Evidence for herbivorous cave bears (Ursus spelaeus) in Goyet Cave, Belgium: implications for palaeodietary reconstruction of fossil bears using amino acid δ¹⁵N approaches

Abstract

Insights into causes of extinction in fossil animals can contribute to an understanding of how environmental or anthropogenic processes may affect extant animals. Cave bears that went extinct in the late Pleistocene in Europe have been considered largely herbivorous based on tooth, skull and jaw morphology. Nitrogen and carbon isotopic composition (δ15N, δ13C) of bone collagen of many cave bears having values similar to or lower than those of coeval herbivores support an exclusive plant diet and their occurrence in habitats with denser vegetation. A complicating aspect of this hypothesis is that isotopic compositions of bulk collagen, especially those of nitrogen, could reflect environmental fluctuation as well as behavioural and physiological traits, which are not related to trophic position and so may lead to uncertainty in palaeodietary reconstruction. Here we show that δ15N analysis of individual collagen amino acids of fossil bears from Goyet Cave (Belgium) indicates that cave bears had a constant trophic position of 1.9–2.1, indicating purely herbivorous diets, while brown bears had a trophic position of 2.0–2.4, indicating a slightly more omnivorous diet. Results might support the hypothesis of the extinction of cave bear due to the inflexibility in feeding habits.

The diverse dietary profiles of MIS 3 cave bears from the Romanian Carpathians: insights from stable isotope (δ13C and δ15N) analysis

“…; Naito et al . ) largely supported these interpretations, with low δ 15 N values indicating little evidence of protein from meat consumption among these bears. Yet, other isotopic analyses have inferred that cave bears had a more flexible (omnivorous) diet, given δ 15 N values distributed from low (herbivorous) to higher (omnivorous to carnivorous) values (Hilderbrand et al .…”

Heavy reliance on plants for Romanian cave bears evidenced by amino acid nitrogen isotope analysis

“…Considering this error together with a general offset of 0.1-0.2 (accuracy) between calculated TP based on eqn.1 and known TP that were estimated based on well-controlled field observations or laboratory feeding experiments for extant animals, our estimates for all individuals are well within the range of acceptable values for herbivorous mammals. In addition to predatory carnivores, fossils that so far yielded TP-values above 2.3 originate from brown bears, wild boars, foxes and badgers 54,60 , in contrast to the cave bears with TPs less than 2.2 analyzed in the present study.…”

Comment on “Ecological niche of Neanderthals from Spy Cave revealed by nitrogen isotopes of individual amino acids in collagen” [J. Hum. Evol. 93 (2016) 82–90]

“…We welcome Naito et al s recent efforts to gain greater information about the diet and ecological niche of Neanderthals (Naito, Chikaraishi, et al 2016) . However, the application of a relatively novel technique (compound specific amino acid nitrogen isotopic analysis; Amy K. Styring et al 2010;Chikaraishi et al 2014) is not without its problems.…”

“…We urge caution in the interpretation of data based on measurements that are potentially flawed, be they from extinct hominins or other humans or animals (Naito, Honch, et al 2010;Naito, Chikaraishi, et al 2010;Naito, Chikaraishi, Ohkouchi, & Yoneda 2013;Naito, Chikaraishi, Ohkouchi, Drucker, et al 2013;Itahashi et al 2014;Naito et al 2016/4;Naito, Chikaraishi, et al 2016;Naito, Germonpré, et al 2016) . Dashed line marked is the x=y line, as would be expected based on biochemical pathways.…”

“…Dashed line marked is the x=y line, as would be expected based on biochemical pathways. JAMSTEC data: N=110, measured using GC-C-IRMS after N -pivaloyl/isopropyl (Pv/iPr) derivatization (Naito, Chikaraishi, et al 2010;Naito, Honch, et al 2010;Naito, Chikaraishi, Ohkouchi, & Yoneda 2013;Naito, Chikaraishi, Ohkouchi, Drucker, et al 2013;Itahashi et al 2014;Naito et al 2016/4;Naito, Chikaraishi, et al 2016;Naito, Germonpré, et al 2016) . Bristol data, N=87, measured using GC-C-IRMS after N-acetyl-i-propyl derivatization (O Connell unpubl data; Amy K. Styring et al 2010;Amy Keita Styring 2012) .…”