We analysed directly dated human and animal specimens from layers 6-2 and 6-1 and an additional human from layer 6-1 for isotopic signature (Table 1). Moreover, we selected remains of saiga antelope (Saiga tatarica, n = 6), red deer (Cervus elaphus, n = 2), horse (Equus sp, n = 2), and hare (Lepus sp, n = 1) from layer 6-1 and 6-2. Small mammoth ivory fragments from layer 6-1 could be used since the reconstruction of a body ornament left a few pieces apart (Mammuthus primigenius, n = 1). Carnivores were represented by wolf (Canis lupus, n = 1) and fox (Vulpes vulpes or Alopex lagopus, n = 5). Fish remains are missing in the site despite systematic sieving of the sediment during the excavations. All the selected specimens provided well-preserved collagen, following established criteria32, 33, and were submitted to stable isotope analysis of bulk collagen (Table 2). All the collagen samples, except for one saiga and one horse specimen that could not be included due to technical constraints, were subsequently prepared for amino acid isotopic analysis.

Table 1 List of the sampled bone specimens from Buran-Kaya III and related radiocarbon dates. Full size table

Table 2 Results of stable isotope analyses of collagen (δ13C coll , δ15N coll , δ15N Phe , δ15N Glu ) from the animal and human samples of Buran-Kaya III. Full size table

Environment and diet reconstruction based on bulk collagen

The animal samples can be divided into two groups based on a cluster analysis of their δ13C coll values (Supplementary Fig. 3). The first group exhibited δ13C coll values ranging from −20.7 to −18.7‰ and included red deer, horse, hare and mammoth for the herbivorous species, as well as the wolf of layer 6-1 and the two fox specimens of layer 6-2. The second group corresponded to δ13C coll values ranging from −17.9 to −15.5‰ and encompassed all the saiga and fox samples of layer 6-1, suggesting a predation relationship between the two species.

The δ15N coll values of the fauna exhibited a high variability. Red deer and horse δ15N coll values varied from 7.9 to 10.3‰, while hare showed a lower value of 6.0‰ and saiga provided among the highest δ15N coll values (9.5 to 11.8‰). Finally, the mammoth ivory displayed the highest δ15N coll values with 12.6‰, reaching a comparable range as the wolf (13.0‰). The range of δ15N coll values of the fox specimens from layer 6-1 with relatively low δ13C coll values was even wider (7.8 to 14.2‰) than for the specimens in the second group with higher δ13C coll values from layer 6-2 (9.4 to 17.2‰). Each group corresponded not only to different layers but also possibly to different species (polar fox or red fox). If the foxes of layer 6-1 could clearly have consumed saiga, the foxes of layer 6-2 reflected a drastically different diet. Low abundances in both 13C and 15N can be explained by the specialized hunting of hare, while low 13C with high 15N abundances points to a large proportion of larger herbivore (red deer and/or horse) meat.

The human individuals had δ13C coll and δ15N coll values ranging from −19.4 to −18.8‰ and from 15.4 to 16.8‰, respectively (Fig. 2). Their δ15N coll values were thus at least 1‰ higher than the highest values measured in fox or wolf. This suggests the consumption of prey with higher 15N abundances than those accessible to the animal predators. The δ13C coll on the other hand implies the intake of animals mainly dependent on C 3 plants, and thus does not fit with a dominant saiga-based protein diet. Beyond the single value available for Buran-Kaya III, the mammoth is a species known to display such low δ13C coll for relatively high δ15N coll values10,11,12,13,14, and should be considered as a potential meat contributor to human diet. On another hand, the freshwater resource contribution cannot be ruled out, even if no fish remains have been retrieved from the site, despite water sieving of the excavated sediments.

