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Quaternary Science Reviews 85 (2014) 136e146

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Quaternary Science Reviews

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Early human occupation of Iberia: the chronological andpalaeoclimatic inferences from Vallparadís (Barcelona, Spain)

Kenneth Martínez a,b, Joan Garcia a,b,c,*, Francesc Burjachs a,b,d, Riker Yll a,b,Eudald Carbonell a,b,e

a IPHES, Institut Català de Paleoecologia Humana i Evolució Social (IPHES), C/Marcel$lí Domingo, s/n, Campus Sescelades URV, Edifici W3, 43007 Tarragona,SpainbURV, Universitat Rovira i Virgili, Àrea de Prehistòria, Avinguda de Catalunya 35, 43002 Tarragona, SpaincUOC, Universitat Oberta de Catalunya (UOC), Avinguda del Tibidabo 39-43, 08035 Barcelona, Spaind ICREA, Institut Català de Paleoecologia Humana i Evolució Social (IPHES), Universitat Rovira i Virgili, C/Escorxador s/n, 43005 Tarragona, Spaine Institute of Vertebrate Paleontology and Paleoanthropology of Beijing (IVPP), China

a r t i c l e i n f o

Article history:Received 22 April 2013Received in revised form18 September 2013Accepted 2 December 2013Available online 31 December 2013

Keywords:Mimomys saviniIberomys huescarensisLate Early PleistoceneVallparadísHuman occupation

* Corresponding author. IPHES, Institut Català de Plució Social (IPHES), C/Marcel$lí Domingo, s/n, Campu43007 Tarragona, Spain. Tel.: þ34 699855077.

E-mail address: jgarc338@xtec.cat (J. Garcia).

0277-3791/$ e see front matter � 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.quascirev.2013.12.002

a b s t r a c t

Vallparadís is one of the best calibrated and most accurately dated archaeological sites from the Euro-pean Early Pleistocene. Chronological analyses combined with palaeomagnetism, ESR-U/series and OSL,and the biochronology of macro- and micromammals are fully consistent and situate the site just abovethe upper limit of the Jaramillo subchron. In this article we compare the mandibular first molar (m1) ofindividual adult specimens of Mimomys savini recovered from level 10 (EVT7) at Vallparadís withspecimens from the stratigraphic sequence at Gran Dolina (Atapuerca), Fuente Nueva 3 and BarrancoLeón D (Orce). This comparison allows us to chronostratigraphically relate level 10 at Vallparadís withlevel TD5 at Gran Dolina and to fix the former’s chronology to around 0.98e0.95 Ma (MIS 27) and,therefore, prior to level TD6 in which fossil remains of Homo antecessor were recovered. The chronologyof Vallparadís and the set of contemporary palaeoclimatic proxies regarding the Iberian Peninsulastrengthen the hypothesis that hominins continuously populated Europe, at least in Iberia, throughoutthe late Early Pleistocene between the Jaramillo subchron and the MatuyamaeBrunhes boundary byovercoming the climatic fluctuations and changes to the landscape that occurred during this period.

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1. Introduction

Prior to the discovery of the Vallparadís site there was a gap inthe archaeological record of the Early Pleistocene in the IberianPeninsula (Martínez et al., 2010; Duval et al., 2011, 2012a; Garciaet al., 2011, 2012). Specifically, this gap occurred between the pre-Jaramillo subchron sites, that is on the one hand the Orce sites(Barranco León and Fuente Nueva 3), dated to 1.4e1.2 Ma(Martínez-Navarro et al., 1997; Oms et al., 2000; Agustí andMadurell, 2003; Duval et al., 2012b) and Sima del Elefante (Ata-puerca), with a cosmogenic burial age of 1.22 � 0.16 Ma (Carbonellet al., 2008), and on the other hand the post-Jaramillo subchronsites, that is, Gran Dolina TD6 (MIS 21) (Atapuerca), dated bypalaeomagnetism to ca 0.78 Ma (Carbonell et al., 1995; Parés and

aleoecologia Humana i Evo-s Sescelades URV, Edifici W3,

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Pérez-González, 1995), by ESR-U/series to 0.77 � 0.08 Ma(Falguères et al., 1999; Falguères, 2003; Duval et al., 2012a), by TL to0.9e095 Ma (Berger et al., 2008) and by ESR-OB to 0.88e0.80 Ma(Moreno-García, 2011). Until the discovery of Vallparadís, the onlyarchaeological record from this intermediate period was themeagre record recovered from Gran Dolina TD3, TD4 and TD5, Simadel Elefante TE13 and TE14 and Huéscar 1 (Carbonell andRodríguez, 1994; Ollé et al., 2013). Therefore, filling this chrono-logical gap is particularly important to the debate regarding thefirst human colonization of Europe (Garcia et al., 2011; MacDonaldet al., 2012).

Since the confirmation of human occupation during the EarlyPleistocene in Europe (Roebroeks and van Kolfschoten, 1994;Carbonell et al., 1996), new research lines have investigatedwhether this initial settlement was continuous or discontinuous(Bermúdez de Castro et al., 2013). To do so they have studied whichhominin species first colonized Europe and which technologiesthey were using, how these hominins were affected by climaticfluctuations, whether they were limited to the southern regions of

K. Martínez et al. / Quaternary Science Reviews 85 (2014) 136e146 137

the continent, andwhether they arrived in one or several migratorywaves. Some authors believe that a “short” chronology continues tobe a valid hypothesis in continental and northern regions above45e50�N (Dennell and Roebroeks, 1996). The same authors believethat there could have been intermittent settlements in the Medi-terranean regions resulting from dispersal episodes under favour-able climatic conditions. They describe these intermittent settlersas “occasional visitors” (Dennell, 2003; Dennell et al., 2011) or va-grants, to borrow a term from avian ecology (Pfeifer et al., 2007).

