30/11/2018

New paper in Science:

1.9-million- and 2.4-million-year-old artifacts and stone tool–cutmarked bones from Ain Boucherit, Algeria

Full reference

Sahnouni M., Parés J.M., Duval M., Cáceres I., Harichane Z., Van der Made J., Pérez-González A., Abdessadok S., Kandi N., Derradji A., Medig M., Boulaghraif K., Semaw S. (accepted). 1.9-2.4 million-year-old artefacts and stone tool cutmarked bones from Ain Boucherit, Algeria. Science eaau0008. DOI: 10.1126/science.aau0008.

Abstract

East Africa has provided the earliest known evidence for Oldowan stone artifacts and hominin induced stone tool cutmarks dated to ~2.6 million years ago (Ma). The ~1.8 Ma stone artifacts from Ain Hanech (Algeria) were considered to represent the oldest archaeological materials in North Africa. Here we report older stone artifacts and cutmarked bones excavated from two nearby deposits at Ain Boucherit estimated to ~ 1.9 Ma, and the older to ~2.4 Ma. Hence, the Ain Boucherit evidence shows that ancestral hominins inhabited the Mediterranean fringe in Northern Africa much earlier than previously thought. The evidence strongly argues for early dispersal of stone tool manufacture and use from East Africa, or a possible multiple origin scenario of stone technology in both East and North Africa.

Acknowledgements

Aspects of the dating study have been funded by the Australian Research Council Future Fellowship project (FT150100215).

26/01/2018

New paper in Science

The earliest modern humans outside Africa

Full reference

Hershkovitz, I., Weber, G., Quam, R., Duval, M., Grün, R., Kinsley, L., et al. (2018). The Earliest Modern Human outside Africa. Science 359, pp. 456-459.

Abstract

To date, the earliest modern human fossils found outside of Africa are dated to around 90,000 to 120,000 years ago at the Levantine sites of Skhul and Qafzeh. A maxilla and associated dentition recently discovered at Misliya Cave, Israel, was dated to 177,000 to 194,000 years ago, suggesting that members of the Homo sapiens clade left Africa earlier than previously thought. This finding changes our view on modern human dispersal and is consistent with recent genetic studies, which have posited the possibility of an earlier dispersal of Homo sapiens around 220,000 years ago. The Misliya maxilla is associated with full-fledged Levallois technology in the Levant, suggesting that the emergence of this technology is linked to the appearance of Homo sapiens in the region, as has been documented in Africa.

Acknowledgements

The ESR dating study has been supported by a Marie Curie International Outgoing Fellowship (under REA Grant Agreement n° PIOF-GA-2013–626474) of the European Union’s Seventh Framework Programme (FP7/2007-2013) and an Australian Research Council Future Fellowship (FT150100215).

3D image of the Maxillar Misliya-1

(Credits: Israel Hershkovitz, Tel Aviv University)

25/09/2017

New paper in press in Quaternary International

ESR dating of Middle Pleistocene archaeo-paleontological sites

from the Manzanares and Jarama river valleys (Madrid basin, Spain)

Full reference

Moreno, D., Duval, M., Rubio, S., Panera, J., Bahain, J.-J., Shao, Q., Pérez-González, A., Falguères, C. (accepted). ESR dating of several Middle to Late Pleistocene archaeo-paleontological sites from the Manzanares and Jarama river valleys (Madrid basin, Spain). Quaternary International. https://doi.org/10.1016/j.quaint.2017.09.003

Abstract

In this work, three important Pleistocene sites of the Madrid basin located close to the junction of the Manzanares (PRERESA site) and the Jarama (Valdocarros site and Maresa quarry) rivers have been studied in order to improve the existing chronological framework of the basin and to clarify the

geological evolution of these fluvial systems and their relationship with human occupations. To do so, Electron Spin Resonance (ESR) dating was applied to four fossil teeth and nine optically bleached quartz grain samples. Most of the obtained dates are consistent with the existing preliminary age estimates by biostratigraphy, luminescence (OSL and TL) or Amino Acid Racemization (AAR) dating. This ESR dating study suggests an age of Late Middle Pleistocene (early MIS6) for PRERESA site. At the Jarama valley (Valdocarros site and Maresa quarry), the Arganda I unit could be correlated to the MIS 9 and MIS10, the Arganda II unit seems to belong to MIS8 and MIS7 and the Arganda III to the MIS6.

22/06/2017

New paper published in Ancient TL

Defining minimum reporting requirements for ESR dating of optically bleached

quartz grains

Full reference

Duval, M., Bahain, J.-J., Bartz, M., Falguères, C., Guilarte, V., Moreno, D., Tissoux, H. del Val, M., Voinchet, P. Defining minimum requirements for reporting ESR dating methodology and age estimates based on optically bleached quartz grains. Ancient TL 35(1), pp. 11-19.

Abstract

More than 30 years after the first Electron Spin Resonance (ESR) dating application tooptically bleached quartz grains by Yokoyama et al. (1985), the absence of standardization for reporting methodology and age results remains an obstacle for the development and recognition of the ESR dating method within the Quaternary scientific community. To overcome this issue, the present work proposes some basic guidelines which should hopefully be useful not only for the ESR dating community, but also for any potential reviewers who may not be familiar with the specificities of this field.

25/05/2017

New paper published in Quaternary Science Reviews

Revealing the pace of river landscape evolution during the Quaternary:

recent developments in numerical dating methods

Full reference

Rixhon, G., Briant, B., Cordier, S., Duval, M., Jones, A., Scholz, D. Setting the pace of river landscape evolution at different timescales during the Quaternary: recent developments in numerical dating methods. Quaternary Science Reviews 166, pp.91-113. DOI: 10.1016/j.quascirev.2016.08.016.

