J.-Ph Faivre

B Gravina

L Bourguignon

E Discamps

A Turq

Late Middle Palaeolithic lithic technocomplexes (MIS 5-3) in the northeastern Aquitaine Basin: Advances and challenges

Keywords:

Establishing and interpreting patterns of lithic assemblage variability is of great interest to archae-ologists as they shed light on cultural adaptations in the deep past. Nowhere has this topic provoked more interest and debate than in the Middle Palaeolithic of southwestern France. The region's rich archaeological record has produced numerous sites, many of which have been recently excavated and thus provide a reliable dataset for better structuring Mousterian lithic variability. Researchers working with these types of datasets frequently employ the chaîne op ératoire concept to approach lithic assemblage variability; however, the validity of such analyses has recently been questioned. Here we present results of a combined quantitative and qualitative technological analysis of a large sample of assemblages from numerous well-contextualised sites in the northeastern Aquitaine Basin. We selected clearly identifiable diagnostic elements typical of different flake production systems that can be quantified by different analysts in a replicable fashion. Our results show strong differences in assemblage composition in terms of dominant production systems as well as a smaller number of mixed assemblages that combine two or more flake production methods. When considered together, these results provide not only a means for defining lithic technocomplexes and subse-quently comparing assemblages but also for investigating elements of Neanderthal material culture variability.

Introduction

The last decade has seen renewed and intense interest in Palaeolithic industrial variability, the definition of its constituent elements as well as their interpretation. While commonly associated with the Western European record, similar questions and problems are confronted by researchers around the world, resulting in varying approaches, each with a specific research history. Moreover, varying aspects of lithic assemblages are privileged, such as type fossils (e.g. Cha ^telperronian or Gravettian points), distinct technological (e.g. pressure flaking or the Levallois method) or quantitative features (e.g. numbers and sizes of tools) by different researchers for comparing assemblages. Underlying the selection of the most relevant comparative or interpretative elements lie clear conceptual differences that are at times difficult to articulate together. Even a cursory survey of recent literature concerning lithic analysis reveals what can best be described as 'different schools of thought' built from divergent research trajectories.

This heuristic divide is nowhere more evident than in the interpretation of Middle Palaeolithic assemblage variability, the choice of a proper analytical approach for comparing assemblages from this period, and the relative influence of climatic, environmental, biological, cultural, and demographic factors. These types of questions are of equal importance regardless of the study region, as similar discussions concern, for example, the Middle Stone Age record of North and South Africa, the Mousterian of the Near East and southwestern France, and, for more recent periods, the ethnographic record of Australia [START_REF] Holdaway | A twenty-first century archaeology of stone artifacts[END_REF]. Southwestern France has played a fundamental role in the development of Palaeolithic systematics both in terms of typological aspects, for example, the so-called Bordesian method, as well as defining technological features of lithic assemblages. Its rich archaeological record has been the testing ground for numerous interpretive interpretations beginning with F. Bordes culture-historic 'five tribes' model [START_REF] Bordes | Essai de Classification des industries "mouste ´riennes[END_REF], which was almost immediately countered by chronological [START_REF] Mellars | Sequence and development of Mousterian traditions in south-western France[END_REF][START_REF] Mellars | The chronology of Mousterian industries in the Pe ´rigord region of southwest France[END_REF][START_REF] Mellars | The Neanderthal Legacy: an Archaeological Perspective from Western Europe[END_REF] and functional models [START_REF] Binford | A preliminary analysis of functional variability in the Mousterian of Levallois facies[END_REF], followed by processual approaches that incorporated aspects of tool reduction [START_REF] Dibble | Reduction sequences in the manufacture of Mousterian implements of France[END_REF][START_REF] Dibble | Middle Paleolithic scraper reduction: background, clarification, and review of evidence to data[END_REF] and the influence of occupation intensity and changing climatic conditions [START_REF] Rolland | A new synthesis of Middle Paleolithic assemblage variability[END_REF][START_REF] Dibble | On assemblage variability in the Middle Palaeolithic of Western Europe: history, perspectives and a new synthesis[END_REF]. The relationship between climatic data and the economy of lithic raw material also focused attention on the interrelation between lithic assemblages and group mobility patterns. This situation led to inferences of differential mobility for certain raw materials and tool types or technologies [START_REF] Geneste | Analyse lithique d'industries mouste ´riennes du Pe ´rigord: une approche technologique du comportement des groupes humains au Pale ´olithique moyen[END_REF][START_REF] Geneste | Les industries de la Grotte Vaufrey: technologie du de ´bitage, e ´conomie et circulation de la matie `re premie `re lithique[END_REF][START_REF] Geneste | Syste `mes techniques de productions lithiques: variations technoe ´conomiques dans les processus de re ´alisation des outillages pale ´olithiques[END_REF][START_REF] Turq | Approche technologique et e ´conomique du facie `s Mouste ´rien de type Quina: e ´tude pre ´liminaire[END_REF][START_REF] Turq | Exploitation du milieu mine ´ral: technologie, e ´conomie et circulation des silex[END_REF][START_REF] Turq | Le Pale ´olithique infe ´rieur et moyen entre les valle ´es de la Dordogne et du Lot[END_REF][START_REF] Delagnes | Shifts in Neandertal mobility, technology and sub-sistence strategies in western France[END_REF]. These models, while having clearly enriched our understanding of the possible factors underlying patterns observed in Middle Palaeolithic assemblages, have also led to conflicting interpretations, with each practitioner defending their position or, in extreme instances, highlighting the 'inutility' of certain methodological criteria for studying lithic assemblages (i.e. [START_REF] Monnier | Another Mousterian Debate? Bordian facies, chaîne ope ´ratoire technocomplexes, and patterns of lithic variability in the western European Middle and Upper Pleistocene[END_REF].

