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Journal of Archaeological Science 42 (2014) 456e466

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Journal of Archaeological Science

journal homepage: http: / /www.elsevier .com/locate/ jas

The missing crop: investigating the use of grasses at Els Trocs, aNeolithic cave site in the Pyrenees (1564 m asl)

Carla Lancelotti a,b,*, Andrea L. Balbo b, Marco Madella b,c, Eneko Iriarte d,Manuel Rojo-Guerra e, José Ignacio Royo f, Cristina Tejedor g, Rafael Garrido h,Iñigo García i, j, Héctor Arcusa k, Guillem Pérez Jordà a, Leonor Peña-Chocarro a,l

aGI Arqueobiología, Instituto de Historia, Centro de Ciencias Humanas y Sociales e Consejo Superior de Investigaciones Científicas (CCHSeCSIC), C/Albasanz 26-28, 28037 Madrid, SpainbComplexity and Socio-Ecological Dynamics (CaSEs), Institució Milà i Fontanals e Consejo Superior de Investigaciones Científicas (IMFeCSIC), C/Egipciaques 15, 08001 Barcelona, Spainc Istitut Català de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spaind Laboratorio de Evolución Humana, Departamento Ciencias Históricas y Geografía, Universidad de Burgos, Plaza de Misael Bañuelos, Edificio IþDþi, 09001Burgos, SpaineDepartamento de Prehistoria, Facultad de Filosofía y Letras, Universidad de Valladolid, Plaza del Campus s/n, 47011 Valladolid, Spainf Técnico arqueólogo, Dirección General de Patrimonio Cultural, Gobierno de Aragón, Avda. Gómez Laguna 25, 6a planta, 50009 Zaragoza, Spaing Fundación del Patrimonio Histórico de Castilla y León, Arcadia, Residencia Universitaria Alfonso VIII, C/ Real de Burgos s/n, 47011 Valladolid, SpainhDepartamento de Prehistoria y Arqueología, Facultad de Filosofía y Letras, Universidad Autónoma de Madrid, Carretera de Colmenar Viejo, Km 15,Cantoblanco, 28049 Madrid, Spaini Postdoctoral Programme of the DEUI of the Basque Government, Spain, University of the Basque Country e U.P.V./E.H.U., Spainj Laboratoire TRACES UMR5608 Université de Toulouse Le Mirail 2, IT622-13 Research Group in Prehistory e Basque System of Research, SpainkArqueólogo profesional autónomo, C/ Zaragoza 91113, Esc. 3, 2�C, 50196 La Muela, Zaragoza, Spainl Escuela Española de Historia y Arqueología en Roma e Consejo Superior de Investigaciones Científicas (CSIC), Via di Torre Argentina 18, 00186 Roma, Spain

a r t i c l e i n f o

Article history:Received 16 July 2012Received in revised form31 October 2013Accepted 19 November 2013

Keywords:PhytolithsNeolithicSpanish PyreneesCave settlementsPlant resources

* Corresponding author. Complexity and Socio-EInstitució Milà i Fontanals e Consejo Superior de InveCSIC), C/Egipciaques 15, 08001 Barcelona, Spain.

E-mail addresses: lancelotti.carla@gmail.com,(C. Lancelotti).

0305-4403/$ e see front matter � 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.jas.2013.11.021

a b s t r a c t

The issue of resource exploitation, both plants and animals, by Neolithic communities has alwaysattracted vast interest. In particular, resource exploitation at mountain cave sites is still being widelydiscussed. This paper explores the use of grass resources at the archaeological site of Els Trocs (Aragón,Spain), a Neolithic mountain site in the Pyrenees. The analysis of phytolith samples suggests that grassesgrowing in the surrounding of the site were widely used. The morphological assemblages identified, andtheir spatial distribution, indicate that wild grasses were probably used as floor spread. The integratedapproach used in this study, combining phytolith, spherulite and micromorphological analyses, confirmsthis hypothesis. Furthermore, the analysis of phytolith assemblages and micromorphological traitsindicate the seasonal occupation of the site, placing human frequentation at this location during latespring/early summer. Several studies have highlighted the presence of charred seeds of domesticatedcereals in the archaeological record of mountain cave sites however, in many instances, whether thesecrops were cultivated near the sites or whether the grains were transported to the cave from the valleybottom remains under debate. This paper also contributes to this debate by showing that no crop-processing activities were taking place at the site.

� 2013 Elsevier Ltd. All rights reserved.

cological Dynamics (CaSEs),stigaciones Científicas (IMFe

carla.lancelotti@gmail.com

All rights reserved.

1. Introduction

In Europe, Neolithic mountain cave settlements are ofteninterpreted as animal pens and the main activity associated withthem is pastoralism (Boschian and Montanari-Kokelj, 2000;Brochier et al. 1992; Delhon et al. 2008). Recent archaeobotanicalresearch has recurrently revealed cereal grains and legumes atseveral mountain Neolithic cave sites (Antolín et al., 2010; Delhonet al. 2008; Zapata et al. 2004 and references therein). These

C. Lancelotti et al. / Journal of Archaeological Science 42 (2014) 456e466 457

plants remains normally are not abundant in the archaeobotanicalsamples and little evidence exists of whether crops were cultivatedin the surroundings of these mountain sites. The mainstreaminterpretation is that the grains were transported from the bottomof the valley, ready to be consumed.

