Birch Tar Research Articles

The molecular composition of birch tar and its infrared spectrum

Birch tar was the first substance made by humans that is otherwise not available in nature. The oldest artefacts date to ~ 200 thousand years ago in Europe but birch tar becomes more frequent around 45 thousand years ago and even more so from the Mesolithic onwards. Their study has important implication for our understanding of evolutionary processes such as cognitive capacity and cultural evolution. What remains unknown is the overall molecular composition of birch tar. Several approaches based on gas chromatography-mass spectrometry have shown the potential of studying solvent soluble molecules to understand the botanical origin of different tars, their manufacturing techniques and their post-depositional alteration mechanisms. However, birch tar’s soluble fraction cannot shed light on its mechanical properties. In this study, we conduct gas chromatography-mass spectrometry and spectroscopic analysis of seven bulk birch tar samples, including infrared band assignment and structural refinement of organic molecules in the insoluble fraction. We find that the overall proportion that cannot be analysed by gas chromatography accounts for 85–90% in birch tar. This phase consists of polymerised molecules with a structure analogous to asphaltenes but containing a significantly greater amount of oxygen-related functional groups. Our findings have implications for understanding the viscosity, adhesiveness and stiffness of birch tar and they call for caution in applying analytical techniques that only target soluble molecules in birch tar.

A Neanderthal's specialised burning structure compatible with tar obtention

Here we present multiproxy evidence of a new type of Neanderthal hearth discovered in Vanguard Cave (VC) (Gibraltar), which is dated ∼ 65 kyr, and associated with Middle Paleolithic stone artefacts. The hearth structure coincides with predictions from theoretical studies which require the use of heating structures for obtaining birch tar, commonly used in hafting. We propose that the structure was used for heating rockroses (Cistaceae) under anoxic conditions by burning herbs and shrubs, over a guano mixed with sand layer. We tested this hypothesis experimentally with success. The presence of levoglucosan and retene in the structure's matrix points to combustion of higher resinous plant-derived material. Our results advance our understanding of Neanderthal behaviour, as the ability to organize activities related with the use of fire.

Identifi cation of Adhesives for Repairing Ancient Ceramics: The Case of the Neolithic and Chalcolithic of Far Northeast Europe

This study focuses on the composition of the adhesives used to repair clay vessels, and on the technique of their preparation in the Late Neolithic and Chalcolithic (late 4th to early 3rd millennia BC) sites of Far Northeast Europe (the Republic of Komi and the Nenets Autonomous Okrug). Remains of adhesives were detected on 70 of 171 repaired pots. To date, five samples of ceramics from dwellings of the Chuzhyael culture have been analyzed. Gas chromatography-mass spectrometry revealed no markers of coniferous trees or bitumen; but did reveal markers of birch, suggesting that fractures and cracks on broken pots were plastered with birch tar. The composition of organic compounds in samples indicates the use of two vessels in the technological process: in one of them, birch bark was subjected to pyrolysis, while the other was a receptacle for tar. This comparatively complex technology reveals one more specialization in the domestic manufacture of the taiga hunter-gatherers, including the use of special furnaces. Analytic procedures employed by us open up new prospects for the study of the material culture of Far Northeast Europe, extend our knowledge of domestic manufacture, and offer new material for AMS dating.

Antifungal Activity of Bhurjah (Betula Utilis d. Don) Bark in Human Pathogenic Fungi

Aim: To evaluate the antifungal activity of Bhurjah (Betula utilis D.Don) bark against six fungal strains. Water extract, alcohol extract of bark and essential oil (Birch oil) were screened against six fungal strain Trichophyton rubrum (7859), Epidermophyton floccosum (7880), Microsporum fulvum (7685), Aspergillus flavus (2590), Actinomucour elengi (963) and Candida albicans at four different concentrations (25µl, 50µl, 75µl, 100µl) using “Agar well diffusion method”. The MIC was tested using micro-PDA dilution method at concentrations ranging from (25µl, 50µl, 75µl, 100µl). Bhurjah essential oil showed significantly more inhibitory activity than fluconazole in case of 7880 (p value <0.05) and almost similar inhibitory activity as fluconazole in case of 7685 (p value >0.05). Bhurjah essential oil is shown to be effective against the growth of both M. fulvum with MIC value of 2.5% (v/v) and E. floccosum with MIC value of 2.5% (v/v) as determined by microbroth dilution. Bhurjah essential oil showed antifungal activity against two fungal strains E. floccosum (7880), M. fulvum (7685). Therefore Bhurjah essential oil can be used as antifungal agents for dermatophytosis causing strains i.e. E. floccosum (7880), M. fulvum (7685).

