Microfocus X-ray tomography as a method for characterising macro-fractures on quartz backed tools

Abstract: Here we present the first assessment of microfocus X-ray tomography (micro-XCT) as an analytical technique to generate data about macro-fractures on small quartz backed tools similar to those currently held to represent the oldest known evidence for bow hunting. Our experimental results are derived from 21 replicated quartz backed tools randomly selected from a population (n=218) that were broken in a controlled hunting context. We used 3D data obtained from micro-XCT scans to identify macro-fractures and to derive more accurate measurements for these fractures. Our results demonstrate that the micro-XCT technique overcomes reflected-light challenges associated with analysing quartz through conventional macro-fracture approache s. We were able to increase the total observed macrofracture sample by 33% compared with conventional approaches using a hand-lens. Whereas macro-fracture data could be refined, the additionally gained data did not change interpretations obtained from a conventional macro-fracture analysis. It did, however, marginally change the degree of significance in differences between the different applications. During this study, we also detected micro-fracture features, such as possible fracture wings and microscopic linear impact traces (MILTs).With further studies, the morphometric traits of these micro-fracture features could be useful for distinguishing between ancient weapon-delivery systems

The SKX 1084 hominin patella from Swartkrans Member 2, South Africa: An integrated analysis of its outer morphology and inner structure

SKX 1084 is an isolated partial patella from Swartkrans Member 2, South Africa, attributed to a small-bodied Paranthropus robustus. This study provides complementary information on its outer conformation and, for the first time for a fossil hominin patella, documents its inner structure in the perspective of adding biomechanically-related evidence to clarify its identity. We used X-ray micro-tomography to investigate SKX 1084 and to extract homologous information from a sample of 12 recent human, one Neanderthal, and two adult Pan, patellae. We used geometric morphometrics to compare the outer equatorial contours. In SKX 1084, we identified two cancellous bony spots suitable for textural assessment (trabecular bone volume fraction, trabecular thickness, degree of anisotropy), and two related virtual slices for measuring the maximum cortico-trabecular thickness (CTT) of the articular surface. SKX 1084 shows a more complex articular shape than that for Pan, but still simpler than typical in Homo sapiens. At all sites, its CTT is thinner compared to Pan and approaches the condition in humans. This is also true for the expanded volume of the cancellous network. However, at both investigated spots, SKX 1084 is systematically intermediate between Homo and Pan for trabecular bone volume fraction and trabecular thickness, a pattern already shown in previous analyses on other Paranthropus postcranial remains. In the absence of any structural signal from patellae unambiguously sampling Paranthropus, as well as of comparable evidence extracted from specimens representing early Homo, our results do not allow rejection of the original taxonomic attribution of SKX 1084

Further morphological evidence on South African earliest Homo lower postcanine dentition: Enamel thickness and enamel dentine junction

The appearance of the earliest members of the genus Homo in South Africa represents a key event in human evolution. Although enamel thickness and enamel dentine junction (EDJ) morphology preserve important information about hominin systematics and dietary adaptation, these features have not been sufficiently studied with regard to early Homo. We used micro-CT to compare enamel thickness and EDJ morphology among the mandibular postcanine dentitions of South African early hominins (N = 30) and extant Homo sapiens (N = 26), with special reference to early members of the genus Homo. We found that South African early Homo shows a similar enamel thickness distribution pattern to modern humans, although three-dimensional average and relative enamel thicknesses do not distinguish australopiths, early Homo, and modern humans particularly well. Based on enamel thickness distributions, our study suggests that a dietary shift occurred between australopiths and the origin of the Homo lineage. We also observed that South African early Homo postcanine EDJ combined primitive traits seen in australopith molars with derived features observed in modern human premolars. Our results confirm that some dental morphological patterns in later Homo actually occurred early in the Homo lineage, and highlight the taxonomic value of premolar EDJ morphology in hominin species

The TM 1517 odontoskeletal assemblage from Kromdraai B, South Africa, and the maturational pattern of Paranthropus robustus

