Each recent prehistoric site is valued for its size, the quality of its archaeological record and the exactness of a classification backed up by stratigraphy and absolute chronology. It is also valued for its capacity to be integrated in its geographical and cultural context. In this framework, two kinds of elements are to be found in its material inventory. On one hand, artefacts making up common household items, created, brought to, reactivated and abandoned on the site, and on the other hand, artefacts belonging to the social or ritual sphere (ornaments, offerings, etc.) for a more prolonged use and with sporadic and/or special functions. The latter need more time to be made and imply foreign and good quality raw materials, a social cost incentivising their exchange.

In the Atapuerca mountain range (North of the Iberian Peninsula), a karst system called Cueva Mayor-Cueva del Silo has developed providing support for several Quaternary sites which together make up one of the largest records in European prehistory. Along with its well-known archaeological remains from the Pleistocene (Arsuaga et al., 1997; Bermúdez de Castro et al., 1999) , it also yields others from the Holocene (Figure 1). At Cueva Mayor, occupations during the Holocene developed not only in its large entrance, called El Portalón (Figure S1), but also in the inner galleries as in Galería del Sílex, a place for burials and artistic purposes (Apellániz & Domingo, 1987) .

The archaeological nature of El Portalón has been known since the end of the nineteenth century and an ongoing intervention has yielded a stratigraphy with 11 levels and a potential of over six metres (Figure 2 and Figures S1-S5 and Note S1)

The archaeological material record and a long radio-chronological series situate the occupations from the end of the Pleistocene to the Middle Age (Table 1 and Table S1) (Carretero et al., 2008) .

(1) = Sample number indicated in Figure 2; (2) = Specimen from El Portalón directly dated; (3) = Specimen directly dated studied in this work (Figure 11).

El Portalón would have had a variety of uses throughout its long period of occupation, as a dwelling, a cattle shelter and burial site, activities that would have been complemented by those carried out in Galería del Sílex or nearby caves as El Mirador (Vergés et al., 2008) , as well as on grazing grounds and arable lands on the Sierra.

The purpose of this work is to provide an overview of a collection of pottery and bone objects belonging from the site of El Portalón by examining them through time (from the Neolithic to the Bronze age) and within a large geographical framework. At the same time, we shall discover the keys to the occupation of this cave entrance and its link with the prehistory of the region.

The collection of pottery from El Portalón is as varied as it is large as regards form and decoration. Due to its special interest, we have brought together pottery adorned using the Boquique technique with Neolithic chronology (Alday et al., 2009) (Figure 3 and Figure S6).

The bone industry inventory from El Portalón includes in excess of two hundred objects distributed over several levels, cultural units and industrial categories (Table S2). In this study we shall describe the characteristics of the bi-pointed artefacts, needles/pins, V-perforated buttons, arrowheads and a special human bone awl. Some of them are identified and described here for the first time (for nomenclature and typology Adán, 1997; Barandiarán, 1967; Camps-Fabrer, 1990; Rodanés, 1987; Voruz, 1987 ).

El Portalón of Cueva Mayor was occupied for several millennia during prehistory, and intensely so during the Bronze Age. The sedimentary characters of these levels appear to derive from the use of the shelter as a fold for livestock, with its stabling and cleaning phases (the Atapuerca Mountain Range, at 1000 m above sea level, is suitable for animal husbandry). Although this could have been the one of the site’s main functions during the Bronze Age, its size, over 200 m ² , allows for the development of other activities at the same time and at successive stages. Proof of the fact is the presence at level 7/8 of a Chalcolithic funerary tumulus (Figure 2 and Note S1).

Essential typological characteristics of selected pottery and bone tools production from the Neolithic to Bronze Age have been described as well as their similarities with materials from another Iberian and European sites. This comparison show us that the exchange networks active for this periods in prehistoric Europe and the traffic of these materials (mainly bone artifacts) is an intentional activity where economical, hierarchical and ideological interests are being expressed. Nevertheless in the 2000 years represented by the materials, the social and economic organization suffered important changes and the social capacities differed from each other, what make difficult to interpret completely the material exchanges from long distance.

