The University of New South Wales
Department:Biological, Earth & Environmental Sciences
Position:Faculty Member
Darren started following the work of Chris Stringer.
Darren started following the work of Paul Constantino, Marshall University, Biology.
Darren added 10 papers
Papers
A 150- Year Conundrum: Cranial Robusticity and Its Bearing on the Origin of Aboriginal Australians
The origin of Aboriginal Australians has been a central question of palaeoanthropology since its inception during the 19th Century. Moreover, the idea that Australians could trace their ancestry to a non-modern Pleistocene population such as Homo erectus in Southeast Asia have existed for more than 100 years, being explicitly linked to cranial robusticity. It is argued here that in order to resolve this issue a new program of research should be embraced, one aiming to test the full range of alternative explanations for robust morphology. Recent developments in the morphological sciences, especially relating to the ontogeny of the cranium indicate that character atomisation, an approach underpinning phylogenetic reconstruction, is fraught with difficulties. This leads
to the conclusion that phylogenetic-based explanations for robusticity should be reconsidered and a more parsimonious approach to explaining Aboriginal Australian origins taken. One that takes proper account of the complex processes involved in the growth of the human cranium rather than just assuming natural selection to explain every subtle variation seen in past populations. In doing so, the null hypothesis that robusticity might result from phenotypic plasticity alone cannot be rejected, a position at odds with both reticulate and deep-time continuity models of Australian origins.
Download (.pdf) Evidence of Pathological Conditions In the Florisbad Cranium
Journal of Human Evolution
Palaeopathological studies of the middle Pleistocene cranium from Florisbad (Free State, South Africa) document the presence of extensive cortical lesions and areas of thinning, a widened medullary cavity with destruction of the diploë, orbital roof lesions, a benign ectocranial neoplasm, and evidence for alveolar destruction, resorption, and antemortem tooth loss. Differential diagnosis suggests one or more possible aetiologies, including a haematological disorder, metabolic condition(s), Paget’s disease of bone, or non-specific infection perhaps following trauma. Moreover, if not directly associated with those on the external vault, orbital lesions alone could have been caused by infection or an indeterminable factor such as pressure from an enlarged organ. Multiple parasagittal lesions on the internal vault cortex probably represent expansile lesions left by enlarged arachnoid granulations. A multifactorial model of pathogenesis may be most appropriate to account for dentoalveolar lesions and antemortem tooth loss. Additionally, there are clear indications of diagenetic alteration deep within the vault, as well as multiple signs of degeneration on the cranium. These complicate the assessment of pathological alterations and identification of their possible aetiology. The Florisbad cranium is the latest specimen to join the growing sample of Pleistocene hominin remains with non-fatal and non-trivial pathological disorders adding to understanding of early human ecology and lifestyle.
The craniomandibular mechanics of being human
Proceedings of the Royal Society B In press/on-line
Diminished bite force has been considered a defining feature of modern Homo sapiens, an interpretation inferred from the application of two-dimensional lever mechanics and the relative gracility of the human masticatory musculature and skull. This conclusion has various implications with regard to the evolution of human feeding behaviour. However, human dental anatomy suggests a capacity to withstand high loads and two-dimensional lever models greatly simplify muscle architecture, yielding less accurate results than three-dimensional modelling using multiple lines of action. Here, to our knowledge, in the most comprehensive three-dimensional finite element analysis performed to date for any taxon, we ask whether the traditional view that the bite of H. sapiens is weak and the skull too gracile to sustain high bite forces is supported. We further introduce a new method for reconstructing incomplete fossil material. Our findings show that the human masticatory apparatus is highly efficient, capable of producing a relatively powerful bite using low muscle forces. Thus, relative to other members of the superfamily Hominoidea, humans can achieve relatively high bite forces, while overall stresses are reduced. Our findings resolve apparently discordant lines of evidence, i.e. the presence of teeth well adapted to sustain high loads within a lightweight cranium and mandible.
