The impact of imitative versus emulative learning mechanisms on artifactual variation: Implications for the evolution of material culture

Cultural evolutionary approaches highlight that different social learning processes may be involved in the maintenance of cultural traditions. Inevitably, for traditions to be maintained, they must be transmitted with reasonably fidelity. It has been proposed that 'imitation' (i.e., the direct copying of actions of others displayed in tasks such as toolmaking) generates relatively low rates of copying error. As such, imitation has often been ascribed an important role in the maintenance of traditions and in the 'ratcheting' of technological complexity over time. Conversely, 'emulation' (i.e., the copying of a result but not the behaviors that have led to that result) is allegedly associated with the production of relatively higher rates of copying error. However, to what extent these different social learning mechanisms generate distinct patterns of variation during the manufacture of material traditions remains largely unexplored empirically. Here, a controlled experiment was implemented using 60 participants who copied the shape of a 3D 'target handaxe form' from a standardized foam block. In an 'imitation condition', 30 participants were shown manufacturing techniques employed in the production of the target form and the target form itself. Conversely, in an 'emulation condition', 30 participants were shown only the (target) form. Copying error rates were statistically different, being significantly lower in the 'imitation' condition compared to the 'emulation' condition. Moreover, participants in the imitation condition matched the demonstrated behaviors with significantly higher copying fidelity than the alternative condition. These results illustrate that imitation may be imperative for the long-term perpetuation of visibly distinct archaeological traditions, especially in the case of lithic (reductive) traditions, where copying error rates can be expected to be relatively high. These findings, therefore, provide evidence that imitation may be required to explain the prolonged continuity of broad shape fidelity such as that seen in traditions of 'handaxe' manufacture during the Pleistocene.Leverhulme Trus

Differences in Manufacturing Traditions and Assemblage-Level Patterns: the Origins of Cultural Differences in Archaeological Data

AcceptedArticle in PressThis is the author accepted manuscript. The final version is available from Springer via the DOI in this record.© 2016 Springer Science+Business Media New York A relationship between behavioral variability and artifactual variability is a founding principle of archaeology. However, this relationship is surprisingly not well studied empirically from an explicitly “microevolutionary” perspective. Here, we experimentally simulated artifactual variation in two populations of “artifact” manufacturers, involving only a single behavioral difference in terms of their “tradition” of manufacturing tool. We then statistically analyzed shape variation in the resultant artifacts. In many respects, patterned differences might not have been expected to emerge given the simple nature of the task, the fact that only a single behavioral variable differed in our two populations, and all participants copied the same target artifact. However, multivariate analyses identified significant differences between the two “assemblages.” These results have several implications for our understanding and theoretical conceptualization of the relationship between behavior and artifactual variability, including the analytical potency of conceiving of artifacts as the product of behavioral “recipes” comprised of individual “ingredient” behavioral properties. Indeed, quite trivial behavioral differences, in generating microevolutionarily potent variability, can thus have long-term consequences for artifactual changes measured over time and space. Moreover, measurable “cultural” differences in artifacts can emerge not necessarily only because of a strict “mental template” but as the result of subtle differences in behavioral ingredients that are socially learned at the community level.We are grateful to Noreen von Cramon-Taubadel, Metin Eren, and the anonymous reviewers and editors at JAMT for helpful and constructive comments on this paper. This research was partly supported by the Leverhulme Trust (F/07 476/AR) and by the Research Foundation for the State University of New York

Copying error, evolution, and phylogenetic signal in artifactual traditions: An experimental approach using "model artifacts"

