El Salt Research Articles

The Time of the Stones: A Call for Palimpsest Dissection to Explore Lithic Record Formation Processes

The dissection of archaeological palimpsests has become a crucial process for achieving a diachronic understanding of the history of human groups. However, its widespread application to archaeological deposits has been hampered by both methodological and theoretical limitations, as well as by the inherent characteristics of the deposits. This paper explores whether overcoming these barriers, both methodological and theoretical, truly represents a significant shift in understanding past human behaviour, thereby motivating the pursuit of shorter timescales. To this end, we have analysed the lithic assemblages of Unit Xb from the Neanderthal site of El Salt (Alcoi, Iberian Peninsula) focusing on lithic attributes and raw material analyses, enabling the definition of raw material units and refitting sets. Considering these variables, we have applied archaeostratigraphic and spatial analyses in order to generate units of analysis whose content is compared to that of the entire unit. The defined archaeostratigraphic units display different spatial distributions and lithic composition. Some of them are attached to certain hearths and composed of refitted sets, while other units are related to areas without combustion evidence and integrated with bigger and heavier single products. Through this approach, here, we show that reducing the spatiotemporal scale of the record helps to unravel behavioural variability, reducing interpretative errors implicit in the assemblage-as-a-whole approach. This highlights the role of temporal resolution in reconstructing site formation processes and challenges research perspectives that assert the unnecessary or impossible nature of palimpsest dissection.

The time between Palaeolithic hearths.

Resolving the timescale of human activity in the Palaeolithic Age is one of the most challenging problems in prehistoric archaeology. The duration and frequency of hunter-gatherer camps reflect key aspects of social life and human-environment interactions. However, the time dimension of Palaeolithic contexts is generally inaccurately reconstructed because of the limitations of dating techniques1, the impact of disturbing agents on sedimentary deposits2 and the palimpsest effect3,4. Here we report high-resolution time differences between six Middle Palaeolithic hearths from El Salt Unit X (Spain) obtained through archaeomagnetic and archaeostratigraphic analyses. The set of hearths covers at least around 200-240 years with 99% probability, having decade- and century-long intervals between the different hearths. Our results provide a quantitative estimate of the time framework for the human occupation events included in the studied sequence. This is a step forward in Palaeolithic archaeology, a discipline in which human behaviour is usually approached from a temporal scale typical of geological processes, whereas significant change may happen at the smaller scales of human generations. Here we reach a timescale close to a human lifespan.

Recycling and Implications for Neanderthal Productive Strategies in the Stratigraphic Unit viii of the El Salt Rockshelter (Alcoi, Eastern Iberia)

ABSTRACT Recycling was an activity carried out by ancient hunter-gatherer populations. It has been demonstrated by many studies on this matter. However, there are main issues in relation to it that are still under debate: what we call recycling, how we identify it, and what implications it has for the technoeconomic dynamics of these groups. In order to contribute to this topic, we present here the Neandertal flint materials from the stratigraphic unit viii of the El Salt rockshelter (Alcoi, Alacant, eastern Iberia). We have selected a series of artifacts exhibiting time-dependent postgenetic alterations (i.e. white patinas and thermal alteration) that affect previous technical intervention and, additionally, display subsequent anthropogenic actions that reveal an intermediate stage between the initial and the second use. The data obtained point to a principal relationship of recycling with mobility dynamics, and entail implications for Neandertal lithic technology and provisioning.

Magnetic micro-archaeology: a method for conducting rock magnetic microfacies analysis on archaeological soil micromorphology samples, with a case study from El Salt, Alcoy, Spain

For geoarchaeologists the use of multiproxy and multimethod integrative approaches has become common for studying the sedimentary context of archaeological materials. In this paper, we introduce a novel approach that combines rock magnetic analysis with micromorphological analysis. We first conduct a brief examination of the magnetic properties of organic resins used in micromorphology to understand the potential impact of the resin and manufacturing process on the magnetic signature. It is crucial to understand the original production of the samples to ensure that endothermic reactions do not compromise the magnetic data. We illustrate the advantages of this approach through a case study of a pit hearth from the Neanderthal archaeological site of El Salt in Alcoi, Spain. This study utilises archived micromorphological samples of a pit hearth (combustion structure H77) initially described by Leierer et al. (J Archaeol Sci 123:105237, 2020). Rock magnetic analysis of multiple magnetic parameters—including magnetic susceptibility, natural remanent magnetization, and progressive isothermal remanent magnetization—reveals that each microfacies type exhibits a unique magnetic pattern, even if there is overlapping in signatures across some magnetic parameters. The interpretation of the magnetic data aligns with the results and microfacies descriptions previously provided by Leierer et al. (J Archaeol Sci 123:105237, 2020), further supporting the interpretation of the combustion feature as being in situ with a history of repeated use. The approach presented here offers an enhanced tool for micromorphologists to better understand the magnetic characteristics of microfacies units in higher resolution and establish direct connections to the micromorphological results.

