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International audience; The present study examined rotation velocity regulation in pottery wheel-throwing. Long assumed to be a key parameter in the control of the centrifugal force, we interpret its role rather as a means to control the linear velocity at the point of hand-clay contact. To test this hypothesis, we set up a field experiment with Indian potters working with a low-inertia kickwheel. Six expert potters were asked to produce eight types of pots (four shapes × two masses), each type in five specimens (in total each potter threw 40 vessels). We measured the rotation velocity during the pre-forming and forming fashioning phases, as well as the maximal vessel radii at the end of both phases. Results demonstrated that potters reduced the rotation velocity from the pre-forming phase to the forming phase, but also for the large clay masses compared to the small clay masses, and-uniquely during the forming phase-for the shapes characterized by the largest diameter. Overall, the observed decreases in rotation velocity corresponded to increases in mean vessel diameter, suggesting that the potters were applying a limit on the linear velocity. Our results thus provide empirical evidence supporting the role of linear velocity as a key functional parameter in wheel-throwing. Directly relating to the potter-vessel interaction, it indicates both when and by how much the rotation velocity deceleration caused by the exertion of manual pressure forces should be compensated, as well as how to avoid the risk of velocity-induced collapse. While only preliminary, our results also suggest that large-sized ancient wheel-thrown vessels were most likely produced using low-velocity and high-inertia wheels. Future work, examining rotation velocity regulation over different types of wheels, is needed to allow definite conclusions to be drawn.

International audience; While craft apprenticeship can be understood as socially mediated individual learning, the ensuing prediction of individual and cultural object traits within craft communities has not been investigated. Here we provide an assessment of vessel shape variations occurring through cultural transmission and their visual perception by the craftsmen. To this end, 26 Hebron potters distributed through nine familial transmission units were asked to produce vessels of three different pottery types, then 21 of the participants were invited to visually identify their proper vessels and those of five other potters. We used the Elliptical Fourier method to analyze vessel shape variation among the productions. Our findings demonstrated that the learning process modified the ceramic shape, the cultural morphological traits being combined with new individual traits. Moreover, the individual morphological traits overtook the cultural ones, which is supposed to lead to divergence of vessel shapes within the transmission chain. If certain cultural morphological traits perpetuate through generations, this certainly does not result from fidelity copying occurring through learning but from stabilizing mechanisms such as consumer demand. Our results showed that potters do perceive the subtle same-type vessel shape variations and thereby could select the individual variant they prefer to produce.

International audience; This work aims to improve understanding of the conditions favoring adoption of new craft traits. We investigated the cost of motor skill adaptation in asking seven expert potters to produce familiar vs. unfamiliar shapes and using a familiar vs. unfamiliar wheel. The gestural patterns of the potters (i.e. the succession of their hand positions) were videotaped for quantitative analysis. Results showed that the hand positions varied mostly according to the shape being thrown, whether that shape was familiar or not. Additionally, all potters transferred a major part of their hand positions repertoire from the familiar shapes to the unfamiliar ones. Hence, expert potters produce novel shapes through individual learning which constitutes a low cost of adaptation. In archaeological contexts where ceramic production was distributed among multiple expert potters, new vessel shapes could easily have been adopted because the individual cost was low. On the other hand, we hypothesize that low-skilled potters (e.g. potters specializing in small vessels) would not have achieved such adoption without opportunities for social learning. As for the unfamiliar wheels, results indicated that their use did not influence the hand positions but involved new postures that may be difficult to adopt, this merits further studies.

International audience; Ceramics are quintessential indicators of human culture and its evolution across generations of social learners. Cultural transmission and evolution theory frequently emphasizes apprentices' need for accurate imitation (high-fidelity copying) of their mentors' actions. However, the ensuing prediction of standardized fashioning patterns within communities of practice has not been directly addressed in handicraft traditions such as pottery throwing. To fill this gap, we analysed variation in vessel morphogenesis amongst and within traditional potters from culturally different workshops producing for the same market. We demonstrate that, for each vessel type studied, individual potters reliably followed distinctive routes through morphological space towards a much-less-variable common final shape. Our results indicate that mastering the pottery handicraft does not result from accurately reproducing a particular model behaviour specific to the community's cultural tradition. We provide evidence that, at the level of the elementary clay-deforming gestures, individual learning rather than simple imitation is required for the acquisition of a complex motor skill such as throwing pottery.

This work aims to improve understanding of the conditions favoring adoption of new craft traits.We investigated the cost of motor skill adaptation in asking seven expert potters to produce familiar vs. unfamiliar shapes and using a familiar vs. unfamiliar wheel. The gestural patterns of the potters (i.e. the succession of their hand positions) were videotaped for quantitative analysis. Results showed that the hand positions varied mostly according to the shape being thrown, whether that shape was familiar or not. Additionally, all potters transferred a major part of their hand positions repertoire from the familiar shapes to the unfamiliar ones. Hence, expert potters produce novel shapes through individual learning which constitutes a low cost of adaptation. In archaeological contexts where ceramic production wasdistributed among multiple expert potters, new vessel shapes could easily have been adopted because the individual cost was low. On the other hand, we hypothesize that low-skilled potters (e.g. potters specializing in small vessels) would not have achieved such adoption without opportunities for social learning. As for the unfamiliar wheels, results indicated that their use did not influence the hand positions but involved new postures that may be difficult to adopt, this merits further studies.

