Differences in birch tar composition are explained by adhesive function in the central European Iron Age

Birch bark tar is the most widely documented adhesive in prehistoric Europe. More recent periods attest to a diversification in terms of the materials used as adhesives and their application. Some studies have shown that conifer resins and beeswax were added to produce compound adhesives. For the Iron Age, no comparative large-scale studies have been conducted to provide a wider perspective on adhesive technologies. To address this issue, we identify adhesive substances from the Iron Age in north-eastern France. We applied organic residue analysis to 65 samples from 16 archaeological sites. This included residues adhering to ceramics, from vessel surface coatings, repaired ceramics, vessel contents, and adhesive lumps. Our findings show that, even during the Iron Age in north-eastern France, birch bark tar is one of the best-preserved adhesive substances, used for at least 400 years. To a lesser extent, Pinaceae resin and beeswax were also identified. Through statistical analyses, we show that molecular composition differs in samples, correlating with adhesive function. This has implications for our understanding of birch bark tar production, processing and mode of use during the Iron Age in France and beyond

Understanding family dynamics in a cross-cultural sample: a multi-national study

The Family Systems Circumplex Model posits that balanced levels of cohesion and adaptability are associated with positive familial outcomes, whereas extremely high or low levels of these factors are associated with deleterious outcomes. Despite the popularity and utility of this model in Western cultures, there is a dearth of empirical data supporting its use in more culturally diverse contexts. The current, preregistered study assessed the Family Circumplex Model, cultural factors, and emerging adult outcomes across seven countries (i.e., China, Iran, Nigeria, Switzerland, Turkey, the United Kingdom, and the United States). Participants were N = 3,593 emerging adults, mostly self-identifying as women (71.3%). Collaborators were participants in Psi Chi’s Network for International Collaborative Exchange (NICE) and administered measures related to family dynamics and cultural orientation to participants in a random order. Results indicated that the Family Circumplex Model did not fit cross-culturally. As such, a new model was adapted, the Expanded Circumplex Model, which demonstrated invariance across samples and between women and men. The Expanded Circumplex Model retained 6 constructs with differences regarding the separation of disengagement into 2 variables and the combining of adaptive flexibility and cohesion. The current study suggests that the cultural context in which family dynamics occur should be taken into consideration when conceptualizing family dynamics theory and measurement. Future work should seek to replicate and further apply the Expanded Circumplex Model to familial outcomes

Chemical analyses reveal dual functionality of Early Mesolithic birch tar at Krzyż Wielkopolski (Poland)

Birch bark tar played an important role as an adhesive in the European Middle Palaeolithic and Mesolithic with key practical functions. For the Mesolithic in northern Europe, tar is suggested to have a variety of functions, including decorative, on various artefacts such as amber beads, antler and bone objects. However, no chemical characterisation has been conducted to confirm the organic composition of such decorations. To address this gap, we conducted organic residue analysis on archaeological samples taken from three artefacts excavated at the Early Mesolithic site Krzyż Wielkoposki (Poland). These include a wooden shaft, an antler point, and a perforated antler object with ornamental engravings. We further replicated two potential aceramic birch bark tar production techniques and employed Principal Component Analysis (PCA) for molecular differentiation. Our results show that birch bark tar served a dual functionality in tool hafting and ornamentation at Krzyż. We found compositional differences among archaeological samples, but comparing these results to experimental data presents significant challenges. Our findings shed light on birch bark tar versatility, and imply more widespread use of birch bark tar as a decorative element in the European Mesolithic than has hitherto been recognised

A new method for birch tar making with materials available in the Stone Age

The use of birch tar can be traced back to the European Middle Palaeolithic and is relevant for our understanding of the technical skills and cognitive abilities of Neanderthals. Due to the lack of archaeological evidence, it remains unknown what techniques were used for birch tar making. Efficiency was recently used as a proxy to determine the method most likely used in the Middle Palaeolithic. Todtenhaupt et al. have proposed a technique employing a groove-like structure that is comparable with the recently presented condensation method. The groove method resulted in higher tar yields compared to other experimental aceramic production processes. However, the implications for Palaeolithic tar making remain unclear because some of the materials used in the experiment were not available then (polished granite slabs). To approach this problem, we replicated the groove with river cobbles and, in a second experiment with flint fragments, to evaluate whether similar results can be obtained. We were successful in producing birch tar in multiple runs with the cobble- and flint-grooves, which, in addition, proved to be more efficient than the condensation method in terms of tar yield per bark input. Our experimental study provides an additional possibility to make prehistoric birch tar

The formation conditions of birch tar in oxygen-depleted environments

<jats:title>Abstract</jats:title><jats:p>Birch tar is the oldest manmade adhesive dating back to the European Middle Palaeolithic. Its study is of importance for understanding the cognitive capacities and technical skills of Neanderthals and the aceramic production systems employed in the European Palaeolithic and Mesolithic. Several methods may have been used to make birch tar, the most common proposition being dry distillation in oxygen-depleted atmospheres. One of the major impediments for our understanding of the conditions employed to make Neanderthal birch tar, and ultimately the technique used, is that it remains unknown at which temperatures exactly birch tar forms. The relationship between heating duration and tar formation is also unknown. To address these questions, we conduct a laboratory heating experiment, using sealed glass tubes and an electric furnace. We found that birch tar is only produced at a narrow temperature interval (350 °C and 400 °C). Heating times longer than 15 min have no effect on the quantity of tar produced. These findings, notwithstanding previous propositions of necessarily long heating times and larger tolerances for temperature, have important implications for our understanding of the investment in time needed for Palaeolithic birch tar making.</jats:p&gt

On the performance of birch tar made with different techniques

Abstract Birch tar is one of the oldest adhesives known in human history. Its production has been discussed in the framework of early complex behaviours and sophisticated cognitive capacities. The precise production method used in the Palaeolithic remains unknown today. Arguments for or against specific production pathways have been based on efficiency or process complexity. No studies have addressed the question whether birch tar made with different techniques is more or less performant in terms of its properties. We therefore investigate the adhesive performance of birch tar made with three distinct methods: the open-air condensation method and two variations of underground structures that approximate the double-pot method in aceramic conditions. We use lap-shear testing, a standard mechanical test used for testing the strength of industrial adhesives. Tar made in 1 h with the condensation method has a shear strength similar to, although slightly higher than, tar made underground if the underground process lasts for 20 h. However, tars from shorter underground procedures (5 h) are significantly less strong (by a factor of about 3). These findings have important implications for our understanding of the relationship between the investment required for Palaeolithic birch tar production and the benefits that birch tar represented for early technology. In this regard, the simple and low-investment open-air condensation method provides the best ratio

Hafting of a Neolithic leister: Identification of adhesives from Lolland (Denmark)

Birch tar has been identified as the predominant adhesive used for hafting purposes in the European Mesolithic and Neolithic. Its role in the manufacture of composite tools and weapons comprising wooden, bone and flint components attests its importance during these periods. The discovery of birch tar lumps, some bearing tooth imprints, suggests a broader range of functions beyond its adhesive properties. In this study, we present an analysis of five residues from two sites (Syltholm II and Strandholm I) that have been excavated through the Femern project, with the aim to shed light on the adhesives used in relation to their functions. Through chemical analyses, we show that birch tar constitutes the main component of two lumps and one chewed piece. We also found that birch tar served to haft a bone point within leister prongs, providing new information on its previously unknown role in composite fishing tool technology. These findings have significant implications for our understanding of the functional role and performance of birch tar in aquatic environments