Atapuerca Gran Dolina Research Articles

New chronological constraints for the lowermost stratigraphic unit of Atapuerca Gran Dolina (Burgos, N Spain)

We present the results of a combined Electron Spin Resonance (ESR) and Luminescence dating study for the lowermost stratigraphic unit (TD1) of the palaeoanthropological site of Atapuerca Gran Dolina, Spain. Ten samples collected through the Main Section were dated using either the Multiple Centre (MC) ESR approach or the single-grain thermally transferred optically stimulated luminescence (SG TT-OSL) technique, both of which were applied to quartz grains. The two methods yield consistent ages, providing a robust chronostratigraphic framework for the TD1 deposits and enabling improved correlation of the magnetostratigraphic succession (comprising three intervals of normal polarity; N1 to N3, from bottom to top) with the Geomagnetic Polarity Time Scale. Specifically, the results provide a late Early Pleistocene chronology for TD1, and clearly position the deposits in the post-Olduvai time range (<1.77 Ma). The final age estimates range from 1.30 ± 0.14 Ma (TT-OSL) close to the bottom of the section to a mean ESR age of 1.05 ± 0.12 Ma (1 s.d.) for three samples from the N3 interval towards the top. Consequently, the N3 interval may confidently be correlated to the Jaramillo Subchron, while we propose a correlation of N1 and N2 with the Cobb Mountain subchron and Punaruu excursion, respectively; although we cannot exclude that these two normal intervals may correspond to other, unknown, geomagnetic events given the existing uncertainties associated with the ESR and luminescence ages. From a methodological point of view, the ESR MC approach shows that the Titanium signal provides the most reliable burial ages for TD1. In contrast, the Aluminium centre yields systematically overestimated age estimates, as a result of incomplete resetting of the signal before sediment deposition. The SG TT-OSL ages presented here are amongst the oldest published so far, and highlight the potential of the high temperature SG TT-OSL 290 approach for obtaining finite ages exceeding 1 Ma at Atapuerca. Finally, these new dating results provide key insights into the rates and nature of sedimentary processes at Gran Dolina, modifying long-standing interpretations of the cave formation and infilling dynamics. An age of at least 1.4 Ma may be inferred for the base of the sedimentary infill at the Main Section, providing minimum age constraint for the formation of the cavity and, by extension, for the intermediate level of the Atapuerca karst. The opening of the cave, which pre-dates human occupation, most likely occurred close to or slightly after 0.9 Ma. This suggests that both TD4 and TD6 archaeological levels were deposited within a relatively short time range of <100 kyr. The so-called autochthonous fluvial deposits from TD1 unit, or at least those dated in the present study, were also clearly primarily derived from outside the karst system, and were not reworked from older deposits within the karst. They experienced sufficient daylight exposure and minimum transport times within the karst system to enable consistency between the ESR and TT-OSL burial ages and the independent magnetostratigraphic evidence. Our results highlight the need to reconsider the terminology traditionally employed to differentiate the two main phases of Gran Dolina's sedimentary infill. New numerical age results for stratigraphic unit TD1 of Atapuerca Gran Dolina, Spain The presence of Jaramillo magnetic Subchron (1.07-0.99 Ma) is confirmed The base of the sedimentary infill post-dates Oduvai Subchron (<1.77 Ma) Cave opening occurred ca. 0.9 Ma ago, suggesting that TD4-6 units deposited in < 100 kyr TD1 fluvial deposits do not originate from within the karst

The first direct ESR dating of a hominin tooth from Atapuerca Gran Dolina TD-6 (Spain) supports the antiquity of Homo antecessor