A review of early Homo in southern Africa focusing on cranial, mandibular and dental remains, with the description of a new species (Homo gautengensis sp. nov.)
Homo-Journal of Comparative Human Biology
The southern African sample of early Homo is playing an increasingly important role in understanding the origins, diversity and adaptations of the human genus. Yet, the affinities and classification of these remains continue to be in a state of flux. The southern African sample derives from five karstic palaeocave localities and represents more than one-third of the total African sample for this group; sampling an even wider range of anatomical regions than the eastern African collection. Morphological and phenetic comparisons of southern African specimens covering dental, mandibular and cranial remains demonstrate this sample to contain a species distinct from known early Homo taxa. The new species Homo gautengensis sp. nov. is described herein: type specimen Stw 53; Paratypes SE 255, SE 1508, Stw 19b/33, Stw 75–79, Stw 80, Stw 84, Stw 151, SK 15, SK 27, SK 45, SK 847, SKX 257/258, SKX 267/268, SKX 339, SKX 610, SKW 3114 and DNH 70. H. gautengensis is identified from fossils recovered at three palaeocave localities with current best ages spanning not, vert, similar2.0 to 1.26–0.82 million years BP. Thus, H. gautengensis is probably the earliest recognised species in the human genus and its longevity is apparently well in excess of H. habilis.
Naturalism and style in Jinsha River rock art, China and the Magdalenian art of Europe: creative cognates or curious coincidence?
Cambridge Archaeological Journal
The naturalistic rock art of Yunnan Province is poorly known outside of China despite two decades of investigation by local researchers. The authors report on the first major international study of this art, its place in antiquity and its resemblance to some of the rock art of Europe, southern Africa and elsewhere. While not arguing a direct connection between China, Europe and other widely separated places, this article suggests that rock-art studies about the nature of style, culture contact and the transmission of iconography across space and time need to take better account of the results of neuroscience research, similar economic/ecological circumstances and the probability of independent invention.
A multi-disciplinary seriation of Homo and Paranthropus bearing palaeocave deposits in southern Africa
Quaternary International
Fossils of early Homo and Paranthropus have been recovered from several sites in southern Africa. Unfortunately, their precise age has historically been difficult to assess, hampering the reconstruction of their relationships to each other and to fossils from eastern Africa. Multi-dating strategies combining biochronological, archaeological, palaeomagnetic, electron spin resonance (ESR) and uranium series techniques are now clarifying their age. The following sequencing of sites is suggested: Swartkrans Member 1 (not, vert, similar2.0 Ma), Gondolin (not, vert, similar1.8 Ma), Kromdraai (1.8–1.7 Ma), Sterkfontein M5A (1.8–1.4 Ma), Swartkrans M2 (1.7–1.1 Ma), Sterkfontein M5B (1.4–1.1 Ma), Sterkfontein M5C (1.3–0.8 Ma), Swartkrans M3 (not, vert, similar1.0–0.6 Ma). The position of Coopers D and Drimolen is difficult to access because they only have faunal age ranges (1.9–1.6 Ma). ESR suggests mixing is a potential major problem in multi-generational sites. The oldest southern African representatives of early Homo and Paranthropus occur around 2.1–1.9 Ma in Swartkrans Member 1 and are recorded almost continuously in the palaeocave deposits until around 1.0–0.6 Ma in Swartkrans Member 3. Currently, these data suggest that Paranthropus and Homo first occur significantly later in the southern African record than the eastern African record. Moreover, Paranthropus persists much later in southern Africa than in eastern Africa.