EXPERIMENTAL ASSESSMENT OF THE ACUTE TOXICITY OF "KUBAZOL" – SOLUTION FOR EXTERNAL APPLICATION BASED ON BIRCH TAR

Laboratory studies were conducted to determine the acute toxicity of the veterinary drug "Kubazol" on white rats. The drug "Kubazol" - a veterinary drug (spray for external use, solution) contains birch tar in its composition. Intended for the treatment and prevention of lesions of the skin (wounds, dermatitis, eczema), claws (injuries, superficial panaritium), hooves and hooves (foot rot, etc.) in dogs, wild pigs, wild birds and sports horses. According to the results of determining the parameters of the acute toxicity of the drug "Kubazol" (spray for external use, solution), in the case of a single intragastric administration, the LD50 for male rats is 7328.87±878.80 mg/kg of body weight, which allows us to classify it as toxic up to V class - practically non-toxic substances (LD50 5001-15000 mg/kg), and according to the degree of danger - up to IV class - low-hazard substances (LD50 > 5000 mg/kg). According to the results of toxicological studies of the veterinary drug "Kubazol" (spray for external use, solution), the LD50 indicator could not be calculated, since the death of laboratory animals was not detected within 14 days after application to the skin of rats. At the same time, the maximum dose of the drug "Kubazol (spray for external use, solution) applied to the skin of rats (based on the absolute weight of the drug) was 15,000.0 mg/kg of body weight, which allows the drug to be classified according to the degree of danger to the IV class - low-hazardous substances (LD50Сut>2500.0 mg/kg of body weight). Further studies will be the next stage of pre-registration tests aimed at studying the chronic toxicity of "Kubazol", which is mandatory material in the section "Studies on safety and residues" of the dossier for this drug.

Testing non-destructive spectrometric methods for the identification and distinction of archaeological pine wood tar and birch bark tar

Archaeological findings prove the appearance and use of birch bark tar since the Middle Palaeolithic. The production and use of birch bark tar and pine wood tar has overlapped since at least the late Neolithic, but probably for much longer. The reliable chemical identification of such archaeological tar residues can offer valuable insights into, for example, ancient technical complexity, trade and culture. In this context, the scarcity of these mainly organic residue findings in the archaeological record bears the need for non-destructive analytical tools. However, there is currently no systematic proposed way for this purpose. We aim here to verify the organic nature and test the reliability of the identification of archaeological pine wood tar and birch bark tar with a combination of SEM-EDS, FTIR microspectroscopy in reflectance mode and XRD. We examined a set of experimental adhesive replicas of pine tar and birch tar in pristine form, but also after a three-year-long weathering experiment. Additionally, we studied a set of archaeological samples, consisting of Mesolithic bone/antler points with adhering hafting residues, form the Dutch North Sea. This research shows that degradation negatively influences the reliable verification and identification of the organic residue constituents significantly. SEM-EDS as a starting point of analysis verifies the residue’s organic nature, but it cannot be used to identify birch or pine tar. XRD can identify crystalline additives in the adhesive mixture, like ochre and wax, as well as phases related to the artefact’s environment of burial and provenance. Micro-FTIR is also capable of verifying the organic matter of the residue constituents. The differentiation of birch and pine tars is hindered by vibrational modes occurring in neighbouring wavenumbers for both tars, and by the limited research on degradation markers indicative of thermal treatment to prove tar production. Until reference collections also account for degradation and include a wide variety of adhesives, results of FTIR collected in reflectance mode are best treated with some caution.

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.