Hillman realised from ethnographical work in Europe and theNear East that the cereal grains, the type of seeds and the chaff thatform a charred assemblage are indicative of the activities thatplayed a role in the assemblage formation (Hillman, 1973, 1981).From these observations it emerged that in situ crop processinginvolves the production of a number of by-products, such as chaffand straw, which are normally incorporated in the charred as-semblages. However grains and grain fragments are often the onlymacroscopic cereal remains recovered from Neolithic mountainsites, thus impeding any conclusions on whether the cultivationtook place in situ (Martin et al. 2008). The investigation of plant-related exploitation strategies at mountain sites has thereforefocused mostly on fuel use, by means of charcoal analysis, and onthe consumption of wild fruit (Martin et al. 2008 and referencestherein). Conversely, the consumption and the use of grasses haveremained marginal and the use of this kind of plants by Neolithicgroups occupying mountain sites is not yet fully understood. Theinterests in wild grasses exploitation at mountain sites during theNeolithic could have been many folded. Apart from the evident useas fodder for animals, they could have served as material for con-ditioning the occupational space, as sources of fibres for makingbasketry as well as a possible food resource alternative to domesticplants or wild fruits. Indeed, many species of wild grasses that areoften considered just as weeds of cultivated cereals have a potentialnutritional value that is often underestimated. For example, Galiumaparine (which was encountered in the archaeobotanical analyses

Table 1Preliminary results of the archaeobotanical analysis of charred macro-remainsexpressed as presence/absence.

Millennium

VI V IV

CerealsHordeum vulgare L. x xTriticum aestivum-durum x x xLegumesLens culinaris Medikus xcf. Pisum sativum xWild fruitsBerberis sp. xCornus sanguinea L. xCorylus avellana L. x x xCytisus sp. xJuniperus oxycedrus L. xLiliaceae. Asparagus type xMalus/Sorbus x xPomo cf. Malus x xPrunus cf. spinosa L. xQuercus sp. xRosa sp. x x xRosaceae x xRubus sp. x x xTaxus baccata L. x xWeedsAgrimonia type xAmaranthus sp. xChenopodium sp. x xGalium aparine L. xGalium sp. x x xGramineae xLeguminosae xFallopia convolvulus (L.) Á.Löve xPolygonum sp. xVicia/Lens x x

of Els Trocs, see Table 1) is not only edible but also have possiblemedicinal uses (Davis, 2013).

The study-site of Els Trocs (1564m asl) is located well below theHolocene tree line level for the Pyrenees (2400 m asl in Cunill et al.,2012). However, at the time of Neolithic occupation grasses prob-ably constituted a rich source of plant material around the site. Thiswould also justify the location of Els Trocs in terms of its utility as apastoral location, as indicated by the numerous recovered bones ofsheep and goat. Indeed, one of the principal features identifiedmacroscopically during excavation at the cave are alternations offinely laminated ash and charcoal layers, which are possible fumiersderived by stabling episodes (Angelucci et al., 2009 and referencestherein).

Archaeobotanical analyses of plants macro-remains haverevealed the presence at Els Trocs of cereals and legumes, alongsideother wild plant remains (Table 1). In this paper we focus our studyon the plant micro-remains (phytoliths) as these plant parts can beinformative on the anatomical origin of the assemblage andtherefore can be used to draw interpretations on resource man-agement strategies of the people who inhabited the site.

The aim of the current work is threefold:

� Understanding whether the cereal grains consumed in the caveare related to local cultivation or to transport of food resourcesfrom the lower parts of the valley;

� Understanding the use of wild grasses from the surroundingarea;

� Investigating the activities carried out during occupations(floors) in a Neolithic mid-mountain cave site.

1.1. The study site: Els Trocs cave

1.1.1. Location and morphologyEls Trocs cave is situated in the village of Bisaurri (Huesca

province) in the Central Pyrenees of Aragón, Spain (E: 298.198; N:4.702.955), at 1564 m asl (Fig. 1). The entrance of the cave is locatedat the bottom of a steep, south-east-facing slope part of a largelimestone outcrop, densely vegetated with heath (Erica sp.) andboxwood (Buxus sempervirens L.). This outcrop dominates the sur-rounding landscape, a plain locally known as Selvaplana, formed bycollapsed dolines covered in C3 grasses (e.g. various species offescues, Festuca spp., and meadow-grasses, Poa spp.) and borderedby woods dominated by conifers and boxwood (the current treeline for Pyrenees is located at c. 2000 m asl). The cave consists of asingle cavity of about 15 m by 6 m, with two shallow left and rightsecondary branches (Fig. 2). Speleological explorations show thatthe current configuration of the cave is due to subsidence ordisplacement of large blocks that have shaped its northern andeastern sides. In fact, the cavity continues in its eastern part with anarrow gallery at least 10 m long. The interior of the cave (veryhumid and cold) is filled with a well-developed sediment depositover 2 m thick, very rich in organic material.