The different terms commonly used to define the first humanoccupation of Europe can generate confusion regarding their pre-cise meaning. Occupation, population, colonization and migrationhave at times been mistakenly used indiscriminately. To preventconfusion and foster clarity, some authors have simplified the issueby adopting the terms “visitors” and “residents” to distinguishbetween short-term visitors and longterm residents (Dennell,2003). Population continuity would imply continuous humanpopulations on the continent who prospered and provided thegenetic, technological and cultural background of the Early Pleis-tocene. According to the fossil evidence, hominin populationsevolved in Europe as a result of geographical isolation and/orinterbreeding between Eurasian populations (Martinón-Torreset al., 2007; Bermúdez de Castro et al., 2011; Bermúdez de Castroand Martinón-Torres, 2012). A high turnover rate of macro-mammals can be seen from 1.2 Ma onwards and the presence ofmany mammal fossil species in the record is comparatively brief.This is probably the result of the intense and constant climaticfluctuations of the “Mid-Pleistocene revolution” (Head andGibbard, 2005) and of establishment of new species with similarecological requirements and strategies that would have led todirect competition (Brugal and Croitor, 2007; Kahlke et al., 2011;O’Regan et al., 2011). A similar situation of intra/inter speciescompetition within the Homo genus may have occurred in Europe,without, however, this necessarily leading to generalized depopu-lating of the continent.

Consequently, determining the influence of climatic fluctuationson the first European colonization is one of the principal axesaround which the debate has revolved. The Early-Middle Pleisto-cene transition coincided with the greatest and most wide-rangingclimatic variability that had been experienced up to that moment. Itmanifested itself in the progressive cooling of temperatures andincreased aridity, which was most intense between the Jaramillosubchron and the MatuyamaeBrunhes limit, with MIS 22 (0.87 Ma)being the first glacial period of the Pleistocene (Head and Gibbard,2005; Muttoni et al., 2010). Nevertheless, within this generalcontext, the climatic conditions and ecosystems present at localand regional level in Europe are not well known and have led todiverging conclusions depending on which set of data is analyzed.There are certain discrepancies in the palynological and herpeto-fauna when attempts are made to determine the climatic condi-tions at the Gran Dolina site in Atapuerca (Blain et al., 2009;Rodríguez et al., 2011).

Europe is highly diverse in terms of its physiography, ecosys-tems and types of climate, and is characterized by a climaticgradient from dry and continental in the east to wetter andtemperate in the west. If any interpretation is to avoid excessivedeterminism, it must take this diversity into account because itallows for the existence of local areas with less severe conditionsduring the most extreme climatic episodes. These areas are usuallyreferred to as refugia that allowed for more stable and thuscontinuous populations of flora and fauna (Bennett and Provan,2008; Stewart et al., 2009). The Mediterranean region and itspeninsulas have traditionally been regarded as refugia, as haverecently the Atlantic regions of north-eastern Europe on the basis ofarchaeological evidence uncovered at Pakefield and Happisburgh 3

(England). These sites have been dated to>0.78Ma and interpretedas the adaptation of hominins to Atlantic coastal and fluvial habi-tats rich in biodiversity and with less severe climates due to thewarm ocean air currents (Parfitt et al., 2005, 2010; Finlayson et al.,2011; Cohen et al., 2012).

The Iberian Peninsula is in effect a little continent with a varietyof diverse climates and landscapes and is thus similar to an islandwith its own endemic flora and fauna (González-Sampériz et al.,2010). With a surface of some 583,254 km2, and between lati-tudes 36e44�N, three quarters of it is surrounded by the waters ofthe Mediterranean and the Atlantic. The interior is a plateau withan average altitude of 600 m AMSL, whereas the periphery featuresmountain ranges of Alpine origin with altitudes of over 3000 m. Ofthese ranges, the Sierra de Atapuerca is widely regarded as apossible refugia. A study that used a set of palaeoclimatic data fromthe sites of Sima del Elefante, Gran Dolina and Trinchera Galeríaconcluded that conditions throughout the Early and Middle Pleis-tocene were constant and not extremely harsh. These results showno evidence of any chronological relationship between environ-mental change and cultural change at the Sierra de Atapuerca(Rodríguez et al., 2011).

Thanks to the site at Vallparadís, we have been able to increasethe available archaeological evidence regarding the human occu-pation of the Iberian Peninsula during the Early Pleistocene and todetermine the chronology of this settlement (Martínez et al., 2010;Duval et al., 2011, 2012a; Garcia et al., 2011, 2012). In this article wefix the chronology of Vallparadís to within a tight time frame ofbetween 0.98 and 0.95 Ma, and we compare the chronological datafrom Vallparadís, Atapuerca and Orce sites and order them into anante and post quem sequence. The aims are to verify the existence(or not) of archaeological gaps, to relate the human occupationswith palaeoclimatic data and to assess whether there are archae-ological gaps that could be related to climatic deterioration (Agustíet al., 2009).

2. Numerical data and macromammal biochronology

The Vallparadís site was excavated between 2005 and 2008during work to build a railway station on the left bank of theVallparadís stream, which crosses the centre of the town of Terrassa(Barcelona, Spain). The excavation covered an area of almost6000m2 andwent to a depth of some 14m. The excavation dug intoQuaternary deposits from the Middle and Early Pleistocene thatform part of an alluvial fan. Twelve stratigraphic units have beendistinguished in the deposit that can be grouped into two packetsseparated by an erosion surface (EVT5) (Fig. 1). These stratigraphicunits correspond to fluvial levels, that is, sedimentary clay depos-ited in a context of flood plains, weakly developed river bars andtravertine formations, interspersed with levels of alluvial sedi-mentary clays, alluvial/colluvial conglomerates and a marsh levelrich in macromammals and fossil wood remains (bottom of EVT4).Lithic industry and faunal remains have been found in the strati-graphic units EVT2e7. The whole of unit EVT7 (some 780 m2 and1.5 m deep) was excavated following an extensive archaeologicalmethodology. In this unit EVT7 two archaeological levels wereidentified (10 and 10c) and an abundant record of fossils and lithicobjects was recovered (Martínez et al., 2010; Garcia et al., 2013a).