Abstract

During the last twenty years, several technical developments have considerably intensified the use of numerical dating methods for the Quaternary. The study of fluvial archives has greatly benefited from these enhancements, opening new dating horizons for a range of archives at distinct time scales and thereby providing new insights into previously unanswered questions. In this contribution, we separately present the state of the art of five numerical dating methods that are frequently used in the fluvial context: radiocarbon, Luminescence, Electron Spin Resonance (ESR), 230Th/U and terrestrial cosmogenic nuclides (TCN) dating. We focus on the major recent developments for each technique that are most relevant for new dating applications in diverse fluvial environments and on explaining these for non-specialists. Therefore, essential information and precautions about sampling strategies in the field and/or laboratory procedures are provided. For each method, new and important implications for chronological reconstructions of Quaternary fluvial landscapes are discussed and, where necessary, exemplified by key case studies. A clear statement of the current technical limitations of these methods is included and forthcoming developments, which might possibly open new horizons for dating fluvial archives in the near future, are summarised.

11/05/2017

New paper published in the Proceedings of the 2nd Meeting of African Prehistory

La primera ocupación humana en el norte de Africa:

Evidencia de la secuencia plio-pleistocena de Ain Boucherit-Ain Hanech.

Full reference

Sahnouni, M., Perez-Gonzalez, A., Parés, J.M., Abdessadok, S., Van Der Made, J., Duval, M., Harichane, Z., Caceres, I., Kandi, N., Boulaghraif, K., Derradji, A., Medig, M., Mouhoubi, Y., Hamlat, A., Chibane, S. (2017). La primera ocupación humana en el norte de Africa: Evidencia de la secuencia plio-pleistocena de Ain Boucherit-Ain Hanech. In Spanish. Proceedings of the 2nd Meeting of African Prehistory, pp.263-296.

Abstract (Main text in Spanish)

The Ain Boucherit-Ain Hanech sequence in northeastern Algeria documents evidence of the earliest hominid presence in North Africa. The stratigraphic sequence is rich with Lower Pleistocene fluvio-lacustrine deposits. There are four main fossil and artifact-bearing localities, including two deposits at Ain Boucherit, Ain Hanech, and El-Kherba. Ain Boucherit occurrences are encased in Members P and R of the Ain Hanech Formation, while those from the localities of Ain Hanech and El-Kherba are located stratigraphically higher up in Member T of the same formation. Normal geomagnetic polarity is correlated to the Olduvai subchron dated to 1.78-1.95 Million years ago (Ma). Ain Hanech and El Kherba are located near the top the Olduvai subchron. The stage of evolution of Kolpochoerus and the presence of Anancus corroborate the paleomagnetic interpretation. The lower members P and R are estimated to be older than 1.8 Ma. All faunas have several of the aquatic elements such as hippopotamus, aquatic turtles, crocodiles, frogs or fish. However, most elements are indicative of a relatively dry or open habitat in all the sites. However, the environment became more open in Ain Hanech and El Kherba as suggested by the abundance of equids and the decrease in small antelopes such as Gazella and in particular Parantidorcas. In all the sites, the lithic artifact assemblages are primarily made of limestone and flint, and comprise flaked cobbles and cores, debitage, and retouched pieces. The assemblages are Oldowan similar to those known in East Africa. Subsistence analysis indicates that Ain Hanech hominids were overall responsible for modifying animal carcasses and documents for the first time evidence of early hominid large animal foraging capabilities in northern Africa during the Lower Pleistocene.

10/05/2017

New paper published in eLife

The age of Homo naledi and associated sediments

in the Rising Star Cave, South Africa

Full reference

Dirks, P.H.G.M., Roberts, E.M., Hilbert-Wolf, H., Kramers, J.D., Hawks, J., Dosseto, A., Duval, M., Elliott, M., Evans, M., Grün, R., Hellstrom, J., Herries, A.I.R., Joannes-Boyau, R., Makhubela, T.V., Placzek, C.J., Robbins, J., Spandler, C., Wiersma, J., Woodhead, J., Berger, L.R. (2017). The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa. eLife, 6:e24231. http://dx.doi.org/10.7554/eLife.24231. Link

Abstract

New ages for flowstone, sediments and fossil bones from the Dinaledi Chamber are presented. We combined optically stimulated luminescence dating of sediments with U-Th and palaeomagnetic analyses of flowstones to establish that all sediments containing Homo naledi fossils can be allocated to a single stratigraphic entity (sub-unit 3b), interpreted to be deposited between 236 ka and 414 ka. This result has been confirmed independently by dating three H. naledi teeth with combined U-series and electron spin resonance (US-ESR) dating. Two dating scenarios for the fossils were tested by varying the assumed levels of 222Rn loss in the encasing sediments: a maximum age scenario provides an average age for the two least altered fossil teeth of 253 +82/–70 ka, whilst a minimum age scenario yields an average age of 200 +70/–61 ka. We consider the maximum age scenario to more closely reflect conditions in the cave, and therefore, the true age of the fossils. By combining the US-ESR maximum age estimate obtained from the teeth, with the U-Th age for the oldest flowstone overlying Homo naledi fossils, we have constrained the depositional age of Homo naledi to a period between 236 ka and 335 ka. These age results demonstrate that a morphologically primitive hominin, Homo naledi, survived into the later parts of the Pleistocene in Africa, and indicate a much younger age for the Homo naledi fossils than have previously been hypothesized based on their morphology.