Important aspects concerning Palaeolithic systematics continue to be problematic, including confusion surrounding the emergent designation of archaeological assemblages as lithic techno-complexes (e.g. [START_REF] Delagnes | Les technocomplexes du Pale ´olithique moyen en Europe occidentale dans leur cadre diachronique et ge ´ographique[END_REF][START_REF] Jaubert | A new look at the end of the Middle Palaeolithic sequence in southwestern France[END_REF][START_REF] Jaubert | A new look at the end of the Middle Palaeolithic sequence in southwestern France[END_REF] and the possible risk of plunging us into 'another Mousterian debate' (Monnier and Missal, 2014: our emphasis). While the actors have changed, disagreements concerning the degree to which climate, culture, form and function underlie the character of lithic assemblages remain effectively the same e in other words, the curtain never really closed on the original Mousterian debate of Bordes and Binford. From the mid 1980s onwards, the culturehistoricism underlying Bordes' 'facies' with its emphasis on retouched tool frequencies came to be replaced by a more holistic approach to lithic assemblage composition embodied in the chaîne op ératoire concept (hereafter CO) and associated technological approaches [START_REF] Tixier | Notice sur les travaux scientifiques de J. Tixier (The `se d'Etat)[END_REF][START_REF] Tixier | Pre ´histoire de la pierre taille ´e 1, terminologie et technologie[END_REF][START_REF] Cahen | Me ´thodes d'analyse technique, spatiale et fonctionnelle d'ensembles lithiques[END_REF][START_REF] Geneste | Analyse lithique d'industries mouste ´riennes du Pe ´rigord: une approche technologique du comportement des groupes humains au Pale ´olithique moyen[END_REF][START_REF] Geneste | Syste `mes techniques de productions lithiques: variations technoe ´conomiques dans les processus de re ´alisation des outillages pale ´olithiques[END_REF][START_REF] Boëda | Approche technologique du concept Levallois et e ´valuation de son champ d'application: e ´tude de trois gisement saaliens et weichseliens de la France septentrionale[END_REF][START_REF] Inizan | Technology and Terminology of Knapped Stone: Followed by a Multilingual Vocabulary Arabic, English, French, German, Greek, Italian[END_REF]. The CO approach moved attention away from retouched tools, focusing instead on the totality of a lithic assemblage. In doing so, assemblages were viewed from the perspective of the organisation of the different technical processes and actions responsible for the ultimate form of an artefact, its place within the reduction sequence, as well as the segmentation of actions in time and space (see [START_REF] Bleed | Trees or chains, links or branches: conceptual alternatives for consideration of stone tool production and other sequential activities[END_REF][START_REF] Bar-Yosef | The chaîne ope ´ratoire approach in Middle Paleolithic archaeology[END_REF]Soressi and Geneste, 2011 for syntheses).

In parallel, the last decade has seen the development of alternative methods of lithic analysis based on the statistical treatment of quantitative and categorical attributes (e.g. [START_REF] Brantingham | Constraints on Levallois core technology: a mathematical model[END_REF][START_REF] Tostevin | A Quest for Antecedents: a Comparison of the Terminal Middle Palaeolithic and Early Upper Palaeolithic of the Levant. More than Meets the Eye: Studies on Upper Palaeolithic Diversity in the Near East[END_REF][START_REF] Tostevin | Seeing Lithics[END_REF][START_REF] Dibble | Introducing a new experimental design for controlled studies of flake formation: results for exterior platform angle, platform depth, angle of blow, velocity, and force[END_REF][START_REF] Lycett | Levallois economics: an examination of 'waste' pro-duction in experimentally produced Levallois reduction sequences[END_REF][START_REF] Scerri | Can lithic attribute analyses identify discrete reduction trajectories? A quantitative study using refitted lithic sets[END_REF]. Lithic analysts working within these alternative analytical paradigms have contested the ability of technological studies, more specifically, the validity of the CO approach, for investigating and interpreting lithic assemblage variability. Certain researchers have gone so far as describing the identification of particular end-products, the attribution of elements to a specific reduction phase, or the ability of such approaches to track cultural trends as a 'fallacy' based on 'intuition' (Monnier and Missal, 2014:61). Thus, the core issue at hand for palaeoanthropology appears to be the choice of the most appropriate methodology for both analysing and best comparing lithic assemblages.

The opinion that technological analyses boil down to 'intuition' neglects the fact that, as with other methods, the CO approach can infuse interpretations with quantitative data acquired in a reproducible fashion. The CO approach frequently uses refitting and experimentation data to characterise assemblages and facilitate their comparison. In order to move the debate forward and answer to critics, we 1) selected common diagnostic technological elements that can be securely identified by different analysts and 2) tested if statistical analysis of the proportions of these elements in a selected region, the north-eastern Aquitaine Basin of southwestern France, over a given period (MIS 5-3), highlights differences between assemblages that are coherent with previous research performed within a CO framework. The selected study region has produced amongst the highest densities of recently excavated Middle Palaeolithic enclosed and open-air sites anywhere in the world. Nearly four decades of technological analyses, experimentation, and refitting combined with comprehensive raw material surveys create an ideal testing ground for exploring the structure of Mousterian lithic assemblage variability. Finally, we conclude by reflecting on the present and future role of lithic technology in material culture studies.

Material and methods

The northeastern Aquitaine Basin is limited by the Garonne Valley to the south, the Dronne Valley to the north and the Massif Central in the northeast. This region includes a varied topography and numerous hydrological networks centered around four main rivers, the Isle, Dordogne, Lot and Garonne and their tributaries (Fig. 1). The sample includes 41 assemblages from 24 Middle Palaeolithic sites, including caves and rock-shelters as well as open-air occupations, which were either recently excavated or revised and for which the artificial mixing of material from different layers can be ruled out. Table 1 presents the dominant group of retouched tools for each assemblage alongside associated flake production system described by previous CO analyses as either exclusive or mixed. We focused our analysis on a sub-sample of 24 assemblages for which detailed technological counts are available (Table 2). The dataset was explored using correspondence analysis performed with the PAST software package on artefact numbers for 7 specifically chosen technological artefact types that are best suited for inter-assemblage comparisons (see below).

