Understanding preservation and identification biases of ancient adhesives through experimentation

Paul R B Kozowyk,Annelou L Van Gijn,Geeske H J Langejans

doi:10.1007/s12520-020-01179-y

Abstract

Adhesive production is one of the earliest forms of transformative technology, predating ceramics and metallurgy by over 150,000 years. The study of the adhesives used by Neandertals and early modern humans currently plays a significant role in debates about human technological and cognitive evolution. Depending on the type of adhesive used, different production sequences were required. These can vary in complexity and would have needed different knowledge, expertise, and resources to manufacture. However, our knowledge of this important technological development is severely hampered by poorly understood taphonomic processes, which affects the preservation and identification of adhesive materials and leads to a research bias. Here we present the results from a 3-year field preservation experiment. Flint flakes hafted and non-hafted with replica adhesives were left to weather naturally on and below the surface at two locations with different soils and climatic conditions. Differential preservation was recorded on a variety of natural adhesives by digitally measuring the surface area of each residue before and after the elapsed time. Residues were further assessed and photographed using metallographic optical microscopy. Results show that certain adhesives preserve to a significantly higher degree than others, while some materials may be more easily overlooked or visually misdiagnosed. We must therefore be aware of both taphonomic and identification biases when discussing ancient adhesive technology. This research provides a first look that will help us understand the disparities between which adhesives were used in the past and what we find in the archaeological record today.

Highlights

Adhesives and hafting have recently become the focus of intense study within the field of Palaeolithic archaeology
The results are first divided into two main categories based on the location of the experiment: those conducted at Horsterwold in the Netherlands and those conducted at Forensic Anthropology Research Facility (FARF) in the USA
The adhesives with the second highest preservation index are what we find archaeologically from the Middle Palaeolithic and Middle Stone Age; only these are found considerably later than the oldest known birch bark tar (CharriéDuhaut et al 2013; Degano et al 2019)

Summary

Introduction

Adhesives and hafting have recently become the focus of intense study within the field of Palaeolithic archaeology. Both securely dated and chemically identified Middle Palaeolithic hafting adhesives include material from just seven locations: Campitello Quarry, Fossellone and Sant’Agostino caves, Italy; Konigsaue, Germany; Zandmotor, the Netherlands, and Hummal and Um el Tlel, Syria (Boëda et al 2008a; Degano et al 2019; Hauck et al 2013; Koller et al 2001; Mazza et al 2006; Niekus et al 2019). Adhesive remains from the Middle Stone Age in Africa are rare and include Diepkloof Rock Shelter (CharriéDuhaut et al 2013), Sibudu (Villa et al 2015), and Border caves (Villa et al 2012). Many residues lack secure chemical identification of organic remains and instead are inferred based on the presence of use-wear and/or inorganic residues, such as ochre, which is believed to have been a component of compound adhesives to improve strength (Kozowyk et al 2016)

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Results

Discussion

Conclusion