scholarly journals Accessory cusp expression at the enamel-dentine junction of hominin mandibular molars

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11415
Author(s):  
Thomas W. Davies ◽  
Zeresenay Alemseged ◽  
Agness Gidna ◽  
Jean-Jacques Hublin ◽  
William H. Kimbel ◽  
...  
Keyword(s):  
Type Specimen ◽  
Homo Erectus ◽  
Enamel Surface ◽  
Distal Margin ◽  
Dental Morphology ◽  
Australopithecus Afarensis ◽  
Opposite Pattern ◽  
Mandibular Molars ◽  
Homo Habilis ◽  
Occlusal Wear

Studies of hominin dental morphology frequently consider accessory cusps on the lower molars, in particular those on the distal margin of the tooth (C6 or distal accessory cusp) and the lingual margin of the tooth (C7 or lingual accessory cusp). They are often utilized in studies of hominin systematics, where their presence or absence is assessed at the outer enamel surface (OES). However, studies of the enamel-dentine junction (EDJ) suggest these traits may be more variable in development, morphology and position than previously thought. Building on these studies, we outline a scoring procedure for the EDJ expression of these accessory cusps that considers the relationship between these accessory cusps and the surrounding primary cusps. We apply this scoring system to a sample of Plio-Pleistocene hominin mandibular molars of Paranthropus robustus, Paranthropus boisei, Australopithecus afarensis, Australopithecus africanus, Homo sp., Homo habilis and Homo erectus from Africa and Asia (n = 132). We find that there are taxon-specific patterns in accessory cusp expression at the EDJ that are consistent with previous findings at the OES. For example, P. robustus M1s and M2s very often have a distal accessory cusp but no lingual accessory cusp, while H. habilis M1s and M2s show the opposite pattern. The EDJ also reveals a number of complicating factors; some apparent accessory cusps at the enamel surface are represented at the EDJ only by shouldering on the ridges associated with the main cusps, while other accessory cusps appear to have little or no EDJ expression at all. We also discuss the presence of double and triple accessory cusps, including the presence of a double lingual accessory cusp on the distal ridge of the metaconid in the type specimen of H. habilis (OH 7–M1) that is not clear at the OES due to occlusal wear. Overall, our observations, as well as our understanding of the developmental underpinnings of cusp patterning, suggest that we should be cautious in our comparisons of accessory cusps for taxonomic interpretations.

scholarly journals Homoplasy in the evolution of modern human-like joint proportions in Australopithecus afarensis

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Anjali M Prabhat ◽  
Catherine K Miller ◽  
Thomas Cody Prang ◽  
Jeffrey Spear ◽  
Scott A Williams ◽  
...  
Keyword(s):  
Upper Limb ◽  
Lower Limb ◽  
Modern Human ◽  
Homo Erectus ◽  
Australopithecus Afarensis ◽  
Modern Humans ◽  
Homo Habilis ◽  
Hominin Evolution ◽  
Parsimonious Explanation ◽  
Phylogenetic Hypotheses

The evolution of bipedalism and reduced reliance on arboreality in hominins resulted in larger lower limb joints relative to the joints of the upper limb. The pattern and timing of this transition, however, remains unresolved. Here, we find the limb joint proportions of Australopithecus afarensis, Homo erectus, and Homo naledi to resemble those of modern humans, whereas those of A. africanus, Australopithecus sediba, Paranthropus robustus, Paranthropus boisei, Homo habilis, and Homo floresiensis are more ape-like. The homology of limb joint proportions in A. afarensis and modern humans can only be explained by a series of evolutionary reversals irrespective of differing phylogenetic hypotheses. Thus, the independent evolution of modern human-like limb joint proportions in A. afarensis is a more parsimonious explanation. Overall, these results support an emerging perspective in hominin paleobiology that A. afarensis was the most terrestrially adapted australopith despite the importance of arboreality throughout much of early hominin evolution.

Plio-pleistocene Hominids: Epistemological and Taxonomic Problems

1970 ◽  
Vol 9 (1) ◽  
pp. 169-202
Author(s):  
Jolanta Koszteyn
Keyword(s):  
Homo Sapiens ◽  
Single Species ◽  
Homo Erectus ◽  
Australopithecus Afarensis ◽  
Homo Heidelbergensis ◽  
Genealogical Tree ◽  
Homo Neanderthalensis ◽  
Homo Habilis ◽  
Homo Antecessor ◽  
Historical Times

Within the historical times, which roughly corresponds with the Holocene epoch, the whole of mankind is believed to be a single species. Homo sapiens. But the human genealogical tree (phylogeny) is populated by a really astounding number of paleontological species and paleontological genera: Ardipithecus ramidus, Australopithecus anamensis, Australopithecus afarensis, Australopithecus africanus, Paranthropus robustus, Paranthropus boisei, Homo habilis, Homo georgicus. Homo erectus, Homo ergaster, Homo antecessor, Homo heidelbergensis, Homo neanderthalensis, Homo sapiens. (cf. Gyula 2002). In fact there are many more (Sahelanthropus tchadensis, Orrorin tugenensis, Kenyanthropus platyops, Australopithecus garhi, Australopithecus aethiopicus) but Foley (2002), quite reasonably, states that the evidence for their existence is, at present, insufficient. The existence of these multiple forms is beyond any doubt. The doubt, however arises concerning the human or „prehuman" status of them. Were they really true specific forms, half-way between the apes and Holocene man? Is it possible that they constitute a number of different ecotypes (or paleoraces) within the same natural species of Homo sapiens?