In addition to assemblage size and proportion of retouched tools for each context studied, we quantified products belonging to seven specific, consistently identifiable technological categories typical of welldocumented Middle Palaeolithic flake production methods. The first and second categories comprise Levallois flakes and cores (Fig. 2). The Levallois method produces predetermined removals according to specific recurrent modalities (unipolar, bipolar, centripetal, convergent;e.g. Boëda, 1986e.g. Boëda, , 1994;;[START_REF] Geneste | Les industries de la Grotte Vaufrey: technologie du de ´bitage, e ´conomie et circulation de la matie `re premie `re lithique[END_REF][START_REF] Boëda | Identification de chaînes ope ´ratoires lithiques du Pale ´olithique ancien et moyen[END_REF][START_REF] Delagnes | L'organisation de la production lithique au Pale ´olithique moyen: approche technologique a ` partir de l'e ´tude des industries de La Chaise-de-Vouthon[END_REF][START_REF] Van Peer | The Levallois Reduction Strategy[END_REF]; articles in [START_REF] Dibble | The Definition and Interpretation of Levallois Technology[END_REF][START_REF] Lycett | Levallois economics: an examination of 'waste' pro-duction in experimentally produced Levallois reduction sequences[END_REF] or a single flake for preferential or lineal modalities [START_REF] Boëda | Approche technologique du concept Levallois et e ´valuation de son champ d'application: e ´tude de trois gisement saaliens et weichseliens de la France septentrionale[END_REF]. The Levallois products identified in the studied assemblages therefore correspond to a wide range of sizes and shapes (e.g. elongated, triangular, quadrangular) that clearly result from Levallois flaking methods as evidence by associated cores.

The third and fourth category includes pieces with a thick 'back' that corresponds to a removed portion of the lateral edge of the core. This 'back' may retain a combination of contrabulbs, flake negatives or cortical portions [START_REF] Locht | Le de ´bitage discoïde du gisement de Beauvais (Oise): aspect de la chaîne ope ´ratoire au travers de quelques remontages[END_REF][START_REF] Jaubert | Coudoulous, Le Rescoundudou, Mauran: diversite ´ des matie `res premie `res et variabilite ´ des sche ´mas de production d'e ´clats[END_REF][START_REF] Pasty | Le gisement pale ´olithique moyen des Meillers (Allier): un exemple de la variabilite ´ du de ´bitage discoïde[END_REF][START_REF] Peresani | Discoid Lithic Technology[END_REF].

Table 1 Technological and typological data for the overall Middle Palaeolithic assemblage sample.

As originally defined by [START_REF] Boëda | Le de ´bitage discoïde et le de ´bitage Levallois re ´current centripe `te[END_REF], these products are detached along a chordal orientation meaning that their flaking or technological axisis oblique to the axis of the piece. We distinguish two types of chordal flakes. The first (Fig. 2, n ○ 8-14) have a distal point created by the intersection of two either unilineal or crossed removals opposite the 'back', referred to as a "pseudo-Levallois point" by [START_REF] Bordes | Typologie du Pale ´olithique infe ´rieur et moyen[END_REF], while the second type (Fig. 2, n ○ 15-18), termed éclat d ébordant, has a lateral back oriented along the technological axis of the flake that is opposite one or two edges. Although both the Levallois and Discoid methods produce pseudo-Levallois points and éclats d ébordants, they are significantly more abundant and thicker in Discoid assemblages (see below).

The fifth category corresponds to cores fulfilling the techno-logical features of the Discoid method (e.g. [START_REF] Boëda | Le de ´bitage discoïde et le de ´bitage Levallois re ´current centripe `te[END_REF][START_REF] Peresani | Discoid Lithic Technology[END_REF]. These cores have a single (unifacial) surface (Fig. 3, n ○ 1) or at least two (bifacial or multidirectional) opposed surfaces (Fig. 3, n ○ 3) formed by a series of secant, primarily obliquely oriented removals that are both predetermined and predetermining and simultaneously maintain the necessary surface convexities.

Certain raw materials, particularly metaquartzites, are more often associated with the unifacial modality or bipolar percussion (Fig. 3, n ○ 4-6).

The sixth category corresponds to large asymmetrical flakes (in section or profile) with thick, large cortical or flat platforms typical of the Quina flaking method [START_REF] Turq | Approche technologique et e ´conomique du facie `s Mouste ´rien de type Quina: e ´tude pre ´liminaire[END_REF][START_REF] Bourguignon | La conception de de ´bitage Quina[END_REF][START_REF] Bourguignon | Le Mouste ´rien de type Quina: nouvelles de ´finitions d'une entite ´ technique[END_REF][START_REF] Faivre | Organisation techno-e ´conomique des syste `mes de production dans le Pale ´olithique moyen re ´cent du Nord-est Aquitain: Combe-Grenal et les Fieux[END_REF][START_REF] Hiscock | Quina procurement and tool production[END_REF]Fig. 4, n ○ 1-7). Despite their asymmetry, these flakes clearly differ morphologically from the chordal flakes described above [START_REF] Turq | Approche technologique et e ´conomique du facie `s Mouste ´rien de type Quina: e ´tude pre ´liminaire[END_REF][START_REF] Bourguignon | La conception de de ´bitage Quina[END_REF], 1997, Fig. 4, n ○ 1-7). The substantial volume of these pieces potentially permits both long tool reduction sequences (i.e. sharpening, resharpening, Fig. 4, n ○ 8-10) and act as a raw material reserve for producing additional flakes (Fig. 4, n ○ 11). The seventh category comprises products associated with non-Levallois blade production systems (Fig. 5). Mousterian blade technologies are now well recognized and widely documented in Europe, especially northern France and Belgium (e.g. [START_REF] Boëda | Le concept laminaire: rupture et filiation avec le concept Levallois[END_REF][START_REF] Conard | Tonchesberg and its Position in the Paleolithic of Northern Europe[END_REF][START_REF] Otte | Rocourt (Lie `ge, Belgique): industrie laminaire ancienne[END_REF][START_REF] Revillion | Technologie du de ´bitage laminaire au Pale ´olithique moyen en Europe septentrionale: e ´tat de la question[END_REF][START_REF] Delagnes | Blade production during the Middle Paleolithic in Northwestern Europe[END_REF][START_REF] Kuhn | The late Middle and Early Upper Paleolithic in Italy[END_REF]Kozlovsky, 2001;[START_REF] Depaepe | Le Pale ´olithique moyen de valle ´e de la[END_REF], where these assemblages are particularly well represented in MIS 5. These types of flaking systems, while considerably less frequent in south-western France, have nevertheless been documented from contexts spanning MIS 5b to 3 [START_REF] Soressi | Le Mouste ´rien de tradition acheule ´enne du sud-ouest de la France. Discussion sur la signification du facie `s a ` partir de l'e ´tude compare ´e de quatre sites: Pech-de-l'Aze ´ I[END_REF][START_REF] Blaser | Une se ´rie lithique a ` composante Laminaire dans le Pale ´olithique moyen du Sud-Ouest de la France: le site de Cantalouette 4 (Creysse, Dordogne, France)[END_REF][START_REF] Faivre | A material anecdote but technical reality: bladelet and small blade production during the recent Middle Paleolithic at Combe-Grenal rock shelter[END_REF][START_REF] Ortega | La produccio ´n laminar durante el Paleolítico medio en el norte y el sur-oeste de Francia: el aporte de la experimentacio ´n[END_REF]. Our sample includes prismatic or semi-prismatic cores as well as laminar removals clearly distinct from Levallois products given their elongation, robustness and trapezoidal or triangular cross-sections. Elements related to the maintenance of the debitage surface and volume (e.g. neo-crests, corticallybacked blades) were also counted.

