Production method of the Königsaue birch tar documents cumulative culture in Neanderthals

Abstract

Birch tar is the oldest synthetic substance made by early humans. The earliest such artefacts are associated with Neanderthals. According to traditional interpretations, their study allows understanding Neanderthal tool behaviours, skills and cultural evolution. However, recent work has found that birch tar can also be produced with simple processes, or even result from fortuitous accidents. Even though these findings suggest that birch tar per se is not a proxy for cognition, they do not shed light on the process by which Neanderthals produced it, and, therefore, cannot evaluate the implications of that behaviour. Here, we address the question of how tar was made by Neanderthals. Through a comparative chemical analysis of the two exceptional birch tar pieces from Königsaue (Germany) and a large reference birch tar collection made with Stone Age techniques, we found that Neanderthals did not use the simplest method to make tar. Rather, they distilled tar in an intentionally created underground environment that restricted oxygen flow and remained invisible during the process. This degree of complexity is unlikely to have been invented spontaneously. Our results suggest that Neanderthals invented or developed this process based on previous simpler methods and constitute one of the clearest indicators of cumulative cultural evolution in the European Middle Palaeolithic.

Reply to: Problems with two recent Petri net analyses of Neanderthal adhesive technology

“…Looking forward, larger and more diverse datasets can feed and refine in-silico models like ours to answer questions that are difficult to explore with individual experimental designs. In that light, we are happy to see that recent experimental and archaeological work by Schmidt and Tennie 18 confirms our theoretical expectations about the evolution of technology.…”

Ochre-based compound adhesives at the Mousterian type-site document complex cognition and high investment

“…We therefore attempted to identify other possible performance gains of a high ochre load in bitumen. It is known from Neanderthal birch tar finds ( 5 , 32 ) that adhesives were used as handles directly attached to stone tools (as opposed to being used for hafting stone tools to wooden handles or shafts). We therefore molded handles of fresh bitumen to stone tools ( Fig.…”

“…Alternatively, what are the implications if these compound adhesives were made by Neanderthals? It has recently been shown that Neanderthal birch tar making relied on the cumulative cultural transmission of techniques ( 32 ). This was proposed to be one of the core criteria for understanding ancient adhesives as proxies of evolutionary processes ( 12 ).…”

“…The implications of Neanderthal birch tar are still debated [compare ( 27 , 28 )], but what is certain is that Neanderthals made the effort to produce it, although other adhesive substances could simply have been collected in nature [see the discussion in ( 9 , 29 , 30 )]. Thus, similarly to the modern human record from Africa, the known European adhesive technology documents innovative behavior and even cumulative cultural transmission of techniques ( 31 , 32 ). In addition, from the Gravettian on and in later periods, there are indications that European H. sapiens made compound adhesives using ochre ( 24 , 25 ), a behavior similar to that of early H. sapiens in Africa.…”

Problems with two recent Petri net analyses of Neanderthal adhesive technology

“…It was not claimed that the amount of cobbles tested in that study (three) were actually used—and in this way—by Neanderthals. And indeed, it has recently been shown 6 that Neanderthals made birch tar with an elaborate underground technique that was most likely the improvement of an earlier aboveground technique. Thus, a specific claim that the condensation method “likely needed to be scaled up” 2 is not rooted in archaeological data.…”