## 2 Materials and Methods  
### Samples  
A wide range of samples available in an experimental reference collection were tested (Table 1). These samples were chosen based on availability and based on the types of samples and materials typically encountered during an archaeological recovery. Residues were from modern samples which were either collected directly (_i.e._, from plants or animals) or were collected from experimental stone tools. The former were immediately placed in vials for analysis. The latter were derived from modern reproducations of archaeological stone tools, which were used in modern settings for a range of activities relevant for prehistoric lifeways (e.g., hunting, butchering, hideworking, _etc._). In order to extract the residues from these stone tools, two types of commonly used extraction techniques [25; 26] were investigated. Water extraction was performed by pipetting 4 \(\mu\)L of distilled water onto the surface of the item, agitating the liquid with the pipette tip, and then reaspirating the water into a headspace vial. Solvent extraction was also performed in the same manner but using a mixture of ethanol (VWR collection, Fontenay-sous-Bois, France), distilled water (Delhaize, Liege, Belgium), and acetonitrile (Merck Millipore, Darmstadt, Germany) in a 1:1:1 ratio. Pipetting was performed with a Transferpette(r) S (VWR International, Leuven, Belgium) with polypropylene tips. Water extraction with ultrasonication was also performed on some samples which involved placing the material in a weigh boat with 5 mL of distilled water and performing ultrasonication (Elmasonic P 120 H, Elma, Singen, Germany) for 5 min at 37 kHz, after which the liquid and material were poured into a headspace vial. A full description of extractions and treatments performed to prepare sample vials is shown in Table 1. All samples were prepared in 20 mL screw cap headspace vials with 1.3 mm PTFE septa (Gerstel(r), Kortrijk, Belgium). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample Name** & **Mode of Preparation** & **Approximate Age (If Known)** \\ \hline Ivory (dry) & Water extraction & 3 years \\ Ivory powder & Manually placed in vial & \\ Bone (dry) & Water extraction & 3 years \\ Bone powder & Manually placed in vial & \\ Sediment \& bone powder & Mixture of sediment and powder manually & \\  & placed in vial & \\ Meat \& starch & Water extraction & \\ Meat \& starch & Water extraction/ultrasonic bath & \\ Meat, blood \& fat & Water extraction & \\ Meat, blood \& fat & Solvent extraction & \\ Sample name & Mode of preparation & Approximate age (if known) \\ Hide (fresh) & Water extraction & 4 months frozen \\ Hide (fresh) & Solvent extraction & 4 months frozen \\ Hide (fresh) & Piece manually placed in tube & 4 months frozen \\ Hand residue 1 & Water extraction & \\ Hand residue & Solvent extraction & \\  & 1:1 mixture prepared by heating until liquid & \\ Resin 2 \& beeswax 3 mixture & and mixing together, 2 g of final mixture & \\  & was manually placed in vial & \\ Resin \& beeswax mixture & Prepared as above but heated for an & \\ (Heated 1 h) & additional 1 h after mixing & \\ Plastiline 4 & Water extraction & \\ Antler & Water extraction & \\ Leather from binding & Water extraction & \\ Sediment & Water extraction/ultrasonic bath & 33,000 years \\ Blank vial & N/A & \\ \hline \hline \end{tabular}  
* Hand residue: A stone tool was handled by the researcher without gloves and an extraction was taken afterwards; 2 Picea abies resin, Natural, Rochefort, Belgium; 3 Beeswax, Natural, Rochefort Belgium; 4 Plastiline, [PERSON], Paris France.  
\end{table} 
Table 1: Preparation of sample vials containing organic residue prior to SPME sampling. Although the residues were from modern references, a sediment sample on an ancient stone tool was also analyzed. This sample was derived from a stone tool found in a stratified cave site in a layer dated to approximately 33,000 years ago.