Sexual dimorphism in Southeast Asian crania: a geometric morphometric approach
Homo-Journal of Comparative Human Biology
Despite a number of studies stating that sexual dimorphism is population specific, sexual differences in Southeast Asian populations have received little attention. Previous studies in this region have focused on samples from Thailand or East Asian populations from China and Japan, examining sexual dimorphism predominantly of the postcranial bones, teeth and mandible with comparatively few cranial studies. These earlier studies have used traditional methods to metrically assess differences between the sexes. The aim of this study is to use geometric morphometric methods for the first time to quantify sexual dimorphism of Southeast Asian crania and extend knowledge of cranial sexual dimorphism beyond China, Japan and Thailand. A total of 35 unilateral and midline landmark coordinates were collected from 144 mainland and island Southeast Asian crania (89 male, 55 female). Using the shape analysis software Morphologika, principal components analysis and thin plate splines allowed for the statistical and visual exploration of shape differences. Differences included relative facial breadth, particularly across the zygomatic and postorbital regions and cranial vault breadth. Significant size dimorphism was also apparent. Overall expected accuracies were highest in the discriminant analysis using both shape and centroid size (86.8%).
Possible causes and significance of cranial robusticity among Pleistocene and early Holocene Australians
Journal of Archaeological Science
An analysis of possible developmental-functional causes of cranial form suggests that the morphology of ‘robust’ Pleistocene/Early Holocene Australians such as Willandra Lakes Human 50 might best be explained by four underlying factors: possession of a (1) large neurocranium, (2) narrow cranial base, (3) viscerocranium with considerable midfacial projection, and (4) large dentition, especially the cheek teeth, with their associated large jaws and high volume masticatory muscles. Some of these features are likely to be highly heritable, while others are caused/exaggerated by influences from ageing processes, diet, and a hunter-gatherer lifestyle in an arid environment. These underlying ‘causes’ are either apomorphies of Homo sapiens (1 and 2) and thus absent from pre-modern specimens such as from Ngandong, or represent plesiomorphic features of latter Homo (3 and 4). It is concluded that combining current knowledge of cranial development-function with genetic studies of the population history of Aboriginal Australians provides the most parsimonious solution to understanding their origins.
High-Resolution Three-Dimensional Computer Simulation of Hominid Cranial Mechanics
The Anatomical Record
In vivo data demonstrates that strain is not distributed uniformly on the surface of the primate skull during feeding. However, in vivo studies are unable to identify or track changes in stress and strain throughout the whole structure. Finite element (FE) analysis, a powerful engineering tool long used to predict the performance of man-made devices, has the capacity to track stress/strain in three dimensions (3-D) and, despite the time-consuming nature of model generation, FE has become an increasingly popular analytical device among biomechanists. Here, we apply the finite element method using sophisticated computer models to examine whether 3-D stress and strain distributions are nonuniform throughout the primate skull, as has been strongly suggested by 2-D in vivo strain analyses. Our simulations document steep internal stress/strain gradients, using models comprising up to three million tetrahedral finite elements and 3-D reconstructions of jaw adducting musculature with both cranium and mandible in correct anatomical position. Results are in broad concurrence with the suggestion that few regions of the hominid cranium are clearly optimized for routine feeding and also show that external stress/strain does not necessarily reflect internal distributions. Findings further suggest that the complex heterogeneity of bone in the skull may act to dissipate stress, but that consequently higher strain must be offset by additional strain energy. We hypothesize that, despite energetic costs, this system may lend adaptive advantage through enhancing the organism's ability to modify its behavior before reaching catastrophic failure in bony or dental structures.
Characteristics of Pleistocene Megafauna Extinctions In Southeast Asia
Palaeogeography, Palaeoclimatology, Palaeoecology
The extinction of large-bodied taxa from the Pleistocene in Southeast Asia is examined. Although the chronological resolution of these extinctions is poor, and number of excavations in the region relatively few, broad characteristics of these extinctions can be
described. Many taxa which became extinct appear to have been endemic to regions within Southeast Asia, while some taxa which experienced extinction or severe range reduction occurred in several regions. Members of the latter group include proboscideans (Stegodon and Palaeloxodon), the pygmy hippopotamus Hexaprotodon), the orangutan (Pongo), hyenas (Crocuta and Hyaena), the giant panda (Ailuropoda), tapirs (Tapirus and Megatapirus), rhinoceroses (Rhinoceros), and the giant Asian ape Gigantopithecus. The loss of these species cannot be assigned to a single cause. Rather their disappearance is likely tied to both climatic
and human agents. Unlike other regions which experienced megafauna extinctions, eustatic changes in sea level in Southeast Asia seems to have been an important factor.