Use-wear analysis applied in a dissected palimpsest at the Middle Palaeolithic site of El Salt (eastern Iberia): working with lithic tools in a narrow timescale

Use-wear analyses are very useful to increase knowledge about the economic and subsistence dynamics carried out by Neanderthals. In general terms, functional results traditionally came from the analysis of tools belonging to stratigraphic units whose timescale refers to geological time. This is due to the fact that many Neanderthal sites are palimpsests of reiterated occupations over time, which must be dissected to approach us to human timescale. In the stratigraphic unit xa of El Salt (Alcoi, eastern Iberia), high temporal resolution archaeostratigraphic studies have been carried out. Diachronic material assemblages have been identified, allowing us to analyse more precisely the variability of Neanderthal behaviour over time. Amongst these assemblages, three have been selected (i.e. 5.3.1, 5.3.2 and 5.3.3) in order to analyse the lithic material functionality. The results obtained bring out the performance of different tasks within each analytical framework: woodworking in 5.3.1, woodworking and animal processing in 5.3.2, and butchering activity in 5.3.3. These results reflect the existence of a series of diachronic tasks carried out in overlapping activity areas. In this way, this work evidences flint use variability in a specific area of the site across time that could have been recognised only by means of high temporal resolution analytical frameworks.

An instance of Neanderthal mobility dynamics: a lithological approach to the flint assemblage from stratigraphic unit viii of El Salt rockshelter (Alcoi, eastern Iberia)

The relationship between hunter-gatherer group mobility and lithic raw material procurement strategies is central to the study of Neanderthal productive behaviours. In this framework, determination of flint procurement sources through lithological analysis is key to infer Neanderthal group mobility patterns. El Salt rockshelter (Alcoi, Alacant, eastern Iberia) features different nearby flint sources, including primary outcrops and secondary deposits containing flint. In this study, we sourced the stratigraphic unit viii archaeological flint assemblage based on identification of geogenic and postgenetic lithological traits. Our results indicate that flint procurement at El Salt during the stratigraphic unit viii Neanderthal occupations was mainly linked to Pleistocene secondary deposits along the upper and middle courses of Serpis river. The artefacts were made predominantly on alluvially reworked nodules of different flint types. Connecting these procurement areas with their corresponding knapping products reveals a direct relationship between flint-source distance and degree of technical intervention, and defines a hypothetically unidirectional series of rivershore itineraries of procurement.

Applying the UDA-ODA discrimination technique to a herpetological association: the case of the Middle Palaeolithic site of El Salt (Alcoi, Spain)

El Salt (Middle Palaeolithic; Alcoi, Spain) is a key site for understanding the disappearance of Neanderthals in the eastern Iberian Peninsula, a process that is observed along its stratigraphic sequence. To improve our understanding of the palaeoclimatic context in which this process took place, we applied the UDA-ODA discrimination technique to the fossil herpetological assemblages from Stratigraphic Units (SU) Xb (52.3 ± 4.6 ka) and V (45.2 ± 3.4/44.7 ± 3.4 ka). This method is based in the application of an ecological criterion, the maximum altitude of each species on each Iberian range, to discern and remove those areas that do not meet their ecological requirements (UDA) from those that do (ODA), which are included in its distribution from Atlases from which the common distribution species is going to be extracted. Results indicate the existence of an alternation between “cold and wet” moments with “warm and dry” ones, all of them in a more humid context than nowadays. Climate was slightly warmer than nowadays in SU Xb, whereas was cooler in SU V. Regarding MAP, our results show less variation between SUs than it has been provided by previous studies. These results do not fully agree with those provided by small mammals from the same SUs, which indicate an increase of the temperatures whereas rainfall experienced the contrary. These differences could be related with the wider distribution of the Iberian herpetofauna, and some differences in the applied ecological criterion. Furthermore, herpetofaunal palaeoclimatic reconstruction shows that the abandonment of the site by Neanderthals seems to have occurred during an arid phase.

