Mortality analysis of Pleistocene bears and its paleoanthropological relevance

Bear bones and Paleolithic stone artefacts often co-occur in Pleistocene cave deposits of Eurasia, raising the question of how these associations come about and the need for effective methods with which to obtain a clear answer. Building upon knowledge of modern bears, I present a method for testing two competing hypotheses about the causes of bear mortality in hibernation contexts. The first hypothesis proposes that age-dependent deaths resulted from non-violent causes (principally starvation), implying that bears' presence in a cave was not linked in time to human activities there. The second hypothesis proposes that random bear deaths in caves resulted from hunting by humans or other large predators, implying a temporal link between them; the expectation of a nonselective age pattern in this circumstance arises from the fact that the individual characters of hibernating bears are hidden from predators. Three elements of the method and its development are presented: (1) a brief review of the biological bases of hibernation-related mortality in modern Ursus, its paleontological consequences, and test expectations drawn therefrom; (2) a detailed, illustrated technique for age-scoring isolated bear cheek teeth based on tooth eruption-wear sequences, developed primarily for cave and brown bears; and, (3) a simple, accurate way to evaluate real cases in terms of contrasting mortality models. The final step is demonstrated by application to a Middle Pleistocene cave bear assemblage (Ursus deningeri) from Yarimburgaz Cave in Turkey, a large collection found in general stratigraphic association with Paleolithic artefacts. The advantages of the method include its ability to (a) handle small samples, (b) use isolated tooth specimens, and (c) evaluate cases simultaneously in terms of idealized age structure models and the variation that normally is associated with each under natural conditions. While the more obvious benefit of bear mortality analysis may be to research on ancient bear demography, the principles and procedures offered here are equally pertinent to archaeological studies of carnivore-mediated formation processes in cave sites. As is generally true in taphonomic research, however, bear mortality patterns are most effective when used in combination with independent lines of evidence to address questions about assemblage formation.