Acknowledgements

We would like to thank Chris Stringer and four anonymous reviewers for their constructive comments that have greatly helped improve this paper. We would also like to thank the many funding agencies that supported various aspects of this work. In particular we would like to thank the National Geographic Society, the National Research Foundation and the Lyda Hill Foundation for significant funding of the discovery, recovery and initial analysis of this material. Further support was provided by ARC (DP140104282: PHGMD, ER, JK, HHW; FT 120100399: AH). The ESR dosimetry study undertaken by CENIEH and Griffith University has been supported by a Marie Curie International Outgoing Fellowship (under REA Grant Agreement n° PIOF-GA-2013–626474) of the European Union’s Seventh Framework Programme (FP7/2007-2013) and an Australian Research Council Future Fellowship (FT150100215). ESR and U-series dating undertaken at SCU were supported by ARC (DP140100919: RJB). We would also like to thank the University of the Witwatersrand, the Evolutionary Studies Institute and the South African National Centre of Excellence in PalaeoSciences for hosting many of the authors while studying the material, and allowing original material to be made available for dating. We would like to thank the South African Heritage Resource Agency for the necessary permits to work on the Rising Star site; the Jacobs family and later the Lee Berger Foundation for granting access. The assistance of members of the Speleological Exploration Club, in various safety aspects within the cave during excavations is gratefully acknowledged. Zenobia Jacobs and Bert Roberts of the University of Wollongong are thanked for helping with initial OSL tests for single grain analyses and for helpful discussions. We would also like to thank Wilma Lawrence, Bonita De Klerk, Natasha Barbolini, Merrill van der Walt, Wayne Crichton and Justin Mukanku for their assistance during all phases of the project. RG and MD thank Les Kinsley, ANU, for his invaluable help to keep the Neptune in tune. ME would like to thank Stephan Woodborne (iThemba LABS, Gauteng) for his help in unravelling the spectrometer results related to OSL and ESR dating.

15/04/2017

HR_ESR Marie Curie IOF project officially 626474 finalized !

More information about the project details can be found here.

HR_ESR Report Summary is available here.

10/02/2017

New paper published in American Journal of Physical Anthropology

Quantifying the impact of µCT-scanning of human fossil teeth on ESR age results

Full reference

Duval, M. and Martín-Francés, L. (2017). Quantifying the impact of µCT-scanning of human fossil teeth on ESR age results. American Journal of Physical Anthropology. DOI: 10.1002/ajpa.23180. Link

Abstract

Fossil human teeth are nowadays systematically CT-scanned by palaeoanthropologists prior to any further analysis. It has been recently demonstrated that this noninvasive technique has, in most cases, virtually no influence on ancient DNA preservation. However, it may have nevertheless an impact on other techniques, like Electron Spin Resonance (ESR) dating, by artificially ageing the apparent age of the sample. To evaluate this impact, we µCT-scanned several modern enamel fragments following the standard analytical procedures employed by the Dental Anthropology Group at CENIEH, Spain, and then performed ESR dose reconstruction for each of them. The results of our experiment demonstrate that the systematic high-resolution µCT-scanning of fossil hominin remains introduces a nonnegligible X-ray dose into the tooth enamel, equivalent to 15–30 Gy depending on the parameters used. This dose may be multiplied by a factor of ∼8 if no metallic filter is used. However, this dose estimate cannot be universally extrapolated to any µCT-scan experiment but has instead to be specifically assessed for each device and set of parameters employed. The impact on the ESR age results is directly dependent on the magnitude of the geological dose measured in fossil enamel but could potentially lead to an age overestimation up to 40% in case of Late Pleistocene samples, if not taken into consideration.

Acknowledgements

The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007–2013) under REA Grant Agreement no PIOF-GA-2013-626474. Some aspects of this work have also been covered by an Australian Research Council Future Fellowship grant (FT150100215). LM-F is beneficiary of a Fundación Atapuerca Post-Doctoral Research Grant. The authors would like to thank M. Lebon (MNHN) for supplying the modern bovid teeth and M. Martinón-Torres (UCL) and J.M. Bermúdez de Castro (CENIEH) for their support and useful advice on the manuscript. Two anonymous reviewers provided constructive comments on an earlier version of the article.

02/12/2016

New paper published in the French journal Spectra Analyse

Datation directe de restes humains fossiles :

au-delà du 14C, la méthode par Résonance Paramagnétique Électronique (RPE)

Full reference

Duval, M. (2016). Datation directe de restes humains fossiles : au-delà du 14C, la méthode par Résonance Paramagnétique Électronique (RPE). Spectra Analyse 312, pp. 45-53.

Abstract (in French)

La datation directe de restes humains fossiles a depuis toujours constitué un challenge important en paléoanthropologie, car permettant de positionner les nouvelles découvertes au sein de l’arbre évolutif de l’espèce humaine. La rareté de ces fossiles et leur inestimable valeur rendent de plus en plus crucial le développement de méthodes de datation adaptées à cette situation. Si le Carbone 14 reste sans discussion la méthode la plus fi able et précise pour les derniers 45 000 ans, la RPE se présente comme une alternative intéressante pour des périodes plus anciennes, en particulier si une approche semi-destructive combinant les techniques analytiques les plus avancées est utilisée.

Acknowledgements (in French)

Durant la réalisation de ce travail, l’auteur a été financé par une bourse européenne Marie Curie International Outgoing Fellowship PIOF-GA-2013-626474 (associée au projet intitulé « Datation par RPE de dents fossiles : développement d’une nouvelle approche à haute résolution et contribution à l’amélioration de la chronologie des premières occupations humaines dans le pourtour méditerranéen. ») et par une bourse australienne Australian Research Council Future Fellowship FT150100215 (associée au projet « Élaboration de chronologies robustes pour évaluer le timing et la synchronicité des peuplements du Paléolithique inférieur autour du bassin méditerranéen.»). L’auteur remercie le/la relecteur/rice scientifique anonyme ainsi que Camille Saïsset, Rédactrice en chef de Spectra Analyse, pour les commentaires constructifs qui ont permis d’améliorer significativement la clarté de cet article.