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Spatio-temporal patterns of artifactual variation are increasingly being studied via the explicit application of cultural evolutionary theory and methods. Such broad-scale (macroevolutionary) patterns are mediated, however, by a series of small-scale (microevolutionary) processes that occur at the level of individual artifacts, and individual artifact users and producers. Within experimental biology, "model organisms" have played a crucial role in understanding the role of fundamental microevolutionary processes, such as mutation and the inheritance of variation, in respect to macroevolutionary patterns. There has, however, been little equivalent laboratory work to better understand how microevolutionary processes influence macroevolutionary patterns in artifacts and their analysis. Here, we adopt a "model artifact" approach to experimentally study the issues of copy error (mutation) and resultant phylogenetic signal in artifact traditions. We used morphometric procedures to examine shape copying error rates in our "model artifacts." We first established experimentally that statistically different rates of copying error (mutation) could be induced when participants used two different types of shaping tool to produce copies of foam "artifacts." Using this as a baseline, we then tested whether these differing mutation rates led to differing phylogenetic signal and accuracy in two separate experimental transmission chains (lineages), involving participants copying the previous participant's artifact. The analysis demonstrated that phylogenetic reconstruction is more accurate in artifactual lineages where copying error is demonstrably lower. Such results demonstrate how fidelity of transmission impacts directly on the evolution of technological traditions and their empirical analysis. In particular, these results highlight that differing contexts of cultural transmission relating to fidelity might lead to differing patterns of resolution within reconstructed evolutionary sequences. Overall, these analyses demonstrate the importance of a "model artifact" approach in discussions of cultural evolution, equivalent in importance to the use of model organisms in evolutionary biology in order to better understand fundamental microevolutionary processes of direct relevance to macroevolutionary archaeological patterns.We are grateful to Noreen von Cramon-Taubadel, Robin Torrence, and our anonymous reviewers for helpful and constructive comments on this paper. This research was partly supported by the Leverhulme Trust (F/07 476/AR) and by the Research Foundation for the State University of New York

Considering the role of time budgets on copy-error rates in material culture traditions: an experimental assessment

This is the final version of the article. Available from the publisher via the DOI in this record.Ethnographic research highlights that there are constraints placed on the time available to produce cultural artefacts in differing circumstances. Given that copying error, or cultural 'mutation', can have important implications for the evolutionary processes involved in material culture change, it is essential to explore empirically how such 'time constraints' affect patterns of artefactual variation. Here, we report an experiment that systematically tests whether, and how, varying time constraints affect shape copying error rates. A total of 90 participants copied the shape of a 3D 'target handaxe form' using a standardized foam block and a plastic knife. Three distinct 'time conditions' were examined, whereupon participants had either 20, 15, or 10 minutes to complete the task. One aim of this study was to determine whether reducing production time produced a proportional increase in copy error rates across all conditions, or whether the concept of a task specific 'threshold' might be a more appropriate manner to model the effect of time budgets on copy-error rates. We found that mean levels of shape copying error increased when production time was reduced. However, there were no statistically significant differences between the 20 minute and 15 minute conditions. Significant differences were only obtained between conditions when production time was reduced to 10 minutes. Hence, our results more strongly support the hypothesis that the effects of time constraints on copying error are best modelled according to a 'threshold' effect, below which mutation rates increase more markedly. Our results also suggest that 'time budgets' available in the past will have generated varying patterns of shape variation, potentially affecting spatial and temporal trends seen in the archaeological record. Hence, 'time-budgeting' factors need to be given greater consideration in evolutionary models of material culture change.This work was funded by the Leverhulme Trust (Research Project Grant F/07 476/AR). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip

Factors affecting Acheulean handaxe variation: Experimental insights, microevolutionary processes, and macroevolutionary outcomes

PublishedJournal ArticleThis is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The “Acheulean” is comprised of individual knapping events undertaken by individual hominins. In other words, it is a particular component of hominin behavior that we draw out and amalgamate into a wider “pattern.” The resultant phenomenon (i.e., “the Acheulean”) is an entity that stretches over the space of three continents and spans a time period in excess of one million years. If such an exercise has any merit, it is because it provides a means of comparative (behavioral) analysis over these swathes of time and space. Comparative research can document, measure, and statistically assess temporo-spatial patterns of artifactual variation, and so test hypotheses regarding the character of that variation. However, it does not provide an independent means of examining some of the key phenomena which it is necessary to further understand in order to increase our comprehension of this archaeological legacy. Here, we review and synthesize recent experimental work that we have undertaken, which has specifically investigated some of the factors potentially responsible for the generation and constraint of variation within the Acheulean techno-complex. We examine issues of raw material, copying errors, and their relationship to mechanisms of social learning. Understanding these microevolutionary factors via experiments, we contend, is essential in order to reach a secure understanding of the macroscale phenomenon typically referred to as the “Acheulean.” Moreover, we outline how a “quantitative genetic” framework to these issues provides an essential means of linking these inherent micro- and macro-evolutionary factors into a coherent whole, while also simultaneously reconciling the potential influence of different sources of variation that are part of a temporally and geographically dispersed entity such as the Acheulean.We thank Marie-Hélène Moncel and Daniele Schreve for their invitation to take part in this issue. We are also grateful to the four reviewers (Michael O'Brien and three anonymous), whose thoughtful and constructive comments on the manuscript were much appreciated. Much of the work reported in this paper was funded by the Leverhulme Trust

