Cueva de El Toro

Fifty vessels from phase IV (5280-4780 2σ cal BC) and sub-phase IIIb (4250-3950 2σ cal BC) from the cave of Cueva de El Toro were analysed. Of the 24 sherds were animal fats were detected (48%), 14 come from phase IV and 10 from sub-phase IIIB. A total of 18 samples (11 samples from phase IV and 7 samples from sub-phase IIIB) were extracted by solvent extraction (TLE mean = 27.87 μg·g^-1), while 6 samples (3 samples from phase IV and 3 samples from sub-phase IIIB) were re-extracted by using acidified methanol

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(TLE mean = 542.53 μg·g^-1). Among the biomarkers identified, the presence of animal fats, vegetables and resins has been detected inside the containers.

In samples CTM01 and CTM04, polycyclic polyaromatic hydrocarbons (PAHs), such as Anthracene and Phenanthrene, were identified. These volatile compounds are produced during the combustion of woody products over 300ºC (Kilops and Kilops 2005). In the case of Cueva de El Toro, the traces amount of PAHs could be related to the exposure of the container and its contents to a heat source, but in the absence of ketones that con-firm the heat treatment of fats, we believe that PAH can come from exogenous contam-ination with the sediment.

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Table 5.6. Organic residues analysis from Cueva de El Toro results. Abbreviations stand for: FA, fatty acids;

TLE, total lipid extract; AMS, accelerator mass spectrometer.

C16:0

±0,3 (‰ ) C18:0

±0,3 (‰ )

CTM03 11,36 FA (16<18);

PAHs: phenanthrene, anthracene -31,28 -32,94 Ruminant adipose fat

CTM07 9,13 FA (16<18, 10, 12, 14) -27,65 -25,18 Non-ruminant adipose fat

CTM11 12,83 FA (16<18, 8, 10, 12, 14) -24,07 -24,69 Non-ruminant adipose fat

CTM12 32,84 FA (16>18, 12, 14, 18:1) -23,82 -22,31 Non-ruminant adipose fat

CTM16 22,4 FA (16>18) -26,46 -26,61 Non-ruminant adipose fat

CTM24 35,97 FA (16>18) -31,65 -27,14 Non-ruminant adipose fat

CTM32 78,4 FA (16<18, 10, 12, 14, 20);

MAGs, DAGs, TAGs -26,75 -30,13 Non-ruminant adipose fat

CTM33 14,93 FA (16<18) -27,58 -24,39 Non-ruminant adipose fat

CTM35 58,41 FA (16<18) -24,76 -23,88 Non-ruminant adipose fat

CTM41 43,69 FA (16<18) -27,14 -26,01 Non-ruminant adipose fat

CTM42 15,3 FA (16<18) -27,76 -27,54 Non-ruminant adipose fat

CTM43 834,48

CTM44 325,3 FA (8, 10, 12, 14, 16>18, 16:1, 18:1);

Diterpens: dehydroabietic acid, abietic acid -30,56 -32,43 Ruminant adipose fat Pine Resin

CTM51 722,11 FA (14, 16>18, 20) -27,55 -30,44 Dairy fat

CTM01 40,07 FA (16<18) -28,61 -30,03 Ruminant adipose fat

CTM04 374,25

CTM09 46,46 FA (16<18) -25,95 -25,73 Non-ruminant adipose fat

CTM13 21,31 FA (16>18, 12, 14, 18:1) -28,18 -30,20 Ruminant adipose fat

CTM38 537,2

CTM40 40,65 FA (16<18) -25,82 -23,88 Non-ruminant adipose fat

CTM46 53,22 FA (16<18) -27,82 -28,33 Ruminant adipose fat

CTM49 33,84 FA (16<18) -27,56 -28,84 Ruminant adipose fat

CTM50 78,36 FA (16<18) -29,31 -30,37 Ruminant adipose fat

IIIB (4250-3950

186 5.3.2.1. Animal fats

In 14 samples from phase IV the presence of high concentrations of palmitic (C16:0) and stearic acid (C18:0) were detected. These fatty acids are usually in the greatest abundance in archaeological lipid extracts with an even carbon number preference. Lipid profiles dominated by these fatty acids have been often observed in degraded animal fats (Cop-ley et al. 2001). The presence of TAGs in the CTM32 sample, although in very low con-centrations, allows the animal origin of the fats to be assured. In general, the P/S ratio is very balanced, with the exception of samples CTM12, CTM43, CTM44, CTM04, CTM13 and CTM38, although they also present biomarkers of vegetable origin.

To provide more specific information, 24 sherds with the most abundant C16:0 and C18:0

acids were selected for GC-C-IRMS analyses with the aim of distinguishing the origins of these compounds based on their stable carbon isotope value (δ¹³C).

