The late persistence of the Middle Palaeolithic and Neandertals in Iberia: A review of the evidence for and against the “Ebro Frontier” model

Abstract

In the Franco-Cantabrian region and Catalonia, the Upper Palaeolithic begins with three assemblage-types found in stratigraphic order through the interval between 45,000 and 37,000 years ago: the Châtelperronian, the Protoaurignacian, and the Early Aurignacian. A stone tool, the Châtelperron point, and a bone tool, the split-based point, are index fossils of the first and the last, respectively, but neither was ever found elsewhere in Iberia. This observation triggered the proposition that, in regions situated to the south of the River Ebro drainage, the Middle Palaeolithic persisted until the time when the Early Aurignacian gave way to the Evolved Aurignacian, which is documented across all of Iberia by assemblages containing its index fossil, the Roc-de-Combe bladelet. Put forth thirty years ago, this Ebro Frontier model found support in the little radiometric evidence then available. Since, it has been shown that most apparently late occurrences of the Middle Palaeolithic were an artefact of dating error, caused by incomplete decontamination of radiocarbon dating samples, while claims have surfaced for the Early Aurignacian to be more widespread than hitherto thought. While the validity of Ebro Frontier's premises has thereby been called into question, continued support for the model is provided by the excavation of new sites, the re-excavation of old ones, the application of luminescence techniques, and the radiocarbon dating of robustly pre-treated samples. Moreover, and highlighting the key role that site formation process and taphonomy continue to play in ongoing controversies, issues of association between the samples and what they are supposed to date cast doubt on the two key claims for the presence of the Early Aurignacian in Andalusia and Portugal. Along with the Iberian System range, the Cantabro-Pyrenean cordillera represents a formidable physical obstacle to travel and communication, potentially enhanced during Last Glacial times because of rapid and major fluctuations in aridity, glacier extent, and plant cover. This barrier effect underpins the divergent culture-historical trajectories that we see unfolding at various times during the Upper Pleistocene. Beyond the Middle-to-Upper Palaeolithic transition, a well-known case in point is the interval between 20,000 and 22,000 years ago, during which the Badegoulian and the Initial Magdalenian of France and northern Spain developed in parallel with facies of the Upper Solutrean and the Solutreo-gravettian then persisting across all Iberian regions situated between Valencia and Portugal. Given known associations between technocomplexes and human types, these regions' Late Mousterian can be taken as a proxy for the persistence of Neandertal populations, and therefore constitutes a case study of choice for analyses of the variation in the intensity and frequency of biological and cultural interactions among low-density, small-scale populations of Palaeolithic hunter-gatherers. Such analyses have implications for models of the spread of genes, populations, and ideas in the course of Human Evolution, which would greatly benefit from due consideration of the issues of historical contingency that the Iberian evidence sheds much light on.