All of these categories correspond to products of particular, welldocumented flaking methods. We have, however, intentionally excluded bifacial tools and evidence for their production in the analysis for several reasons. First, bifacial shaping is seldom exclusively represented in any assemblages and, those that do have a heavy bifacial component (bifaces and/or evidence for their manufacture) come from old excavations (e.g. La Ferrassie, Pech de L'Aze I, Le Moustier, Abri Peyrony) suffering clear collector bias and lacking systematic sieving. Second, site function issues, the high spatio-temporal fragmentation of bifacial shaping [START_REF] Geneste | Analyse lithique d'industries mouste ´riennes du Pe ´rigord: une approche technologique du comportement des groupes humains au Pale ´olithique moyen[END_REF][START_REF] Turq | Pale ´olithique infe ´rieur et moyen entre Dordogne et Lot[END_REF][START_REF] Soressi | Le Mouste ´rien de tradition acheule ´enne du sud-ouest de la France. Discussion sur la signification du facie `s a ` partir de l'e ´tude compare ´e de quatre sites: Pech-de-l'Aze ´ I[END_REF][START_REF] Turq | The fragmented char-acter of Middle Palaeolithic stone tool technology[END_REF][START_REF] Brenet | The function and role of bifaces in the Late Middle Paleolithic of southwestern France: examples from the Charente and Dordogne to the Basque Country[END_REF]Deschamps, in press) in combination with the high potential of resharpening of bifacial tools [START_REF] Boëda | Identification de chaînes ope ´ratoires lithiques du Pale ´olithique ancien et moyen[END_REF](Boëda et al., , 1991;;[START_REF] Bourguignon | Apports de l'expe ´rimentation et de l'analyse techno-morphofonctionnelle a ` la reconnaissance du processus d'ame ´nagement de la retouche Quina[END_REF] as well as the elevated mobility of bifaces presently makes discerning the importance of bifacial shaping in any given assemblage difficult. For example, while no bifaces and a handful of bifacial thinning flakes were recovered from layer K of Les Fieux (Faivre, 2006) the opposite is true for La Plane [START_REF] Turq | Pale ´olithique infe ´rieur et moyen entre Dordogne et Lot[END_REF].

Finally, our database of recently excavated and critically reassessed assemblages shows nearly half (n 19) to be associated with one or several of the dominant flake production systems (Table 1). Before bifacial shaping can be integrated in any discussion of the structure of Mousterian variability considerable work needs to be done, including new modern excavations, which fortunately is the case for several of the sites mentioned above, alongside a systematic revision of small finds from recent field projects in order to identify typical by-products associated with biface manufacture and maintenance (e.g. Gravina, in press).

Results

Table 2 presents raw counts of technologically diagnostic ele-ments for each assemblage. Correspondence analysis demonstrates three factors to explain 91.4% of the variability in our dataset (Fig. 6). Factor 1 distinguishes assemblages principally according to the abundance of Quina-type flakes. Factor 2 separates assemblages richer in pseudo-Levallois points, éclats d ébordants and Discoid cores (these 3 variables being highly correlated) from assemblages with a heavy Levallois (flakes and cores) and non-Levallois blade component. Factor 3 individualises assemblages with more evidence of non-Levallois blade production.

Plotting the assemblages along these 3 factors (Fig. 6) reveals a strong clustering of assemblages in at least 3 distinct groups. These three groups gather assemblages that were previously described as being dominated by Quina, Discoid or Levallois CO. In no case does an assemblage previously identified with one dominant CO appear in a cluster correlated with any of the other two. The first group is the most distinctive in that it contains assemblages where the Quina CO is exclusive. In the second group, assemblages exclusively associated with the chordal Discoid CO are highly clustered together and separated from other assemblages; while the more "mixed" assemblages of Combe-Grenal level 12 (chordal Discoid Levallois laminar) and the quartz component from Les Fieux level K (Centripetal Discoid bipolar anvil) are closer to the other groups. Assemblages from the third group, dominated by Levallois CO (green and blue circles (in the web version) on Fig. 6), can be partially separated from each other on the third axis, with two assemblages (Cantalouette 1 and Combe-Grenal level 29-30) richer in non-Levallois blade products. The comparison of retouched tools proportions with flake pro-duction systems, as well as their exclusive or coexisting character, highlights several notable differences (Fig. 7). The Quina assemblages from Roc-de-Marsal are distinguished by a higher percentage of retouched tools than in all the other assemblages.

As noted elsewhere [START_REF] Faivre | Modalite ´s d'occupations et exploitation des milieux au Pale ´olithique dans le Sud-Ouest de la France: l'exemple du Quercy Actes du Colloque organise ´ dans le cadre du XVIe `me Congre `s de l'UISPP[END_REF][START_REF] Gravina | MTA-B or not to be? Recycled bifaces and shifting hunting strategies at Le Moustier and their implication for the late Middle Palaeolithic in southwestern France[END_REF], assemblages in which the chordal Discoid method is exclusive or dominant contain less than 10% retouched tools. The same is true for Les Fieux (level K), where the use of metaquartzites likely conditioned flaking choices (bipolar on anvil and centripetal Discoid), the low rate of retouched tools (in most cases less than 5% of the entire series) being closely correlated to chordal Discoid flaking method. Assemblages dominated by Levallois CO have more variable percentages of retouched tools, but remain low when the Levallois method is exclusive.