23/10/2016

New paper published in Quaternary Geochronology

Electron spin resonance dating of optically bleached quartz grains from the Middle Palaeolithic site

of Cuesta de la Bajada (Spain) using the multiple centres approach

Full reference

Duval, M., Arnold, L.J., Guilarte, V., Demuro, M., Santonja, M. and Pérez-González, A. (2016). Electron Spin Resonance dating of optically bleached quartz grains from the Middle Palaeolithic site of Cuesta de la Bajada (Spain) using the multiple centres approach. Quaternary Geochronology. DOI: 10.1016/j.quageo.2016.09.006.

Abstract

Electron spin resonance (ESR) dating of optically bleached quartz grains was performed on three sediment samples collected from the Middle Palaeolithic site of Cuesta de la Bajada (Spain). A standard multiple grain and multiple aliquot additive dose procedure was employed, and both the Al and Ti centres were measured as part of the multiple centres approach.

ESR age estimates obtained for the three samples indicate that the Al centre provides a maximum possible chronology; use of the Ti centres show that the Al signal was likely not systematically reset to its residual level during sediment transportation. A direct comparison between ESR ages based on the Ti centres and single grain optically stimulated luminescence (OSL) ages from samples collected nearby shows broadly consistent results. The Ti-H centre also appears to provide suitable chronologies for at least two of the three Middle Pleistocene samples studied here. Surprisingly, the only sample showing consistent ESR ages between the Al and Ti centres appears to be overestimated in comparison with the Ti-centre and OSL ages derived from the other two samples. This indicates either incomplete bleaching of both the Al and Ti centres for this sample, or unexpected impacts of other sources of De uncertainty, such as multi-grain averaging effects. The ESR dating results overall indicate that the archaeological sequence of Cuesta de la Bajada CB-3 is most likely correlated to either MIS 7 or 9.

Acknowledgements

Some of the data shown in the present study were derived from analysis covered by the project CGL2010-16821 from the Spanish Ministry of Science and Innovation. M. Duval's research was funded by a Marie Curie International Outgoing Fellowship of the EU's Seventh Framework Programme (FP7/2007–2013), awarded under REA Grant Agreement No. PIOF-GA-2013-626474. L. Arnold and M. Demuro were partly supported by Australian Research Council Future Fellowship grant FT130100195 and Discovery Early Career Researcher Award DE160100743, respectively, during the course of this study. Finally, we thank the two anonymous reviewers for their constructive comments.

03/10/2016

New ARC Future Fellow at Griffith University, Brisbane, Australia.

Abstract

The project seeks to contribute to our understanding of early human evolution in the Mediterranean and provide tested dating methods for Early Pleistocene sites. It aims to answer a major question in Quaternary geochronology and Mediterranean archaeology - when hominins reached the edges of the Mediterranean - by building more robust chronologies for Early Pleistocene sites located in non-volcanic context. After testing a series of dating protocols at known-age localities, the project plans to apply a new multi-technique dating approach combining different numerical methods and Bayesian modelling on a range of Lower Palaeolithic sites in three key areas: Southern Spain, Northern Africa and the Near East.

Granted: $692,015.

29/09/2016

Participation to the European Researchers' Night: exploring science whilst having fun.

Conference

Duval, M. (2016). Investigar el tiempo prehistorico: tras los pasos de un geocronologo del CENIEH. European Researchers' Night: exploring science whilst having fun, Burgos (Spain), 29/09/2016.

Diario de Burgos (01/10/2016)

14-18/09/2016

Contribution to the 6th Annual ESHE meeting, Madrid, Spain

Full reference

Duval, M., Grün, R., Martín-Francés, L., Bermúdez de Castro, J.M. (2016). Direct dating of human remains beyond the radiocarbon time range: what about using ESR? Poster. 6th Annual ESHE meeting, Madrid (Spain), 13-17/09/2016.

01/09/2016

New paper published in Quaternary Geochronology

OSL dating of individual quartz ‘supergrains’ from the Ancient Middle Palaeolithic site of Cuesta de la Bajada, Spain

Full reference

Arnold, L.J., Duval, M., Demuro, M., Spooner, N.A., Santonja, M., Pérez-González, A. (2016). OSL dating of individual quartz ‘supergrains’ from the Ancient Middle

Palaeolithic site of Cuesta de la Bajada, Spain. Quaternary Geochronology 36, pp. 78-101.

