Jesús Francisco Jordá Pardo

The timing and spatiotemporal patterning of Neanderthal disappearance

The timing of Neanderthal disappearance and the extent to which they overlapped with the earliest incoming anatomically modern humans (AMHs) in Eurasia are key questions in palaeoanthropology. Determining the spatiotemporal relationship between the two populations is crucial if we are to understand the processes, timing and reasons leading to the disappearance of Neanderthals and the likelihood of cultural and genetic exchange. Serious technical challenges, however, have hindered reliable dating of the period, as the radiocarbon method reaches its limit at ∼50,000 years ago. Here we apply improved accelerator mass spectrometry 14C techniques to construct robust chronologies from 40 key Mousterian and Neanderthal archaeological sites, ranging from Russia to Spain. Bayesian age modelling was used to generate probability distribution functions to determine the latest appearance date. We show that the Mousterian ended by 41,030–39,260 calibrated years bp (at 95.4% probability) across Europe. We also demonstrate that succeeding ‘transitional’ archaeological industries, one of which has been linked with Neanderthals (Châtelperronian), end at a similar time. Our data indicate that the disappearance of Neanderthals occurred at different times in different regions. Comparing the data with results obtained from the earliest dated AMH sites in Europe, associated with the Uluzzian technocomplex, allows us to quantify the temporal overlap between the two human groups. The results reveal a significant overlap of 2,600–5,400 years (at 95.4% probability). This has important implications for models seeking to explain the cultural, technological and biological elements involved in the replacement of Neanderthals by AMHs. A mosaic of populations in Europe during the Middle to Upper Palaeolithic transition suggests that there was ample time for the transmission of cultural and symbolic behaviours, as well as possible genetic exchanges, between the two groups.

Radiocarbon dating casts doubt on the late chronology of the Middle to Upper Palaeolithic transition in southern Iberia

It is commonly accepted that some of the latest dates for Neanderthal fossils and Mousterian industries are found south of the Ebro valley in Iberia at ca. 36 ka calBP (calibrated radiocarbon date ranges). In contrast, to the north of the valley the Mousterian disappears shortly before the Proto-Aurignacian appears at ca. 42 ka calBP. The latter is most likely produced by anatomically modern humans. However, two-thirds of dates from the south are radiocarbon dates, a technique that is particularly sensitive to carbon contaminants of a younger age that can be difficult to remove using routine pretreatment protocols. We have attempted to test the reliability of chronologies of 11 southern Iberian Middle and early Upper Paleolithic sites. Only two, Jarama VI and Zafarraya, were found to contain material that could be reliably dated. In both sites, Middle Paleolithic contexts were previously dated by radiocarbon to less than 42 ka calBP. Using ultrafiltration to purify faunal bone collagen before radiocarbon dating, we obtain ages at least 10 ka 14C years older, close to or beyond the limit of the radiocarbon method for the Mousterian at Jarama VI and Neanderthal fossils at Zafarraya. Unless rigorous pretreatment protocols have been used, radiocarbon dates should be assumed to be inaccurate until proven otherwise in this region. Evidence for the late survival of Neanderthals in southern Iberia is limited to one possible site, Cueva Antón, and alternative models of human occupation of the region should be considered.

The far south: the Pleistocene–Holocene transition in Nerja Cave (Andalucı́a, Spain)

Abstract The archaeological site of Cueva de Nerja (Malaga, Spain) provides significant data about the bioclimatic conditions of one of the most southern European temperate regions. The bioclimatic and palaeogeographic changes that have occurred during the 20,000 years of human occupation of the site can be analysed by relating the geodynamic processes, the palaeobotany and the palaeofauna recovered from its archaeological deposits.

Bayesian chronological analyses consistent with synchronous age of 12,835-12,735 Cal B.P. for Younger Dryas boundary on four continents.