Discussion

The nature of any lithic assemblage is, by necessity, structured by different elements, including natural processes such as sedimentation rates. Cultural factors (choices) determine artefact use and discard as well as the form in which artefacts are ultimately incorporated into the archaeological record, each resulting from a specific phase in the reduction of a volume of raw material. Experimental data collected over the last 20 years and commonly employed in CO analysis permits many but certainly not all diagnostic objects to be reliably placed in a specific stage of the reduction sequence (e.g. [START_REF] Geneste | Les industries de la Grotte Vaufrey: technologie du de ´bitage, e ´conomie et circulation de la matie `re premie `re lithique[END_REF][START_REF] Turq | Exploitation du milieu mine ´ral: technologie, e ´conomie et circulation des silex[END_REF][START_REF] Brenet | Elaboration d'un protocole d'expe ´rimentation lithique pour la compre ´hension des comportements techniques et techno-e ´conomiques au Pale ´olithique moyen[END_REF][START_REF] Brenet | Elaboracio ´n de un protocolo de experimentacio ´n lítica para la comprensio ´n del comportamiento te ´cnico y tecnoecono ´mico durante el Paleolítico medio[END_REF][START_REF] Brenet | Approche expe ´rimentale de la variabilite ´ des industries du Pale ´olithique moyen. L'inte ´re ^t d'e ´valuer les niveaux de compe ´tence et d'efficience des expe ´rimentateurs[END_REF][START_REF] Roussel | La percussion a ` la pierre tendre au Pale ´olithique moyen: intentionnalite ´ ou opportunisme. Expe ´rimentation et analyse du mate ´riel de « Chez-Pinaud », Jonzac (Charente-Maritime)[END_REF]Bourguignon et al., 2011a[START_REF] Bourguignon | Lascas de puesta en funcionamiento, de reacondicionamiento y de reciclado de las raederas Quina: Estimacio ´n e interpretacio ´n tecno-econo ´mica[END_REF][START_REF] Ortega | La produccio ´n laminar durante el Paleolítico medio en el norte y el sur-oeste de Francia: el aporte de la experimentacio ´n[END_REF]. Moreover, progress in raw material sourcing and the tracing of their postgenetic alteration [START_REF] Fernandes | Itine ´raires et transformations du silex: une pe ´troarche ´ologie refonde ´e, application au Pale ´olithique moyen[END_REF] allow aspects of artefact mobility and the segmentation of the CO to be better understood [START_REF] Turq | The fragmented char-acter of Middle Palaeolithic stone tool technology[END_REF]. What emerged from these works was not, as misunderstood by Monnier and Missal (2014:61), a "severe blow to the notion that the CO approach enables us to reconstruct the intentions of prehistoric knappers", but simply that other artefact forms (e.g. large cortical and non-cortical flakes, cores, etc.) in addition to identifiable end-products are also moved around the landscape (see also Turq et al., in press), reflecting more complex economic choices than previously thought.

The identification of any specific reduction sequence, for example Levallois or Discoid, should never be determined solely on the presence of a single object. The presence of éclats d ébordants is not necessarily synonymous with Levallois or Discoid debitage, it is, rather, the conjunction of typical products and by-products with specific technical criteria determined by experimentation and refitting that allows the production methods underlying the formation of an assemblage to be determined.

In the same sense, assemblage type should never be determined solely with recourse to core type or form. 2.

For example, while 30 years ago the problems originally noted by [START_REF] Lenoir | Recurrent centripetal debitage (Levallois and Discoidal): continuity or discontinuity[END_REF] and repeated by [START_REF] Monnier | Another Mousterian Debate? Bordian facies, chaîne ope ´ratoire technocomplexes, and patterns of lithic variability in the western European Middle and Upper Pleistocene[END_REF] did exist in terms of distinguishing Discoid from Levallois debitage, they have, in no small part, been resolved by refitting studies, numerous technological analyses and experimentation (e.g. articles in [START_REF] Peresani | Discoid Lithic Technology[END_REF].

On the identification and definition of technocomplexes

Correspondence analysis confirms that a quantitative technological approach is possible, and that the commonly employed groups (Quina, Discoid, Levallois) pertain to genuine differences in the relative representation of technologically diagnostic elements in lithic assemblages. Moreover, the artifact counts treated in the correspondence analysis were produced by different analysts (Table 2), reinforcing the reproducibility of a technological approach to Middle Palaeolithic lithic assemblages.

The proportions of these diagnostic technological elements can serve as the structural framework for better defining lithic technocomplexes (LTC). Middle Palaeolithic LTC were initially defined as the material expression of the practical know-how evident in lithic reduction sequences (or chaîne op ératoire), which is shared across a range of human groups [START_REF] Delagnes | Les technocomplexes du Pale ´olithique moyen en Europe occidentale dans leur cadre diachronique et ge ´ographique[END_REF]. Defined as such, this concept was subsequently used to restructure Mousterian variability and revisit the archeo-sequences from southwestern France [START_REF] Jaubert | A new look at the end of the Middle Palaeolithic sequence in southwestern France[END_REF][START_REF] Jaubert | Les arche ´o-se ´quences du Pale ´olithique moyen du Sud-Ouest de la France: quel bilan un quart de sie `cle apre `s François Bordes[END_REF]. This revision, while not completely departing from certain of Bordes' facies, provided a new vision of the chronological patterning of Mousterian assemblage types in the region. Monnier and Missal (2014:63) took exception to this new synthesis, while at the same time clearly recognizing the fact that Jaubert had underlined the preliminary nature of the synthesized Middle Palaeolithic archaeo-sequence for south-western France.

They note that (1) no data is presented to support the technocomplexes, (2) it is unlikely that different researchers would attribute the same assemblage to the same LTC, and (3) that these LTC are not explicitly defined. We have already addressed the first two criticisms above.

