and what they imply about social learning. The goal is to propose a quantitative, testable framework—derived from a modern cooking analogy—to interpret transformative techniques beyond step-count-based complexity assessments.

The paper synthesizes prior work on transformative techniques and broader behavioural markers: (1) Transformative techniques and early engineering: Heat treatment of stone is the earliest intentional alteration of material properties in Homo sapiens, present in Africa before 125 ka and persisting into the Holocene; it appears also in Australia with initial colonists and in Upper Paleolithic Europe (Solutrean, Dyuktai). Techniques and specific heating methods are well studied in some African contexts but remain poorly known or fragmentary elsewhere (Australia, European Solutrean). Debates concern cognitive demands (e.g., analogical reasoning for underground heating) and resource costs (wood fuel/time). Ochre heat treatment for enhanced staining properties appears by ~100 ka in South Africa and Israel, and later in Europe; its association with symbolically charged behaviours raises questions about technique interdependence. Adhesive production (e.g., birch tar) appears by ~200 ka (Italy) and later in the Netherlands and Germany; importantly, birch tar lacks visible precursors and requires distillation. (2) Learning and cultural transmission: There is debate about whether techniques required cultural transmission or could be re-invented (reliance on observation vs. reinvention). Concepts of cognitively opaque skills (Csibra & Gergely) suggest some hidden processes necessitate high-fidelity transmission; Lewis & Laland emphasize fidelity for cumulative culture, though counter-arguments exist. (3) Complexity in archaeology: The notion of complexity is variably used (often equated with “complicatedness” or as a proxy for modernity) and criticized for arbitrariness and colonial implications in societal classifications. Quantitative approaches that count steps can work for shape-transforming techniques (e.g., lithic knapping) where physical traces of steps exist, but are problematic for transformative techniques where steps leave few or no archaeological traces. This motivates a shift to measurable criteria such as investment, difficulty (risk of failure), and discovery versus invention (ratcheting).

The paper is theoretical and proposes a framework using an analogy between two cooking processes—steak tournedos (visible, monitorable) and beef Wellington (hidden, recipe-driven)—to derive three testable hypotheses for Stone Age transformative techniques. Core approach: - Identify measurable proxies instead of inferring step counts. - Distinguish techniques by (i) investment (time/resources), (ii) difficulty/risk (success rates), and (iii) degree of technological evolution (random discovery vs. purposeful invention indicating ratcheting). Operationalization and test conditions: 1) Investment hypothesis: - Reproduce techniques experimentally or under laboratory conditions to measure reaction kinetics (e.g., heating temperature/time profiles). - Use chemical analyses to count raw materials present in artefacts (e.g., number of components in composite adhesives). - Compare time and resource costs across transformative vs. non-transformative techniques within the same contexts. 2) Technological evolution (ratcheting) hypothesis: - Experimentally reproduce techniques through multiple pathways to build reference collections. - Identify diagnostic proxies (chemical/material markers) that indicate particular transformation pathways (e.g., oxygen-depleted underground vs. oxygenated open-air). - Compare archaeological artefacts to references to infer actual pathways and assess whether processes could be discovered accidentally or required invention based on prior knowledge. 3) Difficulty/high-fidelity copying hypothesis: - Conduct controlled experiments with learners and experts to measure success rates across techniques, emphasizing presence/absence of hidden (invisible) processes. - Compare success rates with those of other known techniques (e.g., stone knapping) to infer required fidelity of transmission. Application example (birch tar): - Current artefact chemistry and CT scans (e.g., Zandmotor) show charcoal/sediment inclusions but no deliberate mix of multiple ingredients. - Kinetics indicate tar formation can be fast (≈15 minutes at given temperatures). - Proposes building a reference chemical library of aceramic tar made via different methods to identify markers of formation environments and infer whether Neanderthals used hidden or visible processes, enabling evaluation of hypotheses 2 and 3.

