Research Articles (Evolutionary Studies Institute)

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Developmental simulation of the adult cranial morphology of australopithecus sediba.
(Academy of Science of South Africa (ASSAf), 2016-07) Carlson, K.B.; De Ruiter, D.J.; Dewitt, T.J.; Mcnuity, K.P.; Tafforeau, P.; Berger, L.R.; Carlson, K.J.
The type specimen of Australopithecus sediba (MH1) is a late juvenile, prompting some commentators to suggest that had it lived to adulthood its morphology would have changed sufficiently so as to render hypotheses regarding its phylogenetic relations suspect. Considering the potentially critical position of this species with regard to the origins of the genus Homo, a deeper understanding of this change is especially vital. As an empirical response to this critique, a developmental simulation of the MH1 cranium was carried out using geometric morphometric techniques to extrapolate adult morphology using extant male and female chimpanzees, gorillas and humans by modelling remaining development. Multivariate comparisons of the simulated adult A. sediba crania with other early hominin taxa indicate that subsequent cranial development primarily reflects development of secondary sexual characteristics and would not likely be substantial enough to alter suggested morphological affinities of A. sediba. This study also illustrates the importance of separating developmental vectors by sex when estimating ontogenetic change. Results of the ontogenetic projections concur with those from mandible morphology, and jointly affirm the taxonomic validity of A. sediba.
Earliest hominin cancer: 1.7-million-year- old osteosarcoma from Swartkrans Cave, South Africa
(Academy of Science of South Africa (ASSAf), 2016-07) Odes, E.J.; Randolph-Quinney, P.S.; Steyn, M.; Thockmorton, Z.; Smilg, J.S.; Zipfel, B.; Augustine, T.N.; de Beer, F.; Hoffman, J.W.; Franklin, R.D.; Berger, L.R.
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.
A hominin first rib discovered at the Sterkfontein Caves, South Africa.
(Academy of Science of South Africa (ASSAf), 2016-05) Tawane, G.; Garcia-Martinez, D.; Eyre, J.; Bastir, M.; Berger, L.R.; Schmid, P.; Nalla, S.; Williams, S.A.
First ribs - the first or most superior ribs in the thorax - are rare in the hominin fossil record, and when found, have the potential to provide information regarding the upper thorax shape of extinct hominins. Here, we describe a partial first rib from Member 4 of the Sterkfontein Caves, South Africa. The rib shaft is broken away, so only the head and neck are preserved. The rib is small, falling closest to small-bodied Australopithecus first ribs (AL 288-1 and MH1). Given that it was recovered near the StW 318 femur excavation, which also represents a small individual, we suggest that the two may be associated. Three-dimensional geometric morphometric analyses were used to quantify the rib fragment morphology and compare it to extant hominoid and other fossil hominin ribs. While only the proximal end is preserved, our analyses show that South African Australopithecus share derived features of the proximal first rib more closely resembling A. afarensis and later hominins than great apes.
Homo naledi and Pleistocene hominin evolution in subequatorial Africa
(eLife Sciences Publications Ltd, 2017-05) Berger, L.R.; Hawks, J.; Dirks, P.H.G.M.; Elliott, M.; Roberts, E.M.
New discoveries and dating of fossil remains from the Rising Star cave system, Cradle of Humankind, South Africa, have strong implications for our understanding of Pleistocene human evolution in Africa. Direct dating of Homo naledi fossils from the Dinaledi Chamber (Berger et al., 2015) shows that they were deposited between about 236 ka and 335 ka (Dirks et al., 2017), placing H. naledi in the later Middle Pleistocene. Hawks and colleagues (Hawks et al., 2017) report the discovery of a second chamber within the Rising Star system (Dirks et al., 2015) that contains H. naledi remains. Previously, only large-brained modern humans or their close relatives had been demonstrated to exist at this late time in Africa, but the fossil evidence for any hominins in subequatorial Africa was very sparse. It is now evident that a diversity of hominin lineages existed in this region, with some divergent lineages contributing DNA to living humans and at least H. naledi representing a survivor from the earliest stages of diversification within Homo. The existence of a diverse array of hominins in subequatorial comports with our present knowledge of diversity across other savanna-adapted species, as well as with palaeoclimate and paleoenvironmental data. H. naledi casts the fossil and archaeological records into a new light, as we cannot exclude that this lineage was responsible for the production of Acheulean or Middle Stone Age tool industries.