Getting Under the Skin of Clinical Inertia in Insulin Initiation: The Translating Research Into Action for Diabetes (TRIAD) Insulin Starts Project

Purpose The purpose of this cross-sectional study is to explore primary care providers’ (PCPs) perceptions about barriers to initiating insulin among patients. Studies suggest that many patients with poorly controlled type 2 diabetes do not receive insulin initiation by PCPs. Methods As part of the Translating Research Into Action for Diabetes study, the authors conducted structured interviews in health systems in Indiana, New Jersey, and California, asking PCPs about the importance of insulin initiation and factors affecting this decision. The authors calculated proportions choosing each multiple-choice response option and listed the most frequently offered open-ended response categories. Results Among 83 PCPs, 45% were women; 60% were white; and they averaged 13.4 years in practice. Four-fifths of PCPs endorsed guideline-concordant glycemic targets, but 54% individualized targets based on patient age, life expectancy, medical comorbidities, self-management capacity, and willingness. Most (64%) reported that many patients were resistant to new oral or insulin therapies due to fears about the therapy and what it meant about their disease progression. Two-thirds (64%) cited patient resistance as a barrier to insulin initiation, and 43% cited problems with patient self-management, including cognitive or mental health issues, dexterity, or ability to adhere. Eighty percent felt that patient nonadherence would dissuade them from initiating insulin at least some of the time. Conclusions PCPs perceived that patient resistance and poor self- management skills were significant barriers to initiating insulin. Future studies should investigate whether systems-level interventions to improve patient-provider communication about insulin and enhance providers’ perceptions of patient self-management capacity can increase guideline-concordant, patient-centered insulin initiation

Eruptive shearing of tube pumice: pure and simple

Abstract. Understanding the physico-chemical conditions extant and mechanisms operative during explosive volcanism is essential for reliable forecasting and mitigation of volcanic events. Rhyolitic pumices reflect highly vesiculated magma whose bubbles can serve as a strain indicator for inferring the state of stress operative immediately prior to eruptive fragmentation. Obtaining the full kinematic picture reflected in bubble population geometry has been extremely difficult, involving dissection of a small number of delicate samples. The advent of reliable high-resolution tomography has changed this situation radically. Here we demonstrate via the use of tomography how a statistically powerful picture of the shapes and connectivity of thousands of individual bubbles within a single sample of tube pumice emerges. The strain record of tube pumice is dominated by simple shear (not pure shear) in the late deformational history of vesicular magma before eruption. This constraint in turn implies that magma ascent is conditioned by a velocity gradient at the point of origin of tube pumice. Magma ascent accompanied by simple shear should enhance high eruption rates inferred independently for these highly viscous systems. </jats:p

Fecal coliform disappearance in a river impoundment

Fecal coliform (FC) disappearance studies were conducted in Ford Lake during the summer of 1979. Ford Lake, an artificial impoundment at the lower end of the Huron River drainage basin below Ypsilanti, Michigan, receives all upstream flow (2072 km2 of drainage). During dry weather an overall daytime FC disappearance rate of 0.4 (h-1) (K base e) was measured using dye tracer for timed collection. assuming a first order equation of the Chick type. Sedimentation was demonstrated as important in the overall FC disappearance in the upper end of the lake. Rooftop studies showed light level to affect daytime disappearance. Two types of wet weather conditions were documented: (1) where a substantial increase in flow occurred due to an isolated upriver storm; and (2) as a result of two different storm events in the Ford Lake area itself. In both cases, Ford Lake was effective in substantially reducing the large FC contribution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25455/1/0000905.pd