Magnetostratigraphic analysis has identified three phases ofpolarity during this sequence: 1) normal polarity (N1) from thebase of sequence EVT12 to unit EVT8; 2) reverse polarity (R1) fromunit EVT7 to bottom unit EVT3; and 3) normal polarity (N2) fromEVT3 to the top of the stratigraphic sequence (Fig. 1). The bio-chronological micromammal data in the upper part of the sequenceshow the presence of Arvicola mosbachensis and thus relate unitEVT3 to the Early Toringian stage (Minwer-Barakat et al., 2011).

Fig. 1. Geological and chronological setting of Gran Dolina (left) and Vallparadís (right) showing the synthetic stratigraphic columns (Parés and Pérez-González, 1995; Martínezet al., 2010) and numeric dates (Falguères et al., 1999, 2001; Berger et al., 2008; Martínez et al., 2010; Duval et al., 2011, 2012a; Moreno-García, 2011). The MatuyamaeBrunhesboundary is located within stratigraphic level TD7 at Gran Dolina and within units bottom EVT4 at Vallparadís. The low and positive VGP latitude at the bottom of both sectionsmay correspond to the Jaramillo subchron (Parés and Pérez-González, 1999; Madurell-Malapeira et al., 2010; Martínez et al., 2010). Gran Dolina: a: mesozoic limestone, b: spe-leothem, c: lutite/terra-rossa, d: bat guano, e: clays and laminated silts, f: calci-lutite or calci-arenite, g: clastic flow of gravel and boulders and h: downfall gravel and boulders.Vallparadís: 1: Upper Pleistocene terrace, 2: clays and muds with gastropods, 3: unit 5, 4: red clays and muds, 5: unit 7 (levels 10 and 10c), 6: brown clays and muds, 7: con-glomerates and 8: paleo-floor.

K. Martínez et al. / Quaternary Science Reviews 85 (2014) 136e146138

Therefore, the combination of data allows us to divide the sequenceexcavated at Vallparadís into three parts: the lower levels EVT12eEVT8, with an age of 1.07e0.99 Ma, correspond to the normal-polarity Jaramillo episode, the middle units EVT7-bottom unitEVT3, with an age of 0.99e0.78 Ma, correspond to the temporaryphase between the Jaramillo episode and the MatuyamaeBrunhesboundary, and the units from EVT3, with an age of <0.6 Ma,correspond to the normal polarity of the Middle Pleistocene.

An average age of 0.83 � 0.07 Ma has been obtained for level 10(EVT7) on the basis of ESR-U/series dating of two equinemolars from level 10 and OSL dating of four samples of quartzgrains taken from the top of stratigraphic unit EVT8, immediatelybelow the archaeological levels (Duval et al., 2011). This datecoincides with a previous date of 0.83 � 0.13 Ma obtained by ESR-U/series for two equine molars (Martínez et al., 2010). This com-bined ESR-U/series dating method has been used at Gran DolinaTD6 to provide a date of 0.77� 0.08 Ma and at Fuente Nueva 3 withan age of 1.19 � 0.21 Ma (Duval et al., 2011, 2012b). Recently, newESR ages obtained for optical bleached quartz grains have put thedate of level TD6 at 0.88e0.80 Ma (Moreno-García, 2011). There-fore, the radiometric dates available for Vallparadís and TD6 indi-cate that they are chronologically close to one another (Duval et al.,2012a) (Fig. 1).

The macromammal assemblage from level 10 (EVT7) at Vallpar-adís has been described as Epivillafranchian and contains an asso-ciation of: Pseudodama vallonnetensis, Equus altidens, Praemegacerosverticornis, Bison sp., Stephanorhinus hundsheimensis, Hippopotamusantiquus, Lynx sp., Canis mosbachensis, Panthera gombaszoegensis,Pachycrocuta brevirostris (Madurell-Malapeira et al., 2010) andMacaca sylvanus cf. florentina (Alba et al., 2008), along with Galerianspecies such as Elephas antiquus, Ursus deningeri and Sus cf.scrofa (Palombo and Ferretti, 2005; Palombo et al., 2008). This as-sociation is also found at the Orce sites (Martínez-Navarro et al.,

2003) and Atapuerca (Sima del Elefante, Carbonell et al., 2008 andGran Dolina TD6; Rodríguez, 2001). Of particular note is the presenceof E. antiquus in level 10 at Vallparadís, given that this is the oldestexample of this African species in the European record and wouldseem to indicate that it arrived before other Galerian immigrantsfrom Africa. Some authors have proposed that the increase in aridityduring MIS 22 (0.87 Ma) opened a window of opportunity thatallowed African savannah species such as E. antiquus and Homo toenter the refugia in the northern Mediterranean (Muttoni et al.,2010). The fall in sea level would facilitate movement along coastalroutes, as in the Po valley, and enable species to cross from eastern towestern Europe at a timewhen northern Europe remained closed offby Alpine glaciers. However, the remains at Vallparadís mean thatE. antiquusmust have arrived before MIS 22. Likewise, the absence ofother Galerian species in level 10 (EVT7) that are present later in theMiddle Pleistocene levels of the site, such as Cervus elaphus, maychronologically correlate Vallparadís with Gran Dolina (Atapuerca).The earliest record of this taxon in Europe below the MatuyamaeBrunhes boundary is the local appearance in the level TDW4 of GranDolina (ca 0.8 Ma; van der Made, 1998), meanwhile, in Vallparadís,C. elaphus is only recorded in the Early and Middle Pleistoceneboundary (EVT4) (Madurell-Malapeira et al., 2010). However, thereare still some uncertainties regarding the chronology of the TD4 levelfrom Gran Dolina along with some lithic objects (Carbonell andRodríguez, 1994). TDW4 is dated of <0.98 Ma (van der Made, 1998;Falguères et al., 1999; Cuenca-Bescós et al., 1999, 2011; Cuenca-Bescós and García, 2007; Berger et al., 2008), and the latest radio-metric dates placed it in 0.94 � 1.00 ESR-OB (Moreno-García, 2011).