1.1.2. Archaeological explorations: the identification of occupational“floors” and burning features

The excavation showed that the cave had been occupied duringthe Early and Middle Neolithic, starting from the end of the VImillennium B.C. (Rojo Guerra et al. 2012). At least four Neolithiclevels were identified and interpreted as active occupation surfaces(Rojo et al. in press):

Layer 1 (Stratigraphic Unit 1) corresponds to the last Neolithicoccupation of the cave. In this level there are important

Fig. 1. Localisation of the Els Trocs cave. S. MTN25 Raster/H. 213 Pont de Suert/Cuadro 1/1:25.000 �Instituto Geográfico Nacional de España (www.cnig.es).

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archaeological remains and several combustion structures ofdifferent typologies and dimensions;Layer 2 (S.U. 10) is a level of small- to middle-sized stones thatrepresent a floor of the early Neolithic phase. In the uppermostpart of the layer pottery remains (plain and decorated sherds),lithic material as well as animal bones were recovered. A largeintact structure interpreted as a fireplace, and stratigraphicallyrelated to the layer’s surface, was identified in the central part ofthe cave (SS.UU. 8, 9, 11 and 12);

Fig. 2. Plant and topographic profile of Els Trocs cave with indication of

Layer 3 (S.U. 14) represents a transition or a preparation phase ofa new floor (S.U. 10). In this layer scarce archaeological materialwas recovered but two important features (SS.UU. 29 and 57)were documented: S.U. 29 macroscopically looks like a fumier(an alternation of compacted, horizontal layers of charred andashed material); S.U. 57 is interpreted as a large combustionstructure;Layer 4 (SS.UU. 20 and 53) corresponds to the first two episodesof Neolithic occupation of the cave. A regular mixture of small-

the excavated quadrants (modified after Rojo et al. in press).

Table 2Concentration, number of morphotype identified and general composition of phytolith assemblages. The last column shows spherulite counts for each of the samples analysed.

n % n

Phytolith concentration Morphotypes Inflorescence Leaf/culm Woody dicot Unid Spherulites(in 180 fields)

Value Mean Value Mean Value Mean Value Mean Value Mean Value Mean

s.u. 29 ETR 1 609,129.72 1,015,575.35 16 11.8 2.04 1.0 62.34 70.7 14.50 7.8 10.69 10.83 30ETR 2 3,799,335.69 14 2.27 83.52 2.27 3.69 25ETR 3 217,013.57 10 0.00 78.30 4.25 4.72 22ETR 4 278,200.64 9 0.00 70.13 5.19 5.19 8ETR 5 577,472.16 13 0.26 59.38 11.46 22.92 56ETR 6 612,300.34 9 0.00 75.86 4.14 9.66 3

s.u. 10 10-526 835,941.55 1,102,931.33 16 14.5 1.79 1.3 74.23 82.3 5.87 2.5 6.63 4.00 010-527 1,825,949.49 19 1.63 86.68 1.90 0.27 010-528 1,053,992.00 13 0.00 82.81 2.87 0.57 010-529 231,095.93 11 0.93 79.63 0.69 6.94 010-556 529,022.95 17 1.03 77.84 3.61 9.28 010-557 3,626,046.96 12 1.12 90.48 1.12 0.00 010-558 503,719.65 12 2.20 91.21 1.37 0.00 010-559 217,682.11 16 1.66 77.49 2.61 6.64 0

s.u. 20 20-496 1,664,587.97 1,842,628.19 18 14.2 1.26 0.8 84.38 82.7 3.02 2.8 6.55 6.39 020-526 4,136,296.30 15 0.00 81.66 4.87 4.01 020-527 1,652,520.95 13 1.07 80.53 6.40 6.40 75320-528 1,781,401.28 14 0.85 92.96 1.13 0.85 020-529 2,693,482.93 16 1.08 62.53 4.31 26.68 020-556 1,148,237.59 10 0.00 88.04 0.54 2.17 199120-557 2,105,418.30 11 1.11 82.50 0.56 1.94 219220-558 571,398.30 14 1.69 87.89 1.69 2.82 020-559 830,310.12 17 0.00 84.62 2.56 5.38 305

s.u. 53 53-436-6 409,321.44 324,671.58 14 12.1 2.16 0.8 77.84 66.9 4.86 15.7 4.32 7.26 053-436-7 181,593.94 11 0.00 50.58 37.21 0.00 053-436-8 186,090.89 12 2.90 55.07 27.54 10.87 253-437 158,425.21 8 0.00 76.68 8.58 3.75 053-438 252,903.95 18 0.50 58.60 17.71 12.47 053-467 1,285,495.93 11 0.50 81.95 3.26 10.28 053-468 29,323.46 11 0.00 45.95 35.14 10.81 053-469 94,217.82 12 1.15 39.08 27.59 18.39 107

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sized stones, abundant fragments of plain and decorated potterysherds, and animal bones constitute the floors of these occu-pation phases. All the pottery fragments and animal bonesrecovered within SS.UU. 20 and 53 were lying horizontally. Nosigns of damage or breakage due to trampling were identifiedduring excavation and post-excavation analyses. A radiocarbondate on animal bone from this layer places this occupation at theend of 6th millennium cal. BC. (5196-4842 cal. BC 2s) (Rojo et al.in press).

