A Neandertal dietary conundrum: Insights provided by tooth enamel Zn isotopes from Gabasa, Spain

Abstract

The characterization of Neandertals' diets has mostly relied on nitrogen isotope analyses of bone and tooth collagen. However, few nitrogen isotope data have been recovered from bones or teeth from Iberia due to poor collagen preservation at Paleolithic sites in the region. Zinc isotopes have been shown to be a reliable method for reconstructing trophic levels in the absence of organic matter preservation. Here, we present the results of zinc (Zn), strontium (Sr), carbon (C), and oxygen (O) isotope and trace element ratio analysis measured in dental enamel on a Pleistocene food web in Gabasa, Spain, to characterize the diet and ecology of a Middle Paleolithic Neandertal individual. Based on the extremely low δ⁶⁶Zn value observed in the Neandertal's tooth enamel, our results support the interpretation of Neandertals as carnivores as already suggested by δ¹⁵N isotope values of specimens from other regions. Further work could help identify if such isotopic peculiarities (lowest δ⁶⁶Zn and highest δ¹⁵N of the food web) are due to a metabolic and/or dietary specificity of the Neandertals.

Keywords: Iberian Neandertals; Middle Paleolithic; carnivory; hominin; zinc isotope ratios.

Fig. 1.

(A) Location of the Gabasa site as well as other Neandertal sites mentioned in the text. (B) Detailed map of the Gabasa region. San Estaban de Litera and Benabarre are nearby modern cities.

Fig. 2.

Enamel δ⁶⁶Zn values per mammalian taxon for different dietary groups from Gabasa, Spain given as boxplots. Note that subsamples taken from one single tooth reflect differences in dietary ⁶⁶Zn values. See text for detailed discussion about the low Neandertal δ⁶⁶Zn value.

Fig. 3.

Average dental enamel isotope and trace element ratios for the different dietary categories at Gabasa, Spain. (A) δ⁶⁶Zn_enamel. (B) ⁸⁷Sr/⁸⁶Sr. (C) δ¹³C_enamel. (D) δ¹⁸O_enamel. (E) log(Ba/Ca). Omnivores correspond to one single taxon (cave bears) as well as carnivores with significant bone consumption (cave hyenas).

Fig. 4.

Zinc isotope values (δ⁶⁶Zn, average dental enamel values per tooth) cross-plotted versus (A) carbon (δ¹³C), (B) oxygen (δ¹⁸O), and (C) strontium (⁸⁷Sr/⁸⁶Sr) isotope composition as well as (D) Ba/Ca ratios measured in faunal and Neandertal tooth enamel at Gabasa, Spain. Each point corresponds to a single tooth, except for the horse tooth, for which five samples were taken (samples are connected with a line). Error bars correspond to the SD between analytical duplicates for C and O isotopes (0.02 to 0.36 ‰; one sample with higher SD has been removed) and for Zn (analytical duplicates: 0.00 to 0.04 ‰; SD for separate samples taken from a single tooth: 0.04 to 0.21 ‰). SEs for strontium isotope ratios are 0.000003 to 0.000010 and are too small to display.