Archaeobotanical investigations and experimental activity performed at Bàsura Cave (Toirano, NW Italy) reveal clues on Epigravettian cave lighting systems

The Bàsura Cave (Toirano, NW Italy) is one of the most important caves in northern Italy conserving the fossilised footprints of a walking trail left by a small group of humans accompanied by a canid dating to the Epigravettian and an impressive cave bear bone deposit of the middle Pleistocene. In 2016 a new research project entitled “The Bàsura Revisited”, returned to fieldwork through a multidisciplinary approach, with the aim of understanding the nature of the human and animal presence in the cave. In this paper we present the results of a multidisciplinary investigation of archaeobotanical remains, stratigraphic sequences, and experimental reconstructions relating to Late Upper Palaeolithic human activity in the Bàsura Cave. The study is centered on the anthracological and palynological remains which led to the identification and interpretation of cave lighting system based on controlled experiments. The study provides new insights into the patterns of human exploration in Palaeolithic cave systems, highlighting the reliance on small-diameter pine twigs as a source of light. The interpretation of the local vegetation environment has been inferred from palynological evidence. The palynological analysis conducted on samples from the innermost space of the cave (“Hall of Mysteries”) suggests that the landscape around the cave consisted of a sparse pine forest of Pinus sylvestris/mugo- type interspersed with steppe herbaceous formations. In the upper level, this is enriched with modest amounts of mesophilous broadleaved trees and thermophilic species. The pollen input likely derived from particles adhering to the fur of bears and infiltrations from the external environment of the cave. Finally, we performed an experimental study aimed at understanding the cave's lighting systems adopted at Bàsura Cave, reconstructing the nature of the lighting instruments and the way the prehistoric explorers moved in the cave. The test confirmed the burning of small twigs rather than the use of torches. The use of twigs is inferred by the traces of small-diameter branches obtained from Pinus sylvestris -type, used individually or tied in small bunches. The experiment revealed that, despite the small size, burning twigs produces enough light to ensure a longer permanence in the cave depth and a safe pathway back, and at the same time minimises dazzling and fast consumption of wood fuel.