The Continuum of Psychosis and Its Genetic Origins

1990 ◽  
Vol 156 (6) ◽  
pp. 788-797 ◽  
Author(s):  
T. J. Crow
Keyword(s):  
Sex Chromosome ◽  
Homo Sapiens ◽  
Polymorphic Marker ◽  
Cerebral Dominance ◽  
Homo Erectus ◽  
Evolutionary Development ◽  
Pseudoautosomal Region ◽  
Sibling Pairs ◽  
Homo Habilis ◽  
Y Chromosomes

Attempts to draw a line of genetic demarcation between schizophrenic and affective illnesses have failed. It must be assumed that these diseases are genetically related. A post-mortem study has demonstrated that enlargement of the temporal horn of the lateral ventricle in schizophrenia but not in Alzheimer-type dementia is selective to the left side of the brain. This suggests that the gene for psychosis is the ‘cerebral dominance gene‘, the factor that determines the asymmetrical development of the human brain. That the psychosis gene is located in the pseudoautosomal region of the sex chromosomes is consistent with observations that sibling pairs with schizophrenia are more often than would be expected of the same sex and share alleles of a polymorphic marker at the short-arm telomeres of the X and Y chromosomes above chance expectation. That the cerebral dominance gene also is pseudoautosomal is suggested by the pattern of verbal and performance deficits associated with sex-chromosome aneuploidies. The psychoses may thus represent aberrations of a late evolutionary development underlying the recent and rapid increase in brain weight in the transition fromAustralopithecusthroughHomo habilisandHomo erectustoHomo sapiens.

scholarly journals Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Lee R Berger ◽  
John Hawks ◽  
Darryl J de Ruiter ◽  
Steven E Churchill ◽  
Peter Schmid ◽  
...  
Keyword(s):  
South Africa ◽  
Single Species ◽  
Homo Erectus ◽  
Cranial Morphology ◽  
Human Populations ◽  
Early Homo ◽  
Homo Habilis ◽  
Cave System ◽  
Unknown Species ◽  
Cradle Of Humankind

Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.

scholarly journals Thoracic vertebral count and thoracolumbar transition in Australopithecus afarensis

2017 ◽  
Vol 114 (23) ◽  
pp. 6000-6004 ◽  
Author(s):  
Carol V. Ward ◽  
Thierra K. Nalley ◽  
Fred Spoor ◽  
Paul Tafforeau ◽  
Zeresenay Alemseged
Keyword(s):  
Vertebral Column ◽  
Cervical Vertebrae ◽  
Homo Erectus ◽  
Thoracic Vertebrae ◽  
Australopithecus Afarensis ◽  
Australopithecus Africanus ◽  
African Apes ◽  
Thoracic Level ◽  
Thoracolumbar Transition ◽  
Considerable Discussion

The evolution of the human pattern of axial segmentation has been the focus of considerable discussion in paleoanthropology. Although several complete lumbar vertebral columns are known for early hominins, to date, no complete cervical or thoracic series has been recovered. Several partial skeletons have revealed that the thoracolumbar transition in early hominins differed from that of most extant apes and humans. Australopithecus africanus, Australopithecus sediba, and Homo erectus all had zygapophyseal facets that shift from thoracic-like to lumbar-like at the penultimate rib-bearing level, rather than the ultimate rib-bearing level, as in most humans and extant African apes. What has not been clear is whether Australopithecus had 12 thoracic vertebrae as in most humans, or 13 as in most African apes, and where the position of the thoracolumbar transitional element was. The discovery, preparation, and synchrotron scanning of the Australopithecus afarensis partial skeleton DIK-1-1, from Dikika, Ethiopia, provides the only known complete hominin cervical and thoracic vertebral column before 60,000 years ago. DIK-1-1 is the only known Australopithecus skeleton to preserve all seven cervical vertebrae and provides evidence for 12 thoracic vertebrae with a transition in facet morphology at the 11th thoracic level. The location of this transition, one segment cranial to the ultimate rib-bearing vertebra, also occurs in all other early hominins and is higher than in most humans or extant apes. At 3.3 million years ago, the DIK-1-1 skeleton is the earliest example of this distinctive and unusual pattern of axial segmentation.

How We Got Here: Evolutionary Changes in Skull Shape in Humans & Their Ancestors

2012 ◽  
Vol 74 (2) ◽  
pp. 106-110 ◽  
Author(s):  
Rebecca M. Price
Keyword(s):  
Homo Sapiens ◽  
Homo Erectus ◽  
Australopithecus Afarensis ◽  
Skull Shape ◽  
Evolutionary Changes

This activity uses inquiry to investigate how large changes in shape can evolve from small changes in the timing of development. Students measure skull shape in fetal, infant, juvenile, and adult chimpanzees and compare them to adult skulls of Homo sapiens, Homo erectus, and Australopithecus afarensis. They conclude by re-interpreting their findings in light of Ardipithecus ramidus.