The present study reports the results of the first direct Electron Spin Resonance (ESR) dating study of Homo antecessor, the oldest known hominin species identified in Western Europe. The analysis of a tooth (ATD6-92) from TD6 unit of Atapuerca Gran Dolina (Spain) following a “semi non-destructive” procedure provides a final age estimate ranging from 624 to 949 ka, which covers all possible uranium uptake scenarios. Last, the additional magnetostratigraphic data collected within TD6 enables to further constrain the initial ESR chronology and to propose an age of between 772 and 949 ka for Homo antecessor, in agreement with previous dating works. Although our new results do not refine the existing chronology of TD6 unit, they nevertheless support the antiquity of H. antecessor, which pre-dates the estimated divergence age of modern and archaic human lineages based on genetic evidence. This work illustrates the challenges of dating human teeth by means of the ESR method, with the main pitfalls that are sometimes inherent to this specific application (e.g., systematic μCT-scanning of fossil hominin teeth; limited knowledge about the original sedimentary environment for teeth coming from old excavations; heterogeneous spatial distribution of the U-series elements in dental tissues). We identified several sources of uncertainty that may directly impact the accuracy of the age result. In particular, a slight contamination of dentine (<6%) in the enamel fragment measured by ESR was found to induce a significant age underestimation (33%) if not taken into consideration. It indeed caused not only a DE underestimation (by about 8%), but also produced a massive internal dose rate overestimation (by a factor of about 3.5). In contrast, other sources of uncertainty, such as the heterogeneity of the sedimentary environment, the variability of the water content over time, the previous μCT-scanning of the tooth or the potential preferential creation of unstable NOCORs in the ESR signal, showed here a limited impact on the final age result. Given our current understanding of the ESR method and the existing uncertainties associated with the evaluation of the DE and dose rate, this is probably as far as we can presently go in the dating study of ATD6-92 sample.

Evidence of trauma in a ca. 1-million-year-old patella of Homo antecessor, Gran Dolina-Atapuerca (Spain)

We present the palaeopathological study of a left patella (ATD6-56) belonging to the Early Pleistocene species Homo antecessor (Atapuerca-Gran Dolina, Spain). The abnormal morphology observed in the inferior margin of the patella is an osseous overgrowth (osteophyte). Macroscopic and microscopic techniques, including microtomography and zoom stereomicroscope, were used to describe the lesion. Externally, the osteophyte has a smooth and porous texture; the boundary between the more radiolucent osteophyte and the normal bone can be identified in X-ray images. We suggest that the observed signs could be secondary to a local trauma. The lesion would have involved either the bone or related soft tissues of the left limb, possibly affecting the stability of the joint. Consequently, the individual's knee would have suffered an abnormal mechanical load that could have eventually triggered osteoarthritic changes. This is also supported by the lack of changes observed in the associated right patella (ATD6-22).

Revisiting the ESR chronology of the Early Pleistocene hominin occupation at Vallparadís (Barcelona, Spain)

ESR dating was applied to fossil teeth and optically bleached quartz grain samples from two units of the sequence at Vallparadís (Barcelona, Spain): weighted mean ESR age estimates of 858 ± 87 ka and 849 ± 48 ka were obtained for EVT-7, which includes the archaeological level 10, and EVT-8, respectively. These results are in good agreement with the existing magneto-biostratigraphic framework that constrain these deposits between 780 and 990 ka, and indicate that Vallparadís EVT-7 has a chronology very close to that of Atapuerca Gran Dolina TD-6 (Spain).

The medial pterygoid tubercle in the Atapuerca Early and Middle Pleistocene mandibles: evolutionary implications.

Numerous studies have attempted to identify the presence of uniquely derived (autoapomorphic) Neandertal features. Here, we deal with the medial pterygoid tubercle (MTP), which is usually present on the internal face of the ascending ramus of Neandertal specimens. Our study stems from the identification of a hypertrophied tubercle in ATD6-96, an Early Pleistocene mandible recovered from the TD6 level of the Atapuerca-Gran Dolina site and attributed to Homo antecessor. Our review of the literature and study of numerous original fossil specimens and high quality replicas confirm that the MTP occurs at a high frequency in Neandertals (ca. 89%) and is also present in over half (ca. 55%) of the Middle Pleistocene Sima de los Huesos (SH) hominins. In contrast, it is generally absent or minimally developed in other extinct hominins, but can be found in variable frequencies (<ca. 25%) in Pleistocene and recent H. sapiens samples. The presence of this feature in ATD6-96 joins other traits shared by H. antecessor, the SH hominins and Neandertals. Since the TD6 hominins have been attributed either to MIS 21 or to MIS 25, it seems that a suite of assumed derived Neandertal features appeared in the Early Pleistocene, and they should be interpreted as synapomorphies shared among different taxa. We suggest that H. antecessor, the SH hominins and Neandertals shared a common ancestor in which these features appeared during the Early Pleistocene. The presence of the MTP in taxa other than H. neanderthalensis precludes this feature from being a Neandertal autapomorphy.

