The conservation of Shanidar Z at a glance
Shanidar Cave (Iraqi Kurdistan) was excavated in two phases. In the first stage (1951-1960), the team led by Ralph Solecki recovered 10 Neanderthal individuals [1-2]. They have been assigned to two periods: Shanidar 1, 3, and 5 to 46-50 ka, and Shanidar 2, 4, 6, 7, 8, 9, and 10, to around 75 ka. In 2015, excavations were resumed by a new team, and new Neanderthal remains were recovered, including some belonging to Shanidar 5 [3], an individual currently named Shanidar Z [4], and further adult elements presented at the 2023 ESHE meeting. Here we give the first report on the conservation of Shanidar Z, the largely complete upper body of an adult recovered in 2018-2019 [4]. The Shanidar Z remains were directly adjacent to the block of sediment that Solecki’s team lifted to recover Shanidar 4, probably truncating Shanidar Z in the process. The skull of Z was superimposed on the left upper limb and the thoracic elements. Though severely distorted and flattened, the skull was recognisable. Underneath, the bones of the upper left limb were delicate, but more visible and less crushed. Below, the ribs and spine were articulated, with some ribs slightly displaced, but all the bones extremely crushed and friable. After careful excavation and consolidation with Paraloid B72 in situ, the bones were lifted in numerous small blocks with some of the sediment. Only a few hand elements were lifted individually. The blocks were wrapped in aluminium foil. Once at the University of Cambridge facilities on loan from the General Directorate of Antiquities & Heritage, Iraqi Kurdistan, the blocks were microCT scanned without opening them, and preserved in a cold and stable environment until the physical conservation of the skeleton could begin. The general steps for the conservation treatment were: 1) collection of the field documentation and visualization of the 3D reconstruction of the bones before opening the packages; 2) photography of the blocks and elements before treatment; 2) microexcavation of the blocks; cleaning, and stabilisation of the recovered fragments; and bonding of fragments contained in the same package; 3) reconstruction of the elements recovered in different blocks; 4) final documentation; 5) packing. Conservation techniques were similar to those used for another hominin find [5]. In short, the work was carried out with small manual tools (e.g., soft brushes, wooden sticks, scalpels and dental picks) to remove the sedimentary matrix and clean the bones. Consolidation and bonding of fragments was performed with Paraloid B72 dissolved in acetone (5-25%). We also used fibreglass cloth strips impregnated with Paraloid, both to temporarily hold the pieces in place, and as a final bond reinforcement for some of the elements. The final packing of the bones used clean polyethylene plastic bags, foam blocks and boxes, adapted to each element. After this conservation treatment, the Shanidar Z bones are clean, stable and prepared. Most upper limb elements are well reconstructed, but additional reconstruction work may improve some of the elements, particularly the highly fragmented thoracic bones. The skull is reshaped, but the lack of physical contact among some cranial elements does not allow a complete physical reconstruction, so virtual reconstruction is also underway. The conservation took over a year. The main challenges were the bones’ significant fragmentation and friability. Hundreds of tiny pieces needed to be cleaned and consolidated before attempting the reconstruction. That posed a challenge resolved by exhaustive documentation to keep track of the fragments. This documentation, crucial to the conservation work, will also be a useful legacy for future research on these remains.