Abstract

Dose saturation represents a fundamental limitation for obtaining finite optically stimulated luminescence (OSL) quartz ages over Middle Pleistocene timescales. Single-grain OSL studies typically reveal significant intra- and inter-sample variability in quartz dose saturation properties at the individual grain level. This enhanced variability may offer the potential to obtain extended-range chronologies exceeding the traditional upper age limits of multiple-grain OSL dating. However, there have been relatively few detailed assessments of single-grain OSL properties over high dose ranges. In this study we investigate extended-range single-grain OSL dating potential at Cuesta de la Bajada, one of the most important Ancient Middle Palaeolithic sites in the Iberian Peninsula. The quartz samples from this site exhibit exceptional dose saturation properties and contain significant populations of individual ‘supergrains’ with bright OSL signals, very high characteristic saturation dose (D0) limits of 200 to >600 Gy, and doseresponse curves that closely conform to single saturating exponential functions. Assessments of OSL signal composition and the ability to successfully recover a known laboratory dose of 470 Gy support the potential for obtaining high equivalent dose (De) values with reasonable fitting uncertainties. A series of novel sensitivity tests are used to assess potential biases in supergrain De estimation over high dose ranges related to (i) thermally transferred signal contributions, (ii) choice of dose-response curve fitting function, and (iii) insufficient dose saturation properties of individual grains. The single-grain De values obtained using the standard quality assurance criteria and novel sensitivity tests are consistent at 2s, and are in agreement with quartz Ti-centre ages obtained on two of three paired electron spin resonance (ESR) samples collected from Cuesta de la Bajada. These comparisons support the suitability of our single-grain OSL results and suggest there may be good potential for using quartz supergrains to establish extended-range chronologies at some Middle Pleistocene sites. Comparisons with other singlegrain OSL studies across the Iberian central plains suggest that favourable dose saturation properties may be influenced by regional-scale geological controls. The importance of undertaking single-grain OSL dating at Cuesta de la Bajada is also demonstrated by the results of synthetic aliquot experiments, which reveal multiple-grain age offsets of 60e170 ka when unsuitable grain types are inadvertently included in the final age calculations. The single-grain OSL results indicate that the main archaeological horizon at Cuesta de la Bajada (unit CB3) accumulated between 264 ± 22 and 293 ± 24 ka. These ages are consistent with the chronologies of other key early Middle Palaeolithic sites in the region (Ambrona AS6 and Gran Dolina TD10) and indicate that the Ancient Middle Palaeolithic techno-complex likely spread across Iberia from at least Marine Isotope Stage 9 onwards.

The Early-Middle Pleistocene transition (EMPT), also known as the “mid-Pleistocene revolution" or “mid-Pleistocene transition“ (~1.4 to ~0.4 Ma), has become a major research topic in the last few decades. Evidence recorded by numerous multidisciplinary studies indicates that changes in the Earth’s orbital cyclicity during this time period strongly impacted both the marine and terrestrial realms, as borne out by a wide range of physical and biotic proxies (see overview in Head and Gibbard, 2005). This influence has been especially pronounced in the Northern hemisphere and particularly in Europe, where the EMPT demonstrably corresponds to significant changes in mammalian evolution and dispersals, including a major faunal turnover, the arrival of the genus Homo and important techno-cultural advances (e.g. Rook and Martinez-Navarro, 2010; Abbate and Sagri, 2010; Carbonnell et al., in press).

Two major palaeomagnetic events have been identified within the EMPT, the Jaramillo Subchron and the Brunhes-Matuyama (B-M) geomagnetic reversal. The latter is perhaps among the most widely known chronological constraints in Quaternary studies, representing the boundary between Early and Middle Pleistocene subseries (0.77 Ma). In contrast, there has been relatively limited interest in the Jaramillo (1.07-0.99 Ma) since its discovery in the mid 1960's (Doell and Dalrymple, 1966). In recent years, the Jaramillo has been subject of renewed attention, as it is increasingly being identified in both continental and marine records. With a duration of about 80 ka, the Jaramillo is the longest normal subchron between the top of the Olduvai (1.78 Ma) subchron and the base of the Brunhes (0.78 Ma) chron. It is now frequently used in European continental records as a chronological marker for the second half of the Matuyama chron, particularly for faunal turnovers (e.g. Rook and Martínez-Navarro, 2010; Cuenca-Bescos et al., 2010). Additionally, it has proven to be especially useful for chronological inferences, where it can be combined with biostratigraphic evidence and numerical dating results to build correlative chronostratigraphic frameworks (e.g. Martínez et al., 2010). However, a review of the literature indicates that the number of localities where the Jaramillo is accurately identified in the European terrestrial record is currently quite limited, especially in archaeo-paleontological contexts (Parés et al., 2013). Moreover, where the Jaramillo subchron has been identified in the European terrestrial record it is commonly the case that associated geochronological data are sub-optimal or ambiguous (i.e., the dating methodologies are not fully detailed, or further studies are impossible since the site no longer exists) (Parés et al., 2013). Its significance and role, if any, in the EMPT remain relatively unclear, and it is still extremely difficult to identify significant “pre-” and “post-” Jaramillo changes in Earth system responses at the biotic and physical levels.

To address these issues, and to better understand the nature of the EMPT and its impact at the Earth’s surface, a multidisciplinary scientific meeting was organised in Burgos in September 2013. The publication of the present special volume of Quaternary International directly arose from this workshop. We are pleased to propose a dense compilation of 18 original papers covering the EMPT from a wide range of perspectives, providing an updated overview of the topic some 10 years after the seminal publication by M.J. Head and P.L. Gibbard (Head and Gibbard, 2005). This volume will hopefully contribute to an improved understanding of a critical time period that formed the backdrop to the present-day climate system.

Duval, M. and Grün, R. (2015). Are ESR dose assessments on fossil tooth enamel reliable?. Oral communication. 4th Asia Pacific Luminescence and Electron Spin Resonance Dating (APLED) Conference (Adelaide, Australia), 22-25 November 2015.

Arnold L.J. , Demuro M., Duval M., Spooner N.A., Santonja M., Perez-Gonzalez, A. (2015). OSL dating of individual quartz 'supergrains' from the Early Middle Palaeolithic site of Cuesta de la Bajada, Spain. APLED2015 conferecne, Adelaide, Australia, 22-25 Nov. 2015.

