Ancient biomolecules suggest learned foraging strategy in extinct cave bears

Learning plays an important role in the ecology and evolution of species. Although learning has been extensively studied in extant populations, studying learning in long extinct species represents a much greater challenge because individuals and thei behaviour cannot be directly observed, and their individual relatedness is more challenging to study using molecular methods. However, an interdisciplinary approach combining dietary behaviour revealed by isotope analysis and relatedness estimated using ancient DNA might offer new insights into the learning behavior of extinct species and populations. In this study, we examine dietary variation in Late Pleistocene cave bears from the Romanian Carpathians using stable isotopes. We find that dietary variation among these cave bears is not associated with genetic relatedness inferred using mitochondrial DNA, nor is it associated with Late Pleistocene large scale-climatic oscillations, since different dietary niches existed contemporaneously. Individual cave bears within the same population therefore appear to have had different dietary preferences. This implies that dietary preference was not determined at birth, and instead developed during the early life stages of the animal, most likely facilitated through learning which was not necessarily acquired from close kin. Combining diet inferred from stable isotopes with genetic relationships inferred from ancient mitogenomes thus reveals aspects of the behavioral ecology of an extinct Pleistocene animal with an unprecedented level of detail.