3. Micromammal biochronology

The micromammal assemblage found in level 10 (EVT7) ofVallparadís is made up of the following species: Ungaromys

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nanus, Iberomys huescarensis, Mimomys savini, Eliomys quercinus,Apodemus sp., Talpa europaea and Crocidura sp. (Martínez et al.,2010) (Fig. 2). Minwer-Barakat et al. (2011) also identify Sten-ocranius gregaloides, Apodemus cf. sylvaticus andHystrix refossa. Thisfauna is similar to that of Gran Dolina TD4/3 and TD6 (Cuenca-Bescós et al., 1995, 1999, 2010). The presence of M. savini situateslevel 10 (EVT7) in the Biharian period, which is marked by the FAD(first appearance datum) and the LAD (last appearance datum) ofthis species (Fejfar et al., 1998). The identification of I. huescarensisindicates that this level corresponds to the final phase of the EarlyPleistocene (Cuenca-Bescós et al., 1999, 2010; Madurell-Malapeiraet al., 2010). On the basis of the correlation between EVT7 andthe levels at the neighbouring site of Cal Guardiola, Madurell-Malapeira et al. (2010) assigned this level to the biozone of Allo-phayomis chalinei (Cuenca-Bescós et al., 2010), which is defined bythe association of I. huescarensis, S. gregaloides, A. chalinei andM. savini. At Atapuerca, U. nanus has been recorded in levels TE8e12of Trinchera Elefante, in Faunal Unit 1 (ca 1.4e1.2 Ma), but is absentfrom the following faunal units, which correspond to the lowerlevels of Gran Dolina (TD3e6) (Cuenca-Bescós et al., 2010;Rodríguez et al., 2011). However, evidence of this species datingback to approximately 1 Ma has been found at the Le Vallonet site(Chaline, 1988), which is also included in the A. chalinei biozonedescribed by Cuenca-Bescós et al. (2010), as is level 10 atVallparadís.

Consequently, the micromammal biochronology is marked bythe associationM. savinieI. huescarensis (Cuenca-Bescós et al., 1999,2010; Agustí et al., 2007; Minwer-Barakat et al., 2011). An initialstudy related Vallparadís to the lower levels of Gran Dolina on thebasis of the presence of I. huescarensis (Martínez et al., 2010; Garciaet al., 2012), which is the site’s most biochronologically

Fig. 2. Occlusal surface of micromammal molars from level 10 of Vallparadís. 1:I. huescarensis, left lower m1, 2: I. huescarensis, left lower m1, 3: I. huescarensis, leftlower m1, 4: I. huescarensis, left lower m1, 5: I. huescarensis, right lower m1, 6: U. nanus,right lower m1 and 7: M. savini, right lower m1 (scale 1 mm) (drawings by J. M. López).

characteristic element and which is also present at other sites suchas Huéscar 1 (the Guadix-Baza Basin), Sima del Elefante and GranDolina (Atapuerca). Themetric values of the I. huescarensis teeth arecomparable to those in Gran Dolina TD3, TD4 and TD4b, especiallywhen the L and A/L values are compared (sensu van der Meulen,1973). However, the lower molars of I. huescarensis have a lessderived morphology than those from the lower levels at GranDolina (e.g. a less prominent BSA3), and are thus closer to thesample from Huéscar 1 and Sima del Elefante. Given that thearchaeological level 10 (EVT7) is located in the reverse polarityphase, these results push the site’s age towards the upper limit ofthe Jaramillo subchron (0.98 Ma).

In this paper, we have taken the species M. savini into consid-eration and have compared the average occlusal plane lengths ofthemandibular first molar (m1) of adult individuals present in level10 (EVT7) at Vallparadís with the data published for Gran Dolina,Fuente Nueva 3 and Barranco León D (Cuenca-Bescós et al., 1999).Likewise, we have studied the percentage of the adult population ofthis species that retains enamel islets because a decrease in thispercentage indicates the presence of more modern populations(von Koenigswald, 1982; von Koenigswald and van Kolfschoten,1996; Cuenca-Bescós et al., 1999) (Figs. 3 and 4). The percentageof adult individuals with an enamel islet in level 10 is 17.3%, whichis higher than the percentage at TD6 (Cuenca-Bescós et al., 1999)(Table 1). Consequently, level 10 at Vallparadís seems to be olderthan TD6 given that more modern populations of M. savini havefewer individuals with enamel islets.

Likewise, given that as M. savini evolved its cutting ability, thelength of its occlusal plane increased (Heinrich, 1978; Rabeder,1981; Viriot et al., 1990; Chaline et al., 1999; Lozano-Fernándezet al., 2012), we can see that the population of level 10 (EVT7)has values between those of TD5b and TD5a. This would situate thelevel within a chronological range of between 0.98 and 0.95 Maaccording to the dates published by Falguères et al. (1999), Bergeret al. (2008) and Cuenca-Bescós et al. (2011) (Figs. 3, 4 and 5 andTable 1), and in the same biozone as A. chalinei, which has beenrecorded at Gran Dolina TD3-TD6, Sima del Elefante, Huéscar 1(Alberdi et al., 2001; Agustí et al., 2007), le Vallonet (de Lumleyet al., 1988) and Untermassfeld (Kahlke, 2006).

