Symbolic use of marine shells and mineral pigments by Iberian Neandertals 115,000 years ago

INTRODUCTION

The emergence of symbolic material culture represents a threshold in the evolution of our species. Artifacts with a functional value that lies in the informational realm are proxies for the presence of language and, thus, of the fundamental aspects of human cognition as we know it (1, 2). For more than a century, the evidence seemed to suggest that symbolic artifacts appeared relatively late in the Pleistocene and in the context of the so-called Upper Paleolithic revolution—the apparently sudden appearance in Europe, around 40 thousand years (ka) ago, of cave art, sculpted figures, decorated bone tools, and jewelry made of bone, tooth, ivory, shell, or stone (3, 4).

The past two decades of research have critically shaken the empirical foundations of this paradigm. In both southern and northern Africa, perforated and ochred marine shell beads were retrieved in a number of sites of the Middle Stone Age (MSA) dated to the Last Interglacial, more than 70 ka ago (5–7). These discoveries led to suggestions that such material symbols represented “modern behavior,” the emergence of which being understood (i) as part and parcel of the speciation of anatomically modern humans and (ii) as an explanation of the latter’s eventual prevalence over coeval Eurasian humans. Being anatomically archaic, such Eurasian populations, namely, the Neandertals, were thereby assumed to have also been behaviorally archaic, that is, devoid of symbolism and possibly even of language (8, 9).

On the basis of the association of Neandertals with tooth and bone pendants in the Châtelperronian culture of southwestern Europe, an alternative view was that symbolic material culture appeared as the result of a complexification of social relations—triggered by demographic growth, requiring the production of modes of individual and group identification, and occurring across the entire Old World, irrespective of human taxonomic boundaries (10, 11). This alternative was furthered by the presence of perforated and ochred marine shells, yellow and red colorants, and shell containers with residues of complex pigment mixes—the same kinds of finds made in the African MSA—in the Neandertal-associated Middle Paleolithic of Cueva de los Aviones (Cartagena, Region of Murcia, Spain; 37°35′7.30″N, 0°59′8.66″W) (Figs. 1 to 3) (12). Radiocarbon dating of food shells (Patella ferruginea limpets) dated this archaeological context to a period 45 to 50 ka ago, slightly earlier than the Châtelperronian but still within the range of some age estimates for the first wave of modern human dispersals into Europe that would eventually lead to Neandertal demise (13). Therefore, it remained possible that the finds from both Aviones and the Châtelperronian could have been associated with modern humans, either directly, as its makers, or indirectly, as providers of models copied by Neandertals in acculturation or in an “imitation without understanding” manner (14–16).

RESULTS AND DISCUSSION

Cueva de los Aviones is a sea cave. The base of its fill, found at sea level, is a cemented marine conglomerate—the beach rock of a Last Interglacial sea-level high stand (12). Elsewhere in the Mediterranean, deposits of this age are found 4 to 7 m above present sea level, but this stretch of the Spanish Mediterranean coast is an area of relative subsidence (17). Analysis of these deposits has posed several challenges. First, the overlying archaeological breccia is contiguous with the basal conglomerate and itself features no significant internal discontinuity. Second, the age estimates obtained through radiocarbon dating are at the limits of detection for this method. Third, shell can behave in an open-system manner, leading sometimes to radiocarbon results spanning the later Pleistocene and the Holocene for samples that are known with certainty to be of much earlier age (18). Finally, the deposit’s abundant shellfish remains suggest close proximity to the sea, whereas a marine isotope stage (MIS) 3 chronology implies a distance of 1 to 2 km from the paleoshoreline. For these reasons, it was necessary to verify that the radiocarbon dates obtained were not just minimum ages.

To do so, we sampled the flowstone capping the deposit (Fig. 2). Its stratigraphic relationship with the underlying sediment is demonstrated by (i) the 1985 excavation’s notes and stratigraphic records (19) and (ii) field observation, supported by the comparison between photos taken before and after the excavation with those made when the extant section was geologically described and sampled, in 2009 and 2013 (Figs. 1, C and D, 2A, and 4 and figs. S2 to S4). Lying conformably and in continuity with the underlying sediments, as is well apparent in our sectioned samples, the time of deposition of this flowstone therefore provides an unambiguous minimum age for the Cueva de los Aviones symbolic finds. In addition, note that, despite >25 years of exposure to weathering, the 1985 section remained intact, owing to its heavy cementation, which explains the preservation in this part of the site of a remnant of the original fill, now >90% lost, and confirms the stratigraphic integrity of the archaeological context.