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Figure 5.22. Scatter plot with δ¹³C values of the C16:0 and C18:0 fatty acids from Cueva de El Toro site com-pared with δ¹³C values from modern reference animal fat. Top figure corresponds to Phase IV, and bottom figure corresponds to sub-phase IIIb.

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The situation in the scatter plot of the obtained values of δ¹³C16:0 and δ¹³C18:0 is com-pared with the modern animal fats from Iberian Peninsula. The situation in the scatter plot of the values obtained in the archaeological samples in relation to the modern val-ues of lipids, allows to determine the origin of the identified lipids. The results of the δ¹³C values (Figure 5.22 top) reveal that sherds from phase IV dominates the consump-tion of pig adipose fats (samples CTM07, CTM11, CTM12, CTM16, CTM24, CTM33, CTM35, CTM41, CTM42 and CTM43), followed by the consumption of domestic rumi-nants adipose fats (samples CTM03 and CTM44) and dairy product fats (samples CTM32 and CTM51).

In 10 sherds from sub-phase IIIb animal fatty acids (predominated by C16:0 and C18:0) were detected. From the determination of the isotopic value of the carbon from fatty acids (δ¹³C) (Figure 5.22 bottom), it can be seen that in sub-phase IIIB, predominate those that have fatty fats of ruminant adipose fats (samples CTM01, CTM05, CTM13, CTM38, CTM46, CTM49 and CTM50), being lower the presence of sherds containing non-rumi-nant adipose fats (samples CTM04, CTM09 and CTM40).

5.3.2.2. Plant lipids

Plant biomarkers have also been identified in samples CTM04, CTM05 and CTM38 from phase IIIb. The characterisation of plant products has been possible thanks to the high concentration of these samples of palmitic acid (C16:0) and oleic acid (C18:1), as well as the vegetal sterols Ergosta-5,22-dien-3-ol, Stigmastam-3,5-dien, Stigmasterol y β-sitos-terol (Evershed et al. 1991; Cert et al. 1994).

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Figure 5.23. GC-MS chromatogram of the CTM04 sample extracted by H2SO4: MeOH.

Vegetable oils are present in large quantities in certain seeds or fruits (Marinval 2005;

Evershed and Lockheart 2007). In sub-phase IIIB of Cueva de El Toro a large number of carbonised cereal seeds and legumes were found, as well as wild fruits, such as olives, acorns and myrtle and poppies (Papaver somniferum ssp. Somniferum), which, in addi-tion to its use as a synanthropic plant, the possibility of using its seeds to obtain oil is also pointed out (Buxó 2004; Guerra-Doce and López-Sáez 2006; Rovira-Buendía 2007;

Martín-Socas et al. 2018). The biomarkers of vegetable oils preserved in the vessels of Cueva de El Toro could be evidence of the processing of some of these species, which could have been roasted, boiled or bathed in water (Hally 1986; Amouretti 2005; Mason and Nesbitt 2009). These procedures allow eliminating the toxic tannins of some fruits, making them suitable for human consumption (Saul et al. 2012).

In the samples of Cueva de El Toro in which substances with vegetable origin have been identified, the presence of animal fats has also been detected. This makes possible to raise the possibility that the mixture of these products could have been intentional with

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the purpose to enhance the taste of food, some containers were used in the processing of various products at different times.

5.3.2.3. Resin

In samples CTM43 and CTM44, where non-ruminant and ruminant fats have been tected respectively, biomarkers of vegetable resin have also been identified, such as de-hydroabietic acid and abietic acid (figure 5.24). The natural resins are exudates from the tree that, in certain cases and when are exposed to the light and air for a long period of time, undergo an oxidation process, as happens for example with pine resin (Azemard et al. 2016). The same oxidation effect can also occur when the resins are exposed to a heat source (Marchand-Geneste 2003). The oxidation process causes the apparition of specific compounds (diterpenes and dehydroabietic acid) which serve as biomarkers of vegetal resins.

Figure 5.24. Partial gas chromatogram of the trimethylsilylated TLEs from CTM44 pottery sample show-ing the various biomarkers detected: animal fats (FAx:y are fatty acids where x is the carbon chain length and y is the degree of unsaturation), pine resin (dehydroabietic and abietic acid) and contami-nation from plants and handling (unsaturated fatty acids and *A are a long chain of alkanes, with odd-numbered carbon dominance).

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The characterization of the abietic acid, dehydroabietic acid and 7-oxo-dehydroabietic acid in the potsherds analysed indicate that the dehydrogenation of the compounds ex-plains the application of more than 110ºC to melt the resin and to be able to apply it on the surface as a post-cooking treatment in order to waterproof the walls of the sherds (Charters et al. 1995, Pietrzak, 2012) in order to develop an effective use probably re-lated to the storage or processing of animal fats in liquid or semiliquid state (Correa-Ascencio et al. 2014).

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Chapter VI. Subsistence and product acquisition strategies