Significance A cosmic impact event at ∼12,800 Cal B.P. formed the Younger Dryas boundary (YDB) layer, containing peak abundances in multiple, high-temperature, impact-related proxies, including spherules, melt glass, and nanodiamonds. Bayesian statistical analyses of 354 dates from 23 sedimentary sequences over four continents established a modeled YDB age range of 12,835 Cal B.P. to 12,735 Cal B.P., supporting synchroneity of the YDB layer at high probability (95%). This range overlaps that of a platinum peak recorded in the Greenland Ice Sheet and of the onset of the Younger Dryas climate episode in six key records, suggesting a causal connection between the impact event and the Younger Dryas. Due to its rarity and distinctive characteristics, the YDB layer is proposed as a widespread correlation datum. The Younger Dryas impact hypothesis posits that a cosmic impact across much of the Northern Hemisphere deposited the Younger Dryas boundary (YDB) layer, containing peak abundances in a variable assemblage of proxies, including magnetic and glassy impact-related spherules, high-temperature minerals and melt glass, nanodiamonds, carbon spherules, aciniform carbon, platinum, and osmium. Bayesian chronological modeling was applied to 354 dates from 23 stratigraphic sections in 12 countries on four continents to establish a modeled YDB age range for this event of 12,835–12,735 Cal B.P. at 95% probability. This range overlaps that of a peak in extraterrestrial platinum in the Greenland Ice Sheet and of the earliest age of the Younger Dryas climate episode in six proxy records, suggesting a causal connection between the YDB impact event and the Younger Dryas. Two statistical tests indicate that both modeled and unmodeled ages in the 30 records are consistent with synchronous deposition of the YDB layer within the limits of dating uncertainty (∼100 y). The widespread distribution of the YDB layer suggests that it may serve as a datum layer.

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

A major cosmic-impact event has been proposed at the onset of the Younger Dryas (YD) cooling episode at ≈12,800 ± 150 years before present, forming the YD Boundary (YDB) layer, distributed over >50 million km2 on four continents. In 24 dated stratigraphic sections in 10 countries of the Northern Hemisphere, the YDB layer contains a clearly defined abundance peak in nanodiamonds (NDs), a major cosmic-impact proxy. Observed ND polytypes include cubic diamonds, lonsdaleite-like crystals, and diamond-like carbon nanoparticles, called n-diamond and i-carbon. The ND abundances in bulk YDB sediments ranged up to ≈500 ppb (mean: 200 ppb) and that in carbon spherules up to ≈3700 ppb (mean: ≈750 ppb); 138 of 205 sediment samples (67%) contained no detectable NDs. Isotopic evidence indicates that YDB NDs were produced from terrestrial carbon, as with other impact diamonds, and were not derived from the impactor itself. The YDB layer is also marked by abundance peaks in other impact-related proxies, including cosmic-impact spherules, carbon spherules (some containing NDs), iridium, osmium, platinum, charcoal, aciniform carbon (soot), and high-temperature melt-glass. This contribution reviews the debate about the presence, abundance, and origin of the concentration peak in YDB NDs. We describe an updated protocol for the extraction and concentration of NDs from sediment, carbon spherules, and ice, and we describe the basis for identification and classification of YDB ND polytypes, using nine analytical approaches. The large body of evidence now obtained about YDB NDs is strongly consistent with an origin by cosmic impact at ≈12,800 cal BP and is inconsistent with formation of YDB NDs by natural terrestrial processes, including wildfires, anthropogenesis, and/or influx of cosmic dust.

New human fossil to the last Neanderthals in central Spain (Jarama VI, Valdesotos, Guadalajara, Spain)

The morphology of the Neanderthal first metatarsals and those of modern humans are quite similar. Following Trinkaus (1983), the Neanderthal first metatarsals only exhibit a moderate degree of robusticity. This robusticity could be related to the shortness of the Neanderthal first metatarsals, but unfortunately the total length of the Jarama IV metatarsal is not preserved. In our metric comparisons of first metatarsals, it was difficult to discriminate between Neanderthals and modern humans. Neanderthal shafts presented lower values in dorsoplantar diameter than modern humans, although a high degree of variation was observed. The morphology and dimensions of the Jarama VI hallucial metatarsal are very similar to those of recent humans and Neanderthals. The presence of the accessory articular facet for the second metatarsal and the midshaft dimensions of the Jarama VI fossil suggest a Neanderthal affinity, although this hypothesis remains tentative. A precise taxonomic attribution of the Jarama VI first metatarsal must await the recovery of further remains. In Iberia, all Mousterian-related or OIS 3a human remains are ascribed to the species Homo neanderthalensis.We therefore believe that the Jarama VI metatarsal is more likely to be from a Neanderthal than a modern human. The taphonomic study reveals that the metatarsus was altered by a small canid. This agent has also affected a small part of all of the large mammals of Jarama, although abundant cutmarks suggest that the hominids were the main agents of transport and consumption of the herbivores. The technological features of Jarama VI suggest expedited knapping for local materials. Coupled with the scarcity of evidence of hearths, this suggests that visits to the site were short-term occupations during which the Jarama inhabitants obtained edges, especially without retouching, for activities related to hunting and processing fauna and possibly other functions.

