Early Modern Human from Tianyuan Cave, China

Chapter 12 Paleopathology of theTianyuan 1 Partial Skeleton

171 C h a p t e r 1 2 Paleopathology of the Tianyuan 1 Partial Skeleton THROUGHOUT THE chapters on the individual skeletal elements of Tianyuan 1, there are many references to pathological abnormalities. Some of these are briefly described since they relate to the paleobiology of concern in those chapters, but detailed description and diagnosis of them is presented here. Some of the relevant details and illustrations are in Chapters 5 through 10. Developmental Stress Indicators Dental Enamel Hypoplasia Extensive wear of the I2 –M2 and the loss of most of the M1–2 buccal crown means that only the right M3 has sufficient crown for an assessment of dental enamel hypoplasia (DEH) or developmental defects of the enamel (see Figures 5-1–5-3). The M3 has a small pit at the occlusal edge (Figure 12-1), on the buccal side of the mesiobuccal cusp, 4.7 mm from the cervix. Given M3 crown formation in the late first and early second decade postnatal (Smith, 1991), this defect probably formed between the ages of 9 and 11 years of age. A variety of localized or systemic insults, including especially dietary deficiencies and infections, can produce such a minor DEH (Kreshover, 1960; Sweeney et al., 1971; Goodman et al, 1991; Hillson, 1996). However, M3 DEH is less frequent than on the more mesial molars among recent humans [in the rare cases when they are recorded (e.g., El-Najjar et al., 1978)] and among Late Pleistocene early modern humans (Trinkaus, Hillson, et al., 2006). They are nonetheless the most common location for molar defects among the Neandertals (Ogilvie et al., 1989). But the overall frequencies of all of the analyzed Late Pleistocene samples are within recent human ranges of variation (Ogilvie et al., 1989; Brennan, 1991; Guatelli-Steinberg et al., 2004; Trinkaus, Hillson, et al., 2006). CHAPTER 12 172 Growth Arrest (Harris) Lines There are relatively few sufficiently intact metaphyseal regions on the Tianyuan 1 appendicular remains for which the presence of growth arrest (transverse; Harris ) lines (Aufderheide and Rodríguez-Martin, 1998: p. 422) can be assessed. Moreover , the moderately advanced adult age of the individual (Chapter 11) suggests that many originally present growth arrest lines would have been remodeled and removed. It is nonetheless possible to assess the presence of these features on the distal left humerus, the distal right tibia, and the proximal left metatarsal 1 (Figure 12-2). Figure 12-1. Buccal (top) and mesial (bottom) views of the Tianyuan 1 right mandibular dentition and mandibular corpus. The arrow points to the minor hypoplasia on the M3 . PALEOPATHOLOGY OF THE TIANYUAN 1 PARTIAL SKELETON 173 The distal humerus has about six mediolateral lines of increased radiodensity across the distal diaphysis, proximal of the olecranon fossa area. These lines are distant from the original metaphyseal line, and it is unclear whether they represent growth arrest lines or merely trabeculae associated with the supraolecranon area. On the distal tibia, however, there is a distinct line at the level of the proximal medial malleolus above the lateral half of the trochlear surface in the posteroanterior view but extending the full depth of the metaphysis in the lateromedial view (Figure 12-2). It is farther from the trochlear surface posteriorly and laterally . There is a similar dorsoplantar line across the proximal metatarsal 1 metaphysis , extending across the full dorsoplantar metaphysis and slightly farther from the medial cuneiform facet plantarly. These lines probably represents a growth arrest during adolescence given the mid to late second decade fusion of the distal tibial and proximal first metatarsal epiphyses (Scheuer and Black, 2000). They were probably of modest duration but sufficient in intensity for lines to form that persisted for a few decades of life. It is possible that the lines reflect the same insult as the trivial hypoplasia on the M3 , given the probable ages of formation of the two sets of defects, but it is more likely that the M3 defect represents a slightly earlier stress event. Growth arrest lines have been identified on a number of immature and mature Late Pleistocene human remains (Brennan, 1991; Trinkaus et al., 2002; Cowgill et al., 2007). However, the persistent difficulties of consistently identifying them on incomplete remains, their uncertain association with stress episodes, and the reFigure 12-2. Radiographs of the Tianyuan 1 distal left humerus in anteroposterior (AP) view, of the distal right tibia in posteroanterior (PA) and lateromedial...