Contribution of small mammal taphonomy to the last Neanderthal occupations at the El Salt site (Alcoi, southeastern Spain)

AbstractThe El Salt site (Alcoi, Alicante, Spain) is one of the latest Neanderthal sites in the south-eastern Iberian Peninsula. The disappearance of this human group is controversial and needs detailed studies from different research areas. Taphonomy is essential to establish how representative is a fossil assemblage of the past living organisms that produced it and to interpret the formation process of the fossil site. In the case of El Salt, we have analyzed the micromammal assemblages of Units X and V, which contain fossils of Neanderthals and/or evidence of their activity. In contrast with previous identifications of the little owl (Athene noctua), our detailed taphonomic study shown here allows us to conclude that the main predator involved in the production of the micromammal assemblages was the European eagle owl (Bubo bubo). This is an opportunistic predator whose feeding preferences and behavior reflect the abundance of local micromammalian species, which can therefore provide a representation of past ecosystems near El Salt. The taphonomic information provided by this study also indicates the absence of transport and reworking processes, and reinforces previous paleoecological interpretations, suggesting an increase of aridity at the top of El Salt sequence that coincided with the local disappearance of Neanderthals.

Amphibians and reptiles as palaeonvironmental proxies during the Late Pleistocene (MIS3): The case of Stratigraphic Unit V of El Salt, Alcoi, Spain

The locality of El Salt (Alcoi, Spain) is a key site for understanding the extirpation of Neanderthals in the eastern part of Iberia. In this paper, we analyse an assemblage of amphibians and reptiles from Stratigraphic Unit V (45.2 ± 3.4 ka to 44.7 ± 3.4 ka), which corresponds to one of the last regional records of Neanderthals, to improve knowledge of the palaeoecology and palaeoclimate of this event. The assemblage comprises three anurans (Pelodytes sp., Alytes obstetricans, and Epidalea calamita), two lizards (Lacertidae indet. and Chalcides bedriagai), and five snakes (Colubridae indet., Coronella sp., Coronella sp./Zamenis sp., Natrix maura, and Vipera latastei). Palaeoclimatic reconstruction, based on the Mutual Ecogeographic Range method, indicates that climate was cooler and slightly wetter climate than the present day climate of the Alcoi area. Applying the Habitat Weighting Method, we infer that the area surrounding El Salt was dominated by open dry regions, alternating with rocky areas with scarce scrubs and forest patches that would have developed under mesomediterranean conditions. These results are not entirely consistent with those obtained with other proxies (charcoal and small mammal assemblages) from the same site, which suggest slightly warmer and drier conditions. We hypothesise that these divergences may be partly related to the current wide distribution of reptiles and amphibians across Iberia. A key finding is that the extirpation of the Neanderthals in Iberia coincided with aridification.

Small vertebrates from a Holocene gravelly deposit at El Salt (Alcoi, Alicante)

The small-vertebrates’ assemblage recovered comes from Units I to IV from El Salt site (Alcoi, Spain). The sample is composed by nearly 310 remains, and includes one toad (Epidalea calamita), two lizards (Lacertidae indet. and Chalcides cf. bedriagai), two snakes (Coronella cf. girondica and cf. Coronella sp.), two insectivores (Crocidura sp. and Sorex sp.), one lagomorph (Oryctolagus cuniculus) and seven rodent taxa (Arvicola sapidus, Microtus sp., M. arvalis, M. cabrerae, M. duodecimcostatus, Apodemus sylvaticus, and Eliomys quercinus). All the species described in the present work are consistent with a Late Pleistocene-Holocene chronology. The presence of M. cabrerae (absent in the Middle Pleistocene) and M. duodecimcostatus (absent in the Mediterranean until the Late Pleistocene) seem to confirm this age. The presence of Neolithic pottery and M. arvalis in the same deposit is inconsistent from a biochronically point of view since this species was extirpated from this region at the end of the Late Pleistocene. Several taphonomic alterations related to transport within the small mammal remains have been identified. Further taphonomical and geoarchaeological work is needed to clarify the provenience of the studied faunal assemblages, which, given the high energy, erosional morphology and lithology of the sedimentary deposit, could have been reworked in a more recent time period.

