2 New investigations (2009-2011)
Since 2009, a multidisciplinary team of researchers has been re-examining the human remains of Zweeloo Woman to verify the overall state of preservation of both hard and soft tissues and to confirm or reject the previous tentative diagnosis of dyschondrosteosis.
An important question in the interpretation of the human remains is their possible post-depositional deformation and shrinkage.
The preservation of the skeleton along with muscle and ligaments is surprisingly variable in bog bodies. The bones and teeth of most of the skeletons from bogs are severely decalcified because of the acidic environment (Brothwell & Gill-Robinson 2002, 123). Demineralisation is due to the diagenetic influence of the bog acids, which leach minerals (calcium) from the bone. This leaching involves all bony structures, but may affect them to different degrees (Lynnerup et al. 2007, 114; Villa et al. 2011, 167).
Bones of bog bodies are often distorted and compressed during interment, as observed in the cases of Lindow II and Lindow III and Grauballe Man (Pyatt et al. 1991; Schilling et al. 2008; Lynnerup et al. 2007, 114- 120). In the case of Huldremose Woman, anomalous curvature of the bones of the forearm and femur was caused post mortem by decalcification and pressure of wood within the peat (Brothwell & Gill- Robinson 2002, 128; Jurik 2007, 99).
Many bog bodies also prove to have shrunk. Because most of these bodies were allowed to dry naturally, they show considerable shrinkage and deformation in single bones or even entire limbs (see Van der Sanden 1996, 18, fig. 15, Lynnerup et al. 2007, 119; Lynnerup 2010, 444-445).
Histological analysis was performed to assess the state of preservation of bone and viscera in Zweeloo Woman (section 3.1). The level of skin tissue preservation was assessed by means of atomic force microscopy (AFM) (section 3.2). The results were then used in a metrical analysis to arrive at a more precise estimate of stature and new estimates of body proportions. Lastly, a preliminary review of the observed abnormalities, especially of the forearms and lower limbs, is given (sections 3.3 and 3.4). CT scanning led to a more precise identification and specification of the previously described abnormalities, additionally revealing a series of cut marks on the bones.
2.1.1 Histological analysis
A bone sample was analysed according to the protocol outlined by Maat et al. (2000); the intestine samples, liver and kidney, were typed according to their shape and internal position in the mummy’s bundle of viscera (Van der Sanden 1996, 116). Small tissue biopsies (0.5 cm x 0.5 cm) that were macroscopically identified as liver and kidney tissues were analysed according to the methods described in Mekota & Vermehren (2005).
After rehydration in Solution III for 48 hours, samples were fixed for 24 hours in 4% formaldehyde, dehydrated and finally embedded in paraffin blocks. The embedded samples were cut into 3µm-thick sections using a microtome (Leica, RM2245). The paraffin sections were histochemically counterstained with either haematoxylin and eosin stain (H&E) or Gram stain (Mulisch & Welsch 2010, 214; 243-244).
2.1.2 Atomic force microscopy
Atomic force microscope (AFM) imaging, a well-established technique for obtaining information on the surface properties of a sample, was used to determine the collagen preservation in histological skin samples of the mummy.
2-4-µm-thick transverse sections of Zweeloo Woman’s skin were processed as described in section 2.2.1, applied to glass slides, dewaxed and rehydrated in a descending alcohol series. The samples were then analysed using an atomic force microscope (NanoWizard®II, JPK Instruments, Berlin, Germany) operating in intermittent contact mode. Measurements were performed in ambient conditions. Silicon cantilever (BS Tap 300, Budget Sensors, Redding, USA) with typical spring constants of 40 N/m and nominal resonance frequencies of 300 kHz were used. The tip radius was smaller than 10 nm. Image analysis was carried out using SPIP (SPIP 220.127.116.11, Image Metrology, Denmark).
2.1.3 CT scanning
A single radiographic evaluation of the entire skeleton was performed in 16 layers using a CT scanner (CT Gemini TF, Philips, NL). The scanning parameters were: 120 KV; 98 mAs; slice thicknesses 0.8 and 1 mm; reconstruction interval 0.75 mm, rotation time 0.5 sec; filter D, image matrix 512x512. The total number of axial slices was 1378. Post-processing, including axial scans evaluation and multiplanar reconstructions, was performed using a Workstation EBW Brilliance (Philips, NL).