Non-metallic decorative inlays in La Tène jewellery - contribution of archaeometry to the understanding of production technologies

The study provides a detailed investigation into several representatives of La Tène jewellery. Primarily, it deals with non-metallic decorative inlays from the Late La Tène period, particularly with their application on a metal base. Unique artefacts have been selected for the study, all coming from the Czech Republic and Slovakia. A prime representative of the finds is a torc coming from a La Tène burial site in Prague (Czech Republic, Central Europe). In this geographical context, such finds are rather exceptional. The torc examined is remarkable both in terms of its origin and the production technology utilised, namely the application of decorative inlays made of red opaque glass. Available literature classifies this decorative element as an enamel technique. The highly specific type of red soda high-lead glass applied there was examined using LA-ICP-MS. Based on the trace elements detected, it can be established that the glass is most likely related to contemporary Egyptian production. Other items of the artefact set consist of two Münsingen brooches from Moravia and an exceptional brooch from Slovakia. The latter find was found to be decorated with coral (as confirmed by Raman spectroscopy). Besides identifying the materials of the decorations, we were also able to characterize the binder between individual decorative inlays and their metal base. The analysis of the binder has revealed the presence of birch tar (determined by FTIR and GC/MS). The results obtained expand the knowledge about the production technologies applied to the jewellery from the La Tène period.

Complicating the debate: Evaluating the potential of gas-chromatography-mass spectrometry for differentiating prehistoric aceramic tar production techniques

Birch bark tar was used extensively throughout human history. While later ceramic-based production technologies are known, prehistoric aceramic techniques leave little to no archaeological evidence. Experimental tar production attempts to fill this gap and suggest potential techniques. However, their archaeological relevance is unclear. Through an in-depth biomolecular analysis using Gas Chromatography-Mass Spectrometry, this study attempts to differentiate tars produced using four experimental aceramic techniques: condensation, ash mound, pit roll, and raised structure. In doing so we publish the largest collection of GC-MS results of aceramic birch tars. The results show that pentacyclic triterpenoids, characteristic of birch bark, vary between the production techniques in relation to heating exposure and perhaps the tar collection method. This allows for a tentative identification of tars produced through the condensation and ash mound techniques, which were formed consistently using short periods of heating and collected systematically by scraping. In contrast, tars produced using the pit roll and raised structure techniques do not have consistent molecular signatures. Despite the partial success of Gas Chromatography-Mass Spectrometry, the archaeological relevance is questioned because this technique is only applicable to samples from optimum lipid preservation conditions when a high number of pentacyclic triterpenoids are preserved. Therefore, using Gas Chromatography-Mass Spectrometry to determine the transformation methods of organics, like birch bark, may not be an appropriate standalone technique to fairly discuss the technological capabilities of past populations.

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.

Working Ethically with Ancient DNA from Composites in the United States

AbstractThis article discusses ethical frameworks for planning and implementing composite research in the United States. Composites, defined here as archaeological materials with multiple genetic sources, include materials such as sediment, coprolites, birch pitch, and dental calculus. Although composites are increasingly used in genetic research, the ethical considerations of their use in ancient DNA studies have not been widely discussed. Here, we consider how composites’ compositions, contexts, and potential to act as proxies can affect research plans and offer an overview of the primary ethical concerns of ancient DNA research. It is our view that ethical principles established for analyses of Ancestral remains and related materials can be used to inform research plans when working with composite evidence. This work also provides a guide to archaeologists unfamiliar with genetics analyses in planning research when using composite evidence from the United States with a focus on collaboration, having a clear research plan, and using lab methods that provide the desired data with minimal destruction. Following the principles discussed in this article and others allows for engaging in composite research while creating and maintaining positive relationships with stakeholders.

Characterization of bacterial biofilms developed on the biodegradable polylactide and polycaprolactone polymers containing birch tar in an aquatic environment

Birch tar was added to polylactide (PLA) and polycaprolactone (PCL) to create films with antimicrobial properties. After incubating the films for seven days in lake water, the diversity of bacterial communities developed on the surfaces of PCL and PLA with embedded birch tar (1 %, 5 %, and 10 %, w/w) was assessed with amplicon sequencing of the 16S rRNA gene on a MiSeq platform (Illumina). Notably, Aquabacterium and Caulobacter were more abundant at the surface of PCL compared to PLA (13.4 % vs 0.2 %, p < 0.001 and 9.5 % vs 0.2 %, p < 0.001, respectively) while Hydrogenophaga was significantly more abundant at the surface of PLA compared to PCL (6.1 % vs 1.8 %, p < 0.01). Overall, lower birch tar concentrations (1 % and 5 % on both polymers) stimulated bacterial diversity in biofilms compared to the control. The number of reeds assigned to Flavobacterium and Aquabacterium showed a rising trend with the increase of birch tar concentration on the surface of both polymers.