Investigating industrial variability via coarse-grained patterns in median Levallois or biface indices, relative proportions of Levallois versus non-Levallois assemblages, retouched tool frequencies with the basic chronological unit being Marine Isotope Stage, as Monnier and Missal have done [START_REF] Monnier | The Lower/Middle Paleolithic periodization in western Europe: an evaluation[END_REF][START_REF] Monnier | Another Mousterian Debate? Bordian facies, chaîne ope ´ratoire technocomplexes, and patterns of lithic variability in the western European Middle and Upper Pleistocene[END_REF] appears inadequate, particularly given both the increasing recognition of rapid technological change within MIS 3 alone and the current resolution of absolute dating methods for the periods in question (e.g. [START_REF] Discamps | Human choices and environmental constraints: deciphering the variability of large game procurement from Mousterian to Aurignacian times (MIS 5-3) in southwestern France[END_REF][START_REF] Jaubert | A new look at the end of the Middle Palaeolithic sequence in southwestern France[END_REF][START_REF] Faivre | The contribution of lithic production systems to the interpretation of Mousterian industrial variability in south-western France: the example of Combe-Grenal (Dordogne, France)[END_REF][START_REF] Gravina | MTA-B or not to be? Recycled bifaces and shifting hunting strategies at Le Moustier and their implication for the late Middle Palaeolithic in southwestern France[END_REF]. The key element for both defining LTC and addressing aspects of Neanderthal techno-economic behavior should remain lithic production systems, which can be exclusive or coexist within assemblages. Several decades of research, experimentation and refitting, within a CO framework or otherwise, have resulted in a series of clearly identifiable and quantifiable elements (i.e. the technological groups used in the correspondence analysis, see above) that distinguish each system. Based on the above, at least three main techno-complexes can be identified in our study region.

Levallois system LTC

In the LTC based on the Levallois system [START_REF] Boëda | Approche technologique du concept Levallois et e ´valuation de son champ d'application: e ´tude de trois gisement saaliens et weichseliens de la France septentrionale[END_REF][START_REF] Boëda | Le concept Levallois: variabilite ´ des me ´thodes[END_REF][START_REF] Boëda | Techno-logique & Technologie. Une pale ´o-histoire des objets lithiques tranchants[END_REF][START_REF] Geneste | Les industries de la Grotte Vaufrey: technologie du de ´bitage, e ´conomie et circulation de la matie `re premie `re lithique[END_REF][START_REF] Boëda | Identification de chaînes ope ´ratoires lithiques du Pale ´olithique ancien et moyen[END_REF], the organisation of core reduction sequence plays a central role (Fig. 8). The Levallois system [START_REF] Boëda | Approche technologique du concept Levallois et e ´valuation de son champ d'application: e ´tude de trois gisement saaliens et weichseliens de la France septentrionale[END_REF][START_REF] Boëda | Le concept Levallois: variabilite ´ des me ´thodes[END_REF][START_REF] Geneste | Les industries de la Grotte Vaufrey: technologie du de ´bitage, e ´conomie et circulation de la matie `re premie `re lithique[END_REF][START_REF] Boëda | Identification de chaînes ope ´ratoires lithiques du Pale ´olithique ancien et moyen[END_REF] produces standardized blanks with a high degree of predetermination [START_REF] Lycett | Levallois economics: an examination of 'waste' pro-duction in experimentally produced Levallois reduction sequences[END_REF]. The productivity of the method can vary, ranging from a single preferential flake to multiple production episodes [START_REF] Bourguignon | Syste `mes de production lithique, gestion des outillages et territoires au Pale ´olithique moyen: où se trouve la complexite ´[END_REF], following the reinstallation of the core volume and the removal of specific convexity management flakes (Boëda's 2013, Type E). Levallois products present a wide range of functional features, either when unmodified or following resharpening or reduction trajectories of different intensities resulting in various scraper and denticulate tool forms [START_REF] Dibble | Interpreting typological variation of Middle Paleolithic scrapers: function, style, or sequence of reduction[END_REF][START_REF] Dibble | Reduction sequences in the manufacture of Mousterian implements of France[END_REF][START_REF] Dibble | Middle Paleolithic scraper reduction: background, clarification, and review of evidence to data[END_REF]. This large variety of tool types, the foundation of Bordes' facies, is a component of the Levallois techno-complex not a defining feature. The fact that unmodified Levallois products are readily functional likely explains the low number of retouched tools in several assemblages (Fig. 7). Moreover, the exportation of both large Levallois and other types of flakes from certain sites, as demonstrated by a technological analysis and refitting of the open-air assemblage from Cantalouette 2 [START_REF] Bourguignon | L'occupation mouste ´rienne de la Doline de Cantalouette II: Spe ´cificite ´s technologiques et e ´conomiques premiers re ´sultats d'une analyse inte ´gre[END_REF], probably also influences the proportion of retouched Levallois products.

Discoid system LTC

The LTC based around the Discoid system [START_REF] Boëda | Le de ´bitage discoïde et le de ´bitage Levallois re ´current centripe `te[END_REF]Mourre and Jaubert, 1993;[START_REF] Peresani | Discoid Lithic Technology[END_REF] are marked by flaking modalities (one, two or several flaking surfaces) whose particular configuration produces a series of predetermining and predetermined flakes (Fig. 8). However, the initial configuration stage is less complex [START_REF] Bourguignon | Syste `mes de production lithique, gestion des outillages et territoires au Pale ´olithique moyen: où se trouve la complexite ´[END_REF]; flaking surfaces are unprepared and require no specific maintenance flakes (Type D volume; [START_REF] Boëda | Techno-logique & Technologie. Une pale ´o-histoire des objets lithiques tranchants[END_REF]. Removals are essentially oriented around the continual maintenance of suitable flaking angles between flaking surfaces and striking platforms, with the creation of ridges (guides) as the main predetermining criteria. In the study region, the chordal Discoid method (see above) is geared around the recurrent production of flakes with the same morpho-technical features along the same technological axis (oblique) of the core [START_REF] Boëda | Le de ´bitage discoïde et le de ´bitage Levallois re ´current centripe `te[END_REF]. This highly productive flaking system is primarily connected to the production of "pseudo-Levallois points" and éclats d ébordants. The identification of a ramified Discoid reduction sequence involving flakes, often thick cortical elements, used as cores introduces variability in the sizes of these two main production objectives [START_REF] Bourguignon | Une chaîne ope ´ratoire de de ´bitage sur e ´clat du Mouste ´rien a ` denticule ´s aquitain: les exemples de Champs de Bossuet et de Combe-Grenal c.14[END_REF]Bourguignon et al., 2004;[START_REF] Faivre | Organisation techno-e ´conomique des syste `mes de production dans le Pale ´olithique moyen re ´cent du Nord-est Aquitain: Combe-Grenal et les Fieux[END_REF][START_REF] Gravina | MTA-B or not to be? Recycled bifaces and shifting hunting strategies at Le Moustier and their implication for the late Middle Palaeolithic in southwestern France[END_REF].