New evidence of bones used as fuel in the Gravettian level at Coímbre cave, northern Iberian Peninsula

The use of bone as fuel has been already documented in some sites dated to the Middle and Upper Palaeolithic. They contribute to a longer combustion time due to their durability; consequently, they are useful to reduce the need for firewood, a good advantage in open palaeoenvironmental contexts with limited arboreal vegetation. The use of bones as fuel can be identified by several lines of evidence. The main one is a large number of burned bones, with an intense cremation–charring or calcination, together with high fragmentation resulting from the long contact with the fire. Other features may be present, although they can also result from individual circumstances. They include either the presence of complete skeletal profiles–which implies using all the bones of the animal–or a selection of the anatomical parts which contribute better to combustion, i.e. epiphyses and axial elements. In this article, we argue that the faunal assemblage of level Co.B.6 of Coímbre cave fully corresponds to this model. Moreover, this level coincides with a cold palaeoclimatic event, which was correlative to the climatic deterioration that occurred at the end of MIS 3, and an open environment. Thus, we propose that this level contains the first known use of bones as fuel in the Cantabrian Gravettian.

Where are the ‘Asturian’ dwellings? An integrated survey programme on the Mesolithic of northern Spain

Abstract Mesolithic hunter-gatherer settlements generally leave ephemeral archaeological traces and are notoriously difficult to detect. Nowhere is this more so than on the northern coast of Spain, despite a long tradition of Mesolithic research. In this project, evidence of Mesolithic activity together with the geomorphological and topographical suitability of particular locations were used to select areas for large-scale geophysical survey. The results demonstrate the potential of the new methodology: magnetometry survey at El Alloru revealed the very first Asturian open-air settlement site to be discovered.

El Tossal de la Roca: The Pleistocene-Holocene Transition in the Mediterranean Region of Eastern Spain

A series of marked environmental changes took place during the transition from Pleistocene to Holocene, to which the hunter-gatherers adapted by modifying their technology and subsistence practices. In parallel with these changes, territoriality increased and significant transformations in artistic expression occurred. This paper assesses the archaeological record of the Iberian Mediterranean watershed to analyze various aspects of this adaptive process, which unfolded gradually from the end of the Magdalenian to the beginning of the Neolithic.

Reply to Holliday and Boslough et al.: Synchroneity of widespread Bayesian-modeled ages supports Younger Dryas impact hypothesis.

Holliday (1) rejects age-depth models for the Younger Dryas boundary layer (YDB) in Kennett et al. (2), claiming that they are incorrect for several reasons, including age reversals, high age uncertainties, and use of optically stimulated luminescence (OSL) dating. These same claims previously were presented in Meltzer et al. (3) and were discussed and refuted in Kennett et al. (2). These criticisms apply to nearly all dated archaeological and geological sequences, including the Odessa meteorite impact crater, where paradoxically, Holliday et al. (4) modeled an impact age using OSL dating (>70% of dates used) with large uncertainties (to >6,000 y) and age reversals (>40% of dates are reversals). Thus, Holliday (1) argues against a practice that he and many other researchers have used and continue to use today. In an ideal world, all dates would be in perfect chronological order with high accuracy and certainty, but such scenarios are rarely possible (2). It is because of such dating difficulties that Bayesian analysis is a powerful chronological tool, and is rapidly becoming the archaeological standard.