4. Palaeoclimatic inferences

At the paleoenvironmental level, the association of micro-mammals in level 10 (EVT7) presents taxa that are characteristic offour distinct habitats: 1) open humid meadow: I. huescarensis andT. europaea, 2) water edge: M. savini, 3) woodland and woodlandmargin: E. quercinus and Apodemus sp., and 4) open-dry meadow:Crocidura sp. (Chaline, 1985; Marquet, 1989; Guillem, 1995;Michaux, 1995; Repenning, 2001; López-Antoñanzas and Cuenca-Bescós, 2002; Cuenca-Bescós et al., 2005). On the basis of theminimum number of individuals from each taxon and the per-centage that this represents of the total number of micromammalsin level 10 (EVT7), we can determine the dominant landscapeduring the period in which the level was deposited. This landscapewas dominated by water edge (58.18%) and open humid meadow(27.9%), with small areas of woodland and woodland margin(13.95%) and open-dry meadow (6.97%) (Fig. 6 and Table 2). Withthis interpretation it is important to bear in mind that level 10corresponds to an alluvial context and that small mammals’ habitatrequirements have been extrapolated from closely related livingspecies. However, this approach could underestimate the adapt-ability of small mammals (Rodríguez et al., 2011). Moreover, fewsmall European mammals may be classified as strictly woodlandspecies given that most open country species may also be found inwoodlands (Mitchell-Jones et al., 1999).

Fig. 3. Mandibular first molar of adults of M. savini from level 10 (EVT7) of Vallparadís(scale 1 mm). A: individual with enamel islet, enamel-free areas and roots in formation(lingual view, A1; occlusal view, A2; buccal view, A3). B: individual without enamelislet, enamel-free areas and roots in formation (buccal view, B1; occlusal view, B2;lingual view, B3). C: individual without enamel islet, enamel-free areas and fullyformed roots (lingual view, C1; occlusal view, C2; buccal view, C3). D and E are fromGran Dolina TD5b (D) and TD5a (E). Individuals without enamel islets, enamel-freeareas and fully formed roots (scale 3 mm).

K. Martínez et al. / Quaternary Science Reviews 85 (2014) 136e146140

Amphibian and squamate reptile fossil remains are scarce inlevel 10 (EVT7) of Vallparadís but do show the presence of thewestern spadefoot toad (Pelobates cf. cultripes), one indeterminateanuran, one indeterminate lacertid and two colubrine snakes (?Natrix natrix and cf. Rhinechis sp.) (Martínez et al., 2010). Such anassociationmay characterize aMediterranean landscape (meso andthermo-Mediterranean bioclimatic levels) with sunny open-dry

areas, little or no vegetation, loose or rocky soils and laterallymore humid areas with presence of water and open Mediterraneanwoodlands. Such climatic and environmental conditions seem to bein accordance with the amphibian and squamate reptile proxies atTD5 that document an open landscape (Blain et al., 2008) andsuggest an evolution from temperate-wet to cold and more humidconditions (Blain et al., 2009). Given the numeric dates and bio-chronology TD5 is related to MIS 27 or 29 (Cuenca-Bescós et al.,2011; Blain et al., 2012). Different disciplines agree in character-izing TD5 as a complex period that evolved towards colder humidconditions. A decrease in temperature towards the top of TD5, assuggested by García-Antón and Sainz-Ollero (1991), is consistentwith the absence of Rhinechis scalaris, a Mediterranean snake pre-sent in the lower part of TD5.

For their part, the palynological analyses carried out at Vall-paradís have given results mainly for the marsh levels in the lowerpart of unit EVT4 (MatuyamaeBrunhes boundary). The unit EVT4has provided pollen data that suggests that the landscape wascovered with more than 60% AP dominated by Pinus, evergreenQuercus and Corylus. This would indicate a temperate climate(semi-cool and semi-humid) that would favour coniferous forests(Pinus and Cupressaceae) with smaller more humid areas thatwould favour deciduous trees such as oaks (deciduous Quercus),willows (Salix), ash (Fraxinus) and hazel (Corylus). The landscapebecame poorer in terms of diversity and Mediterranean taxa (e.g.Erica), although the cold periods were not strong enough to isolateMediterranean taxa such as Holm Oak and Kermes Oak (evergreenQuercus-type) and olive-tree (Olea/Phillyrea). Thermophilous spe-cies (e.g. OleaePhillyrea) coexist alongside steppic species (e.g.Ephedra). The fact that the largest percentage is made up of pines,Cupressaceae, Holm Oak, Kermes Oak or Ephedra indicates a drierclimate, although this does not obviate the growth of hygrophyte(Cyperaceae, Typha/Sparganium) and aquatic taxa (Myriophyllum,Polygonum persicaria-type) in and near rivers.

In contrast to the palynological data from Vallparadís, thepalynological analysis of the richest neighbouring fossil level (D2)of the Cal Guardiola site, dated to the lower boundary of the Jar-amillo subchron, shows an open landscape with only 12% AP,including 1% of riverbank trees species (Postigo et al., 2007). Thekey to this landscapewould have been a system of seasonal rainfallsthat would have enabled the development of great meadows dur-ing the rainy seasons. This flora suggests a temperate, sub-arid,Mediterranean climate, with a seasonal distribution of rainfall(Fig. 7). Consequently, a change can be observed in the vegetation/climate between the level D2 of Cal Guardiola and the unit EVT4from Vallparadís. During the D2 episode (pre-Jaramillo at CalGuardiola) the climate was semi-arid (e.g. Chenopodiaceae,Lygeum) and temperate (e.g. evergreen Quercus and OleaePhil-lyrea), so that the immediate landscape was dominated by seasonalgrass meadows (Poaceae) with trees reminiscent of savannah, withdeciduous and coniferous forests in the regional mountains.Furthermore, the most characteristic species from this period arethe exotic taxa (e.g. Pinus haploxylon type, Taxodiaceae and Carya),who represent survivors from the Pliocene. Shrubs and bushes arenot represented in the diagram although that we know that thepollen from these taxa is always underrepresented in the record.Likewise, the marsh environment was fed by waters from theregional mountains and is represented by a diverse range of hygro-hydrophytes and Pteridophyta taxa and by tree species such aswillow (Salix), elm (Ulmus), tamarisk (Tamarix) and poplar(Populus).