Affinities of the Swartkrans Early Homo mandibles
Homo-Journal of Comparative Human Biology
The southern African early Homo assemblage continues to make important contributions to understanding the systematics, adaptations and evolutionary history of the human genus. However, the taxonomy of this sample is in a state of flux. This study examines the size and shape of the mandibular bodies of Swartkrans SK 15 and SK 45 comparing them with variation in two early Homo taxa (H. habilis sensu lato and H. sapiens erectus). The research aims to clarify their phenetic affinities and systematics through univariate statistics, inferential testing and multivariate analysis employing size (Log-transformed) and shape (Mosimann variables). Neither of them strongly resembles H. habilis sensu lato or H. sapiens erectus, rather, they probably sample a novel species of Homo not seen in East Africa. Moreover, there is considerable morphological variability within the Swartkrans sample and the possibility of more than one novel species being sampled at this site cannot be excluded.
Description, new reconstruction, comparative anatomy, and classification of the Sterkfontein Stw 53 cranium, with discussions about the taxonomy of other southern African early Homo remains
Specimen Stw 53 was recovered in 1976 from Member 5 of the Sterkfontein Formation. Since its incomplete initial description and comparison, the partial cranium has figured prominently in discussions about the systematics of early Homo. Despite publication of a preliminary reconstruction in 1985, Stw 53 has yet to be compared comprehensively to other Plio-Pleistocene fossils or assessed systematically. In this paper, we report on a new reconstruction of this specimen and provide a detailed description and comparison of its morphology. Our reconstruction differs in important respects from the earlier one, especially in terms of neurocranial length, breadth, and height. However, given that Stw 53 exhibits extensive damage, these dimensions are most likely prone to much error in reconstruction. In areas of well-preserved bone, Stw 53 shares many cranial features with Homo habilis, and we propose retaining it within this species.
We also consider the affinities of dental remains from Sterkfontein Member 5, along with those from Swartkrans and Drimolen previously assigned to Homo. We find evidence for sympatry of H. habilis and Australopithecus robustus and possibly Plio-Pleistocene Homo sapiens sensu lato in Sterkfontein Member 5. At Swartkrans and Drimolen, we find evidence of H. habilis. We also compare the morphologies of Stw 53 and SK 847 and find compelling evidence to assign the latter specimen to H. habilis, as has been proposed.
On the Number of Ancestral Human Species
Encyclopedia of Life Sciences
The number of species within the human evolutionary tree remains a major point of debate. Genomic distances for living humans and other apes may be used to estimate hominin diversity and therefore to set boundaries for palaeontological scenarios. A minimum of five species is recognizable but scenarios involving much higher estimates of diversity cannot be ruled out.
Modern human origins in Australasia: Testing the predictions of competing models
Homo-Journal of Comparative Human Biology
The evolutionary background to the emergence of modern humans remains controversial. Four models have been proposed to explain this process and each has clearly definable and testable predictions about the geographical origins of early Australians and their possible biological interaction with other Pleistocene populations. The present study considers the phenetic affinities of early Australians from Kow Swamp (KS 1 and KS 5) and Keilor to Pleistocene Africans and Asians from calvarial dimensions. The study includes analyses employing log-transformed and size-corrected (Mosimann variables) data. The strongest signals to emerge are as follows: (1) a phenetic pattern in which Australians are most like each other, (2) all three crania possess a mosaic of archaic and modern features, (3) Kow Swamp crania also show strong affinities to archaic remains, (4) Keilor is more modern than KS 1 and KS 5 and (5) Keilor shows affinities to Pleistocene East Asian modern crania (Liujiang and Upper Cave 101) providing evidence for a broad regional morphology. The results refute the predictions of multi-species replacement models for early Australians but are consistent with single-species models. Combined with published evidence from DNA, the present study indicates that the Assimilation model presently offers the best explanation for the origins of Pleistocene Australians.