Components of a Neanderthal gut microbiome recovered from fecal sediments from El Salt

A comprehensive view of our evolutionary history cannot ignore the ancestral features of our gut microbiota. To provide some glimpse into the past, we searched for human gut microbiome components in ancient DNA from 14 archeological sediments spanning four stratigraphic units of El Salt Middle Paleolithic site (Spain), including layers of unit X, which has yielded well-preserved Neanderthal occupation deposits dating around 50 kya. According to our findings, bacterial genera belonging to families known to be part of the modern human gut microbiome are abundantly represented only across unit X samples, showing that well-known beneficial gut commensals, such as Blautia, Dorea, Roseburia, Ruminococcus, Faecalibacterium and Bifidobacterium already populated the intestinal microbiome of Homo since as far back as the last common ancestor between humans and Neanderthals.

Erratum to “Palaeoecological context for the extinction of the Neanderthals: A small mammal study of Stratigraphic Unit V of the El Salt site, Alcoi, eastern Spain” [Palaeogeography, Palaeoclimatology, Palaeoecology 530 (2019) 163–175

Abstract El Salt is an important reference site for understanding the extinction of Neanderthal populations in the eastern Iberian Peninsula during MIS 3. In this paper, we describe the small mammal assemblage from Stratigraphic Unit V, the youngest unit with evidence of human presence, based on nearly 1300 specimens. A total of seven rodents (Microtus arvalis, Microtus duodecimcostatus, Microtus cabrerae, Sciurus vulgaris, Arvicola sapidus, Eliomys quercinus and Apodemus sylvaticus), three insectivores (Talpa occidentalis, Crocidura sp., Sorex sp.) and one lagomorph (Oryctolagus cf. cuniculus) were identified. Palaeocological analyses point to drier conditions in this part of the stratigraphic sequence, supporting the hypothesis that an aridification scenario may have played a role in the extinction of the Neanderthal groups inhabiting this region of the Iberian Peninsula.

High-resolution Neanderthal settlements in mediterranean Iberian Peninsula: A matter of altitude?

Neanderthals are widely known to be a resilient human species that successfully faced constant and strong environmental fluctuations modifying the landscapes they inhabited and the availability of their potential resources. It has been traditionally assumed that environmental features could strongly affect human behaviour due to the stretch relationship between their potential prey and the availability of habitats. Environmental changes would produce a high variability in the settlement patterns of the Neanderthal groups. However, the preponderant influence of environmental conditions on these human groups has recently been strongly questioned. This is especially true for the Iberian Peninsula, where latitudinal position and orographic features supported the persistence of environmental conditions that allowed the permanence of a wide range of biotopes and animal and vegetal resources. In the present study, we reconstruct the Neanderthal settlement patterns (i.e. duration and season) from four archaeological sites located in the Mediterranean area of the Iberian Peninsula: Arbreda Cave (Serinyà, Girona), Teixoneres Cave (Moià, Barcelona), Abric Romaní (Capellades, Barcelona), and El Salt (Alcoy, Alicante). We focus on identifying whether they show a high variability in settlement patterns and check for the existence of local influences, such as the altitude. To reach these objectives, we designed a multi-proxy approach combining tooth wear and dental cementum analysis of the main Neanderthal preys: Cervus elaphus, Equus ferus, Equus hydruntinus, Bos primigenius and Capra pyrenaica. Our results first suggest that local features (i.e. orography, altitude, and environment) appear to be predominant factors determining the main feeding behaviour of the ungulates hunted by Neanderthals. Additionally, seasonal environmental variations seem to have influenced horse migratory behaviour, involving altitudinal movements in search of high-nutritive pastures. Neanderthal survival strategies and settlement patterns seem to have been less affected by environmental particularities and more linked to selective prey procurement based on the seasonal resource availability. Therefore, the duration and seasonality of their settlement patterns and their mobility throughout the landscape indicate they had a high level of knowledge on the territory they inhabited, as well as on the behaviour and availability of their potential preys.