The Origins of Speech

1998 ◽  
Vol 8 (1) ◽  
pp. 69-94 ◽  
Keyword(s):  
Vocal Tract ◽  
Careful Analysis ◽  
Spoken Language ◽  
Homo Erectus ◽  
Homo Habilis ◽  
Early Hominids ◽  
Heated Debate ◽  
The Subject ◽  
The One ◽  
The Brain

Spoken language is one of the defining human characteristics — the crucial accomplishment which makes us human and separates us from other species. Naturally enough, the origins of this accomplishment — which must lie somewhere back in the Palaeolithic — have been the subject of lively and often heated debate, not least since speech leaves no direct material residues. Many people have sought to resolve the question by careful analysis of the material remains of early hominids. But do patterns of tool-making or evidence of sophisticated subsistence strategies really provide an adequate base from which to deduce the presence of linguistic ability? Furthermore, is language inextricably bound up with the ability to vocalize and to speak? Are studies of the vocal tract of Neanderthals or Homo erectus really relevant to the question of language origins?The wide diversity of view on the antiquity of human spoken language is very clear from the brief contributions which make up this feature. On the one hand is the evidence for the presence of Broca's and Wernicke's areas in the brain of Homo habilis around 2 million years ago. Does this provide grounds for believing that Homo habilis could speak? Did the use of tools as icons by Homo erectus play a key role in the development of human spoken language? Or should we instead go along with the growing consensus — supported by many linguists —that spoken language is a late addition to the range of human abilities, originating along with fully modern humans only within the last 200,000 years? And dare we go even further, and nominate Africa as the locus of language origin?The time may come when we are able to specify not only when human spoken language first developed, but also where. For the present, however, the debate shows no sign of imminent resolution. In the pages which follow, we bring together the views of archaeologists from a number of different backgrounds; but we begin with a linguist's perspective, and seven propositions to set the scene for the archaeological enquiry.

Anthropological Approach of the Proximal Tooth Area: A Systematic Review

2020 ◽  
Vol 7 ◽  
Author(s):  
Tabchi Yosra ◽  
Rajae El Haddaoui ◽  
Assmae Bahoum ◽  
Fatima Zaoui
Keyword(s):  
Homo Sapiens ◽  
Contact Region ◽  
Contact Point ◽  
Homo Erectus ◽  
Dental Wear ◽  
Homo Habilis ◽  
Cochrane Database ◽  
Choice Of Treatment ◽  
Masticatory System ◽  
Anthropological Literature

An analysis of dental anthropological literature dealing with the dental wear of prehistoric men, reveals that little information about interproximal dental attrition and its evolution with the modern man is available. This observation marked anthropologists and dentists for long. The objective of this review is to determine the origin of the interproximal contact region of the tooth. In other words, which interproximal contact was first to appear in human dentitions? Is it the interproximal contact point or the contact surface?An electronic search was performed in four databases: PUBMED, SCOPUS, Cochrane Database, and EBSCO. Our search was limited to articles in English. We included in our research dental and anthropological studies concerning Homo sapiens and excluded all the other species such as Homo Habilis, Homo Erectus, Homo Rhudolfensis, and Homo Neandertalensis. Attritional occlusion and flattened proximal facets are considered some of the main characteristics of the masticatory system of nonindustrialized men. Theories and dental researches tried to explain the proliferation of malocclusion and severe tooth crowding in modern society.The study of dental wear is a path of research that highlights the evolution of the manducatory system and thus, it influences the choice of treatment in our practices.

scholarly journals Endocast morphology of Homo naledi from the Dinaledi Chamber, South Africa

2018 ◽  
Vol 115 (22) ◽  
pp. 5738-5743 ◽  
Author(s):  
Ralph L. Holloway ◽  
Shawn D. Hurst ◽  
Heather M. Garvin ◽  
P. Thomas Schoenemann ◽  
William B. Vanti ◽  
...  
Keyword(s):  
South Africa ◽  
Great Apes ◽  
Homo Erectus ◽  
Behavioral Evolution ◽  
Homo Habilis ◽  
Endocranial Volume

Hominin cranial remains from the Dinaledi Chamber, South Africa, represent multiple individuals of the species Homo naledi. This species exhibits a small endocranial volume comparable to Australopithecus, combined with several aspects of external cranial anatomy similar to larger-brained species of Homo such as Homo habilis and Homo erectus. Here, we describe the endocast anatomy of this recently discovered species. Despite the small size of the H. naledi endocasts, they share several aspects of structure in common with other species of Homo, not found in other hominins or great apes, notably in the organization of the inferior frontal and lateral orbital gyri. The presence of such structural innovations in a small-brained hominin may have relevance to behavioral evolution within the genus Homo.

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