As in most of the Iberian Peninsula, in this region, the Neolithic way of life started to take over at the end of the first half of the seventh millennium BP (Alday et al., 2009) . By the last third of this millennium it was fully established on the coastal areas and in the interior of the Iberian Peninsula. The organisation of a sheepfold cave network for domestic livestock is one of the most patent strategies in the early Neolithic, and even more so in subsequent stages. El Portalón, El Mirador, Cueva Lóbrega, Los Husos I and II, to cite examples close to us, are large-sized shelters with a similar occupation and management programme. The livestock activities are complemented by other agricultural activities in open-air settlements, hunting in rock shelters and burial rites in diverse tombs. The organization of the territory is dynamic and integrating in concept, where inter- and supra-regional relations play an essential role. The Neolithization in the Iberian Peninsula then created complex scenes in which some external influences with different origins and directions were received and in which the distribution, interests and participation from the local groups were not uniform. These differences will be reflected in the pottery decorative tradition from Early Neolithic, the cardial type linked to Mediterranean and Southern and middle Portuguese Atlantic littoral, whereas the Boquique pottery was linked to inner Iberia, some Portuguese areas and to the Middle Ebro river Basin (Alday et al., 2011) . Therefore, pottery making in the early Neolithic in the Iberian Peninsula reveals a stylistic compartmentalisation related to the interests of each group and with the relations they establish. If we consider pottery with printed cardial decoration an identity sign of the Mediterranean, then Boquique ornamentation should be that of the hinterland. This is the case of the Sierra de Atapuerca where its Boquique production, technically and stylistically homogeneous, points to local production but with a high degree of engagement with communities established in the Upper and Middle Ebro Basin, the Eastern part of the Bay of Biscay, the Meseta and part of Portugal. It is local production based on stylistic and ideological standards shared among several regions. The Boquique pottery from El Portalón, Galería del Sílex and El Mirador sites is the local recreation of a style linked to one of the organizational cores from the Iberian Neolithic.

Regional documentation for the middle and late Neolithic is very poor, except in the case of the burial system with active rituals in the Chalcolithic. Their funerary offerings provide the archaeologist with the materials to study the relationships between groups, as the circulation of semi-precious raw materials, bell-shaped pottery, ornamentation elements, metal tools, etc. Some previous works have establish links between the Northern Meseta territory and the French Atlantic facade, south east France and the Rhone valley (Delibes, 1983; Alday, 2001) . Materials from El Portalón presented here offer similar readings, with the particularity of having been recovered from the domestic sphere instead from burials. They reinforce the thesis of prehistoric communities in permanent contact, with networks in which materials circulated as back up for economic, social and ideological transactions (detected also in El Portalón through the genetics of the livestock (Anderung et al., 2005) . Bi-pointed needles and V-perforated buttons point to societies established in the far east of the Pyrenees, Rhone Valley and Switzerland; the buttons with a straight perforation take us there or to the French Atlantic facade. The bony pins and bi-pointed objects were probably sumptuary samples. They could be cloth and/or elaborated hairstyles supplements, with a value beyond the useful (exceeding their traditional cost). All of them were exchanged objects between the Meseta Castellana and Central Europe along these routes. We do not rule out the possibility of the connections actually going in other directions, but archaeological evidence published on the Iberian Peninsula fails to disclose this. The Sierra de Atapuerca is in the region where the Ebro and Duero Basins converge, and it is logical that even clearer connections will be found in the future. Some V-shaped perforated buttons were made by exotic material like ivory, and some pottery containers and metal tools from El Portalón are, when found in other sites, generally explained like exchanges of both, containers and contents, during feasts or ritual activities. Although we have focused on specific archaeological items in this work, the site’s inventory provides other arguments to support the idea of a network of intergroup relations: a recipient with mixed bell-shaped decoration which is known to have circulated widely throughout Europe (Alday, 2001) , an array of metal artefacts with prototypes widely spread over diverse areas as Fontbouisse-type daggers, compass-type daggers and pedunculate points, and flat axes and ornaments made out of sea shells which link the Burgos region with coastal sites.

Finally, regarding the awl made on a human radius, although there are some artefacts made of human bones in other European sites, their connection with that of El Portalón is questionable and interpretations going beyond the merely functionality corresponding to its form are not clear in this case.

The set of archaeological materials presented in this work belongs to two distinct cultural periods, the Early Neolithic on the one hand and the advanced Chalcolithic/Bronze Age on the other hand, the latter with presence of metal objects and both within the same cultural dynamics. The interval phase between these two periods, Middle-Late Neolithic and the pre bell-baker Chalcolithic, is only represented in the Portalón through complex funeral rituals.