Overall, layers 2 and 4 (SS.UU. 10, 20 and 53) can be described asa sort of ‘anthropogenic breccia’, which coarse component is madeof more or less regularly arranged stones and pottery sherds.

2. Material and methods

Bulk sediment samples were collected during the excavation,whereas undisturbed samples were collected from the excavationprofiles. Bulk samples were analysed for phytolith content andmorphology; the incidental presence of spherulite and relativeabundance was also recorded. Targeted micromorphology wascarried out in parallel to the analysis of phytoliths to contextualisethe assemblages within the microstratigraphy of the cave and tosupports the evidence from the quantitative study of bulk samples.

2.1. Bulk sediment samples

2.1.1. SamplingAn extensive archaeobotanical sampling strategywas put inplace

at Els Trocs: the totality of the excavation sediments was floated forrecovering all possible charred material (Rojo et al. in press). Beforefloatation part of the sediment was bagged for phytolith analysis

making samples available from each quadrant, spit and stratigraphicunit. For this work, phytoliths were extracted from the units identi-fied as Neolithic floors (SS.UU. 10, 20 and 53) to acquire possible ev-idences of plant processing and use during the occupation related tothe Neolithic surfaces and floors recognised during excavation. Inaddition, six samples were collected from the south profile (quad-rants 468e469) where a structure visually identified as a fumierwaspresent (see Table 2 for a list of the samples analysed).

2.1.2. Phytolith extraction, identification and countingPhytoliths were extracted following Madella et al. (1998)

modified to calculate the Acid Insoluble Fraction (AIF e Lancelotti,2010). Observations were conducted with a Leica DM2500 trans-mitted light microscope at 630 magnifications. Identification ofphytoliths was achieved by comparison with published (amongothers, Albert and Weiner, 2000; Ball, 2002, 2009; Barboni et al.1999; Bowdery et al. 2001; Bozarth, 1985; Brown, 1984; Fuller,2007; Iriarte and Paz, 2009; Lu et al. 2009; Pearsall, 2008;Piperno, 2006; Runge, 1999) and reference material of the Bio-GeoPal Laboratory at the IMF-CSIC. The nomenclature followed thatproposed by the International Committee for Phytolith Nomen-clature (ICPN, Madella et al., 2005). For each sample a minimum of350 disarticulated silica phytoliths were counted so to reach astatistically significant number of particles (Lancelotti, 2010;Madella and Lancelotti, 2012; Van der Veen and Fieller, 1982;Zurro, 2010). Articulated silica skeletons, when present, wereincluded into the analysis but counted separately.

2.1.3. Spherulite observationSpherulites were observed in the phytolith preparations using

cross-polarised light and identified according to the criteria pro-posed by Canti (1998) and Courty et al. (1991). These particles were

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encountered in great quantities in some of the phytolith slidesexamined notwithstanding the fact that hydrochloric acid usedduring phytolith extraction presents a potential problem for spher-ulite preservation (Canti,1999). To assess the presence of spherulites,a semi-quantitative estimation of their amount was carried out, bycounting single spheruliteswithin 180fields of view (3 tracks). Semi-quantitative analysis was preferred in respect to absolute countingtaking into consideration the possibility of loss caused by chemicaltreatment. For the same reason, it was decided not to adopt a con-servative approach and to include in the counting evenparticles thatwere deviating from clearly identifiable dung spherulites, andwhichcould represent distorted or damaged spherulites.

2.1.4. Statistical analysisANOVA tests were used to compare means and principal

component analysis (PCA) was run to detect patterns and similar-ities between samples. Although the analyses were run on a mix ofnormally and not normally distributed data, ANOVA has beenpreferred as it is more robust to the violation of its assumptions(Field, 2005). PCA was carried out on untransformed values usingthe FactoMineR package (Husson et al., 2008) of R statistics version2.15.1 (codes for both ANOVA and PCA are provided asSupplementary material e SM_ANOVA.pdf and SM_PCA.pdf).

2.2. Micromorphology samples

The sampling of undisturbed sediments from exposed profileswas conducted using aluminium U-section bars. Thin sections wereproduced at the McBurney Laboratory for Geoarchaeology, Uni-versity of Cambridge, following established protocols. Micromor-phological analysis of thin sections reported here focuses on thecontexts related to floors surfaces as identified during the excava-tion. The analysis of thin sections from the contact between thefloors and the above-lying deposits aimed at contextualizing thephytolith data by the characterization of the floor surface and thedetection of the potential activities carried out on the preparedfloors. Micromorphological traits were described using a LeicaMZ95 stereomicroscope and a Leica DM2500. Thin sections wereobserved under plane-polarized light (PPL) and cross-polarizedlight (XPL), following established guidelines (Bullock et al. 1985;FitzPatrick, 1993; Stoops, 2003, 2010).