Therefore, Cal Guardiola and Vallparadís sequences show asuccession of open vegetation during cold, glacial phases, followedby dry, open vegetation (forested steppe and open Mediterranean-like woodlands), and then deciduous forest, mixed forest and

Fig. 4. Graphic representation of the mean length of the occlusal plane (L) of the mandibular first molars of the populations from Barranco León D (BLD), Fuente Nueva 3 (FN3), GranDolina levels (TD4/3, TD5b, TD5a and TD6) and level 10 (EVT7) of Vallparadís. The different sites and levels are chronologically ordered from the oldest to the most recent, with theoldest situated at the left of the graphic. EVT7 has been situated between TD5b and TD5a on the basis of the average lengths of the occlusal plane of the m1 of the M. savini foundthere. All the chronologies have been obtained using the combined U-series/ESR dating method following Martínez et al. (2010), Duval et al. (2012a,b) and Moreno-García (2011).

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humid conifer forest (Leroy et al., 2011). This palaeoclimatic data isconsistent with the general trend observed in the Middle Pleisto-cene transition towards a drier climate with lower temperaturesand the progressive impoverishment of the landscape (Leroy, 2008;Leroy et al., 2011).

5. Discussion

The successive human occupations in the archaeological recordsfrom Vallparadís and Gran Dolina (Atapuerca) seem to confirm thepresence of a continuous population in the Iberian Peninsula be-tween the Jaramillo subchron and the MatuyamaeBrunhesboundary. This hypothesis is based on the following data: 1) Levels10 and 10c (EVT7) at Vallparadís and levels TD3eTD5 at Atapuercaare penecontemporaneous at the upper limit of the Jaramillo sub-chron (ca 0.99e0.95 Ma). Lithic objects were recovered from levelTD4 (Carbonell and Rodríguez, 1994; Ollé et al., 2013) and cut-marks have been identified on a rib from TD5 (Huguet et al.,2013). An abundant collection of lithic objects and examples ofcut-marked bones have been recovered from levels 10 and 10c atVallparadís (Martínez et al., 2010; Garcia et al., 2013a). 2) TD6 issituated in between the two previous archaeological levels 10 and10c (EVT7) at Vallparadís and TD3e5 at Atapuerca and theMatuyamaeBrunhes boundary (ca 0.88e0.78 Ma). The record fromTD6 is well known due to the presence of fossil remains of

Table 1Length of the occlusal plane of the m1 of M. savini and percentages of individualswith enamel islets. Level 10 (Vallparadís), TD4/3, TD5b, TD5a and TD6 (Gran Dolina),FN3 (Fuente Nueva 3) and BLD (Barranco León D). n Corresponds to the number ofm1 for each population.

Level Mean SD Max Min e.i. n Reference

TD6 3.508 0.245 3.895 3.053 14% 16 Cuenca-Bescóset al., 1999

TD5a 3.49 0.142 3.81 3.11 10.2% 49 This paperTD5b 3.46 0.143 3.77 3.04 15.7% 57 This paperTD4/3 3.38 0.139 3.61 3.25 e 5 Cuenca-Bescós

et al., 1995FN3 3.28 0.098 3.55 3.06 18.18% 45 This paperBLD 3.25 0.119 3.65 2.91 18% 53 This paperVallparadís

(level 10)3.48 0.152 3.73 3.14 17.3% 23 This paper

Homo antecessor (Carbonell et al., 1995). 3) At Vallparadís, a humanpresence is confirmed to ca 0.78 Ma (albeit from only a few lithicelements), that is, to within the MatuyamaeBrunhes boundary.Lithic objects were recovered from units EVT7e2 (Martínez et al.,2010, 2013; Garcia et al., 2011, 2012, 2013a).

The Jaramillo subchron has been identified in the lower levels ofVallparadís in units EVT12e8 (a rich fossil assemblage was recov-ered from EVT12) (Madurell-Malapeira et al., 2010), but the pres-ence of hominins could not be ascertained. In contrast, the Jaramillosite of Huéscar 1 has yielded some lithic objects (Martínez-Navarroet al., 1997). The presence of hominins has also been confirmed atUntermassfeld (Germany), where lithic objects associated with cut-marked bones were recently found (Landeck, 2010; Garcia et al.,2013b). Prior to the Jaramillo subchron >1.07 Ma, the archaeolog-ical record available is to be found at Sierra de Atapuerca, specif-ically at Sima del Elefante, where level TE9 has provided some lithicobjects, cut-marked bones and hominin remains of mandible(Carbonell et al., 2008). The cosmogenic burial age has been used todate this level to 1.22 � 0.16 Ma (Carbonell et al., 2008), and themicromammal species situate it in the Allophayomis lavocati bio-zone (Cuenca-Bescós et al., 2010) together with Fuente Nueva 3 andBarranco León (Agustí et al., 2010), in which a human presence iswell documented (Toro-Moyano et al., 2011). Consequently, thearchaeological evidence now available from the Iberian Peninsulashows a succession of uninterrupted human settlements at theGran Dolina and Vallparadís archaeological levels that covers thewhole period from the Jaramillo subchron to the MatuyamaeBrunhes boundary. If we add the evidence from Sima del Elefante(Atapuerca) and the Orce sites at the Guadix-Baza basin (FuenteNueva 3, Barranco León and Huéscar 1) (Agustí et al., 2010) thissuccession can be pushed back to the Jaramillo and pre-Jaramilloperiods. This would therefore indicate a continuous human pres-ence in the Iberian Peninsula between 1.4 and 1.2 Ma toMatuyamaeBrunhes boundary (Agustí et al., 2010; Garcia et al.,2011; Bermúdez de Castro et al., 2013).