This system appears organised around the production of identical or highly similar removals, and finds some similarities with Levallois systems. Both are flake production methods, varying in complexity depending on the operational stage, whose objective is the production of standardized flakes in terms of form. The functionally predetermined nature of Levallois products is equally evident in those produced by the Discoid flaking system, as can be seen in the low retouch frequencies for most Discoid assemblages in the northeastern Aquitaine Basin. Typical Discoid products (i.e. pseudo-Levallois points and éclats d ébordants), with their predetermined functional properties, an active edge opposite a "back", were probably used unretouched, as supported by several use-wear analyses [START_REF] Bourguignon | Le gisement mouste ´rien de Champ de Bossuet[END_REF][START_REF] Lemorini | Technomorphological and use-wear functional analysis: an integrated approach to the study of a discoid industry[END_REF][START_REF] Rios Garaizar | Industria litica y sociedad en la transicio ´n del Paleolítico medio al superior en torno al golfo de Bizkaia (The `se de doctorat)[END_REF]. These types of assemblages have also been associated with specific site types geared around butchery activities [START_REF] Brugal | Etude de populations des grands bovide ´s europe ´ens: inte ´re ^t pour la connaissance des comportements humains au Pale ´olithique[END_REF][START_REF] Locht | L'industrie lithique du gisement de Beauvais (Oise, France): objectifs et variabilite du debitage discoide[END_REF][START_REF] Martinez | Discoid Technology and Use-wear Analysis from Abric Romaní[END_REF][START_REF] Coumont | Taphonomie pre ´historique: mammife `res fossils en contexte naturel, les avens pie `ges, apports pour l'e ´tude des arche ´ofaunes[END_REF][START_REF] Brugal | Les Peuplements mammaliens au Ple ´istoce `ne moyen et supe ´rieur en Quercy. In: Settlement Dynamics and Environment Resources in the Palaeolithic of Southwest France: the Case of the Quercy Region[END_REF].

If the chordal modality is best represented in the studied as-semblages, the centripetal Discoid modality appears uniquely in association with the use of metaquartzites, which are the main raw materials available in certain geographical areas (e.g. Quercy region). Several technological studies have shown that this modality, often associated with bipolar flaking on anvil, could be a response to raw material contraints, with the natural convex surface of quartz pebble serving as effective striking platforms [START_REF] Jaubert | Coudoulous, Le Rescoundudou, Mauran: diversite ´ des matie `res premie `res et variabilite ´ des sche ´mas de production d'e ´clats[END_REF]Thie ´baut et al., 2008;[START_REF] Faivre | Modalite ´s d'occupations et exploitation des milieux au Pale ´olithique dans le Sud-Ouest de la France: l'exemple du Quercy Actes du Colloque organise ´ dans le cadre du XVIe `me Congre `s de l'UISPP[END_REF]. These modalities produce secant centripetal flakes with wide, thick cortical platforms opposite two convergent edges. Whatever the flaking modality (chordal on flint or centripetal on quartz), end-products seem to share the same morphotechnical features (Faivre, 2004).

Quina system LTC

The Quina system [START_REF] Turq | Approche technologique et e ´conomique du facie `s Mouste ´rien de type Quina: e ´tude pre ´liminaire[END_REF][START_REF] Bourguignon | La conception de de ´bitage Quina[END_REF][START_REF] Bourguignon | Le Mouste ´rien de type Quina: nouvelles de ´finitions d'une entite ´ technique[END_REF][START_REF] Faivre | Organisation techno-e ´conomique des syste `mes de production dans le Pale ´olithique moyen re ´cent du Nord-est Aquitain: Combe-Grenal et les Fieux[END_REF][START_REF] Faivre | Organisation techno-e ´conomique des syste `mes de production dans le Pale ´olithique moyen re ´cent du nord-est aquitain: Combe-Grenal et les Fieux[END_REF] is structured around a combination of operational stages that are no less complex than either the Levallois or Discoid systems. Central to the Quina flaking methods is the production of a wide range of predetermining and predetermined flakes which are integrated into various functional and production objectives (Fig. 9). Importantly, the Quina system is not limited to strictly functional objectives represented by a specific tool groupside-scrapers with Quina or demi-Quina retouch. Quina debitage is organised around the production of asymmetrical flakes (in section or profile) with at least one elongated edge opposite a thick face (lateral back or platform) [START_REF] Turq | Approche technologique et e ´conomique du facie `s Mouste ´rien de type Quina: e ´tude pre ´liminaire[END_REF][START_REF] Bourguignon | La conception de de ´bitage Quina[END_REF][START_REF] Bourguignon | Le Mouste ´rien de type Quina: nouvelles de ´finitions d'une entite ´ technique[END_REF][START_REF] Faivre | Organisation techno-e ´conomique des syste `mes de production dans le Pale ´olithique moyen re ´cent du Nord-est Aquitain: Combe-Grenal et les Fieux[END_REF][START_REF] Faivre | Organisation techno-e ´conomique des syste `mes de production dans le Pale ´olithique moyen re ´cent du nord-est aquitain: Combe-Grenal et les Fieux[END_REF]. These products, although varying in size over the course of the reduction sequence, nevertheless remain essentially identical and afford diverse and complementary morpho-functional possibilities [START_REF] Bourguignon | Syste `mes de production lithique, gestion des outillages et territoires au Pale ´olithique moyen: où se trouve la complexite ´[END_REF]. Moreover, the volumetric potential of Quina-type flakes, particularly in terms of their thickness, allows different core-on-flake/tool (the éclat matrice in French; Bourguignon et al., 2004;[START_REF] Faivre | Organisation techno-e ´conomique des syste `mes de production dans le Pale ´olithique moyen re ´cent du nord-est aquitain: Combe-Grenal et les Fieux[END_REF] reduction sequences. This represents an important departure from the standardised products typical of the Levallois and Discoid systems to the extent that technical investment is not primarily focused on the 'core'.