In the Iberian Peninsula, after some pioneering events, the Neolithic begins by the two thirds of the seventh millennium cal BP and consolidates by the end of this millennium. It is within this last phase in which we contextualize the Neolithic remains from El Portalón. Although the evaluation of an isolated site by itself is useful and necessary, we cannot appreciate their full significance until we compare and put into context with other contemporary sites.

In this sense, El Portalón fits perfectly among the networks of Neolithic sites known for the upper basin of the Ebro River, showing that geographical barriers are not insurmountable when it is just a question of exploiting the environment holistically. This network, like others established on the Peninsula, informs us about the existence of a fully stabilized Neolithic at Iberian level, but developed in different “cultural circles”, among which there are common cultural and material exchanges. The “cultural circle” of the Iberian region under study is identified by the Boquique ceramic decoration. In the vicinity of the Sierra de Atapuerca, this type of decoration has its own peculiarities, a family resemblance, in each of the sites where it is present. Thus, there is a deep bond with the Boquique circle, but local identity codes are developed: it is a local production within a regional framework.

As regards the materials from the Bronze Age, local productions combine with those of distant origins. In this line, both arrowheads and V-perforated buttons are part of a local manufacturing. The large sample of arrowheads from El Portalón is surprising however by its scarce variation, especially when such a kind of objects is very variable as a whole. Do the humans have these pieces in stock for internal use, or better yet, for external distribution given its social value? We remember here that this set of bone arrowheads seems to imitate their metal counterparts, much more difficult to obtain. The same is true of the V-perforated buttons. Their regional concentration fits well with a local production, even when they are reminiscent of European styles.

As for needles and bi-pointed objects, their use seems logical as decorative elements in clothing or hairstyles, although for the latter, its possible use as fishing hooks has also been indicated. In any case, both needles and bi-pointed objects are exotic products, with few parallels in the region and linked to European productions of the Rhine-Rhone valley, Switzerland and northern Italy. We think that in this case the idea of a movement of objects (not just the concepts) over long-distances is justified.

At this time in Europe the sociocultural context encourages supra-regional relationships (the Bell Beaker culture is a good example), and the great value of the metals and the need to locate outcrops are another incentives. Furthermore, it is highly suggestive to relate these cultural dynamics to the latest hypotheses derived from genetic studies, which highlight the importance of post-Neolithic demographic processes and the current characterization of the gene pool of recent Europeans (Brandt et al., 2013; Kind, 2010; Ricaut et al., 2012) .

In this situation, where local and foreign products are mixed (as is the case of El Portalón), it is difficult to recognize whether the ideas, objects or persons (or a combination of the three) are involved. And we should also remember the complexity of the funerary world at this time (reusing dolmens, building burial mounds, digging graves and using caves). The complexity of these rituals and the richness and variety of grave goods help us to understand the awl made from a human bone founded at El Portalón, a symbolic element in a time of great social development.

In sum, El Portalón site at the Cueva Mayor complex is easier to understand if we examine it within the historical dynamics in which it develops rather than in its geographical setting. As we have argued here, the site is significant because it belongs to a network intertwined with different socio-economic realities.

We thank Marta Negro, director of the Burgos Museum, for the facilities offered for consulting different materials. We are deeply indebted to Laura Juez Aparicio for her help with the preparation of materials. Special appreciation to the Atapuerca team and our colleagues from the laboratory of Human Evolution at the University of Burgos Elena Santos , Laura Rodríguez and Rebeca García and from Centro UCM-ISCIII Eva Poza and María Cruz Ortega. Many thanks also to the many colleagues and students that since 2000 have made possible the excavation, restoration and inventory of the thousands of archaeological pieces recovered from El Portalón. M.A. Galindo- Pellicena has been supported by a grant from the Spanish Ministry of Science and Innovation (FPI reference BES-2007-15368; 2008-2011), by the Madrid City Council (lodging grant at The Residencia de Estudiantes 2008-2010) and nowadays from Fundación Atapuerca (postdoctoral grant). This research was financed by the Ministry of Science and Innovation via project N˚ CGL2012-38434-C03-01 and project HAR-2011-26364. Excavations at the Atapuerca sites are financed by the Regional Government of Junta de Castilla y Leon and the Fundación Atapuerca.