21/10/2015

New paper published in Radiation Measurements

Assessing the uncertainty on particle size and shape: implications for ESR and OSL dating of quartz and feldspar grains

Full reference

Duval, M., Campaña, I., Guilarte, V., Miguens, L., Iglesias, J., González Sierra, S., 2015. Assessing the uncertainty on particle size and shape: implications for ESR and OSL dating of quartz and feldspar grains. Radiation Measurements 81, pp.116-122. DOI: 10.1016/j.radmeas.2015.01.012.

Abstract

Grain size and shape are two important parameters in Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) dating of sediment, since they have a direct impact on several correction factors that are used for evaluating the dose rate. These parameters were evaluated by static image analysis for a wide range of quartz and feldspar grain samples. Our results indicate that there are many factors that may influence the final grain size and shape. Overall, grains are not perfect spheres, but should be rather approximated to smooth slightly elongated ellipsoids, with a width that is on average about 25% smaller than the length. For multiple grains dating, this may have an influence of a few percents on the beta dose rate evaluation, and thus even less on the total dose rate. However, in the case of single grain dating, the impact may be somewhat more significant given the large variability in size and shape between grains that may be encountered in a natural sediment. For beta micro-dosimetry purpose, it may be thus useful to better characterize the single grain that is going to be dated.

Funding

This study was partially sponsored by the project CGL2010-16821 from the Spanish Ministry of Science and Innovation. MD is currently the recipient of an International Outgoing Fellowship from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement PIOF-GA-2013-626474. IC is the beneficiary of a PhD scholarship from the Spanish MINECO (project CGL2012-38434-C03-02).

20/10/2015

New paper published in Quaternaire

La datation ESR/U-Th de restes paléontologiques, un outil pour estimer le possible remaniement des niveaux archéologiques ?

Complete reference

Bahain, J.-J., Falguères, Shao, Q., Tombret, O., Duval, M., Dolo, J.-M., 2015. La datation ESR/U-Th de restes paléontologiques, un outil pour estimer le possible remaniement des niveaux archéologiques ? Quaternaire 26(3), pp. 213-223.

Abstract

ESR/U-series dating of fossil teeth is a palaeodosimetric method commonly used for Middle and Late Pleistocene archaeological levels. Beyond the geochronological interest (it is often one of the few methods applicable on sites located in non-volcanic or carbonated areas) and despite the relatively important age uncertainties (usually 10-15 %, because of the high number of parameters – over 25 – considered in the age calculation process), ESR/U-series method can allow, in combination with the available stratigraphic and palaeoenvironmental data, the correlation of the studied archaeological levels to a specific marine isotopic (MIS), if the evolution of the dose rate with time since the sample burial is reasonably well described. However, for some sites the results display great age scatter ages that could simply not be explained by local variations of the dose rate for the studied level. It could indicate instead that the palaeontological record is made by several stocks of different ages or dosimetric histories mixed in the same archaeological level.

01/10/2015

New paper published in the Encyclopedia of Scientific Dating Methods

Complete reference

Duval., M. (2015). Electron Spin Resonance Dating of fossil tooth enamel, in Rink, W.J., Thompson, J.W. (Eds.) Encyclopedia of Scientific Dating Methods, Springer Netherlands, pp. 239-246. DOI: 10.1007/978-94-007-6304-3_71.

15/06/2015

New paper published in Radiation Measurements

Evaluating the accuracy of ESR dose determination of pseudo-Early Pleistocene fossil tooth enamel samples using dose recovery tests

The manuscript can be download here (free)

Complete reference

Duval, M. (2015). Evaluating the accuracy of ESR dose assessment of pseudo Early Pleistocene fossil tooth enamel with dose recovery tests. Radiation Measurements, 79, pp. 24-32. DOI: 10.1016/j.radmeas.2015.06.004.

Abstract

In ESR dating of Early Pleistocene fossil tooth enamel samples, the fitting function used for the evaluation of the D_E value is undoubtedly among the major sources of uncertainty. Dose recovery tests performed on fossil tooth enamel showing D_E values >1,000Gy demonstrate: (i) that high precision ESR measurements (<0.5%) and high D_E reproducibility (<5%) may be achieved; (ii) the appropriateness of the Double Saturating Exponential (DSE) fitting function for ESR dose reconstruction. In contrast, the SSE function, which has been almost exclusively used so far, does simply not correctly describe the behavior of the radiation induced ESR signal of tooth enamel with the dose.

Several fitting functions and data weighting options were tested and the combination of a DSE with data weighed by the inverse of the square intensities is the procedure providing the most accurate D_E results. However, the SSE may nevertheless sometimes produce consistent results if D_max does not exceed 6*D_E. Further work is required in that direction in order to determine more precisely in which conditions the SSE could be used as a fair approximation of the DSE function for these samples.

Funding

The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA Grant Agreement nº PIOF-GA-2013-626474.

30/05/2015

New paper published in Radiation Measurements evaluating the potential of the Ti-centers for dosimetric/dating purposes.

The manuscript can be download here.

Complete reference

Duval, M. and Guilarte, V. (2015). ESR dosimetry of optically bleached quartz grains extracted from Plio-Quaternary sediment: evaluating some key aspects of the ESR signal associated to the Ti-center. Radiation Measurements 78, pp. 28-41. DOI: 10.1016/j.radmeas.2014.10.002.

Abstract

The present study aims at investigating several key aspects of ESR dose reconstruction of quartz grains based on the analysis of the Ti-center: (i) the evaluation of the ESR intensity, (ii) its impact on measurements precision, and (iii) the potential of various fitting functions to describe the behavior of the signal with the radiation absorbed dose.

