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1.
Biology (Basel) ; 11(8)2022 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-36009790

RESUMO

Ancient DNA from, Neandertal and modern human fossils, and comparative morphological analyses of them, reveal a complex history of interbreeding between these lineages and the introgression of Neandertal genes into modern human genomes. Despite substantial increases in our knowledge of these events, the timing and geographic location of hybridization events remain unclear. Six measures of facial size and shape, from regional samples of Neandertals and early modern humans, were used in a multivariate exploratory analysis to try to identify regions in which early modern human facial morphology was more similar to that of Neandertals, which might thus represent regions of greater introgression of Neandertal genes. The results of canonical variates analysis and hierarchical cluster analysis suggest important affinities in facial morphology between both Middle and Upper Paleolithic early modern humans of the Near East with Neandertals, highlighting the importance of this region for interbreeding between the two lineages.

2.
Elife ; 102021 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-34812141

RESUMO

Adaptations of the lower back to bipedalism are frequently discussed but infrequently demonstrated in early fossil hominins. Newly discovered lumbar vertebrae contribute to a near-complete lower back of Malapa Hominin 2 (MH2), offering additional insights into posture and locomotion in Australopithecus sediba. We show that MH2 possessed a lower back consistent with lumbar lordosis and other adaptations to bipedalism, including an increase in the width of intervertebral articular facets from the upper to lower lumbar column ('pyramidal configuration'). These results contrast with some recent work on lordosis in fossil hominins, where MH2 was argued to demonstrate no appreciable lordosis ('hypolordosis') similar to Neandertals. Our three-dimensional geometric morphometric (3D GM) analyses show that MH2's nearly complete middle lumbar vertebra is human-like in overall shape but its vertebral body is somewhat intermediate in shape between modern humans and great apes. Additionally, it bears long, cranially and ventrally oriented costal (transverse) processes, implying powerful trunk musculature. We interpret this combination of features to indicate that A. sediba used its lower back in both bipedal and arboreal positional behaviors, as previously suggested based on multiple lines of evidence from other parts of the skeleton and reconstructed paleobiology of A. sediba.


One of the defining features of humans is our ability to walk comfortably on two legs. To achieve this, our skeletons have evolved certain physical characteristics. For example, the lower part of the human spine has a forward curve that supports an upright posture; whereas the lower backs of chimpanzees and other apes ­ which walk around on four limbs and spend much of their time in trees ­ lack this curvature. Studying the fossilized back bones of ancient human remains can help us to understand how we evolved these features, and whether our ancestors moved in a similar way. Australopithecus sediba was a close-relative of modern humans that lived about two million years ago. In 2008, fossils from an adult female were discovered at a cave site in South Africa called Malapa. However, the fossils of the lower back region were incomplete, so it was unclear whether the female ­ referred to as Malapa Hominin 2 (MH2) ­ had a forward-curving spine and other adaptations needed to walk on two legs. Here, Williams et al. report the discovery of new A. sediba fossils from Malapa. The new fossils are mainly bones from the lower back, and they fit together with the previously discovered MH2 fossils, providing a nearly complete lower spine. Analysis of the fossils suggested that MH2 would have had an upright posture and comfortably walked on two legs, and the curvature of their lower back was similar to modern females. However, other aspects of the bones' shape suggest that as well as walking, A. sediba probably spent a significant amount of time climbing in trees. The findings of Williams et al. provide new insights in to our evolutionary history, and ultimately, our place in the natural world around us. Our lower back is prone to injury and pain associated with posture, pregnancy and exercise (or lack thereof). Therefore, understanding how the lower back evolved may help us to learn how to prevent injuries and maintain a healthy back.