AlfonsoAlday,AmaliaPérez-Romero,José-MiguelCarretero,María ÁngelesGalindo-Pellicena,GemaAdán,Juan-LuisArsuaga, (2015) Proofs of Long-Distance Relations between Central Europe and Inland Iberian Peninsula during Neolithic and Bronze Age. Evidences from the Material Culture of the Site of El Portalón (Sierra de Atapuerca, Burgos, Spain). Advances in Anthropology,05,294-323. doi: 10.4236/aa.2015.54023

Note S1: The stratigraphical cultural sequence of el portalón (see Carretero et al. 2008 for more details)

Level 0 (Medieval). It corresponds to an irregular alteration of the first 15 to 68 cm of the top of the sequence and is composed of brown deposits with organic materials, charcoal, faunal remains, and ceramics.

Level 1 (Roman). Is an ashy layer with dispersed charcoal in dark grey clays, with small limestone clasts, and a maximum thickness of 40 cm. Artifacts include ceramics and Roman terra sigillata.

Level 2 (Iron Age I). It consists of organic sediments of anthropogenic origin with abundant ash and dark clay that reach a maximum depth of 30 cm. Hand made ceramics were recovered in this level (Clark, 1979).

Level 3 (Middle Bronze Age). It consists of a thin collection of dark sandy-clayey layers of some 16 cm in thickness. Organic material is abundant with numerous charcoal grains, fragments of hand-made ceramics, and domestic and wild fauna remains (Clark, 1979).

Level 4 (Early Bronze Age). It corresponds to a homogeneous layer of sandy-clayey of between

70 and 150 cm in thickness, increasing in depth toward the west or interior of Cueva Mayor. This level is rich in organic and charcoal material, with numerous stones and large limestone blocks originating from collapse of the cave. Abundant hand-made potsherds, lithics, bone industry and fauna remains are found in this level.

Level 5 (Early Bronze Age). It consists of sandy-clayey of grayish tones with an average thickness of about 35 cm and abundant charcoal and ash in its base. There are abundant sherds and domestic faunal remains. The excavation of J.M. Apellániz (Figure S2) ended in this level documenting one bell beaker sherd typical of the Early Bronze Age.

Level 6 (Bronze Age-Chalcolithic Transition). It consists a 30 - 35 cm of sandy-clayey with abundant organic material and charcoal with grayish color. A lens of ash has been documented 22 cm towards its base lenses of ash are documented. Sherds and animal bone were recovered from this level. The excavation of J.A. Clark and L.G. Straus (Figure S2) terminated in this unit.

Level 7/8 (Chalcolithic). It consists of angular and subangular limestone rocks (15 - 20 cm) without matrix that increase in size within depth. In the base of this level large limestone blocks appear, among which two flat stones of around 70 cm high by 60 cm wide stand out. Abundant human remains have been documented at this level, such as pottery and fauna remains. The remains of a large ceramic vessel with decorations of pellets, a copper awl and the presence of two goats in anatomical articulation on the two large flat stones at the base, point to the use of this cavity during the Chalcolithic for mortuary purpose. As a whole the level may be a funerary tumulus or burial mound. The level reaches a maximum thickness of 200 cm in the South profile, while thinning toward the North (Figure 2 and Figure S5).

Level 9 (Neolithic and Mesolithic). Is the bottom part of the Holocene sequence and is composed of a very homogenous layer of anthropic origin characterized by clayey-sandy deposits with blackish tones, with numerous organic material and rich in charcoal fragments. In this unit sub- angular limestone lasts and small calcareous blocks (10 - 20 cm) are observed, together with some rounded quartzite lasts. It has an average thickness of 125 cm in its southern profile that thickens toward the North to 170 cm. The base of this large layer is broken by an intrusive silo with a depth of about 75 - 80 cm and a diameter of 130 cm that has in turn affected the lower levels 9a and 10. We have distinguished two very different chronological zones within this level. Most of level 9 corresponds clearly to Neolithic with handmade sherds ceramic, macrofauna remains, lithics and bone tools. A bone awl of clearly Neolithic typology was recovered in situ in the North profile beside a charcoal with a Neolithic chronology. And at the base of the level we have detected a Mesolithic occupation of the site, without finding any handmade sherds ceramic in this layer. The dates (Table S1) indicate a large occupation situated fully within the Neolithic (4990 ± 40 to 6100 ± 50 and 6270 ± 4 years BP), and another during the Mesolithic (7790 ± 40 years BP) but with a temporal hiatus of 1720 years between both occupations.

