Dragged, lagged, or undisturbed: reassessing the autochthony of the hominin-bearing assemblages at Gran Dolina (Atapuerca, Spain)

Abstract

The TD6 unit of the Gran Dolina contains an assemblage of the Early Pleistocene, interpreted firstly as a home base. More recently has been proposed a transported origin of the remains according to the sedimentology. Following this model, the remains should be dragged or lagged in a predictable pattern related to their weight, density, shape, and size. Conversely, the debris generated in an undisturbed residential camp should retain spatial relations of codependence caused by the depositional process, not related to inherent variables of materials. To check if the remains were recovered in their original depositional place (aggregated) or are the product of transportation (segregated or random spatial relation), we have evaluated different variables: the spatial arrangement between osteological and lithic tools; the integrity of the bones and their structural characters (shape and tissue composition); postdepositional modifications; and the specimen size distribution. The combined results indicate that the layers that conform the TD6.2 subunit were undisturbed, while TD6.1 was affected by postdepositional processes, probably water flows, resulting in a lagged assemblage. In conclusion, TD6.2 is best interpreted as a well-preserved home base and should play a key role in studies of the behavior of the first European populations.