Polycaprolactone-Based Films Incorporated with Birch Tar-Thermal, Physicochemical, Antibacterial, and Biodegradable Properties.

We present new polymer materials consisting of polycaprolactone (PCL), polyethylene glycol (PEG), and birch tar (D). PEG was introduced into the polymer matrix in order to obtain a plasticizing effect, while tar was added to obtain antibacterial properties and to change the physicochemical properties of the film. The materials were obtained by the solvent method and characterized using a variety of methods to test their performance and susceptibility to biodegradation. The obtained data indicate that the introduction of the bioactive substance (D) into PCL improved the thermal stability and significantly lowered the Young's modulus values of the tested polymers. Moreover, the addition of birch tar improved the barrier and bacteriostatic properties, resulting in a reduction in the growth of pathogenic bacteria on the surface of the film. The films are not mutagenic but are susceptible to biodegradation in various environments. Due to their properties, they have potential for application in agriculture and horticulture and for packaging food, mainly vegetables grown in the field.

BONE POINTS IN TIME: DATING HUNTER-GATHERER BONE POINTS IN THE TERRITORY OF LITHUANIA

ABSTRACTBone points were one of the major hunting implements in northern European hunter-gatherer societies. They differ in shapes, types, and manufacturing techniques. In this paper, we investigate 22 bone points from the territory of Lithuania, by studying their morpho-technological characteristics, direct dates, and adhesive residues. The majority are isolated finds, but four points were selected from excavated archaeological sites dated between the 5th and 3rd millennia cal BC. Most of the points belong to the barbed points category, but six slotted points were also studied. Of the 22, 16 previously undated points were sampled for accelerator mass spectrometry radiocarbon (AMS 14C) dating. The results of 10 successfully dated samples are discussed together with previously published 14C dates of bone points from the same region. ATR-FTIR analysis of adhesive residues from six points suggest that birch bark tar was used to haft barbed points and lithic inserts. The results reveal the diversity of types of Early Holocene bone points in the territory of Lithuania, while the slotted and Kunda-type bone points fall into narrow timeframes.

Scaling Palaeolithic tar production processes exponentially increases behavioural complexity

Technological processes, reconstructed from the archaeological record, are used to study the evolution of behaviour and cognition of Neanderthals and early modern humans. In comparisons, technologies that are more complex infer more complex behaviour and cognition. The manufacture of birch bark tar adhesives is regarded as particularly telling and often features in debates about Neanderthal cognition. One method of tar production, the ‘condensation technique’, demonstrates a pathway for Neanderthals to have discovered birch bark tar. However, to improve on the relatively low yield, and to turn tar into a perennial innovation, this method likely needed to be scaled up. Yet, it is currently unknown how scaling Palaeolithic technological processes influences their complexity. We used Petri net models and the Extended Cyclomatic Metric to measure system complexity of birch tar production with a single and three concurrent condensation assemblies. Our results show that changing the number of concurrent tar production assemblies substantially increases the measured complexity. This has potential implications on the behavioural and cognitive capacities required by Neanderthals, such as an increase in cooperation or inhibition control.

Identifying Palaeolithic birch tar production techniques: challenges from an experimental biomolecular approach

The intentional production of birch bark tar by European Neanderthals as early as 190,000 years ago plays an important role in discussions about the technological and behavioural complexity of Pleistocene hominins. However, research is hampered because it is currently unknown how Neanderthals were producing birch tar. There are several different techniques that could have been employed, but these differ in their apparent production complexity, time and resource efficiency. Identifying production processes in the archaeological record is therefore paramount for furthering research on the technical behavioural repertoire. Organic biomarkers, identified with Gas Chromatograph–Mass Spectrometry (GC–MS), have been used to identify possible production processes during the Neolithic. Here we test whether these biomarkers can also distinguish Palaeolithic (aceramic) tar production methods. We produced tar using five different methods and analysed their biomolecular composition with GC–MS. Our results show that the biomarkers used to distinguish Neolithic tar production strategies using ceramic technology cannot be reliably used to identify tar production processes using aceramic Palaeolithic techniques. More experimentation is required to produce a larger reference library of different tars for future comparisons. To achieve this, complete GC–MS datasets must also be made publicly available, as we have done with our data.