Timing and tempo of primate speciation
Journal of Evolutionary Biology
Published molecular clocks for primates are used to estimate typical divergence times for phylogroups (1.6 Ma), species (3.3 Ma), sister species (2.7 Ma), genera (8.9 Ma) and sister genera (8.6 Ma). Significant median differences exist between major groups (infraorders and superfamilies) for various divergence times. These data are employed to estimate typical maximum duration of speciation. Typical primate values (1.1 Ma) suggest this process to be faster than is characteristic of many vertebrates. However, after considering divergence times for hybridizing congeneric and confamilial primates, this value is likely only to estimate the commencement of prezygotic isolating mechanisms, rather than the completion of reproductive isolation. Thus, speciation typically takes around 1.0 Ma to more than 4.0 Ma to occur, depending on whether prezygotic or post-zygotic isolating mechanisms are emphasized. Typical primate genus age is around 5.3 Ma, but we note differences among major groups. In light of these estimates, the classification of humans and chimpanzees is reconsidered using a molecular yardstick approach. Three taxonomic frameworks may flow from molecular analyses, all of them having major implications for understanding the evolution of humans and chimpanzees.
The question of cranial robusticity
Before Farming
The existence of a morphologically robust Pleistocene Australian population has been controversial. This is largely due to the pivotal role this group has played in the multiregional model of modern human origins. Some researchers have argued that the robust morphology results at least in part from pseudopathology (artificial deformation) or pathology (haemoglobinopathy) rather than representing normal anatomical form. The present contribution puts these alternative explanations to the test. From a package of cranial deformation diagnostics, only one feature (frontal curvature index) suggests possible pseudopathology in one individual (Kow Swamp 5). Thus, the evidence for deformation even in this individual is at best weak. Further, there seems to be no evidence for pathological hyperostosis among Pleistocene Australians including robust crania. On the contrary, the robust morphology continues to be part of the variability characterising living Aborigines. Recently published luminescence dates for Kow Swamp are evaluated. We find that they provide reasonable dates for sediments at the site but are unrelated to buried human remains excavated at Kow Swamp during the 1970s.
Human origins in Australia: the skeletal evidence
Before Farming
This paper commences with a review of the anatomical and genetic evidence for the origins of Aboriginal Australians. Recent controversies surrounding the developmental age and sex of some Pleistocene individuals are reviewed. An updated description and new analyses of the morphological evidence for gracile and robust Pleistocene populations is provided utilising descriptive anatomy, metrics and multivariate analysis. Thirty-four cranial and dental features are outlined that differentiate gracile and robust Australians. Most metrical differences between them are moderate to large on a global scale. We also describe features in robust and gracile Australians that are unusual or apparently unique by contemporary human standards. At least four of them appear not to have been documented in modern humans until now.
Beyond Taung: paleoanthropological research at Groot Kloof, Ghaap Escarpment, Northern Cape Province, South Africa
Nyame Akuma 64, Dec. 2005
We describe some early findings of a project commencing in 2004 to investigate the palaeoanthropological potential of part of the escarpment of the Ghaap Plateau, Northern Cape and North West Provinces, South Africa. This escarpment contains the World Heritage site of Taung, but its potential for pre-Holocene research has remained largely
unexplored for the 80 years since the discovery of
these important hominin remains. The region is also
known for open fluvial and pan sites yielding Lower and Middle Pleistocene tool types and the long though, discontinuous sequence of Wonderwerk Cave. Surface collection and excavation of Groot Kloof site B have yielded fossils from the Florisian Land Mammal Age and lithics that may reflect a late ESA/early MSA type industry. Geological research at Groot Kloof site D provides a preliminary U-Th age for fossil-bearing tufa, and palaeomagnetic analyses show normal magnetic polarities throughout the locality. Together they suggest a late-Middle Pleistocene age for these deposits. Small largely intrusive pockets of LSA bearing breccia are also being investigated. The significance of our discovery is underscored by current debate about the emergence of modern humans.
