Burnt bone assemblages from El Esquilleu cave (Cantabria, Northern Spain): deliberate use for fuel or systematic disposal of organic waste?

Bones or fossil fuels associated with combustion structures have been widely discussed in several works related to Neanderthal lifestyles and subsistence patterns during the MIS 3. El Esquilleu cave (western Cantabria, Spain) can significantly contribute to this issue, particularly with the taphonomic study of layers 21 and 23, which are characterized by the presence of hearths containing abundant burnt and charred faunal remains of ibex. The fragmentation and burning rates as well as bone presence within hearths may suggest that they were used as a supplementary fuel resource. Following previous research on the suitability of bones as a supplement to firewood in hearth combustions, a series of experiments are here presented using goat bones, in consistency with the faunal record present at El Esquilleu. Our experiments proved that small-sized animal (\u3c100 kg in weight) bones also possess appropriate qualities for their use as fuel, particularly epiphyseal and axial parts. This paper critically evaluates whether bones could have been used as fuel by the Neanderthal groups at El Esquilleu or whether their combustion resulted from other behavioural practises. In this sense, we compare our results with different proxy data from this site as well as with the palaeoenvironmental information available for the MIS 3 chronological period in Western Europe