The "Archeology of the Light":  A multiproxy, interdisciplinary and experimental approach to Paleolithic subterranean activities.

Background: This article presents the A-LIGHT project and its main results. The "Archeology of the Light" (A-LIGHT) project aims to improve our knowledge of Palaeolithic cave activities through an interdisciplinary methodology applied to rarely-studied remains: the residues of Palaeolithic light from lamps, fireplaces and torches (specially, charcoal and soot). Methods: The methodology includes different stages such as: 1. Research in caves and sampling, 2 Laboratory analyses (multi-analytical approach adapted to the type of combustion residue analysed, including Anthracology, C14 dating, Bayesian analysis, SEM-EDX, TEM.EDX, Raman), 3. Ethnographic review of firelight, 4. Experimental reproduction and monitoring of Palaeolithic firelight. 5. Analyses, integration of data and synthesis. Results: This approach contributes multifaceted data about the Palaeolithic activities inside the caves (lighting systems selected, fuel used, chronology and intensity of visits or paleo-paths). Experimental reproductions have enabled evaluation of the Palaeolithic lighting potential. This provide essential information for research the visibility and the accessibility of Rock Art from GIS, and allow to more realistic virtual simulations. Conclusions: These data demonstrate that the Archaeology of the Light is "here to stay" and that it is an essential approach for a holistic understanding of Palaeolithic caves. Especially on the lighting systems used by paleo-groups in the underground environment (functioning, selected fuels, duration, light intensity), on the minimum number and date of prehistoric incursions, as well as on aspects related to the visibility and accessibility of Palaeolithic cave art.