Evidence of Stress Fracture in a Homo antecessor Metatarsal from Gran Dolina Site (Atapuerca, Spain)

AbstractWe present the palaeopathological analysis of a right fourth metatarsal (ATD6‐124) recovered from the Atapuerca–Gran Dolina site (Spain). This fossil, ca. 1 Ma, belongs to Homo antecessor, the earliest known European hominin species. The metatarsal exhibits a proliferative lesion on its medial periosteal surface. Periosteal reaction can be the bone response to a wide number of injurious processes. We describe a lesion on the basis of macroscopic and microscopic analyses, including microtomography and scanning electron microscopy. Externally, the osteoblastic lesion presents a highly porotic and disorganised morphology. Internally, we observe a series of micro‐fractures on the compact bone that do not affect the medullary canal. We provide a differential diagnosis and suggest that the ATD6‐124 lesion could correspond to a pedal stress fracture, also known as fatigue or march fracture. Stress fractures have been related to a load increase and muscular fatigue. This type of fracture has been widely reported in the foot of soldiers and athletes, which are usually engaged in strenuous, excessive or prolonged locomotive activities. Despite its high frequency in these groups, stress fractures have not been reported as such in fossil collections, with the exception of a metatarsal belonging to the Sima de los Huesos site (Atapuerca). Copyright © 2013 John Wiley &amp; Sons, Ltd.

ESR chronology of alluvial deposits in the Arlanzón valley (Atapuerca, Spain): Contemporaneity with Atapuerca Gran Dolina site

The Sierra de Atapuerca (Northern Spain) is characterized by a well-developed karst system where several major archaeological sites have been discovered, attesting an almost continuous hominin occupation of the area during the whole Pleistocene period. Previous geomorphological studies showed a connection between genesis of the karst system and the evolution of the nearby Arlanzón river Valley. However, numerical dating results were missing to refine the chronostratigraphical framework of the Arlanzón valley's fluvial incision. To address this, we applied the Electron Spin Resonance (ESR) dating method to sedimentary optically bleached quartz grains from several fluvial terraces. Nine samples were collected from five of the 14 identified terraces. The ESR age results are stratigraphically coherent and in general agreement with both previous geomorphological observations and available palaeomagnetic data. Consequently, an ESR chronology of the geological evolution of the Arlanzón valley is proposed, which can be then correlated to the sedimentary sequence of the palaeoanthropological site of Atapuerca Gran Dolina. Our results provide important information about the chronology of hominid occupation in this area during Early and Middle Pleistocene.

Age of the oldest hominin settlements in Spain: Contribution of the combined U-series/ESR dating method applied to fossil teeth

This paper presents a synthesis of the combined Uranium-Series/ESR age results obtained on fossil teeth from several Early Pleistocene archaeological and/or palaeontological Spanish localities: Atapuerca Gran Dolina TD-6, Fuente Nueva-3, Barranco León, Venta Micena and Vallparadís. While the age results show some scattering, they are nevertheless encouraging and provide a significant contribution to the understanding of the first hominin settlements in Western Europe.These “old” samples are mainly characterised by high 230Th/234U activity ratios that may sometimes exceed secular equilibrium, and by high Uranium concentrations (several tens of ppm or more). The modelling of U-uptake is therefore really crucial for the age calculation process. In the case of the combined US–ESR approach, this uptake is derived from the U-series data measured in dental tissues, which seem to be strongly dependant on the hydro-geological context. Consequently, when dating “old” samples, a special attention has to be paid to the accuracy and the meaning of the U-series data collected from the dental tissues, which may be influenced by several factors such as spatial heterogeneity and recent U-uptake overprint. Some rapid scanning procedures should be developed in order to pre-identify the samples that are the most suitable for ESR dating.

