We started on the archaeological component of the project in 2019 with a study of a newly discovered large lump of Neanderthal tar adhering to a flint flake. The tar object originates from Doggerland, the currently submerged North Sea basin. PI contributed to the design of a comprehensive analytical workflow. We 1) established the age of the artefact and 2) its geological provenance, allowing us to ascertain Neanderthal authorship. We then 3) analysed the object chemically, allowing us to conclude it represents birch bark tar and 4) CT-scanned it. This led to a best-fit interpretation of the production technique Neanderthals used. The final publication (Niekus et al. 2019 PNAS) generated much academic and public interest. The find was featured among others in Dutch national newspapers, on BBC world service and in National Geographic magazine. A productive exchange of views in PNAS followed (Kozowyk et al. 2020; Schmidt et al 2019).
Since then we analysed Mesolithic bone harpoons from the same context. As with the Neanderthal tar, this represents a citizen science endeavour in collaboration with amateur archaeologists who found the objects. For this project an elaboration of the workflow applied to the Neanderthal tar was designed, with analysis now also including SEM, FTIR, Raman spectrography and XRD analysis. This represents an important comparative dataset for the Neanderthal tar. The bone points, a non-lithic material, also inform on whether different adhesive recipes are better suited to different materials. This has resulted in the presentation of initial results at academic conferences and a the Neanderthal tar find and a number of the harpoons with adhesives were featured in a major exhibition of the archaeology of Doggerland at the Dutch National Museum of Antiquities (RMO).
Experimental archaeology is one of the three information pillars of this project, next to the archaeological and ethnographic records experiments allows to check and test ideas. To ascertain the performance of adhesives on bone points, we conducted shooting experiments. In addition, we finalised so-called preservation experiments in which we tested if there is a bias in the adhesives that we find archaeologically. We found that tar preserves much better than resins and gums and this means that what archaeologists find and analyse now, is only a small and limited portion of what people in past used. Finally, we conducted a range of experiments on differing methods of the production of birch bark tar. The tar made in these experiments are part of our work flow study and chemical study into biomarkers; for example we hope to identify biomarkers that are characteristic for specific production methods.
In parallel, we have started adapting formal modelling methods used in business and industry to archaeological application. We focus on Petrie-net modelling. As proof-of-concept the modelling approach was first applied to an ethnographic case-study and the episode of experimental tar production. We found that by modelling a technological system, we can measure its complexity. The first modelling results were presented at several academic conferences. In the future this work will be expanded and we will compare different ways of Neanderthal tar production. Also we will recreate the production of other adhesive types, such as resin-based compound glues. We will further apply our modelling approach on published ethnographic data, and specifically our compiled ethnographic database of adhesive production and use, which currently contains 800 entries. In the future we will also record and model traditional adhesive production in Zambia. These observations will fine tune the Petri nets models.
This work stimulated the consolidation of knowledge of adhesive use throughout human history and the analytical tools available to researchers to determine adhesive composition and production processes. This has resulted in the contribution of an extended encyclopaedic lemma (Langejans et al. in press, Oxford Research Encyclopedia Anthropology).