In contrast with the Al center, the various Ti centers have quite low ESR signal intensities. It is thus crucial to adapt the experimental conditions for the optimization of the signal-to-noise ratio and to perform repeated measurements in order to take into consideration the uncertainty associated to angular dependence of the signal as well as day-to-day variations. Several options (named A to E) for evaluating the ESR intensity of the TieLi and TieH centers are explored and some of them yield too much experimental uncertainty (e.g. options C and E) and are apparently not suitable for accurate ESR dosimetry. In contrast, options A and D usually provide similar equivalent dose (DE) results and can be used together for assessing the dose absorbed by the Ti-Li center.

Our results show a systematic non-monotonic behavior of the ESR signal of the Ti center with the dose, which raise some questions about the suitability of the single saturating exponential (SSE) function that is classically used in ESR dating. Consequently, we explored the potential of other functions that can describe the “radiation bleaching” phenomenon observed at high doses. We recommend the use of a specific fitting function (called Ti-2 in the present paper) previously proposed by Woda and Wagner (2007) for any dose reconstruction, and define some criteria to ensure a good fitting. The SSE function provides DE results that are, in most cases, relatively consistent with those derived from the Ti-2, suggesting that the Ti centers apparently follow a SSE behavior up to, at least, 6.0e6.5 kGy However, the reliability of the DE values obtained with the SSE seems quite dependent on the accuracy of the ESR intensities of the increasing domain of the dose response curve. We also recommend the definition of criteria to check the reliability of the DE results.

Funding

This study was partially sponsored by the projects CGL2010-16821 and CEN001B10-2 from the Spanish Ministry of Science and Innovation and the Junta de Castilla y León, respectively. Data evaluation and manuscript redaction were mainly carried out during MD's 3 month stay at the Research School of Earth Sciences, the Australian National University, which was funded by a Jos.e Castillejo Mobility Fellowship CAS12/00251 from the Spanish Ministry for Education, Culture and Sport. MD is currently the recipient of an International Outgoing Fellowship from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement n. PIOF-GA-2013-626474.

15/05/2015

New paper in Historical Biology about the major issues when using rodents as a chronometric dating tool.

The manuscript can be download here.

Complete reference

Palmqvist, P., Duval, M., Diéguez, A., Ros-Montoya, S., Espigares, M. P., 2015. On the fallacy of using orthogenetic models of rectilinear change in arvicolid teeth for estimating the age of the first human settlements in Western Europe. Historical Biology. DOI: 10.1080/08912963.2015.1025390.

Abstract

Lozano-Fernández et al. (Lozano-Fernández I, Blain HA, López-García JM, Agustí J. 2014. Biochronology of the first hominid remains in Europe using the vole Mimomys savini: Fuente Nueva 3 and Barranco León D, Guadix-Baza Basin, south-eastern Spain. Hist Biol: Int J Paleobiol. doi:10.1080/08912963.2014.920015) recently published age estimates for two Late Villafranchian sites of Orce (Guadix-Baza basin, SE Spain), BL-D and FN-3, which provide some of the earliest evidence of human presence in Western Europe. The estimates were obtained from mean Lm1 values of the water vole Mimomys savini preserved in the sites and a couple of rectilinear equations derived in the Atapuerca TD section for site age on tooth length. However, this chronometric tool has problems that discourage its use in biostratigraphy, including: (1) the assumption of an orthogenetic trend of Lm1 increase during the evolution of the M. savini/Arvicola lineage; (2) the use of a chronology for the TD section not supported by original ESR data; (3) the discrepancies between the mean Lm1 values published for the TD levels and (4) the chronological ranges predicted when the standard deviations are used, which are exceedingly large as to be of value for biostratigraphic purposes. As a result, the pseudo numerical ages estimated for the Orce sites only add noise to the timing of the first human dispersal in Europe, which is based on a combination of results from well-established techniques such as palaeomagnetism, biostratigraphy and ESR.

15/03/2015

New paper in Quaternary International comparing the micromammal associations from Atapuerca Gran Dolina and Sima del Elefante (Spain).

The manuscript can be download here.

Complete reference

Cuenca-Bescós, G., Blain, H.-A., Rofes, J., Lozano-Fernández, I., López-García, J.M., Duval, M., Galán, J., Núñez-Lahuerta, C. (2015). Comparing two different Early Pleistocene microfaunal sequences from the caves of Atapuerca, Sima del Elefante and Gran Dolina (Spain): biochronological implications and significance of the Jaramillo subchron. Quaternary International. DOI: 10.1016/j.quaint.2014.12.059.

Abstract

No ideal method can be used alone to provide an accurate and irrefutable chronology for dating European Early Pleistocene localities. The solution lies in the combination of different, but complementary, approaches for complementing their chronological framework. In that regard, the results of the present study show that biochronology may be a useful additional tool to further refine the chronology of these localities, by providing not only relative chronological information between the sites, but also giving some important indications about a younger or older Jaramillo age.

Our study presents the revised faunal list of each Early Pleistocene levels from the localities of Gran Dolina (TD) and Sima del Elefante (TE), in Atapuerca. Both localities have very likely the richest associations of small mammal species in the Quaternary of Europe. Perhaps the most striking observation is the lack of similarities between the assemblages from each site, which can only be explained by a chronological gap between them. Although the Jaramillo subchron has not been directly identified at Atapuerca, the existing chronostratigraphical framework combined with similarities of the faunal assemblages between Gran Dolina and Vallparadís indicate with some confidence that Sima del Elefante levels are older than the Jaramillo subchron. Consequently, the Early Pleistocene levels of both Atapuerca sites TE and TD are the only sequence from Spain that allows the study of a continuous stratigraphic succession of the interval around the Jaramillo subchron in terrestrial sequences. The biostratigraphy of the Early Pleistocene from Europe, based mainly in the few isolated localities of the Olduvai-Jaramillo time interval, is reinforced by the faunal succession of the Atapuerca sites.