Figure 2 Measured δ13C coll and δ15N coll values of saiga, horse, red deer, mammoth, hare as herbivores (in green) and wolf, fox and anatomically modern humans from layers 6-1 and 6-2 of Buran-Kaya III (in red). Full size image

Diet and trophic position reconstruction based on collagen amino acids

The analysis of compound-specific δ15N values of phenylalanine and glutamic acid serves as a way of detection of possible aquatic contribution in human diet15, 34. The δ15N Phe values of herbivores and carnivores reflect mainly those of the primary producers, at the base of the food chain, due to limited trophic 15N-enrichment19,20,21. The δ15N Phe values of the herbivores of Buran-Kaya III reflected the observed pattern of the δ15N coll with even less overlap between mammoth with the highest value of 17.5‰ and the other herbivores, such as red deer, horse and hare with the lowest values of 12.2 to 13.3‰, and saiga with intermediate values (13.3 to 16.3‰) (Fig. 2). This confirms that the high δ15N coll value of the mammoth is linked to the specificity of its diet rather than to physiological traits18, 35, 36. The δ15N Phe values of the foxes (11.7 to 15.7‰) were relatively consistent with those of the saiga, as expected from their comparable δ13C coll values. An exception was the fox specimen of 6-2 with low δ15N coll value and one individual of 6-1 since both exhibited δ15N Phe values low enough to be comparable to the group of red deer, horse and hare. These foxes had possibly less access to saiga meat than their counterparts. The wolf and the human individuals of layer 6-1 exhibited δ15N Phe values from 17.4 to 17.6‰ that were similar to mammoth (17.4‰), suggesting this large game animal being a significant source of dietary protein. The human sample of layer 6-2 provided a slightly lower value of 16.6‰, which could reflect a lower influence of mammoth meat in the diet and a slightly higher contribution of saiga as source of animal protein.

The calculated trophic positions (TPs) of the herbivores using TP(C 3 ) equation were ranging from 1.8 to 2.0 and averaged at 1.9, slightly lower than the theoretical value for herbivores, which was found at the early Upper Palaeolithic site of Scladina in Belgium (mean TP = 2, excluding cave bears)18. The TP position of the wolf at 3.1 instead of 3 also reflects a possible uncertainty of ± 0.1 in the calculation of the TP value and/or variability in its diet. Interestingly, the foxes’ TP values ranged from 2.6 to 2.7, which is consistent with the omnivorous and opportunistic habits reported for this small canid37, 38.

The calculation of TPs of the human individuals analysed at Buran-Kaya III gave values of 2.5 and 2.6 based on TP(C 3 ) equation, while 1.0 and 1.1 values were obtained using TP(Aqua) equation (Table 2; Fig. 3). If the first result can be interpreted as a terrestrial-based diet with a clear intake of plant protein, the second results would place the human as the same trophic level as aquatic plants, which is unrealistic. In order to test different scenarios including aquatic resources in addition to terrestrial foodstuffs, we have tested a linear model comparing the δ15N Glu measured for the analysed humans with the δ15N Glu values calculated from the measured δ15N Phe at different end-points15 (Supplementary Data 4, Supplementary Fig. 4) for consumption of : aquatic primary consumers (TP(Aqua) = 3), aquatic secondary consumers (TP(Aqua) = 4), terrestrial plants (TP(C 3 ) = 2), terrestrial primary consumers (i.e. herbivore; TP(C 3 ) =3), and a 50:50 mix of terrestrial plant and herbivores (TP(C 3 ) = 2.5). The estimations, with an error of ±10%, should be considered as qualitatively indicative, but underline that the input of plants is necessary (Table 3). The aquatic contribution could go above 10% only in the case that no herbivore meat would be consumed, which is not consistent with the local archaeological evidence of animal hunting by hunter-gatherer at that time. In case of half of the dietary protein being provided by plants, which involves more than half of the diet due to the lower nitrogen content of plant tissues against animal meat, the possible contribution of aquatic resources remains theoretically very low. The intake of human meat due to cannibalism practices has been questioned at Buran-Kaya III due to the occurrence of cut marks testifying to scalping and disarticulation processes, even if the comparison with the human modification on animal remains favours the hypothesis of mortuary practice or ritual cannibalism rather than dietary canibalism28, 29 (Supplementary Data 3). A regular consumption of human meat would have increased the TP over the value of carnivores (TP = 3). The significant consumption of human meat can thus be ruled out for the analysed individuals of Buran-Kaya III.

Figure 3 Measured δ15N Phe and δ15N Glu values on saiga, horse, red deer, mammoth, hare as herbivores and wolf, fox and human remains from layers 6-1 and 6-2 of Buran-Kaya III. Solid, dotted, and dashed lines indicate theoretical lines for δ15N Phe and δ15N Glu values of organisms with TP (Trophic Position) in terrestrial ecosystem = 1, 2, and 3, and aquatic ecosystem = 2 and 3, respectively. Full size image