TraceoLab / Préhistoire

Two primary fire production methods are known from antiquity: wood-on-wood friction and stone-on-stone percussion. The more durable elements of the latter system (i.e. flint and pyrite/marcasite, aka sulphuric iron) are more likely to preserve in archaeological contexts. Yet, known evidence of fire making using flint “strike-a-lights” and sulphuric iron drops off precipitously the further back in the archaeological record one looks, especially as one enters the Palaeolithic. This is most true for the Middle Palaeolithic (and earlier), when evidence of artificial fire making is virtually unknown, though often assumed due to the regular presence of fire traces on Neandertal sites. Is this paucity of fire making tools attributable to an inability to make fire, taphonomic bias, or perhaps technological variability? We propose it is the latter via the “expedient strike-a-light model”, which asserts early fire-making tools were likely used on an ad hoc basis for only a short period of time prior to being discarded. This stands in stark contrast to the more “classic” curated strike-a-lights recovered from Neolithic and Bronze Age contexts that show very heavy use traces, indicative of multiple episodes of use. To lend credence to this model, we look to an a-typical Levallois point from the Middle Palaeolithic (MIS 5) site of Bettencourt (northern France), which is the oldest known tool described in the literature as bearing fire-making traces (after undergoing modern microwear analysis). Until now, systematic testing of the veracity of the interpretation of the Bettencourt piece as a strike-a-light against experimental data has not been performed. Our data show that the use traces observed on the Bettencourt piece can be closely replicated experimentally, both macro- and microscopically, by striking the lateral edge of an elongated flake against a sulphuric iron nodular fragment to produce sparks.

Residue analysis has become a frequently applied method for identifying prehistoric stone tool use. Residues adhering to the stone tool with varying frequencies are interpreted as being the result of an intentional contact with the worked material during use. Yet, other processes during the life cycle of a stone tool or after deposition may leave residues and these residues may potentially lead to misinterpretations. We present a blind test that was designed to examine this issue. Results confirm that production, retouch, prehension, haft-ing, various incidental contacts during use and deposition may lead to residue depositions that significantly affect the accurateness of identifications of tool-use. All currently applied residue approaches are concerned. We therefore argue for a closer interaction with independent wear studies and a step-wise procedure in which a low magnification of wear traces is used as a first step for selecting potentially used flakes in archaeological contexts. In addition, residue concentrations on a tool's edge should be sufficiently dense before linking them with use.

Headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) have traditionally been used, in combination with other analyses, for the chemical characterization of organic residues recovered from archaeological specimens. Recently in many life science fields, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCˆGC-TOFMS) has provided numerous benefits over GC-MS. This study represents the first use of HS-SPME-GCˆGC-TOFMS to characterize specimens from an experimental modern reference collection. Solvent extractions and direct analyses were performed on materials such as ivory, bone, antlers, animal tissue, human tissue, sediment, and resin. Thicker film column sets were preferred due to reduced column overloading. The samples analyzed by HS-SPME directly on a specimen appeared to give unique signatures and generally produced a higher response than for the solvent-extracted residues. A non-destructive screening approach of specimens may, therefore, be possible. Resin and beeswax mixtures prepared by heating for different lengths of time appeared to provide distinctly different volatile signatures, suggesting that GCˆGC-TOFMS may be capable of differentiating alterations to resin in future studies. Further development of GCˆGC-TOFMS methods for archaeological applications will provide a valuable tool to uncover significant information on prehistoric technological changes and cultural behavior.