Odontometric systematic assessment of the Swartkrans SK 15 mandible
Homo-Journal of Comparative Human Biology
This study reports a comparison of molar crown and cusp size and shape in the Swartkrans early Homo mandible SK 15 with relevant Plio-Pleistocene taxa. Univariate and multivariate methods are employed to consider the morphological affinities of this specimen and to assess its taxonomy. The case exists for classifying SK 15 in Homo habilis with 11 features aligning it with this species. The results of multivariate studies are consistent with this hypothesis. Moreover, SK 15 lacks a number of important features that characterise the mandibular molars of Homo sapiens erectus. Considerable evidence for parallelism in the dental morphology of SK 15 and H. habilis with A. robustus is discussed. Fossil evidence for the presence of H. sapiens erectus during the Plio-Pleistocene of South Africa presently seems to be lacking. Archaeological interpretations should take greater account of this gap in the fossil record.
Direct ESR dating of a Pliocene hominin from Swartkrans
Two fragments of a hominin tooth (Australopithecus robustus) and two bovid teeth from the Hanging Remnant of the Swartkrans Formation were analysed with ESR. Research was complicated by the fact that the samples came from a curated collection and their precise provenance is unknown. The environmental dose rate was reconstructed by a series of in situ gamma spectrometric measurements and elemental analyses of a range of sediment samples. U-series isotopic analyses indicated that each of the teeth had a significantly different uranium uptake history, rendering the assumptive early U-uptake and linear U-uptake models ineffective. ESR and U-series data were combined to calculate open system ages, resulting in a best estimate of 1630±160 ka for the Hanging Remnant. An open-system model which provides the maximum age for given U-series and ESR measurements yielded an estimate of about 2100 ka.
Two bovid teeth from Member 2, previously estimated to be between 1·0 and 2·0 Ma, yielded age estimates of between about 100 and 200 ka. No known geochemical processes are likely to explain this severe age underestimation. We conclude that these samples are of Middle to Upper Pleistocene age and their presence in Member 2 was either due to reworking or inadequate stratigraphical discrimination of these deposits.
Number of ancestral human species: a molecular perspective
Homo-Journal of Comparative Human Biology
Despite the remarkable developments in molecular biology over the past three decades, anthropological genetics has had only limited impact on systematics in human evolution. Genetics offers the opportunity to objectively test taxonomies based on morphology and may be used to supplement conventional approaches to hominid systematics. Our analyses, examining chromosomes and 46 estimates of genetic distance, indicate there may have been only around 4 species on the direct line to modern humans and 5 species in total. This contrasts with current taxonomies recognising up to 23 species.
The genetic proximity of humans and chimpanzees has been used to suggest these species are congeneric. Our analysis of genetic distances between them is consistent with this proposal. It is time that chimpanzees, living humans and all fossil humans be classified in Homo. The creation of new genera can no longer be a solution to the complexities of fossil morphologies. Published genetic distances between common chimpanzees and bonobos, along with evidence for interbreeding, suggest they should be assigned to a single species.
The short distance between humans and chimpanzees also places a strict limit on the number of possible evolutionary side branches that might be recognised on the human lineage. All fossil taxa were genetically very close to each other and likely to have been below congeneric genetic distances seen for many mammals.
Our estimates of genetic divergence suggest that periods of around 2 million years are required to produce sufficient genetic distance to represent speciation. Therefore, Neanderthals and so-called H. erectus were genetically so close to contemporary H. sapiens they were unlikely to have been separate species. Thus, it is likely there was only one species of human (H. sapiens) for most of the last 2 million years. We estimate the divergence time of H. sapiensfrom 16 genetic distances to be around 1.7 Ma which is consistent with evidence for the earliest migration out of Africa. These findings call into question the mitochondrial «African Eve» hypothesis based on a far more recent origin for H. sapiens and show that humans did not go through a bottleneck in their recent evolutionary history.