3. Results

3.1. Phytolith concentration, preservation and representativeness

Phytoliths are present in all the samples analysed and althoughtheir concentration varies greatly within the stratigraphic units andcontexts (Table 2), differences are not statistically significant (seeSupplementary material SM_ANOVA.pdf). Average phytolith con-centration is similar in three of the contexts analysed (SS.UU. 29, 10and 20) but markedly lower in S.U. 53. Taphonomy is possiblygreatly affecting the phytoliths: during identification at the mi-croscope clear signs of chemical dissolution were observed both inlong and short cells. Even bulliform phytoliths, among the mostrobust morphotypes, showed signs of dissolution defining thepreservation of phytoliths as ‘poor’ to ‘extremely poor’ (accordingto Fredlund and Tieszen,1997). In addition, short cells dominate theassemblage in all samples, indicating a possible chemical and/orphysical destruction of the more fragile long cells (Madella, 1997;Madella and Lancelotti, 2012). However, there is no correlationbetween the concentration of phytolith per gram of AIF and thenumber of morphotypes identified in the samples (Fig. 3). Thismeans that the concentration of phytoliths does not affect therichness of the assemblages, which can therefore be considered

representative of the original plant input in the sediment(Lancelotti, 2010; Madella and Lancelotti, 2012).

3.2. Phytolith morphology

The number and range of morphotypes identified in the samplesis similar throughout the assemblages (Table 2). The vast majority ofthe morphotypes identified originate from leaf or culm of grasses(average of over 70% in all units/contexts).We include in this categorythe following morphotypes: elongate psilate, elongate non-psilate(but different from echinates or dendritics), bilobate, polylobate,rondel, saddle, parallelepipedal, trapeziform, trapeziformpolylobate,trapeziform sinuate and cross. Of the few silica skeletons (i.e. severalphytoliths in anatomical connection) observed in the samples, almostall pertain yet again to leaf or culm epidermis. Phytoliths unequivo-cally indicative of Gramineae inflorescence (i.e. elongate echinates)and more specifically cereal inflorescence (i.e. dendritics) are veryscarce (between 1% and 2% in average of the total for each contextanalysed). In addition these morphotypes are highly affected bytaphonomic processes, which hampers the possibility to acquiringsignificant morphometric measurements for the identification atgenus/species level. No inflorescence silica skeletons were encoun-tered in the samples analysed. Morphotypes produced in the leavesor wood of dicotyledons (i.e. globular, globular granulate, scallopedand irregulardicotyledonous type)havebeenobserved inall contextsand their frequency vary across the samples between 2% and 15% inaverage.However, the average content of thesemorphotypes ismuchhigher in S.U. 53 than in other contexts.

The four units analysed (the three Neolithic floors and thepossible stabling/fumier) show very similar grass phytolithcomposition (Fig. 4) both in terms of morphotypes and in therelative presence of plant parts (leaf/culm versus inflorescence). S.U.53 has a higher concentration of woody dicotyledonous morphol-ogies compared to the other floor surfaces (17% versus 3% of theother two SS.UU.). Some differences in the number of leaf/culmmorphotypes were noted in the samples, with S.U. 10 and S.U. 20showing a higher concentration of these morphotypes than S.U. 53and S.U. 29. However these differences are not statistically signifi-cant and therefore the phytolith composition of these sedimentsshould be considered homogeneous (Fig. 4 and Table 2). Even a PCArun on all the variables under study (concentration of phytolithsper gram of AIF; number of morphotypes identified; unidentifiedphytoliths; inflorescence, leaf/culm and woody dicotyledons in-dicators, spherulites) did not result in the formation of clear dif-ferentiation in the stratigraphic units analysed (Fig. 5).

The high level of dissolution observed during identificationmade the attribution of short cells to a grass family or subfamilyoften impossible. However, among the identified morphotypes themajority belongs to the C3 subfamily Pooideae (i.e. rondels, tra-peziform sinuate, trapeziform polylobate).

3.3. Spherulites

Spherulites were observed only in few samples and they arepresent in modest quantity in the six samples coming from thepossible stabling layer (S.U. 29). In contrast, spherulites are verycommon in samples ETR 20-527, 20-556, 20-557 and 20-559(Table 2 and S.U. 20 in Fig. 4) all proceeding from S.U. 20, and areconcentrated in the quadrants situated in the north and north-eastern side of the cave (Fig. 2).

3.4. Micromorphology

Two thin sections were analysed that included the surface of S.U.20 and S.U. 53. Full description of the observedmicromorphological

Fig. 3. Correlation scatterplot of phytolith concentration versus number of morphotypes identified. The adjusted R-squared is 0.02222, indicating absence of correlation between thetwo variables.

Fig. 4. Phytolith composition and spherulite quantities within the stratigraphic units analysed. Leaf/culm morphotypes are dominant in all the units and the only marked differencecan be found in the higher amount of woody dicotyledonous indicators found in S.U. 53. Spherulites are present in all units analysed (apart form S.U. 10) but are markedly moreabundant in S.U. 20. Bonferroni post-hoc test showed that there is no statistical significant difference among the groups (no p < 0.05).

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features is given as Supplementary material in SM_Table 1 andSM_Table 2. The main results are summarised below.