Pyrotechnology and lipid biomarker variability in pine tar production

Tar or pitch produced from pine resin and wood played an important role in the past as an adhesive, waterproofing and medicinal product. However, the formation and biomolecular composition of pine tar produced only from resin under different combustion conditions (i.e., temperature and oxygen availability during heating) has not been as widely investigated as pine tar produced by dry distillation of wood or birch bark tar, for which an extensive literature is available. This lack of information hampers technological interpretations of biomolecular data obtained from organic residue analyses of archaeological pine tar products. In this study, we performed controlled laboratory heating sequences with pine resin (Pinus canariensis) at 150, 250, 350 and 450 ºC under both oxygenated and oxygen-limited conditions, and analyzed the products using gas chromatography-mass spectrometry (GC-MS). A control unheated resin sample was also analysed. We found that the formation of pine tar from resin occurs around 250–350 ºC under both oxygenated and oxygen-limited atmospheres. We also present and discuss the lipid biomarkers of pine resin and its combustion products according to changes in temperature and oxygen availability. Our reference data provide new information for the biomolecular identification of archaeological pine tar products and show potential for shedding light on the conditions in which tar was manufactured by ancient populations in different contexts.

The dynamic lives of osseous points from Late Palaeolithic/Early Mesolithic Doggerland: A detailed functional study of barbed and unbarbed points from the Dutch North Sea.

Osseous barbed and unbarbed points are commonly recovered from the Dutch North Sea and other Mesolithic sites of northern Europe. Interpreted as elements of projectile weaponry, barbed points are considered by archaeologists to be a technological innovation in the hunting equipment of hunter-gatherers. However, debate about their exact use and identification of the targeted prey species is still ongoing. To shed light on the function of these tools, we analysed a sample of 17 artefacts from the Netherlands with a multi-disciplinary approach encompassing morphometric, functional, and chemical analysis. 14C-AMS dating yielded the oldest date for a barbed point from the Dutch coast (⁓13000 cal. BP). The observation of microwear traces preserved on the tools provides solid evidence to interpret the function of barbed and unbarbed points. We show that there were two distinct tool categories. 1) Barbed points hafted with birch tar and animal or vegetal binding were likely projectile tips for terrestrial and aquatic hunting. We provide strong clues to support the link between small barbed points and fishing using wear traces. 2) Points without barbs served as perforators for animal hides. Our results highlight the importance of use-wear and residue analysis to reconstruct prehistoric hunting activities. The functional interpretation of projectile points must also rely on microwear traces and not merely on the association with faunal remains, historical sources, and ethnographic comparisons.

Microdestructive analysis with Py-GC/MS for the identification of birch tar: a case study from the Huayang site in late Neolithic China

Microdestructive analysis with Py-GC/MS for the identification of birch tar: a case study from the Huayang site in late Neolithic China

ЭКОЛОГИЧЕСКИ БЕЗОПАСНЫЕ ПРОДУКТЫ ДЛЯ ЗАЩИТЫ ОТ КОРРОЗИИ

The use of cheap, environmentally friendly natural products is especially important for the anti-corrosion protection of agricultural machinery and equipment. The studies were carried out on samples of carbon steel St3.Coatings from sunflower and rapeseed oils and their sediments; birch tar and its emulsion prepared with a homogenizer; decoctions of bifungin, black and green tea, coffee, oak bark, potato and beet peels, orange and banana peel, bay leaf, onion peel, field honey, sugar, currant berries, dried garlic, tobacco, black and red pepper, seasonings hops-suneli, celandine were studied. Gravimetric studies in a G-4 thermal moisture chamber, in a 0.5 M NaCl solution, in decoctions of natural products were used to assess the protective properties of natural products. in 0.5 M NaCl solution and 5-9% - in thermomoisture chamber G-4. The application of vegetable oils on a wet surface practically does not affect their protective effectiveness, and application on a rusty one (preliminarily oxidized for 1 month) leads to a significant decrease in the protective effectiveness of coatings: by 33 and 42% for sunflower and rapeseed oils, by 23 and 40% for their sludge, respectively. Sediments of vegetable oils completely protect the steel surface when tested in a saline solution for 3 months, in a G-4 thermal moisture chamber for 40 days, and in full-scale bench tests for a year. The tar emulsion protects the steel surface well enough in a saline solution. Ecologically safe decoctions of common natural products, such as bay leaf, black coffee, orange peel, dried garlic, ground black pepper can be recommended for effective protection of carbon steel from atmospheric corrosion for a short period.