Three‐dimensional evaluation of root canal morphology in lower second premolars of early and middle pleistocene human populations from atapuerca (Burgos, Spain)

The aim of this study is to describe the morphology of the roots and root canals of permanent lower second premolars (LP4s) with fully developed roots of five hominin groups: Homo sp. (ATE9-1 specimen) from Atapuerca-Sima del Elefante locality, H. antecessor (ATD6-4 and ATD6-125) from Atapuerca-Gran Dolina TD6 locality, H. heidelbergensis from Atapuerca-Sima de los Huesos locality, H. neanderthalensis from Krapina, Regourdou, and Abri Bourgeois-Delaunay localities, and two contemporary H. sapiens groups. The teeth were scanned by means of microtomography. The roots were divided into three virtual segments by three planes: cemento-enamel junction (CEJ), mid-root (MR), and mid-apex (MA). Volumetric and planar direct measurements of the whole teeth and each segment were taken. Descriptive statistical analyses and nonparametric Mann-Whiney test were performed to test for significant differences (P < 0.025) between groups. ATE9-1 and Gran Dolina-TD6 fossils present intricate radicular complexes that might be transitional between the morphologies of Australopithecus robustus and African early Homo and the derived conditions typically found in later Homo. In H. neanderthalensis and H. heidelbergensis, the root canals are wide, with small apical convergence. This trait is particularly pronounced in the Sima de los Huesos sample which may reflect a particularity of this population. Our study demonstrates the potential of hominin roots and root canals as untapped sources of taxonomic information when the tooth crown is fragmented. Future studies, including more fossil specimens and species will shed light in the polarity of the morphologies observed.

L’évolution de l’homme en Eurasie : nouveaux fossiles, nouveaux outils d’analyse

Due to the numerous discoveries of fossils and the technical and analytical improvements in paleoanthropology that occurred recently, a new investigation on the first inhabitants in Eurasia was necessary. The research deals with the facial pattern of the fossil hominids from Europe and Asia and focussed on the ones discovered in the Atapuerca-Gran Dolina site in Spain, which are oldest than 850,000 years and in the Yunxian site in China, which are dated by 936,000 years. Methods used combined 2D and 3D morphometrics providing with the possibility to consider not only the overall conformation but also the more localized measurements. The Procrustes analysis, which put apart the individual size parameter, were used to investigate the morphological alteration of the face during growth in order to interpret the facial conformation juvenile fossils such as those from Atapuerca-Gran Dolina. Moreover, a specific protocol using tomography and 3D imaging techniques was carried out to reconstruct the Yunxian specimens which have been badly crushed during fossilization process. The results of this research put in light two facial patterns: (1) a facial pattern in extension expressed in Neandertals which european lineage could have been older than previously thought including the Atapuerca-Gran Dolina specimens and (2) a facial pattern in contraction shared between modern humans and the oldest fossil hominids from continental Asia (i.e. Yunxian specimens) which suggests that this conformation corresponds to a primitive condition.

Datation par résonance de spin électronique (ESR) de quelques sites pléistocène inférieur d'Europe

In Western Europe, most of the oldest prehistoric sites (ranging from 2 Ma to 500 ka) are associated with clastic or carbonated karstic environments. Here, the electron spin resonance (ESR) dating method is often the only one method permitting to place these localities in the global Quaternary framework, which is mainly based on marine isotopic data and palaeomagnetical record. ESR can be applied on different materials frequently recovered in archaeological sites such as tooth enamel, quartz grains or carbonates. In this paper, we present the results, which have been obtained for more than ten years on different archaeological sites of the late Lower Pleistocene or the early Middle Pleistocene, which are crucial for the understanding of the first human settlements of Europe: Pont‑de‑Lavaud and Grâce‑Autoroute (France), Atapuerca Gran Dolina (Spain), Monte Poggiolo and Isernia La Pineta (Italy). Wherever possible, the ESR results were compared with those of independent dating methods, including 39Ar/40Ar, palaeomagnetism and biostratigraphy. In some cases, the ESR method applied on bleached quartz extracted from fluvial sediments and the ESR/U‑series method on tooth enamel were the only available methods to provide geochronological data.