• Conceptual shift: Proposes replacing step-count-based complexity with three measurable dimensions: (1) investment in time/resources, (2) difficulty as risk of failure (success rates), and (3) necessity of purposeful invention (ratcheting) versus random discovery. - Measurable criteria and test conditions are specified for each hypothesis, enabling empirical assessment through experimental archaeology and materials analysis. - Empirical examples supporting investment measures: Experimental work shows chert requires more than double the time to reach target thermal transformations compared to silcrete under comparable conditions, highlighting quantifiable differences in investment between materials. - Birch tar application (current data): • Reaction kinetics: ≈15 minutes of heating can produce expected tar yields at given temperatures, indicating short minimal time requirements. • Artefact composition: The Zandmotor birch tar CT scans reveal charcoal and possible sediment inclusions, but no evidence for deliberate multi-ingredient mixing; chemically, only birch bark is clearly documented. • Cost inference: Given single raw material and short kinetics, hypothesis 1 (higher investment) is not supported for Middle Palaeolithic birch tar based on current direct evidence. • Hypotheses 2 and 3 (ratcheting and difficulty/high-fidelity copying): Insufficient data at present; determining actual production pathways via chemical markers (oxygen-depleted vs. oxygenated, allothermic vs. autothermic, with/without separation, condensation/dripping) is needed to evaluate these. - Broader empirical context: - Heat treatment of stone appears before 125 ka in Africa and persists into later periods; earliest ochre reddening ~100 ka; earliest birch tar ~200 ka (Neanderthals). - Some contexts (e.g., underground heating) likely entail higher investment and reliance on hidden processes, predicting lower success rates and greater need for high-fidelity copying. - Critique of complexity: Highlights arbitrariness in reconstructing step counts for transformative techniques due to lack of observable step traces, undermining quantitative comparisons based solely on complexity metrics.

The framework addresses the research question by offering quantifiable, testable dimensions—investment, difficulty/success rates, and invention vs. random discovery—that enable meaningful comparison of transformative techniques to contemporaneous technologies without relying on arbitrary step-count complexities. By focusing on proxies measurable in artefacts (chemical signatures, reaction kinetics, raw material counts) and experimental success rates, the approach reduces interpretive arbitrariness and aligns analytical focus with processes central to human uniqueness: mastery of fire-based transformations, coping with cognitively opaque procedures, and the role of high-fidelity social learning. The implications for the field include: - A clearer pathway to assess whether certain techniques required cumulative culture (ratcheting) and pedagogical transmission. - The ability to differentiate technologies that likely emerged from accidental discovery (e.g., open-air ochre reddening) from those necessitating purposeful invention (e.g., controlled underground heating), refining interpretations of cognitive and cultural capacities in different hominin groups. - A reframing of debates around “complexity” by replacing them with empirically grounded measures that can be validated via experimentation and artefact analysis. The birch tar example illustrates both the promise and current evidentiary gaps: investment appears modest per current data, yet the key questions about hidden processes, difficulty, and fidelity remain to be resolved through targeted chemical and experimental studies.

The paper advances a pragmatic, testable framework to interpret Stone Age transformative techniques by: (1) quantifying investment (time/resources), (2) measuring difficulty via success rates (especially for techniques with hidden processes), and (3) determining whether techniques required purposeful invention (ratcheting) or could arise from random discovery. This approach offers a more reliable basis than step-count complexity for comparing technologies and inferring aspects of human cultural evolution, including the reliance on cumulative culture and high-fidelity transmission. Future research should: - Generate experimental reference datasets for multiple transformative pathways (e.g., underground vs. open-air heating; adhesive production variants) with detailed chemical/material proxies. - Systematically measure reaction kinetics and resource inputs across techniques and materials. - Conduct controlled learner-versus-expert experiments to establish success rates and the need for high-fidelity copying. - Apply these references to archaeological artefacts to infer actual Stone Age pathways and evaluate the three hypotheses across contexts.

• The paper is conceptual and does not present new archaeological datasets; it proposes hypotheses and test conditions but relies on future experimental and analytical work. - For many transformative techniques, crucial steps and pathways remain unknown or are poorly documented, limiting immediate hypothesis testing. - Chemical and physical markers necessary to discriminate production pathways are not yet comprehensively established across techniques and contexts. - Current evaluations (e.g., for birch tar) are constrained by limited artefact data and cannot yet resolve questions about ratcheting or required fidelity of transmission. - The framework focuses primarily on fire-based transformative techniques and may require adaptation for other domains.