The amphibians and reptiles in the archaeological levels of GranDolina and Sima del Elefante has been interpreted as demon-strating a temperature range of between 10�C and 13�C and arainfall of 800e1000 mm. These data are considered to provide amargin of tolerance for hominins (Agustí et al., 2009; Blain et al.,2009, 2010) in ecosystems such as savannah, the Mediterranean

Table 2Relation between taxa and their habitats. U. nanus is not known to inhabit anyspecific habitat (indet.) and so was not used to calculate the type of predominanthabitat (% column). MNI is the minimum number of individuals identified for eachtaxon. The habitats of each taxon are determined following Marquet (1989), Chaline(1985), Michaux (1995), Guillem (1995), Repenning (2001), López-Antoñanzas andCuenca-Bescós (2002) and Cuenca-Bescós et al. (2005).

Taxon MNI Habitat %

Ungaromys nanus 4 Indet. e

Iberomys huescarensis 11 Open humid meadow 25.58Mimomys savini 22 Water edge 51.18Eliomys quercinus 4 Woodland and woodland margin 9.3Apodemus sp. 2 Woodland and woodland margin 4.65Talpa europaea 1 Open humid meadow 2.32Crocidura sp. 3 Open-dry meadow 6.97

Fig. 5. Position of level 10 (EVT7) from Vallparadís in relation to the Gran Dolina levels(TD4/3, TD5b, TD5a and TD6), Fuente Nueva 3 (FN3) and Barranco León D (BLD) basedon the mean length of the m1 of M. savini for the different populations of differentsites. The position of this value between TD5b and TD5a allows us to estimate a date ofbetween 0.95 and 0.98 Ma. The dates used are those published by Falguères et al.(1999), Berger et al. (2008) and modified by Cuenca-Bescós et al. (2011) for the GranDolina levels (TD4/3, TD5b, TD5a and TD6) and Duval et al. (2012b) for Barranco León Dand Fuente Nueva 3.

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and the Asian steppes which have a high diversity of habitats andlow seasonality (Kahlke et al., 2011). The sites are usually located inecotones featuring diverse landscapes, wetlands and an abundanceof fresh water (Bar-Yosef and Belmaker, 2011; Carrión et al., 2011;Finlayson et al., 2011). The presence of archaeological remains atHappisburgh 3 increases the range of hominins to coniferous eco-systems and winter temperatures of 0�C and 3�C (Parfitt et al.,2010). Furthermore, the presence of lithic industry at Untermass-feld at a latitude of 50�N in central Europe indicates hominincolonization under continental conditions, although the climatewould have beenwarmer than today (Kahlke, 2000; Landeck, 2010;Garcia et al., 2013b). It remains to be explained how hominins couldhave kept warm without the help of fire, although it may beassumed that any strategy would have involved the consumption ofsignificant amounts of meat (Antón et al., 2002).

Nevertheless, the existence of refugia in the Mediterranean andAtlantic does not necessarily indicate a simple process of ebb andflow of human populations during the Early Pleistocene due toclimatic conditions (Agustí et al., 2009). Postglacial colonizations offlora and fauna of northern Europe from these southern refugiahave been deduced from DNA analysis and the genetic structure of

Fig. 6. Graphic representation of the predominance of specific habitats based on themicromammals found in level 10 of Vallparadís. Water edge and open humid meadowdominate.

human populations may be viewed in the same context (Hewitt,2000). Once a population became isolated in refugia in the face ofclimatic deterioration eventually suffered range contraction andwas either going to go extinct locally or, because it was sufficientlybroadly adapted, survive in the refugium. This population starts todifferentiate into distinct populations and species reinforced bynatural selection due to the new environments it encounters. Thesedifferentiated populations in the several European refugia may mixand merge again when ranges expand during more favourableconditions (Stewart and Stringer, 2012) with their new biologicaland cultural adaptations. Another proposal is the “sink-source”model, which posits the recolonization of northern areas of thecontinent by hominins from the “source”, that is, the refugia insouthern Europe, and also by new immigrants from Asia Minor(Dennell et al., 2011). The most suitable climatic conditions for thearrival of hominins in Europe would have occurred during aglacialeinterglacial transition period when the landscape wouldstill have been still open but the temperatures and rainfall weremore suitable. These windows of opportunity could have occurredseveral times throughout the Early Pleistocene and, as these glacialperiods became increasingly longer, so too would the windows ofopportunity (Leroy et al., 2011). This model allows for the possi-bility of repeated episodes of interbreeding between Europeanpopulations in the refugia in the south and new populations ofoutsiders, which some authors believe explains the morphologicalcomplexity found in hominin fossils dating from the Early andMiddle Pleistocene (Dennell et al., 2011; Bermúdez de Castro andMartinón-Torres, 2013).

In Bòbila Ordis, in the north-eastern Iberian Peninsula (Girona,Spain), glacial and interglacial periods have been correlated to MIS36e33 and rapid and frequent changes in vegetation are recorded.Analyses show periods of drastic deforestation with a mesic pollencomponent of <20% in the glacial phase. However, glacial periodsare brief and the minima and maxima temperature during glacialand interglacial are not so extreme (Leroy, 2008). Glacial-interglacial cycles show a succession of open vegetation duringcold, glacial phases, followed by dry, open vegetation (forestedsteppe and open Mediterranean-like woodlands) and then by de-ciduous forest, mixed forest and humid conifer forest (Leroy et al.,2011). However, analysis of the herpetofauna provides evidencethat does not always coincide with the palynological results (Blainet al., 2009) but that does indicate cold and arid conditions atvarious sites without the presence of archaeological remains suchas those from Cal Guardiola and Almenara-Casablanca 3, whichhave been related to the OIS 22 glacial period (Agustí et al., 2009).This archaeological gap has been interpreted as proof that thepeninsula had become depopulated by that point. Nevertheless, itstill remains to be discussed whether the lack of archaeologicalevidence signifies a lack of population or whether it simply reflects