3.4.1. Stratigraphic Unit 20 (STR 1/1, Fig. 6)A marked change in colour and texture was observed between

the floor (S.U. 20) and the overlying material (S.U.14). The sedimentthat composes the floor is darker and less compacted than theabove layer. Abundant vegetal organic material showing differentdegrees of decomposition was observed at the interface betweenthe two units. Isolated peds, possibly originating from S.U. 20, areobservedwithin S.U.14. These have similar colour, composition andstructure to the material composing the floor, but have a roundrather than polygonal shape. Ceramic fragments were foundembedded in the floor preparation layer. A thin layer of ash wasobserved just above S.U. 14, pertaining to S.U. 57 (described as anaccumulation of combustion residues). This ash layer presents ahigh concentration of grass-pseudomorph ash, as well as fragments

of plant tissue with preserved cell structure. Spherulites wereobserved in limited quantity and isolated spots within S.U. 14,where concentrations never exceed 20%. On the contrary, spheru-lites are very abundant and widespread within S.U. 57.

3.4.2. Stratigraphic Units 53 and 29 (STR 4/2, Fig. 7)S.U. 53 presents a massive microstructure, no laminations and

abundant rock clasts. Ash and isolated round peds are abundant onthe surface of the prepared floor. Clonocylinder voids wereobserved in all the units analysed. This form of bioturbation istypically interpreted as excrements of larvae of Adelidae (fairylonghorn moths) and Bibionidae (March flies), feeding on decom-posing plant tissues (Stoops, 2003,123). Resting on the floor surfaceis a thick layer of ash, interpreted as a fumier during excavation (S.U.29). A thin layer of organic matter can be discerned between thefloor surface and the above lying ash layer. This ashy deposit (S.U.29) shows a laminated alternation of light grey layers of ash and

Fig. 5. PCA plots of analysis run on all samples and all variables. The first two dimensions explain over 50% of the variability and no clear pattern emerges from the analysis apart thestrong component of spherulites in samples 20-556 and 20-557 and the high concentration of woody morphotypes in samples from SU 53 (eigenvalues are provided asSupplementary material SM_PCA.pdf).

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darker layers rich of charcoal fragments usually associated tofumiers (e.g. Angelucci et al. 2009; Diáz and Eraso, 2010; Karkanaset al., 2002). Two ash layers and one charcoal-rich layer havebeen captured within the thin section analysed. All three layersshow poor spherulite concentrations. As a caveat, it should benoted that STR4/2 shows abundant spheroidal micritic features(few mm in size), which could be interpreted as partially degradedspherulites (by means of dissolution) because they appear togetherwith few well-preserved spherulites. In fact, coatings of OM-richash on the surface of clasts embedded in the floor suggest acidic(low pH due to stabling) conditionsmay have developedwithin thisportion of the deposit, also affecting spherulite preservation.

4. Discussion

The analysis of phytoliths extracted from sediments collected atEls Trocs was initiated with the intention of highlighting thepossible presence of remains of cultivated plant material within thearchaeological record of the site. The possibility offered by phyto-lith analysis to distinguishing between the different crop-processing stages (Piperno, 2006, 27e35, Harvey and Fuller,2005; Ruiz-Pérez et al. in press) was here the key character usedto investigate possible crop cultivation in mountain regions duringthe Neolithic.

Plant remains recovered from Els Trocs cave include both cropsand wild species. Cultivated plants are represented both by cereals,such as barley (Hordeum vulgare) and free-threshing wheat (Triti-cum aestivum/durum) as well as by legumes, such as lentil (Lensculinaris) and pea (Pisum sativum). Gathering of wild plantsincluded a relatively large range of species such as Crataegusmonogyna, Cornus sanguinea, Corylus avellana, Juniperus oxycedrus,Malus/Sorbus, Prunus spinosa, Quercus sp., Rosa sp. y Rubus sp.),which were probably used by the inhabitants of the cave. Otherspecies such as Taxus baccata, Cytisus sp., Berberis sp. may have beenintroduced as part of the fuel used at the site. Plants that couldeither beweeds of crops or just represent the vegetation around thesite compose a third group. Some of these, as for example Galiumsp. may have been introduced into the cave as fodder for sheep andgoats or may have entered the assemblage as part of animal dung(Amaranthus sp. and Chenopodium sp.).

The phytolith assemblages identified at Els Trocs suggest aconsistent use of local grass resources throughout the period ofoccupation. The only exception to this pattern is related to thehigher presence of dicotyledonous wood morphotypes in S.U. 53(Fig. 4). Considering that woody plants produce at least eight timesfewer phytolith than grasses (Albert and Weiner, 2001; Fig. 5: 257)the use of wood seem to have been an important activity during theperiod of formation of the S.U. 53, and it is almost certainly relatedwith refuses of combustion processes proceeding from the fire-places scattered on the cave floor. Furthermore, the amount ofwoody dicotyledon morphotypes is higher in the stabling context(S.U. 29) than in SS.UU. 10 and 20, indicating that combustion ofwood and leaves from arboreal species contributes to the formationof this feature.

