Practising pastoralism in an agricultural environment: An isotopic analysis of the impact of the Hunnic incursions on Pannonian populations

We conducted a multi-isotope study of five fifth-century AD cemeteries in modern-day Hungary to determine relationships between nomadic-pastoralist incomers—the historically documented Huns and other nomadic groups—and the sedentary agricultural population of the late Roman province of Pannonia. Contemporary historical sources describe this relationship as adversarial and destructive for the late Roman population, but archaeological evidence indicates high levels of hybridity between different groups. We undertook carbon, nitrogen, strontium and oxygen isotope analyses of bone collagen, dentine and tooth enamel at Keszthely-Fenékpuszta, Hács-Béndekpuszta, Győr-Széchenyi Square, Mözs and Szolnok-Szanda to examine these relationships through past subsistence practices. The patterns at all sites indicate medium to high animal protein consumption with little evidence for a significant contribution of aquatic resources. All populations relied to a great extent on C4 plants, most likely millet. Within each population, diet was heterogeneous, with significant variations in terms of animal protein and C3 and C4 plant consumption. High levels of intra-population and individual variability suggest that populations made use of a range of subsistence strategies, with many individuals exhibiting significant changes over their lifetimes. Rather than being characterised only by violence, the historically-documented influx of nomadic populations appears to have led to widespread changes in subsistence strategies of populations in the Carpathian basin. Nomadic-pastoralist groups may have switched to smaller herds and more farming, and, conversely, local populations may have integrated with a new economic system based on animal herding.


Carbon and oxygen isotope analysis of enamel bioapatite
Tooth enamel powder was obtained using a using a dental drill with a diamond drill attachment. The exterior of the enamel was mechanically abraded to remove any dirt, and the drill bit was cleaned before each sample was taken.
The bioapatite extraction method is described in Balasse et al. [2]. Enamel was treated with sodium hypochlorite 2-3% (24 h) to remove organic matter and then with 0.1 M acetic acid (4 h, 0.1 ml/mg) to remove exogenous carbonate. The samples were lyophilised to remove any remaining liquid. The samples were then transferred into vials sealed with a screw cap holding a septa and PCTFE washer to make a vacuum seal, and the samples reacted with 100% orthophosphoric acid at 90°C using a Micromass Multicarb Sample Preparation System. The carbon dioxide produced was dried and transferred cryogenically into a VG SIRA mass spectrometer for isotopic analysis. Results are reported with reference to the international standard VPDB calibrated through the NBS19 standard [3: 60, 4]. The precision is better than ±0.08‰ for 13 C/ 12 C and better than ±0.10‰ for 18 O/ 16 O.

Strontium isotope analysis
Environmental samples for strontium analysis were pre-treated following the methods described in Maurer et al. [5]. Water samples were filtered through 0.2um nylon filters into 60ml acid cleaned HDPE bottles and acidified with distilled ultra-pure nitric acid to maintain a pH = 2.
Soil samples were taken with an auger to below the topsoil, reaching depths of 0.25 to 0.70 m. Fields under cultivation were avoided to mitigate the impact of fertiliser use. Soil leachates were obtained by shaking 2 g of soil in 20 ml deionised ultrapure water for 24 h in acid-cleaned polypropylene tubes, followed by 1 h in an ultrasonic bath. The solution was centrifuged for 15 minutes at 2000 rpm and filtered through 0.2um nylon filters.
Water and soil leachates were evaporated to dryness. Leaves were rinsed with deionised ultrapure water and dried in an oven at 50C overnight. Approximately 1 g of dried leaves was then ground and ashed in acid-washed silica crucibles at 550C for 12 h. All samples were then transferred into acid-cleaned Teflon vials.
The enamel surface of the tooth was abraded to a depth of >100 microns using a tungsten carbide dental burr and the removed material discarded. Tooth enamel powder was then collected, and the samples were transferred to a clean (class 100, laminar flow) working area for further preparation. In a clean laboratory, the samples were first washed in high purity acetone to remove any grease that might have come from handling the enamel. Then the sample was cleaned ultrasonically in high purity water, rinsed, dried and then weighed into pre-cleaned Teflon vials. The samples were mixed with 84 Sr spike solution and dissolved in Teflon distilled 8M HNO3.
Environmental samples were analysed at the Isotope Geochemistry Laboratory of the Department of Earth Sciences, University of Cambridge; enamel was analysed at the NERC Isotope Geoscience Facilities, Keyworth.
For samples analysed at NIGL, Strontium was collected using Dowex resin columns. Strontium was loaded onto a single Re Filament with TaF following the method of [6], and the isotope composition and concentrations were determined by Thermal Ionisation Mass spectroscopy (TIMS) using a Thermo Triton multi-collector mass spectrometer. The international standard for 87Sr/86Sr, NBS987, gave a value of 0.710251 ± .000005 (n=19, 2 sigma) during the analysis of these samples. All analyses run to internal precision of better than ± 0.000014 (2SE). Blank values were in the region of 100pg.
Samples analysed in Cambridge for strontium were separated using Dowex 50 x 8 (200-400 mesh) cation exchange resin and the strontium isotopic ratios were measured on single Ta filaments on the VG Sector 54 TIMs using triple collector dynamic algorithm, normalised to 86 Sr/ 88 Sr 0.1194 with an exponential fractionation correction [7]. The 46 analyses of NBS 987 during the two year period up to and including these analyses gave a mean value of 0.710257+/-0.000006%(1sigma).