Assuntos
Dorso/anatomia & histologia , Fósseis/anatomia & histologia , Hominidae/anatomia & histologia , Animais , Feminino , Hominidae/fisiologia , Locomoção , Postura
3.
Am J Primatol ; 82(2): e23088, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31961002

RESUMO

A primate's body mass covaries with numerous ecological, physiological, and behavioral characteristics. This versatility and potential to provide insight into an animal's life has made body mass prediction a frequent and important objective in paleoanthropology. In hominin paleontology, the most commonly employed body mass prediction equations (BMPEs) are "mechanical" and "morphometric": uni- or multivariate linear regressions incorporating dimensions of load-bearing skeletal elements and stature and living bi-iliac breadth as predictor variables, respectively. The precision and accuracy of BMPEs are contingent on multiple factors, however, one of the most notable and pervasive potential sources of error is extrapolation beyond the limits of the reference sample. In this study, we use a test sample requiring extrapolation-56 bonobos (Pan paniscus) from the Lola ya Bonobo sanctuary in Kinshasa, Democratic Republic of the Congo-to evaluate the predictive accuracy of human-based morphometric BMPEs. We first assess systemic differences in stature and bi-iliac breadth between humans and bonobos. Due to significant differences in the scaling relationships of body mass and stature between bonobos and humans, we use panel regression to generate a novel BMPE based on living bi-iliac breadth. We then compare the predictive accuracy of two previously published morphometric equations with the novel equation and find that the novel equation predicts bonobo body mass most accurately overall (41 of 56 bonobos predicted within 20% of their observed body mass). The novel BMPE is particularly accurate between 25 and 45 kg. Given differences in limb proportions, pelvic morphology, and body tissue composition between the human reference and bonobo test samples, we find these results promising and evaluate the novel BMPE's potential application to fossil hominins.


Assuntos
Antropometria/métodos , Peso Corporal , Pan paniscus/fisiologia , Animais , República Democrática do Congo , Feminino , Hominidae , Masculino
4.
J Hum Evol ; 133: 61-77, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31358184

RESUMO

The abundant femoral assemblage of Homo naledi found in the Dinaledi Chamber provides a unique opportunity to test hypotheses regarding the taxonomy, locomotion, and loading patterns of this species. Here we describe neck and shaft cross-sectional structure of all the femoral fossils recovered in the Dinaledi Chamber and compare them to a broad sample of fossil hominins, recent humans, and extant apes. Cross-sectional geometric (CSG) properties from the femoral neck (base of neck and midneck) and diaphysis (subtrochanteric region and midshaft) were obtained through CT scans for H. naledi and through CT scans or from the literature for the comparative sample. The comparison of CSG properties of H. naledi and the comparative samples shows that H. naledi femoral neck is quite derived with low superoinferior cortical thickness ratio and high relative cortical area. The neck appears superoinferiorly elongated because of two bony pilasters on its superior surface. Homo naledi femoral shaft shows a relatively thick cortex compared to the other hominins. The subtrochanteric region of the diaphysis is mediolaterally elongated resembling early hominins while the midshaft is anteroposteriorly elongated, indicating high mobility levels. In term of diaphyseal robusticity, the H. naledi femur is more gracile that other hominins and most apes. Homo naledi shows a unique combination of characteristics in its femur that undoubtedly indicate a species committed to terrestrial bipedalism but with a unique loading pattern of the femur possibly consequence of the unique postcranial anatomy of the species.


Assuntos
Fêmur/anatomia & histologia , Fósseis/anatomia & histologia , Hominidae/anatomia & histologia , Animais , Densidade Óssea , Diáfises/anatomia & histologia , Diáfises/fisiologia , Fêmur/fisiologia , Colo do Fêmur/anatomia & histologia , Colo do Fêmur/fisiologia , Hominidae/fisiologia , África do Sul
5.
Am J Phys Anthropol ; 170(1): 5-23, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31228254

RESUMO

OBJECTIVES: The femoral remains recovered from the Lesedi Chamber are among the most complete South African fossil hominin femora discovered to date and offer new and valuable insights into the anatomy and variation of the bone in Homo naledi. While the femur is one of the best represented postcranial elements in the H. naledi assemblage from the Dinaledi Chamber, the fragmentary and commingled nature of the Dinaledi femoral remains has impeded the assessment of this element in its complete state. MATERIALS AND METHODS: Here we analyze and provide descriptions of three new relatively well-preserved femoral specimens of H. naledi from the Lesedi Chamber: U.W. 102a-001, U.W. 102a-003, and U.W. 102a-004. These femora are quantitatively and qualitatively compared to multiple extinct hominin femoral specimens, extant hominid taxa, and, where possible, each other. RESULTS: The Lesedi femora are morphologically similar to the Dinaledi femora for all overlapping regions, with differences limited to few traits of presently unknown significance. The Lesedi distal femur and mid-diaphysis preserve anatomy previously unidentified or unconfirmed in the species, including an anteroposteriorly expanded midshaft and anteriorly expanded patellar surface. The hypothesis that the Lesedi femoral sample may represent two individuals is supported. DISCUSSION: The Lesedi femora increase the range of variation of femoral morphology in H. naledi. Newly described features of the diaphysis and distal femur are either taxonomically uninformative or Homo-like. Overall, these three new femora are consistent with previous functional interpretations of the H. naledi lower limb as belonging to a species adapted for long distance walking and, possibly, running.


