TECHNOLOGY

Birch Tar, the First Synthetic Glue

~200,000 years ago

Palaeolithic · Middle Stone Age · MIS 7

Birch tar is a black, sticky substance obtained by heating birch bark away from the air, which bark does not release on its own; it is the oldest synthetic material known to have been made by early humans. The oldest pieces come from Campitello, in Tuscany: two flint flakes partly coated with tar, taken from a river deposit of gravel and clay, close to the bones of a young adult straight-tusked elephant. Neither flake was dated directly. The small mammals found with them and the geology of the bed place them in a cool episode preceding marine isotope stage 6, at the end of stage 7, hence around 200,000 years. Later finds show how such tar was obtained. Chemical comparison of the two lumps from Königsaue, in Germany, with tars made by Stone Age techniques indicates distillation in a purpose-dug underground setting, closed to the air and invisible while it ran.

Why it matters

Hafting alters what a sharp edge can do: held in the hand it cuts, fixed to a shaft it becomes a spear or an axe, and the force of an arm reaches a point. Tar makes that joint. The material also carries an argument about Neanderthal minds, and the argument has turned twice. Making tar was first read as proof of planning and fire control, a sealed vessel and a narrow temperature range seeming necessary; experiment then showed that useful quantities come from much simpler arrangements. The Königsaue analysis turned it back: the simple method existed, and was not the one used.

Dating & uncertainty

Nothing dates the Campitello flakes directly. Their position is read from the small mammals found with them and from the geology of the bed, which indicate a cool episode before marine isotope stage 6, the assemblage being attributed to the end of stage 7, hence about 200,000 years, within a bracket running from 250,000 to 180,000. What hangs on it is the antiquity of the technique and not its existence, which the chemistry of the Königsaue pieces establishes. A younger attribution would cancel the only evidence that tar was already being made before stage 6.

Sources

1. Mazza et al. (2006), Journal of Archaeological Science · A new Palaeolithic discovery: tar-hafted stone tools in a European Mid-Pleistocene bone-bearing beddoi:10.1016/j.jas.2006.01.006
2. Villa et al. (2016), PLOS ONE · The Acheulian and Early Middle Paleolithic in Latium (Italy): Stability and Innovationdoi:10.1371/journal.pone.0160516
3. Kozowyk et al. (2017), Scientific Reports · Experimental methods for the Palaeolithic dry distillation of birch bark: implications for the origin and development of Neandertal adhesive technologydoi:10.1038/s41598-017-08106-7
4. Schmidt et al. (2023), Archaeological and Anthropological Sciences · Production method of the Königsaue birch tar documents cumulative culture in Neanderthalsdoi:10.1007/s12520-023-01789-2

Our species’ history as one day

08:45:4215 h 14 min before midnight

if the 315,000 years of Homo sapiens were compressed into a single day