New fossil remains of Homo naledi from the Lesedi Chamber, South Africa
(eLife Sciences Publications Ltd, 2017-05) Hawks, J.; Elliott, M.; Schmid, P.; Churchill, S.E.; de Ruiter, D.J.; Roberts, E.M.; Hilbert-Wolf, H.; Garvin, H.M.; Williams, S.A.; Delezene, L.K.; Feuerriegel, E.M.; Randolph-Quinney, P.; Kivell, T.L.; Laird, M.F.; Tawane, G.; DeSilva, J.M.; Bailey, S.E.; Brophy, J.K.; Meyer, M.R.; Skinner, M.M.; Tocheri, M.W.; VanSickle, C.; Walker, C.S.; Campbell, T.L.; Kuhn, B.; Kruger, A.; Tucker, S.; Gurtov, A.; Hlophe, N.; Hunter, R.; Morris, H.; Peixotto, B.; Ramalepa, M.; van Rooyen, D.; Tsikoane, M.; Boshoff, P.; Dirks, P.H.G.M.; Berger, L.R.
The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi. Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species.
Osteogenic tumour in Australopithecus sediba: Earliest hominin evidence for neoplastic disease
(Academy of Science of South Africa (ASSAf)., 2016-07) Randolph-Quinney, P.S.; Williams, S.A.; Steyn, M.; Meyer, M.R.; Smilg, J.S.; Churchill, S.E.; Odes, E.J.; Augustine, T.; Tafforeau, P.; Berger, L.R.
We describe the earliest evidence for neoplastic disease in the hominin lineage. This is reported from the type specimen of the extinct hominin Australopithecus sediba from Malapa, South Africa, dated to 1.98 million years ago. The affected individual was male and developmentally equivalent to a human child of 12 to 13 years of age. A penetrating lytic lesion affected the sixth thoracic vertebra. The lesion was macroscopically evaluated and internally imaged through phase-contrast X-ray synchrotron microtomography. A comprehensive differential diagnosis was undertaken based on gross- and micro-morphology of the lesion, leading to a probable diagnosis of osteoid osteoma. These neoplasms are solitary, benign, osteoid and bone-forming tumours, formed from well-vascularised connective tissue within which there is active production of osteoid and woven bone. Tumours of any kind are rare in archaeological populations, and are all but unknown in the hominin record, highlighting the importance of this discovery. The presence of this disease at Malapa predates the earliest evidence of malignant neoplasia in the hominin fossil record by perhaps 200 000 years.
The stable isotope setting of Australopithecus sediba at Malapa, South Africa.
(Academic of Science of South Africa (ASSAf), 2016-07) Holt, E.; Dirks, P.; PLaczek, C.; Berger, L.R.
We report delta C-13 and delta O-18 results from carbonate-cemented cave sediments at Malapa in South Africa. The sediments were deposited during a short-period magnetic reversal at 1.977±0.003 Ma, immediately preceding deposition of Facies D sediments that contain the type fossils of Australopithecus sediba. Values of delta C-13 range between -5.65 and -2.09 with an average of -4.58±0.54% (Vienna Pee Dee Belemnite, VPDB) and values of delta O-18 range between -6.14 and -3.84 with an average of -4.93±0.44% (VPDB). Despite signs of diagenetic alteration from metastable aragonite to calcite, the Malapa isotope values are similar to those obtained in two previous studies in South Africa for the same relative time period. Broadly, the Malapa delta C-13 values provide constraints on the palaeovegetation at Malapa. Because of the complex nature of the carbonate cements and mixed mineralogy in the samples, our estimates of vegetation type (C4-dominant) must be regarded as preliminary only. However, the indication of a mainly C4 landscape is in contrast to the reported diet of A. sediba, and suggests a diverse environment involving both grassland and riparian woodland.

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