15/01/2015

New paper in Radiation Measurements available online assessing the uncertainty on particle size and shape and its impact on ESR and OSL dating results.

The manuscript can be download here.

Complete reference

Duval, M., Campaña, I., Guilarte, V., Miguens, L., Iglesias, J., González Sierra, S., 2015. Assessing the uncertainty on particle size and shape: implications for ESR and OSL dating of quartz and feldspar grains. Radiation Measurements. DOI: 10.1016/j.radmeas.2015.01.012.

Abstract

Grain size and shape are two important parameters in Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) dating of sediment, since they have a direct impact on several correction factors that are used for evaluating the dose rate. These parameters were evaluated by static image analysis for a wide range of quartz and feldspar grain samples. Our results indicate that there are many factors that may influence the final grain size and shape. Overall, grains are not perfect spheres, but should be rather approximated to smooth slightly elongated ellipsoids, with a width that is on average about 25% smaller than the length. For multiple grains dating, this may have an influence of a few percents on the beta dose rate evaluation, and thus even less on the total dose rate. However, in the case of single grain dating, the impact may be somewhat more significant given the large variability in size and shape between grains that may be encountered in a natural sediment. For beta micro-dosimetry purpose, it may be thus useful to better characterize the single grain that is going to be dated.

Funding

This study was partially sponsored by a project from the Spanish Ministry of Science and Innovation (Grant number: CGL2010-16821). MD is currently the recipient of an International Outgoing Fellowship from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement PIOF-GA-2013-626474. IC is the beneficiary of a PhD scholarship from the Spanish MINECO (project CGL2012-38434-C03-02).

1-3/12/2014

AAA/ASHA 2014 Conference (Cairns, Australia)

Duval, M. (2014). On the interest of using Electron Spin Resonance (ESR) dating method in archaeological context: some examples from the oldest hominin occupations in South-western Europe. Poster. AAA/ASHA 2014 Conference (Cairns, Australia).

25/11/2014

New paper published in Quaternary International revisiting the ESR chronology of the Early Pleistocene hominin occupation at Vallparadís (Barcelona, Spain).

The manuscript can be download here.

Complete reference

Duval, M. and Guilarte, V. (2014). ESR dosimetry of optically bleached quartz grains extracted from Plio-Quaternary sediment: evaluating some key aspects of the ESR signal associated to the Ti-center. Radiation Measurements. DOI: 10.1016/j.radmeas.2014.10.002.

Abstract

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).

Funding

This study was partially sponsored by the project CGL2010-16821 from the Spanish Ministry of Science and Innovation. The Ile-de-France Region Council provided a financial contribution to purchase the ESR spectrometer for the Department of Prehistory, National Museum of Natural History, Paris. LA-ICP-MS U-series

analysis were performed at RSES by MD during a research stay funded by a Jos.e Castillejo Mobility Fellowship CAS12/00251 from the Spanish Ministry for Education, Culture and Sport.

09/10/2014

New paper published in PLOSONE about the Hominid remains from the Middle Plesitocene site at Tourville-la-Rivière.

The manuscript can be download here.

Complete reference

Faivre, J.-Ph., Maureille, B., Bayle, P., Crevecoeur, I., Duval, M., Grün, R., Bemilli C., Bonilauri S., Coutard S., Bessou M., Cottard A., Deshayes Th., Douillard A., Henaff X., Pautret-Homerville C., Trinkaus E. (2014). The Middle Pleistocene site of Tourville-la-Rivière (Normandy, France): Human Settlement and Human Remains from Northwestern Europe. PlosOne, 9 (10), e104111, p. 1-13.

Funding

The ESR dating study has been carried through a collaboration involving Rainer Grün, Les Kinsley (ANU) and Mathieu Duval (CENIEH). The ESR study was sponsored by the project CGL2010-16821 from the Spanish Ministry of Science and Innovation.

02/10/2014

Marie Curie fellow (International Outgoing Fellowship). 2 year project

Outgoing host (Year 1):

Research School of Earth Sciences, The Australian National University, Canberra, Australia.

Return host (Year 2):

Centro Nacional de Investigación sobre la Evolución Humana (CENIEH).

Project title:

Developing High Resolution Electron Spin Resonance (ESR) dating of fossil teeth: contribution to the chronology of early hominid occupations in the Mediterranean area

Abstract:

Electron Spin Resonance (ESR) is the only chronometric method that can be applied to date Early Pleistocene fossil teeth from early hominid occupations in the Mediterranean area. Recent investigations focused on these old samples have highlighted the limitations of the standard procedures, as well as the complexity of the post depositional alteration processes in dental tissues at micro-scale. To overcome these issues, the present project proposes a cutting edge investigation that can only be performed as a joint project between RSES and CENIEH, since these institutions offer complementary facilities and experienced staff. Basically, this work aims at: (i) Investigating the physical and chemical processes that are affecting dental tissues at micro scale and evaluating their impact on the ESR age results, (ii) developing a high resolution combined US-ESR dating approach for fossil teeth.

From a methodological perspective, the project is expected to improve the reliability of the ESR method by contributing to the understanding of why for a given site, some samples yield seemingly reliable results while others do not. This will lead to the identification of some objective criteria to evaluate the suitability of tooth samples for ESR dating.

On the geochronological side, this project will expose new perspectives for the ESR method. This new high resolution approach will improve the accuracy of the age estimates, since several ages per sample will be produced once suitable dental domains have been identified. This project will provide new ESR dating results for some of the oldest archaeological sites in the Mediterranean basin, thus contributing to improve our knowledge of the first hominid settlements in this area.