Heat Treatment of Flint at the Late Neanderthal Site Sesselfelsgrotte (Germany)

We examined lithic artifacts from the late Neanderthal site Sesselfelsgrotte (Bavaria, Germany) in order to evaluate the possibility of fire use and intentional flint heat treatment performed by late Neanderthals. We analyzed 1113 flint pieces from the G-layer complex (~60 to 45 kya; Micoquian) and 946 from the lower-layer complex (~115 to 70 kya; Mousterian). Based on macroscopic traits associated with the exposure of flint to heat and fire, we assigned artifacts to one of three groups: burnt, unburnt, and possibly intentionally heated. Our results show that while both complexes demonstrate the clear presence of fire, fire is more common in the younger G-layer complex. Moreover, possibly intentionally heated pieces are significantly more frequent in the G-layer complex, especially among the tools and specifically among side scrapers, suggesting a link between heat treatment and the production of these tools, most probably due to their functional and cultural significance. We therefore suggest that the flint in the G-layer complex of Sesselfelsgrotte underwent intentional heat treatment. The proportions of burnt flint artifacts in both complexes suggest an intensification in fire use at the site over time, while the appearance of possibly intentionally heated artifacts in the G-layer complex suggests the development of this advanced pyrotechnology by Neanderthals sometime between these two timeframes. Our results are supported by sedimentological and faunal data. We view these results as further indication of the advanced cognitive and technological capabilities of Neanderthals, which did not fall short of those of early modern humans.