Birch tar production does not prove Neanderthal behavioral complexity

Abstract

Birch tar production by Neanderthals—used for hafting tools—has been interpreted as one of the earliest manifestations of modern cultural behavior. This is because birch tar production per se was assumed to require a cognitively demanding setup, in which birch bark is heated in anaerobic conditions, a setup whose inherent complexity was thought to require modern levels of cognition and cultural transmission. Here we demonstrate that recognizable amounts of birch tar were likely a relatively frequent byproduct of burning birch bark (a natural tinder) under common, i.e., aerobic, conditions. We show that when birch bark burns close to a vertical to subvertical hard surface, such as an adjacent stone, birch tar is naturally deposited and can be easily scraped off the surface. The burning of birch bark near suitable surfaces provides useable quantities of birch tar in a single work session (3 h; including birch bark procurement). Chemical analysis of the resulting tar showed typical markers present in archaeological tar. Mechanical tests verify the tar’s suitability for hafting and for hafted tools use. Given that similarly sized stones as in our experiment are frequently found in archaeological contexts associated with Neanderthals, the cognitively undemanding connection between burning birch bark and the production of birch tar would have been readily discoverable multiple times. Thus, the presence of birch tar alone cannot indicate the presence of modern cognition and/or cultural behaviors in Neanderthals.

Middle Paleolithic complex technology and a Neandertal tar-backed tool from the Dutch North Sea

“…To date, 4 methods of tar production, increasing in procedural complexity, have been successfully trialed: condensation, ash mound, pit and vessel, and a raised structure composed of an earthen mound containing a vessel and screen (8,40). Increasing procedural complexity directly relates to increased tar yield efficiency (SI Appendix, Table S1 and Fig.…”

“…To make the amount of tar found at the Zandmotor is feasible with each method, but the simple methods would take considerably more time and energy. The simple methods, and the condensation method in particular (8), provide an excellent explanation for the origin and discovery of birch tar and offer suitable methods of producing small quantities of tar when birch resources are plentiful. However, the latter technique would require 40 times as much bark as the raised structure and would take roughly 10 h to produce the Zandmotor tar (8,40).…”

“…The simple methods, and the condensation method in particular (8), provide an excellent explanation for the origin and discovery of birch tar and offer suitable methods of producing small quantities of tar when birch resources are plentiful. However, the latter technique would require 40 times as much bark as the raised structure and would take roughly 10 h to produce the Zandmotor tar (8,40). Similarly, in a Late Pleistocene open woodland (41), compared with the most complex method, the ash mound requires nearly twice as long to collect the firewood and 10 times as much birch bark, which takes 10 times longer to distill (40, 42) (SI Appendix, Table S1).…”

“…Examples are recent advances in our understanding of Neandertal pyrotechnology (4) and the use of multicomponent tools that rely on hafting and adhesives (5,6). However, despite this mounting evidence, the degree of Neandertal technological innovation is still under debate (7,8). This discussion is complicated, as it is not always specified why a certain behavior or technology is considered complex.…”

When Lithics Hit Bones: Evaluating the Potential of a Multifaceted Experimental Protocol to Illuminate Middle Palaeolithic Weapon Technology

“…Projectile technology permits the targeting of a broader variety of large and medium-sized terrestrial game; importantly, however, it also mitigates against risk by allowing the killing of potentially dangerous prey animals at a distance. In addition, the often complex operational and technological sequences required in the production of different projectile technologies can potentially illustrate the social and cognitive organisation of Palaeolithic groups (Shea 2006;Churchill and Rhodes 2009;Shea and Sisk 2010;Sisk and Shea 2011;Lombard and Haidle 2012;Haidle et al 2016;Iovita and Sano 2016; but see also Schmidt et al 2019;Smith et al 2019).…”