Fig. 7. Composite pollen diagram from Vallparadís and Cal Guardiola site (Terrassa, Spain). Sample Guardiola is an average of 27 samples from the level D2 of Cal Guardiola.Vallparadís’s samples EVT4a and EVT4b come from brownish mudstone sediments and samples EVT4c and EVT4d come from black marsh level (bottom unit EVT4). Black dotsrepresent values of less than 1%. Categories: Mediterranean taxa: evergreen Quercus, Olea/Phillyrea, Cistus and Pistacia; Steppic taxa: Helianthemum, Ephedra, Artemisia, Cheno-podiaceaeeAmaranthaceae, Asteraceae total; Mesic: deciduous Quercus, Juglans, Corylus, Salix, Tilia, Fraxinus, Acer, Carpinus, Carya, Castanea-type, Platanus, Ulmus, Buxus, Vitis,Hedera, Cyperaceae, TyphaeSparganium, Typha/Sparganium, Alisma, Myriophyllum, Utricularia, type Polygonum persicaria and Potamogeton.

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the danger of interpreting absence (MacDonald et al., 2012). Manypalaeontological Early Pleistocene sites are not excavated using anarchaeological methodology and it is not always easy to determinethe presence of humans from the simple elaboration of EuropeanMode 1 lithic objects.

The palaeoclimate data (including analyses of pollen, herpeto-fauna and rodents) do show that these human occupationsoccurred in different environments and under different climaticconditions (Figs. 3e6). Palynological analysis shows that at Vall-paradís (Vallparadís and Cal Guardiola sites) between the pre-Jaramillo level D2 of Cal Guardiola and the MatuyamaeBrunhesboundary of EVT4 there was an evolution from a Mediterraneanclimate and an open landscape to a semi-cool and drier climate andsignificant coniferous tree cover. In between, the main archaeo-logical unit EVT7 and the herpetofauna and rodent records show aMediterranean climate continued that led to an open landscapewith little forest or meadow cover. Changes in the climatic condi-tions are also observed in levels TD5eTD8 at Gran Dolina and atFuente Nueva 3 and Barranco León (Blain et al., 2009; Agustí et al.,2010; Rodríguez et al., 2011). Consequently, the presence of a hu-man continuous population in the Iberian Peninsula indicates thatgroups of hominins overcame climatic fluctuations and adapted tothe particular conditions of Vallparadís (at latitude 33�N and 30 kmfrom the Mediterranean coast and 180 m AMSL), of Sierra de Ata-puerca (in the interior of the peninsula, at latitude 42�N and 980 mAMSL) and of Orce (an inland drainage basin surrounded bymountains, at latitude 37�N and 300 km from the sea and 920 mAMSL).

6. Conclusions

The new chronological and palaeoclimatic data inferred fromthe microfauna situate level 10 (EVT7) of Vallparadís just above theJaramillo palaeomagnetic episode around 0.98e0.95 Ma andcorrelatewith themicromammals at Gran Dolina TD3, TD4 and TD5

(Cuenca-Bescós et al., 2011) (Figs. 1, 3 and 4). This is supported bythe available chronological proxies from magnetostratigraphy,radiometric dating (ESR-U/series and OSL) and the biochronologyof macro and microfauna (Martínez et al., 2010; Duval et al., 2011,2012a). The absolute dates available for level 10 at Vallparadís(EVT7) and level TD6 at Gran Dolina indicate that both levels arechronologically close to one another (Fig. 1). At TD6 various datingmethods have been used, including ESR, ESR-U/series, TL and ESR-OBL. The methods used at level 10 (EVT7) of Vallparadís were ESR-U/series on dental samples and OSL on quartz grain samples. Theresults obtained by the ESR-U/series method indicate that level 10of Vallparadís has an age of 0.83 � 0.13 Ma, which is prior to the0.77 � 0.08 Ma obtained for TD6. The older age of level 10 atVallparadís and its position below TD6 are confirmed by the bio-chronology of the micromammals. This would mean that Vallpar-adís should be included in the same biozone as A. chalinei from thelower levels of Gran Dolina. However, comparative studies of bothM. savini and I. huescarensis show that level 10 at Vallparadís isrelated to levels TD5, TD4 and TD3 from the stratigraphic sequenceat Gran Dolina (Figs. 3 and 4). TD6 has been related to MIS 21,whereas we tentatively propose that level 10 (EVT7) is related toMIS 27, if the correlation with TD5 at Gran Dolina is correct.

The chronological and palaeoclimatic information described hasimportant archaeological implications regarding the first humansettlements in western Europe. It reinforces the hypothesis thatthere was a continuous population during the late Early Pleistocene(Agustí et al., 2010; Garcia et al., 2011, 2012; Duval et al., 2012a;Bermúdez de Castro et al., 2013) rather than the intermittentpopulations conditioned by climatic fluctuations posited by otherhypotheses (Dennell, 2003, 2010; Martinón-Torres et al., 2007;Agustí et al., 2009; Moncel, 2010; Dennell et al., 2011; Bermúdezde Castro and Martinón-Torres, 2013). Consequently, the humancolonization of Europe during this period would be a story ofhominin adaptation to higher latitude Eurasian environments withdiverse ecosystems and mammal communities (Ash and Gallup,

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2007; Garcia et al., 2013b). These adaptations entailed cultural andbiological advances that expanded the human range in Eurasiaduring the Early Pleistocene and are key to the history of first Eu-ropean hominin settlement.

Acknowledgements

The authors would like to acknowledge the pre-doctoral subsidyassigned to the IPHES (Institut de Paleoecologia Humana i EvolucióSocial) by the Fundación Atapuerca and the projects CGL2012e38358 and CGL 2009-12703-C03-03 of the Spanish Ministry ofScience and Innovation and SGR 2009-324 of the Generalitat deCatalunya for their help in writing this paper. We also thank IvánLozano-Fernández, Hugues-Alexandre Blain and Isabel Expósito fortheir contribution to the analysis presented on this paper.

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