It's getting hot in here – Microcontextual study of a potential pit hearth at the Middle Paleolithic site of El Salt, Spain

By studying combustion structures, which conceal information about anthropogenic activity, we might learn about their makers. This is especially important for remote time periods like the Middle Paleolithic, whose archaeological record comprises numerous combustion structures. The majority of these are simple, flat, open hearths, although a small number of features situated in pit-like depressions have been recorded. Given that hearths built on a flat surface can result in pit-like color alteration of the underlying sediment, accurate identification of pit hearths is a crucial step prior to behavioral interpretation. Here we present a comprehensive study of a possible pit hearth from the Middle Paleolithic site of El Salt, Spain, using a microcontextual approach combining micromorphology, lipid biomarker analysis, archaeomagnetism and zooarchaeology. This pit hearth involves a true depression containing a thick plant ash deposit. It reached very high temperatures, possibly multiple burning events and long combustion times. Morphologically distinct combustion structures in a single archaeological context may indicate different functions and thus a diverse fire technology, pointing to Neanderthal behavioral variability.

Amphibians and squamate reptiles from the stratigraphic unit Xb of El Salt (Middle Palaeolithic; Alcoy, Spain): palaeoenvironmental and palaeoclimatic implications

The locality of El Salt (Middle Paleolithic, Alcoy, Spain) is mainly known by having one of the youngest Neanderthals records of the southeastern Iberian Peninsula. In this work, we have analysed the herpetofaunal fossils from the upper part of stratigraphic unit Xb, dated at 52.3 ± 4.6 ka (MIS 3). The faunal list is composed by three taxa of anurans (Alyte obstetricans, Bufo bufo s.l., and Epidalea calamita), one taxon of blanid (Blanus cinereus s.l.), two taxa of lizards (Chalcides bedriagai and cf. Acanthodactylus erythrurus), and one taxon of snakes (cf. Rhinechis scalaris). All of them have a broad distribution range in the Mediterranean, with wide ecological preferences range. This association of amphibians and reptiles from the Unit Xb suggests a slightly warmer and more humid climate than the current one; with an annual temperature range less accused and a similar seasonality of the rainfall than it is recorded nowadays in Alcoy. These results may correspond to a warm period (Daansgard-Oeschger event) during the MIS 3. A landscape composed by bushland and forest patched in which some open areas were present, with presence of permanent water bodies in the nearby areas, would characterize the surroundings areas of El Salt.

On identifying Palaeolithic single occupation episodes: archaeostratigraphic and technological approaches to the Neanderthal lithic record of stratigraphic unit xa of El Salt (Alcoi, eastern Iberia)

Within the framework of archaeological palimpsest dissection, stratigraphic association of lithic remains with hearths and other archaeological materials in undisturbed Neanderthal contexts allows us to seek patterns in lithic and faunal assemblage composition, assess the degree of time averaging within assemblages and investigate the spatial distribution of archaeological remains. So far, the European Neanderthal record shows variability in such spatial parameters, not only among different geographic regions but also across time. This approach has been employed to draw conclusions about the main features of Neanderthal occupations from in situ archaeological contexts within individual site sequences. As contribution to this topic, we present new results from our ongoing archaeostratigraphic investigation of stratigraphic unit xa from El Salt (Alcoi, Alacant, eastern Iberia). Our previous study, based on stratigraphic analysis of the lithic record consisting of raw material units, yielded several micropalimpsests within unit xa. Here, we carry out further technological and spatial analysis of the micropalimpsest units. The results obtained from it suggest that we may be able, in specific cases, to recognise indicators of diachrony within the context of these archaeostratigraphic units. This confirms the existence of a micropalimpsest, and suggests that we have the chance to find analytical frames that are even closer to the human temporal scale than the AU. This should be the target of future interdisciplinary behavioural study of El Salt unit xa. This work illustrates the potential of a spatial and archaeostratigraphic approach to stone tool technology and brings to light the importance of archaeological palimpsest dissection as a first step for behavioural analysis in Palaeolithic research.