Given the large offset in evolutionary rates of molecules and morphology seen in human evolution, Homo species are likely to be characterised by high levels of morphological variation and low levels of genetic variability. Thus, molecular data suggest the limits for intraspecific morphological variation used by many palaeoanthropologists have been set too low. The role of phenotypic plasticity has been greatly underestimated in human evolution.
We call into question the use of mtDNA for studies of human evolution. This DNA is under strong selection, which violates the assumption of selective neutrality. This issue should be addressed by geneticists, including a reassessment of its use for molecular clocks. There is a need for greater cooperation between palaeoanthropologists and anthropological geneticists to better understand human evolution and to bring palaeoanthropology into the mainstream of evolutionary biology.
Problems with the use of cladistic analysis in palaeoanthropology
Homo-Journal of Comparative Human Biology
Cladistic analysis is a popular method for reconstructing evolutionary relationships on the human lineage. However, it has limitations and hidden assumptions that are often not considered by palaeoanthropologists. Some researchers who are opposed to its use regard cladistics as the preferred method for taxonomic «splitters» and claim it has lead to a revitalisation of typology. Typology remains a part of human evolutionary studies, regardless of the acceptance or use of cladistics. The assumption/preference for «splitting» over «lumping» in cladistics (alpha) taxonomy and the general failure to evaluate (post-hoc) such taxonomies have served to reinforce this assertion.
Researchers have also adopted a number of practices that are logically untenable or introduce considerable error. The evolutionary trend of human encephalisation, apparently isometric with body size, and concurrent reduction in the gut and masticatory apparatus, suggests continuous cladistic characters are biased by problems of body size.
The method suffers a logical weakness, or circularity, leading to bias when characters with multiple states are used. Coding of such characters can only be done using prior criteria, and this is usually done using an existing phylogenetic scheme. Another problem with coding character states is the handling of variation within species. While this form of variation is usually ignored by palaeoanthropologists, when characters are recognised as varying, their treatment as a separate state adds considerable error to cladograms.
The genetic proximity of humans, chimpanzees and gorillas has important implications for cladistic analyses. It is argued that chimpanzees and gorillas should be treated as ingroup taxa and an alternative outgroup such as orangutans should be used, or an (hypothetical) ancestral body plan developed. Making chimpanzees and gorillas ingroup taxa would considerably enhance the biological utility of anthropological cladograms.
All published human cladograms fail to meet standard quality criteria indicating that none of them may be considered reliable. The continuing uncertainty over the number and composition of fossil human species is the largest single source of error for cladistics and human phylogenetic reconstruction.
Australia's Oldest Human Remains: Age of the Lake Mungo 3 Skeleton
Journal of Human Evolution 36: 591-612
We have carried out a comprehensive ESR and U-series dating study on the Lake Mungo 3 (LM3) human skeleton. The isotopic Th/U and Pa/U ratios indicate that some minor uranium mobilization may have occurred in the past. Taking such effects into account, the best age estimate for the human skeleton is obtained through the combination of U-series and ESR analyses yielding 62,000±6000 years. This age is in close agreement with OSL age estimates on the sediment into which the skeleton was buried of 61,000±2000 years. Furthermore, we obtained a U-series age of 81,000±21,000 years for the calcitic matrix that was precipitated on the bones after burial. All age results are considerably older than the previously assumed age of LM3 and demonstrate the necessity for directly dating hominid remains. We conclude that the Lake Mungo 3 burial documents the earliest known human presence on the Australian continent. The age implies that people who were skeletally within the range of the present Australian indigenous population colonized the continent during or before oxygen isotope stage 4 (57,000–71,000 years).