To determine the time of formation of the flowstone, we applied the U-Th method to four samples. Sample 1 was cut from the extant vertical section, and samples 2 to 4 were cored from above (Fig. 2, B and C, and the Supplementary Materials). U-Th measurements were undertaken on subsamples taken from near the base of each sample. For samples 1 and 3, which cover the entire thickness of the flowstone and reach the flowstone-sediment boundary, we find consistent results of 117 ± 3 ka and 115 ± 1 ka (table S1 and the Supplementary Materials). These results prove that flowstone had already begun to form atop the Aviones archaeological deposit by 114 ka ago, the youngest possible age of the two results. Global records and the submerged Mallorca speleothems show that sea level began to drop from the last of the high stands of MIS 5e around 120 ka ago (20, 21) and dropped significantly around 118 ka ago (22). Taking 120 to 118 ka as the time when, once the sea had retreated, continental sediments could start accumulating inside the cave, above the beach rock, we can conclude that the deposit represented by the Cueva de los Aviones remnant accumulated quite rapidly during a period of no more than about five millennia.

The ages available for the sites of the African MSA that yielded comparable finds have all been obtained by luminescence dating and therefore typically have associated 2σ uncertainties of at least 6%. This situation hinders comparison with the U-series chronology for Cueva de los Aviones, which is based on results that are about six times more precise. In addition, significant disagreement between estimates derived by different research groups for the same African sites or cultures persists (23, 24). Nevertheless, the most recent luminescence-derived estimates for the Still Bay culture of South Africa, to which the ochred shell beads from Blombos Cave belong and which is the earliest unambiguously defined South African context with symbolic artifacts, suggest that this culture began 78.7 ka ago, at the earliest (25). The age estimated for the shell bead horizon at Grotte des Pigeons, Morocco, is, within error, the same (82.5 ± 5.3 ka ago) (7), as is the mean age estimate (around 92.5 ka ago) for the Middle Paleolithic of Qafzeh Cave, in Israel, which yielded colorants as well as perforated and ochred Glycymeris shells identical to those from Cueva de los Aviones, but in a modern human–associated context (26–28).

The Neandertal-associated evidence from Cueva de los Aviones therefore substantially predates, by 20 to 40 ka, anything comparable known in Africa or western Asia to date. In conjunction with the evidence that cave painting in Europe dates back to at least 64.8 ka ago (29), it leaves no doubt that Neandertals shared symbolic thinking with early modern humans and that, as far as we can infer from material culture, Neandertals and early modern humans were cognitively indistinguishable.

The auditory structures of the Atapuerca/Sima de los Huesos fossils show the ability to produce and perceive the sounds emitted during modern human spoken language (30); and the time spans involved in the evolution of the neural hardware required for that ability to evolve (1) support an ancient origin for language, which is symbolic by definition. Whatever one thinks about the place of Neandertals in human taxonomic schemes, the corollary of these findings is that the capacity for symbolism must have been inherited from a common ancestor. As a working hypothesis, we suggest that the origins of language and the advanced cognition characteristic of extant humans may precede the period before the divergence of the Neandertal lineage, more than half-a-million years ago.

MATERIALS AND METHODS

Samples were collected from a flowstone section [LS01; (12)] capping the archaeological sections excavated in Cueva de los Aviones. One piece was removed with a hammer and a chisel, and three additional samples were core-drilled. Subsamples for U-Th dating were cut from the collected specimen using a band saw fitted with a diamond-coated cutting band. The CaCO₃ pieces were cleaned in an ultrasound bath and dried. Procedures for isotope dilution and purification followed the protocol outlined by Hoffmann et al. (31). Purified U and Th fractions were analyzed in 0.5 M HCl solution by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). Analytical protocols for MC-ICPMS and data reduction are presented in detail by Hoffmann et al. (29, 32). More details about the samples and sample preparation presented in this study can be found in the Supplementary Materials. All U-series results are reported in table S1.

Supplementary Material