The holotype of Paranthropus robustus was discovered by R. Broom in 1938 in an outcrop of bone breccia at the cave site of Kromdraai B, in Gauteng, South Africa [1]. It consists of the left half of a cranium (TM 1517a) and an associated right mandibular corpus (TM 1517b), both bearing teeth, and of seven isolated teeth (a LLP3, a LLP4 and the series URP3-M3 labelled as TM 1517c). A few weeks later, close to the block containing the cranial remains, Broom identified four postcranial elements: the distal end of a right humerus (TM 1517g), the partial proximal end of a right ulna (TM 1517e), and two toe bones (TM 1517k and TM 1517o), all at the time attributed to the same young individual represented by the cranial remains. However, the distal foot phalanx TM 1517o was subsequently attributed to a baboon. While the holotype has been variously referred to as a 'young female', a 'young adult', as 'probably male and immature', or as a 'late adolescent', it certainly represents a dentally immature individual. Since these early descriptions, no study has explored the possibility that the associated postcranial remains preserve evidence of active bone growth or recent epiphyseal closure. Clearly, however, such information would either strengthen, or challenge the idea that the craniodental and postcranial remains belong to a single P. robustus individual and, importantly, might provide the first evidence about the odontoskeletal maturational pattern of this fossil taxon. Accordingly, we performed a micro-XCT-based study aimed at characterising the inner structure of the distal humerus TM 1517g, the proximal ulna TM 1517e and the distal hallucial phalanx TM 1517k. Our 2-3D analyses show that the distal humerus was likely completely fused, while the proximal ulna still displays a faint remnant of fusion, and the distal hallucial phalanx shows evidence of still growing bone. These findings, as well as the observation that the distal humerus and the proximal ulna fit anatomically and morpho-dimensionally [2], provide support for the original attribution of the cranial and the three postcranial remains from Kromdraai B to a single individual representing the P. robustus type specimen. Using extant human dental standards, the age at death estimate of TM 1517 is of 16.5±3 years if based on the LM2 (not fully closed distal apices) and LM3 root developmental stages (root formation stage between half and three-quarters completed). The skeletal age ranges between 14 and 18 years, for a male, and between 11 and 15 years, for a female individual. When a chimpanzee dental growth pattern is considered, TM 1517 fits the c. 10.5 years 'older juvenile' group [3], while chimpanzee skeletal maturity standards place it between 7.95 and 13.5 years. Interestingly, in humans fusion of the distal hallucial phalanx commonly slightly precedes that of the distal humerus. However, a sequence of distal humerus-distal hallucial phalanx-proximal ulna fusion, as displayed by TM 1517, is usually observed in Pan. Taken together, this new evidence for TM 1517 more closely resembles the chimpanzee condition for maturational patterning. This finding is broadly in line with the evidence observed for Australopithecus sediba [4] and Homo erectus from Nariokotome [5]. Nevertheless, since P. robustus seems characterised by sexual bimaturism (with the males experiencing prolonged growth), the uncertain sex attribution of TM 1517 still represents a limiting interpretative factor

Evaluation of the inion and asterion as neurosurgical landmarks for dural venous sinuses: osteological study on a sample of South African skull specimens

BACKGROUND : Sub-Saharan neurosurgeons most likely need to perform invasive procedures without the latest imaging and navigation technology in the operating room. Therefore, these surgeons need to utilize other methods such as superficial surface landmarks for neuro-navigation. Bony landmarks, including the inion and asterion, are commonly used during invasive procedures to pinpoint the location of the confluence of sinuses and transverse-sigmoid sinus junction, respectively. The purpose of this study was to investigate whether the inion and asterion can be used as superficial landmarks for the confluence of sinuses and the transverse-sigmoid sinus junction, respectively, in a South African population. METHODS : Fifty South African human skulls were used (25 male, 25 female). The micro-focus X-ray radiography and tomography facility (MIXRAD) at Necsa scanned and created three-dimensional virtual images of the skull specimens. Reference points were then inserted on the images and the relation between bony landmarks and venous sinuses was documented. RESULTS : The inion was directly related to the confluence of sinuses in 4% of the sample, whereas the asterion was directly related to the transverse-sigmoid sinus junction in 28% of the cases, on both the right and left sides. CONCLUSIONS : This study confirmed that neither the inion, nor the asterion, are directly related the confluence of sinuses and transverse-sigmoid sinus junction, respectively. These bony landmarks are more likely to be located either inferior, or not related at all, to the investigated dural venous sinuses.https://www.minervamedica.it/en/journals/neurosurgical-sciences2022-04-01hj2022Anatom