Development of a QuEChERS-based method combined with gas chromatography-mass spectrometry for the analysis of alkanes in sediments

We present a new method based on the QuEChERS protocol (Quick, Easy, Cheap, Effective, Rugged, and Safe) for the determination of 29 n-alkanes (C12-C40) and two isoprenoid acyclic hydrocarbons (pristane and phytane) in sediments using gas chromatography-mass spectrometry for their separation and determination. Different factors affecting the extraction efficiency of these lipid biomarkers (such as type of extraction solvent, water addition proportion and timing, agitation mode, and type and amount of clean-up sorbent) were optimized by means of a step-by-step approach. The methodology was validated in terms of matrix-matched calibration, detection and quantification limits, and recovery using 5-α-androstane as internal standard. Calibration curve determination coefficients were higher than 0.9902 while relative recovery values varied in the range 60–117% for alkanes C20-C40, C14, C16, and C18 and 34–69% for C12, C13, C15, C17, C19, pristane, and phytane, with relative standard deviation values below 20%. The method's quantification limits ranged between 2.2 and 37.9 ng/g. Finally, five sediment samples from the Neanderthal site of El Salt (Alicante, Spain) were analyzed using the new method, yielding alkanes C22 to C34 with odd to even predominance and C16 to C33. This paper represents the first application of QuEChERS for the extraction of alkanes and the analysis of archaeological or geochemical samples

Predictive Middle Palaeolithic climatic conditions from Eastern Iberia: a methodological approach based on charcoal analysis and modelling

Ecological and climate modelling is increasingly common in archaeological science as it is a useful tool to analyse human behaviour and ecological variables that influenced the conformation of landscapes. Predictive vegetation models, mainly based on palynological data, provide meaningful information about the theoretical distribution of plant formations in the past by creating different hypothetical scenarios. However, factors linked to variability in pollen productivity according to taxa and to the regional scale offered by this proxy in palaeoenvironmental reconstructions have led some authors to propose the use of macrobotanical data in order to detect a higher number of ecological nuances on a local scale. In this paper, we present the results of a study aimed at characterising the theoretical distribution of simulated Middle Palaeolithic biogeographic and climatic values in the local area of the Upper Serpis Valley, Eastern Iberia. Our predictive model is based on the anthracological data from two local sites, Abric del Pastor (MIS 4) and El Salt (MIS 3), and the climatic data from a total of 33 current weather stations located in the study area and adjacent distances. The data suggest that the Serpis Valley was a dynamic geographic area where there may have been different biogeographical and climatic conditions, not perceptible only through charcoal analysis. These nuances may represent the presence of several biotopes in the surroundings of these two sites, where plant taxa with different temperature and humidity requirements could have grown.

Components of a Neanderthal Gut Microbiome Recovered from Fecal Sediments from El Salt

A comprehensive view of our evolutionary history cannot ignore the ancestral features of our gut microbiota. To provide some glimpse into the past, we searched for human gut microbiome components in ancient DNA from 14 archeological sediments spanning four stratigraphic units of El Salt Middle Paleolithic site (Spain), including layers of unit X, which has yielded well-preserved Neanderthal occupation deposits dating around 50 kya. According to our findings, bacterial species belonging to families known to be part of the modern human gut microbiome are abundantly represented across unit X samples, showing that well-known probiotic gut components such as Blautia, Dorea, Roseburia, Ruminococcus, Faecalibacterium and Bifidobacterium already populated the intestinal microbiome of Homo since as far back as the last common ancestor between humans and Neanderthals.

A Granularity-Based Intelligent Tutoring System for Zooarchaeology

This paper presents a tutoring system which uses three different granularities for helping students to classify animals from bone fragments in zooarchaeology. The 3406 bone remains, which have 64 attributes, were obtained from the excavation of the Middle Palaeolithic site of El Salt (Alicante, Spain). The coarse granularity performs a five-class prediction, the medium a twelve-class prediction, and the fine a fifteen-class prediction. In the coarse granularity, the results show that the first 10 most relevant attributes for classification are width, bone, thickness, length, bone fragment, anatomical group, long bone circumference, X, Y, and Z. Based on those results, a user-friendly interface of the tutor has been built in order to train archaeology students to classify new remains using the coarse granularity. A pilot has been performed in the 2019 excavation season in Abric del Pastor (Alicante, Spain), where the automatic tutoring system was used by students to classify 51 new remains. The pilot experience demonstrated the usefulness of the tutoring system both for students when facing their first classification activities and also for seniors since the tutoring system gives them valuable clues for helping in difficult classification problems.