Skip to main content

Ancient Adhesives - A window on prehistoric technological complexity

Periodic Reporting for period 2 - AncientAdhesives (Ancient Adhesives - A window on prehistoric technological complexity)

Reporting period: 2020-08-01 to 2022-01-31

How when and why did complex cognition develop in humans and our extinct cousins? This is one of the main research problems in the study of human evolution. Archaeology is the only field that can contribute data on the functioning of human minds in the human past. One of the main approaches is the reconstruction of technological procedures performed by hominins. Adhesives represent an understudied material. Its production and its function, enabling among others composite tools, make it a central candidate to study the most complicated procedures performed by Palaeolithic people.
The AncientAdhesives projects aims to create a new method to analyse technological complexity in the archaeological record. We do this by collecting and creating as much data as we can on the production and use of adhesives from 1) ethnographic settings, 2) experimental reproductions, and 3) archaeological data from Europe and South Africa. The data provides a window on the technological prowess of not only Homo sapiens but also Neanderthals. In the second phase of the project we will model the data using Petri nets, and we will compare different production systems. Using complexity metrices from the Petri net method we aim to also link technology to specific cognitive functions. This project represents a comprehensive approach to understand the exact technological complexity of prehistoric glues.
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).
The analysis of the Neanderthal tar has allowed us to gain important insight not only in their capacity for complex technological know-how. From our analysis we could test two competing hypothesis on the circumstances under which complex technology develops and is maintained. This find supports the hypothesis of complex technology functioning to mitigate technological risk as it was produced during a very cold and climatically unstable part of the last Ice Age. It refutes the idea that complex technology arises in large groups that are less nomadic, as the date and geological context demonstrate the find was produced by Neanderthals living in small groups at the edge of their ecological tolerance. Our interpretation also stimulated academic debate and innovation by other teams. This demonstrates the great scientific impact of the work. In the future we will analyse more archaeological datasets with this approach, making similar contributions.
The project has also made important methodological advances in designing an optimal workflow for the maximally non-destructive analysis of a rare archaeological find category. Our procedure, having been tried and tested in an academic setting can be adopted by societal partners. We are currently involved in a pilot scheme involving a commercial archaeology company who excavated a small adhesive find in a terminal Palaeolithic/early Mesolithic context to further develop this aspect of the project. The testing of biomarkers will be expanded in the future, with the aim of identifying different archaeological production methods and illuminating the preservation of biomarkers. The data on the characterization of adhesives will be freely shared and will fast-track the analysis of archaeological adhesives.
Finally, the first results of the Petri net modelling show it this approach can be used to study technology is an explicit manner. Petri nets can be applied to archaeology and moreover we were able to link the complexity matrices to cognitive abilities. For example, the density and cyclomatic indices allow us to connect the behaviour of technological systems to working memory and concurrency. This is the first time that we can express cognition in archaeological technology. The AncientAdhesives project also started a collaboration with cognitive roboticists, creating an ontology for tool use. By incorporating this novel approach we will be able to study planning depth in technological behaviours. Both these developments are central to the project and will be expanded in the future. By the end of the project we will have delivered two new archaeological approaches/method.
Birch tar on a stone tool, result from a tar production experiment
For the publication of Neanderthal tool with tar in PNAS we provided the journal cover
Testing adhesives, R-L: shooting apparatus, velocity meter, ballistic jelly with arrow
Close observations of experimental tar production
A Doggerland bone point mounted for analysis in a scanning electron microscope