Inner structural organization of the distal humerus in Paranthropus and Homo

The taxonomic attribution of isolated hominin distal humeri has been a matter of uncertainty and disagreement notwithstanding their relative abundance in the fossil record. Four taxonomically-based morphotypes, respectively representing P. boisei, P. robustus, non-erectus early Homo and H. erectus, have been identified based on the cross-sectional outer shape variation of an assemblage of Plio-Pleistocene eastern and southern African specimens (Lague, 2015). However, the existence of possible differences between Paranthropus and Homo in the inner structural organisation at this skeletal site remains unexplored. We used noninvasive imaging techniques to tentatively characterize the endostructural organization of five early Pleistocene distal humeri from South Africa (TM 1517g, SK 24600, SKX 10924, SKX 34805) and Ethiopia (Gombore IB), which have been variably attributed to Paranthropus or Homo. While the investigated specimens reveal diverse degrees of inner preservation related to their taphonomic and diagenetic history, in all but SK 24600 from Swartkrans we could comparatively assess some geometric properties at the most distal cross-sectional level (%CA, Ix/Iy, Imax/Imin) and quantify cortical bone thickness topographic variation across the preserved shaft portions by means of a 2-3D Relative Cortical Thickness index. Whenever possible, we also provided details about the site-specific organization of the cancellous network and measured the same parameters in a comparative sample of twelve adult extant humans. For most features, our results indicate two main patterns: the first includes the specimens TM 1517g, SKX 10924 and SKX 34805, while the second endostructural morphotype sets apart the robust Homo aff. erectus Gombore IB specimen from Melka Kunture, which more closely resembles the condition displayed by our comparative human sample. Notably, marked differences in the amount and pattern of proximodistal cortical bone distribution have been detected between Gombore IB and SKX 34805 from Swartkrans. Given its discordant outer and inner signatures, we conclude that the taxonomic status of SKX 34805 deserves further investigations

Efficiency of neutron tomography in visualizing the internal structure of metal artefacts from Mapungubwe museum collection with the aim of conservation

To aid conservation management of metal artefacts improved knowledge of the internal structure and degree of corrosion therein is highly desired. In this study, neutron- and X-ray tomography were chosen as two complementary noninvasive visualization techniques to study internal structure and corrosion of five representative examples of archaeological metal artefacts from the Mapungubwe museum collection. Tomography was performed at the Neutron Radiography (SANRAD) facility of the South African Nuclear Energy Corporation where thermal neutrons as well as complementary X-rays are conveniently available under one roof. Comparative studies revealed neutron tomography to be generally superior to X-ray tomography due to the enhanced penetration properties of neutrons through the metal objects. In this paper the rich capability of neutron tomography as a nondestructive visualization aid for scientific conservation purposes is introduced and supported by results achieved for the five selected real artefacts.http://www.sciencedirect.com/science/journal/12962074cp201

Earliest hominin cancer: 1.7-million-year old osteosarcoma from Swartkrans Cave, South Africa

The reported incidence of neoplasia in the extinct human lineage is rare, with only a few confirmed cases of Middle or Later Pleistocene dates reported. It has generally been assumed that premodern incidence of neoplastic disease of any kind is rare and limited to benign conditions, but new fossil evidence suggests otherwise. We here present the earliest identifiable case of malignant neoplastic disease from an early human ancestor dated to 1.8–1.6 million years old. The diagnosis has been made possible only by advances in 3D imaging methods as diagnostic aids. We present a case report based on re-analysis of a hominin metatarsal specimen (SK 7923) from the cave site of Swartkrans in the Cradle of Humankind, South Africa. The expression of malignant osteosarcoma in the Swartkrans specimen indicates that whilst the upsurge in malignancy incidence is correlated with modern lifestyles, there is no reason to suspect that primary bone tumours would have been any less frequent in ancient specimens. Such tumours are not related to lifestyle and often occur in younger individuals. As such, malignancy has a considerable antiquity in the fossil record, as evidenced by this specimen

Harnessing Thor's Hammer: Experimentally induced lightning trauma to human bone by high impulse current

Lightning fatality identification relies primarily on soft tissue traumatic pattern recognition, prohibiting cause of death identification in cases of full skeletonisation. This study explores the effects of high impulse currents on human bone, simulating lightning-level intensities and characterising electrically induced micro-trauma through conventional thin-section histology and micro-focus X-ray computed tomography (μXCT). An experimental system for high impulse current application was applied to bone extracted from donated cadaveric lower limbs (n = 22). μXCT was undertaken prior to and after current application. Histological sections were subsequently undertaken. μXCT poorly resolved micro-trauma compared to conventional histology which allowed for identification and classification of lightning-specific patterns of micro-trauma. Statistical analyses demonstrated correlation between current intensity, extent and damage typology suggesting a multifaceted mechanism of trauma propagation - a combination of electrically, thermally and pressure induced alterations. This study gives an overview of high impulse current trauma to human bone, providing expanded definitions of associated micro-trauma