Mixed system LTC

A number of assemblages (n=11, Table 2) provide evidence for the combination of two or more systems described above. It is important to note that in all of these mixed LTC, one system is clearly dominant (the first listed in Table 2). It is interesting to note that the Quina is the only system never found in association with another one. Levallois and non-Levallois blade systems are found together in 3 instances, 5 cases combine the chordal Discoid and Levallois systems with evidence for non-Levallois blade production, with the final 3 described as a mix of Levallois with the production of unipolar elongated flakes (see below). In some cases, these mixed assemblages may be interpreted as local adaptations to raw material constraints, where imported elements (non-local raw materials) of one system are found alongside those of another produced on-site in, what are often, poor quality raw materials [START_REF] Chalard | Espaces du Pale ´olithique moyen. Te ´moins d'utilisation de silex allochtones en Quercy (France). Un sie `cle de discours scientifique en Pre ´histoire[END_REF][START_REF] Faivre | Modalite ´s d'occupations et exploitation des milieux au Pale ´olithique dans le Sud-Ouest de la France: l'exemple du Quercy Actes du Colloque organise ´ dans le cadre du XVIe `me Congre `s de l'UISPP[END_REF]. More often than not, mixed assemblages concern the same local raw material, rendering it difficult, if not impossible, to distinguish imported elements. Here, the combination of different systems could be interpreted as reflecting disturbances between different non-synchronous assemblages, especially in cave or rock shelter sequences. However, spatial data and refits at open-air sites succinctly demonstrate the coexistence of Levallois and non-Levallois blade production within the same occupation, as at Cantalouette IV [START_REF] Blaser | Une se ´rie lithique a ` composante Laminaire dans le Pale ´olithique moyen du Sud-Ouest de la France: le site de Cantalouette 4 (Creysse, Dordogne, France)[END_REF]Fig. 10). Additionally, several open-air assemblages show the combination of Levallois and chordal Discoid systems in the same knapping areas or, as revealed by refits, between adjacent areas [START_REF] Brenet | Silex et roches me ´tamorphiques au Pale ´olithique moyen. Com-bemenue et Chemin d'Herbe[END_REF].

Conclusion

Lithic technology, like any other research field, is based on concepts and terminology shared by an international community of researchers who worked and are still working on the contexts discussed in this paper. Here we have shown that, based on well-defined technological criteria (i.e. an explicit typology), the chaîne op ératoire approach can rely on quantitative data. Statistical analysis of this quantitative technological data supports previous qualitative CO descriptions. The identification of a specific CO in a given lithic assemblage is thus neither ad hoc nor intuitive, but rather a reliable methodological tool supportable by quantitative data. Certain LTC can be defined both qualitatively and quantitatively and serve as the most secure basis for advancing our un-derstanding of Mousterian techno-economic variability. Similar approaches combining quantitative data and chaîne op ératoire derived observations have also been successively employed to either identify reduction stages [START_REF] Scerri | Can lithic attribute analyses identify discrete reduction trajectories? A quantitative study using refitted lithic sets[END_REF] or incorporate technological analysis with raw material economy [START_REF] Will | Characterizing the late Pleistocene MSA lithic technology of Sibudu, KwaZulu-Natal, South Africa[END_REF]. Despite the fact that the combination of different analytical approaches is more often than not beneficial, the advantages of including technological data in lithic studies are, in our opinion, evident. The chaîne op ératoire approach elaborated here not only succeeded in identifying clear patterns of shared technological behaviour but also infuses models of Neandertal techno-economy, mobility patterns, and landscape exploitation with a dynamism that strictly quantitative approaches are, in our opinion, likely to fail to detect.

The LTC identified here group distinct assemblages that share a common, recurrent and, more often than not, exclusive flake production system. The technological definition of LTC succinctly moves us beyond both the dependence on retouched tool types and the dichotomy of Levallois and non-Levallois assemblages, leading to the ultimate abandonment of the culturally charged 'facies' concept of Bordes. The preliminary adoption of the more neutral term 'techno-complex' embodies shared technological behaviours that structure Mousterian industrial variability. Currently, the search for their 'meaning', however, appears pre-mature, confounded by the lack of faunal data, raw material exploitation patterns, and comparable chronological information for many of the assemblages considered here.

Fig. 1 .

 1 Fig. 1. Study area and Middle Palaeolithic sites included in the analysis.

Fig. 2 .

 2 Fig. 2. Levallois cores (n ○ 1e3) and products (n ○ 4e7). Pseudo-Levallois points (n ○ 8e14) and éclats débordants (n ○ 15e19). Illustrations n ○ 13 and 14 (Le Moustier) by G. Devilder.

Fig. 3 .

 3 Fig. 3. Discoid cores. Unifacial e flint (n ○ 1), unifacial e metaquartzite (n ○ 4), bifacial e flint (n ○ 2, 3). Bipolar debitage on metaquartzite (n ○ 5, 6).

Fig. 4 .

 4 Fig. 4. Quina-type flakes.

Fig. 5 .

 5 Fig. 5. Non-levallois blade cores and products.

Fig. 6 .

 6 Fig. 6. Correspondence analysis. For site codes see Table 2.

  Fig. 6. Correspondence analysis. For site codes see Table 2.

Fig. 7 .

 7 Fig. 7. Proportion of retouched tools by assemblage. For site codes see Table 2.

Fig. 8 .

 8 Fig. 8. Organisation of Levallois and Discoid LTC.

Fig. 9 .

 9 Fig. 9. Organisation of the Quina LTC.

Fig. 10 .

 10 Fig. 10. Refit between a Levallois core and a non-Levallois blade core from Cantalou-ette IV[START_REF] Blaser | Une se ´rie lithique a ` composante Laminaire dans le Pale ´olithique moyen du Sud-Ouest de la France: le site de Cantalouette 4 (Creysse, Dordogne, France)[END_REF].

Table 2

 2 Assemblage sizes, retouched tool proportions and counts of different technological groups of the analysed assemblages included in the correspondence analysis.

Acknowledgements

The authors would like to thank the Service regional d'archeologie (Nathalie Fourment) and the Muse ´e national de Pre ´histoire, especially its director J.-J. Cleyet-Merle, as well as Peggy Jacquement, Stephane Madelaine, Bernard Nicolas. We are also grateful to all the participants of the USIPP B40 e Cleaning up a messy Mousterian: how to describe and interpret Late Middle Palaeolithic chrono-cultural variability in Atlantic Europe (Burgos, September 2014). We would also like to thank G. Devilder for the Le Moustier artefact illustrations. This research forms part of the Ne ´Mo project financed by a grant from the French National Research Agency program Investissements d'avenir (ANR-10-LABX-52), and BG would like to recognise the French Ministry of Culture and Communication (MCC) for an Allocation de Recherche et Formation that helped fund part of this research. We are grateful to Wil Roebroeks and Manuel Will for constructive comments that helped to improve the manuscript.