ESR dating and the human evolution: contribution to the chronology of the earliest humans in Europe

In the last 20 years, the electron spin resonance (ESR) dating method has allowed the establishment of a chronological time frame over most of the history of human evolution. Despite many difficulties found for ESR dating of bones and carbonates, tooth enamel dated by ESR has been proven as a reliable method in its application to fossil teeth and quartz. Both of the latter materials have allowed dating of Early and Middle Pleistocene sites which are not datable using other methods such as the Argon–Argon method. In particular, recent discoveries of human remains in western Europe have been proposed to be sites of the earliest arrival of humans there, and have been dated to the Early Pleistocene by ESR using quartz and tooth enamel. Combined ESR and U-series dating of fossil herbivore teeth are the only means of dating layers from which such ancient remains have been recovered in western Europe. Good examples are the sites of Atapuerca Gran Dolina, Spain and Visogliano, Italy which have been dated using tooth enamel. When no bones and teeth can be found in prehistoric sites, ESR dating on quartz extracted from sediments has been used to date sites whose ages range over the entire Quaternary period. We present here two examples that occur in fluvial terraces of the river Creuse, France and at Monte Poggiolo site, Italy, where several artefacts of an archaic pebble industry have been recovered.

Early human expansions into Eurasia: The Atapuerca evidence

Abstract The first humans to have migrated out of Africa were the ancestors of the Pithecanthropines — Homo erectus — of Java. Different sources point to ca. 1.9 Ma as the date of their exodus. Although the demographic success of early species of genus Homo preceded the 1.9 Ma date, a period of severe environmental crises ensued. A second dispersal was that of the Dmanisi population — H. ergaster, or H. sp. cf. Ergaster — these hominids came out of Africa most probably around 1.7 (earlier than 1.6 Ma BP), a time of continental uplift, aridification, the radiation of the Paranthropines, and the evolution of humans, all of which preceded the development of Paleolithic Mode 2 industries. The third movement of humans from Africa is attested to by the finds of Ubeidiya, with an Acheulean (Mode 2) artifactual assemblage, and a combination of faunal elements from East Africa and Eurasia that indicates an age of no more than 1.4 and barely less than 1.3 Ma. That interval is characterized by warm and humid climatic conditions, and vegetation improvement. The migration of mammals to the north may coincide with an inflection in environmental conditions dated to 1.3 Ma, or later. The record of fossil humans in Africa declines markedly at around 1.3 Ma BP, and recovers only slightly half a million years later, with a few localities between 800 and 600 ka BP. The evaluation of effects on human populations is impeded by physiographic changes globally adverse to sedimentary conditions for fossilization and the preservation of occupation floors. Archaeological and paleoanthropological sites in Eurasia, particularly the Atapuerca-Gran Dolina site, with findings in the “Aurora” Bed, testify to the successful expansion of a deme with modern asiatic traits, descendants of an ancient, not a new out-of-Africa exodus (that is, related neither to Gesher Benot Ya’aqov nor to Ubeidiya). More recent movements, at about 0.6 Ma, may correspond to the African origins of the European preneandertals — H. heidelbergensis — and Neandertals, as can be inferred from studies of the large fossil human sample of the Atapuerca-Sima de los Huesos site. Evidence points to several population movements between Africa and Eurasia in the past, and to a complex origin of modern mankind — Homo sapiens.

Calibration of the Early-Middle Pleistocene transition in the continental beds of the Guadix–Baza Basin (SE Spain)

The magnetostratigraphic and palaeontologic studies carried out in two sections in the Guadix–Baza Basin (SE Spain) have enabled an accurate calibration of the Early-Middle Pleistocene boundary in the continental beds of this basin. The palaeontological record (rodents) in the Cortes de Baza section indicates an age ranging from the earliest Pleistocene (latest Villanyian or early Biharian) to the late Early Pleistocene (late Biharian). The whole Cortes de Baza Section is placed in a reversed magnetic interval identified as the upper part of the Matuyama Chron. In the Guadix–Baza Basin, the Middle Pleistocene (early Toringian) was already known at the locality of Cúllar–Baza I, but new studies in the area have resulted in the recognition of Early Pleistocene deposits in the lower part of the section. Thus, the locality of Cúllar–Baza B is placed in a reversed magnetozone correlated with the uppermost Matuyama, while the locality of Cúllar–Baza C is placed in a normal magnetozone correlated to the lower Bruhnes Epoch. Therefore, the Biharian–Toringian boundary (based on the presence of Arvicola cantiana) falls well within the Bruhnes epoch. This result is consistent with what is found in other Early–Middle Pleistocene sections of Spain (Atapuerca Gran Dolina).