Experimental methods for the Palaeolithic dry distillation of birch bark: implications for the origin and development of Neandertal adhesive technology

P R B Kozowyk,D Pomstra,G H J Langejans,M Soressi

doi:10.1038/s41598-017-08106-7

Abstract

The destructive distillation of birch bark to produce tar has recently featured in debates about the technological and cognitive abilities of Neandertals and modern humans. The abilities to precisely control fire temperatures and to manipulate adhesive properties are believed to require advanced mental traits. However, the significance given to adhesive technology in these debates has quickly outgrown our understanding of birch bark tar and its manufacture using aceramic techniques. In this paper, we detail three experimental methods of Palaeolithic tar production ranging from simple to complex. We recorded the fuel, time, materials, temperatures, and tar yield for each method and compared them with the tar known from the Palaeolithic. Our results indicate that it is possible to obtain useful amounts of tar by combining materials and technology already in use by Neandertals. A ceramic container is not required, and temperature control need not be as precise as previously thought. However, Neandertals must have been able to recognize certain material properties, such as adhesive tack and viscosity. In this way, they could develop the technology from producing small traces of tar on partially burned bark to techniques capable of manufacturing quantities of tar equal to those found in the Middle Palaeolithic archaeological record.

Highlights

The manufacture and use of adhesives for hafting has become a focal point in the debate about the cognitive and technological capabilities of Neandertals and early modern humans[1,2,3,4,5,6,7]
The significance that birch tar production is given in debates about Neandertal and modern human technology and cognition has outgrown our knowledge of the material and its production processes
We present an experimental study testing the dry distillation of birch bark to produce tar using variations of previously explored potential Palaeolithic techniques: the ‘ash mound’ (AM) method[19], the ‘pit roll’ (PR) or cigar roll method[11, 23, 24], and the ‘raised structure’ (RS) method[16,17,18, 20, 25, 26]

Summary

Introduction

The manufacture and use of adhesives for hafting has become a focal point in the debate about the cognitive and technological capabilities of Neandertals and early modern humans[1,2,3,4,5,6,7]. We present an experimental study testing the dry distillation of birch bark to produce tar using variations of previously explored potential Palaeolithic techniques: the ‘ash mound’ (AM) method[19], the ‘pit roll’ (PR) or cigar roll method[11, 23, 24], and the ‘raised structure’ (RS) method[16,17,18, 20, 25, 26] We assessed these production methods in three ways: 1) Yield – time and fuel spent versus tar quantity obtained, 2) Temperature – required degree of temperature control to successfully produce tar, 3) Complexity – number of individual components (cf technounits27) and the number of steps[28] required to produce tar.

Methods

Results

Discussion

Conclusion