International audience; At the crossroad of archaeology and experimental psychology, we addressed the issue of inter-individual variability in traditional ceramic shapes. The goal was to explore whether such variability could imply potter signatures. We setup a field experiment with five expert Nepalese potters, asking them to produce three shapes (replicated five times). The 2D profiles of the experimental productions were analyzed with a shape analysis method borrowed from biology. In a complementary experiment focusing on shape discrimination, the participants were asked to visually identify their own productions and those of their colleagues. Results indicated that the potters produced slightly but significantly different shapes. We assume that during apprenticeship individuals developed their own motor skills, which reflect upon the finished products. Interpreting shape variability in terms of individuals could provide supplementary information on the social organization of the production, either for modern or ancient periods. As for shape discrimination, our preliminary results indicated that a few potters visually distinguished individual signatures. Those craftsmen could play a key role in the selection and evolution of the traditional ceramic shapes.

Indian Prajapati and Multani Kumhar potting communities use different wheels in throwing their vessels. Highly-experienced potters from these communities threw assemblages of (i) familiar shapes using their familiar wheels, (ii) unfamiliar shapes using their familiar wheels and (iii) unfamiliar shapes using unfamiliar wheels. We analyzed how the potters dealt with the novelty provided by the unfamiliar shapes and wheels by assessing their effects on the degree of assemblage standardization. When throwing familiar shapes with familiar wheels, potters demonstrated a high degree of standardization, both at the level of the individual potter and at the level of their respective communities. Throwing unfamiliar shapes considerably affected standardization, especially for the more difficult shapes. Hence, novelty may be detected in archaeological assemblages by the coexistence of (large quantities of) highly standardized artifacts of one type and (smaller quantities of) less standardized artifacts of another type. However, throwing the unfamiliar shapes on unfamiliar wheels (“borrowed” from the other community) did not give rise to additional markers of novelty in the assemblages produced. Thus, at least part of the expert potters’ skill can be transferred from their usual conditions of practice to new, unfamiliar conditions without leaving observable traces in the artifacts produced.

International audience; "This study is aimed at evaluating potters’ skills according to the mechanical characteristics of the vessels they produced. It focuses on wheel thrown vessels. In a first stage, considering that the difficulty of throwing ceramic vessels is to a significant extent determined by the risk of collapse of the thrown structure, we applied the method of finite element modelling to derive an index of mechanical stresses operating within a vessel. Validated via compression tests, the so-called Von Mises stress index was employed as a global index of mechanical difficulty. Because this index allows comparisons between vessels of different form, mass, and clay properties, it provides a more powerful tool than existing techno-morphological taxonomies. In a second stage, in order to relate the Von Mises stress index to throwing difficulty, we analysed the geometrical and mechanical characteristics of vessels thrown by eleven expert potters invited to reproduce four different model forms with two different masses of clay. The results demonstrated that reproductions revealed subtle but systematic deviations from the model forms that allowed a decrease in the mechanical difficulty. More difficult forms showed larger degrees of mechanical optimisation. These results, in combination with a new analysis of data from Roux’s (1990) study with potters of different skill levels, indicate that skill resides, at least to a certain extent, in the capacity to marshal the operative mechanical constraints. In other words, the latter, measured by the Von Mises index, provides a useful signature of a potter’s skills." (source éditeur)

International audience; "The impact of copying error on change in artifact morphology is studied through a field experiment with three groups of potters, each with a distinct potting tradition (one from France and two from India). The nine French potters and the 12 Indian potters had to reproduce – in five specimens – four different model shapes with two different weights of clay (in total, each potter threw 40 pots). Results show that the variability generated while copying depends on both the difficulty of the task and the cultural learning niches of the potters. We conclude that, even though unintended, the copying error is culturally constrained and therefore its amplitude and directions predictable. This is attributed to the cultural selection of motor skills during apprenticeship."

Behavioural variability is likely to emerge when a particular task is performed in different cultural settings, assuming that part of human motor behaviour is influenced by culture. In analysing motor behaviour it is useful to distinguish how the action is performed from the result achieved. Does cultural environment lead to specific cultural motor skills? Are there differences between cultures both in the skills themselves and in the corresponding outcomes? Here we analyse the skill of pottery wheel-throwing in French and Indian cultural environments. Our specific goal was to examine the ability of expert potters from distinct cultural settings to reproduce a common model shape (a sphere). The operational aspects of motor performance were captured through the analysis of the hand positions used by the potters during the fashioning process. In parallel, the outcomes were captured by the geometrical characteristics of the vessels produced. As expected, results revealed a cultural influence on the operational aspects of the potters' motor skill. Yet, the marked cultural differences in hand positions used did not give rise to noticeable differences in the shapes of the vessels produced. Hence, for the simple model form studied, the culturally-specific motor traditions of the French and Indian potters gave rise to an equivalent outcome, that is shape uniformity. Further work is needed to test whether such equivalence is also observed in more complex ceramic shapes. © 2013 Gandon et al.

The observed respect and attention to elders' speech in traditional cultures appears to have a ‘universal’ component which questions its possible biological bases. Animals present differential attention to the vocalizations of other individuals according to their characteristics but little is known about the potential propensity to pay more attention to vocalizations of elders. On the basis of several hundreds of vocal exchanges recorded, here we show that aged female Campbell's monkeys ( Cercopithecus campbelli ), despite being significantly less ‘loquacious’ than their younger adult counterparts, elicit many more responses when calling. These findings show that attention to elders' vocal production appears in non-human primates, leading to new lines of questioning on human culture and language evolution.