Level 9a (Holocene-Pleistocene Transition). It consists of a small layer of bat guano 5 to 8 cm thick cha- racterized by sterile muddy-sand. It represents a transition between the Holocene (Levels 0 to 9) and Pleistocene (Level 10).

Level 10 (Upper Pleistocene). Is the deepest sedimentary unit and it is in turn divided into 12 sub-levels from P1 to P12. It is characterized by an alternation of angular limestone clasts of more than 1 cm originating from debris flow, containing a brownish muddy sandy-clay matrix inserted between levels of clays and sandy-clays which show a near absence of clasts. This level is more than 360 cm thick and has abundant microfaunal remains along with a small amount of macrofauna. Four small blades of flint (BP1G type) were recovered in the P8 sub-level. There is a date of 16980 ± 80 BP for P1 sub-level (60 cm deep) and another one of 30,300 ± 190 BP for P11 sub-level (335 cm deep) (Table S1).

Note S2: Other evidences of tools made on human bones

There is a 25 cm long dagger made of a human fibula in the cave of Bédeilhac, situated either in the Chalcolithic (Malvesin-Fabre et al., 1953) or in the early Bronze age (Guilaine, 1972). Also Guilaine in his work refers to a dagger from the Bronze age in the Tuteil Cave (Midi-Pyrénées) made out of a human ulna. Toussait (2005) report a 16.6 centimetre-long object from Goyet (Gesves) (Figure S22(a)) described as a knife or dagger made out of an adult’s left radius. This is an excellent example of the problems related to the origin of raw materials as, despite the antiquity of its discovery, until recently the human nature of the bone had not been known. Dated at 2420 ± 40 years BP (OxA-8875), it has been compared to the abovementioned French cases as well as to Mechta-el-Arbi in Algeria and to the humerus of a Neolithic child in the Paradou cave in France (Toussait, 2005). Yet another case is that of a Neolithic straightener made out of a human humerus which was recovered from the Nerja Cave in Spain (Adán & Nieto, 1995).

There are still records of perforated teeth as pendants in the Palaeolithic (molars, premolars, canines and even, a lower jaw; Mújika, 2007-2008).

Note S3: Interpreting marks on human bones

Cuts, scraping, fractures and other marks are not uncommon on human bones found in burial sites. They are interpreted as being the result of violence or cannibalism for rituals or for food (Boulestin et al., 2009; Graver et al., 2002). Take for example Fronbrégoua in the south of France (Villa et al., 1986), Perrats in Charente (Toussait, 2005) or Herxheim in Renania-Palatinate (Boulestin et al., 2009). Also in the Sierra de Atapuerca, in the El Mirador site, a secondary deposit of human bones from the Bronze Age has been recorded, with fractures and traces of boiling, thus giving rise to speculation on cannibalism (Cáceres et al., 2007).

Etxeberria (2003) points out that we should be cautious in our reasoning, as many of the marks are not the result of human action but are a consequence of postdepositional processes. He points to the same with respect to the two problematic skull-cups found in Gipuzkoa, altered by the taphonomic effect of erosion. García et al. (2010) holds a similar view with respect to the burial site of Avenc dels Dos Forats (Valencia), where numerous marks on the buried bodies correspond to post-depositional action. It would appear to be proven that the dismembering of cadavers, the disorder in the graves and the breakages respond to an interest in arranging the tombs, and to situations deriving from rigor mortis (Delibes and De Paz, 2000; García et al. 2010). We rule out the Basque cases of the tombs of Kalparmuñobarrena, Argabi and Pagobakoitza as deliberate manipulations, although similarities have been reported with other megalithic monuments (Joussaume, 1977; Maury, 1961). There are doubts also about the circles of bone recovered from several European tombs dating from the Metal Age, interpreted as the result of cranial trepanation (Cordier, 2005). Finds like the button made of a human femoral head at the Frères Cave (Ariège) and the beads of the same material at Saint-Vérèdème and Drôme are anecdotal (Arnal, 1954).

In short, we can appreciate a series of burial practices at different times and in different places, which elect who is to be buried, where and under what conditions and creating a complicated burial rite. Secondary or partial burials are common, resulting in an abundance of marks taken as evidence of cannibalism.