The vast majority of phytoliths identified are short cells that areabundantly producedwithin culms and leavesof grasses. Among themorphotypes that it was possible to identifywith a certain degree ofreliability, the majority are produced in the Poaceae subfamily ofPooideae (i.e. rondels, trapeziform sinuate and trapeziform poly-lobate). Many species of grasses can be included in this subfamily,among which are some major crops (i.e. wheat, barley and oat) andmost of the grasses that are found in pastures in the Pyrenees,especially atmiddle andhigh altitudes (e.g. Festuca spp.,Nardus spp.,Poa spp., Fillat Estaqué et al., 2007; Grau et al. 2011). Identification atthe genus level within this plant group can sometimes be reachedthroughmorphometric analysis of the inflorescence phytoliths (e.g.elongate echinates and dendritics, see for example Ball et al. 1999).However, the limited number of inflorescence morphotypesencountered and the high level of taphonomic alteration impededsuch identification. Inflorescence phytoliths amount to a maximumof 2% of the entire assemblage, a very negligible quantity. Apart fromindicating that no secondary crop processing activity (e.g. de-husking) was taking place inside the cave, the virtual absence ofinflorescence morphotypes from grasses in general (both cereals orwild) suggests that the cavewas occupiedmainly during late springand/or beginning of summer, and that grasses were collected andusedbefore the inflorescence cellswere fully silicified (Madella et al.2009). This full silicification happens at the endof the plant lifecycle,when the inflorescences aremature, which ismid to end of summerat this altitude. This hypothesis is substantiated by the preliminary

Fig. 6. Micromorphology thin section STR1-1. (a) thin section STR 1/1 with indication of boundaries between micromorphological units described (U1-5). (b) epiphysis of bonefragment from microfauna (U1). (c) potsherd PTS (U1). (d) partially decomposed plant remain PR (boundary U1-2). (e) ash pseudomorph showing plant cellular structure APS (U2).(f) transition U1-2. U1 corresponds to the lower third of the image (darker). Note round peds RPD within U2. (g) spherulites (U2).

C. Lancelotti et al. / Journal of Archaeological Science 42 (2014) 456e466 463

results of theongoing archaeozoological studies,which indicate thatbones of neonatal and very young sheep and goat (whose offspringare born in late spring) dominate the faunal assemblage. Further-more, the seasonality of the site occupation is also supported by thebioturbation features observed in thin section, related to the

presence of larvae of Adelidae and Bibionidae, which have a veryshort life cycle, and aremost commonly seen in Europe in spring andearly summer.

The investigated deposits suggest that the cave could have beenused for stabling animals for short periods of time.

Fig. 7. Micromorphology thin section STR 2-4. (a) thin section STR 2/4 with indication of boundaries between micromorphological units described (U1-7). (b) coating CT on clastembedded in the floor (U1). (c) detail of the same showing birefringence within the coating. (d) plant residue PR at the contact between U1-2. (e) clonocylinder voids (U2-7). (feg)clusters of spherulites and possibly partially disegregated spherulites (U2-3).

C. Lancelotti et al. / Journal of Archaeological Science 42 (2014) 456e466464

C. Lancelotti et al. / Journal of Archaeological Science 42 (2014) 456e466 465

Notwithstanding that caprids are good climbers, the steep entranceof the cavity makes it very difficult for animals to enter the cavewithout some help from people. It is therefore probable that not allthe herd was sheltered in the cave and only some of the animals(i.e.. the kids and lambs) were brought inside to offer extra pro-tection. The great amount of faecal spherulites identified in quad-rants 527-556-557 and 559 of S.U. 20 (NE corner of the cave, Fig. 2)indicates that animals were stabled in this part of the cave. Aninteresting result came from the analysis of the feature related tostabling (S.U. 29) in quadrant 439. The thin section seems toconfirm the field hypothesis and effectively represent a fumier-likedeposit, showing organic-rich coating of clasts and horizontalbandings (suggesting in situ deposition) and burnings of organicmaterial with a high content of phosphates (Supplementarymaterial SM_Table 1 and SM_Table 2). The preserved ash plantcell pseudomorphs in the laminated layers imply little lateraltransport after combustion. However, the very limited amount ofspherulites observed in the slides does not agree with results ob-tained from similar contexts elsewhere (Angelucci et al. 2009 andreferences therein). This paucity of spherulites is confirmed in allthe six bulk samples from S.U. 29. The low amount of spherulites inthis unit maywell be due to taphonomic reasons: the high acidity ofthe sediment (organic matter-rich coating of clasts) could havecontributed to the partial dissolution of spherulites. These doubtswill be clarified by the ongoing, in-depth micromorphologicalanalysis.

The amount and common presence of grass phytoliths and ofpartially decomposedplant organicmatter suggests spreads of plantmaterial over the surface of the three analysed floors, not dissimi-larly towhathappenedatearlier sites suchas SibuduCave (Goldberget al. 2009) and Ohalo II (Nadel et al. 2004). A plausible interpreta-tion is that theNeolithic people of Els Trocs,who frequented the caveduring spring/summer, conditioned the surface of the cave creatinga layer of hardmaterial (e.g. a mix of pottery, bones and stones) thatwas then covered with a spread of grass plants collected from thesurrounding meadows. This preparation would have achieved amore comfortable surface, also insulating fromhumidity. The lack ofclear evidence for proper matting in thin section (no clear layer oflaminated phytoliths) further suggests the use of loose plants (aspread) and the regular cleaning of the surfaces, probably to elimi-nate parasites and insects. Sweeping and burning of the plant ma-terial used for the spreads, together with some of the dung from theanimals kept inside the cave have probably contributed to theconfiguration of S.U. 29. The clonocylindrical voids (larvae of insectsfeeding on fresh and partly decomposed plant material, Frouz et al.2003) identified throughout section 4/2, substantiate this hypoth-esis. Furthermore, the phytolith assemblages of the four layersanalysed are not significantly different, pointing to a similar input ofplants in both the floors and the feature lying above them (i.e. thoseinterpreted as fumier during excavation).

The analysis of micromorphological features seems to offer apartial confirmation for this hypothesis in more than one instance:

1. STR1/1 (S.U. 20) can be related to the accumulation of waste.Here the ‘floor’ shows little compaction.While the surface of thefloor is horizontal, units above are deposited sub-horizontally(hip-like) and have irregular boundaries. The great quantity ofash pseudomorphs preserved indicates rapid accumulation andcovering, with little trampling following deposition.

2. STR4/2 (SS.UU. 53 and 29) seems more related to stabling: the‘floor’ shows compaction and sub-horizontal planes. Coating ofclasts suggests filtration of organic-rich liquids (phosphatic)from above (animal stabling). All units in STR4/2 are depositedhorizontally (which is not the case in STR1/1), suggesting in situdeposition and burning. Vesicles (conocylinders) are found

across this thin section, suggesting activity of Adelidae-type(fairy longhorn moths) and Bibionidae-type (March flies)larvae (both feeding mostly on dead vegetation e also found incompost e and leaf litter in spring, possible suggestion ofmatting).

3. The rounded peds embedded in the layers lying immediatelyabove the floor surfaces may indicate periodic sweeping.

On these bases the surface of S.U. 20 may be interpreted as anaccumulation area of residue swept from the floor and S.U. 29 as astabling surface (fumier-like, cake-layer). Floor S.U. 53 is morecompact and stony than floor S.U. 20, which is looser, more porousand with potsherds instead of clasts in the coarse mineral fraction.This means that floor S.U. 53 would have been more impermeable,allowing for the establishment of saturated acidic conditions at thecontact between the floor surface and the stabling deposits above,also favouring spherulite disaggregation. In addition to the tapho-nomic factors above, burning at high temperatures might havefacilitated spherulite breakage by loosening the crystalline structure.

Although the analysis of phytolith assemblages fromEls Trocsdidnot show the presence of crop processing activities at the site, ourresults highlight the importance of carrying out analysis on thedifferent strandof plant evidence tobe able to gather amore realisticunderstanding of Neolithic plant exploitation at mid- and high al-titudes (i.e. above 900 m asl, Grau et al. 2011). Many caves and rockshelters of European mountains where charred macro-remains arepoor and/or devoid of by-products, can possibly represent pastoral(and sometime ritual) outposts periodically occupied byagriculturalgroups settled in the lower valleys. The wheat and barley grains,which make up the charred macro-remains recovered from thesesites, might constitute provisions brought from the permanentsettlements to supplement a diet based onwild plants (Martin et al.2008 and references therein) and milk products. The Els Trocsphytolith record suggests a seasonality of frequentation in accor-dance with an interest in pastoral and not in cultivation activities.The cave probably also played a role in the rituality of these pastoralgroups, as evidenced by the presence of several pits with scatters ofboth human and animal bones (Rojo et al. in press).

5. Conclusions

The results of phytolith, spherulite and micromorphologicalanalyses allow for the reconstruction of some of the socio-ecological dynamics that characterise the Neolithic cave settle-ment of Els Trocs and of European Neolithic mountain sites ingeneral. The combination of archaeological, archaeobotanical andgeoarchaeological data highlight the presence, within the cave ofdifferent strategies for the use of resources. The cave was used as aseasonal (late spring and summer) shelter related to pastoral ac-tivities. The presence of bone remains as well as the concentrationsof spherulites confirms at least a partial stabling of animals in thecave. However, the seasonal occupants also exploited non-foodplant resources available in the surroundings. Phytolith remainsshow the widespread use of grasses, probably as flooring materialto create insulation and to make the living surface more comfort-able, which were periodically burnt. The use of multiple strands ofevidence allows for the interpretation of plant-related practices atlarge, besides those concerned with subsistence. Even though re-mains of cultivated cereals were encountered during archae-obotanical analysis, the analysis of micro-remains shows theabsence of crop processing evidence, thus indicating the possibleconsumption of grains transported clean to the site form other lo-cations (e.g. valley bottoms or sites located at lower altitudes) andcontributes to the debate over the possible cultivation of cereals insitu at mountain sites.

C. Lancelotti et al. / Journal of Archaeological Science 42 (2014) 456e466466

Acknowledgements

The main research of this work developed within the project“Los Caminos del Neolítico” (HAR2009-09027), granted by theGeneral Management of Research and Management of the NationalRþDþi/ Spanish Ministry for Science and Innovation, led by Pro-fessor Manuel Rojo-Guerra and co-funded by the Government ofAragón. The paleoenvironmental research and part of the funding isprovided by the AGRIWESTMED project of the European ResearchCouncil (ERC-2008-AdG 230561) coordinated by Dr Leonor Peña-Chocarro.

Appendix A. Supplementary data

Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.jas.2013.11.021

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