Assuntos
Fêmur , Fósseis , Hominidae , Animais , Antropologia Física , Evolução Biológica , Fêmur/anatomia & histologia , Fêmur/fisiologia , Hominidae/anatomia & histologia , Hominidae/fisiologia , Humanos , África do Sul , Caminhada/fisiologia
6.
J Hum Evol ; 130: 36-44, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31010542

RESUMO

Humans are thought to exhibit an unusual suite of life history traits relative to other primates, with a longer lifespan, later age at first reproduction, and shorter interbirth interval. These assumptions are key components of popular hypotheses about human life history evolution, but they have yet to be investigated phylogenetically. We applied two phylogenetic comparative methods to investigate whether these human life history traits differ from expectations based on other primates: one fits and selects between Brownian and Ornstein-Uhlenbeck models of trait evolution; the other tests for phylogenetic outliers by predicting phenotypic characteristics based on trait covariation and phylogeny for a species of interest. We found that humans have exceptionally short interbirth intervals, long lifespans, and high birth masses. We failed to find evidence that humans have a delayed age at first reproduction relative to body mass or other covariates. Overall, our results support several previous assertions about the uniqueness of human life history characteristics and the importance of cooperative breeding and socioecology in human life history evolution. However, we suggest that several hypotheses about human life history need to be revised in light of our finding that humans do not have a delayed age at first reproduction.


Assuntos
Evolução Biológica , Traços de História de Vida , Filogenia , Primatas/fisiologia , Reprodução , Animais , Humanos
7.
Am J Phys Anthropol ; 166(1): 179-195, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29369332

RESUMO

OBJECTIVES: Predicting body mass is a frequent objective of several anthropological subdisciplines, but there are few published methods for predicting body mass in immature humans. Because most reference samples are composed of adults, predicting body mass outside the range of adults requires extrapolation, which may reduce the accuracy of predictions. Prediction equations developed from a sample of immature humans would reduce extrapolation for application to small-bodied target individuals, and should have utility in multiple predictive contexts. MATERIALS AND METHODS: Here, we present two novel body mass prediction equations derived from 3468 observations of stature and bi-iliac breadth from a large sample of immature humans (n = 173) collected in the Harpenden Growth Study. Prediction equations were generated using raw and natural log-transformed data and modeled using panel regression, which accounts for serial autocorrelation of longitudinal observations. Predictive accuracy was gauged with a global sample of human juveniles (n = 530 age- and sex-specific annual means) and compared to the performance of the adult morphometric prediction equation previously identified as most accurate for human juveniles. RESULTS: While the raw data panel equation is only slightly more accurate than the adult equation, the logged data panel equation generates very accurate body mass predictions across both sexes and all age classes of the test sample (mean absolute percentage prediction error = 2.47). DISCUSSION: The logged data panel equation should prove useful in archaeological, forensic, and paleontological contexts when predictor variables can be measured with confidence and are outside the range of modern adult humans.


Assuntos
Antropometria/métodos , Peso Corporal/fisiologia , Modelos Estatísticos , Adolescente , Estatura , Índice de Massa Corporal , Criança , Pré-Escolar , Feminino , Humanos , Ílio/anatomia & histologia , Masculino
8.
J Hum Evol ; 125: 122-136, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-29169681

RESUMO

In the hominin fossil record, pelvic remains are sparse and are difficult to attribute taxonomically when they are not directly associated with craniodental material. Here we describe the pelvic remains from the Dinaledi Chamber in the Rising Star cave system, Cradle of Humankind, South Africa, which has produced hominin fossils of a new species, Homo naledi. Though this species has been attributed to Homo based on cranial and lower limb morphology, the morphology of some of the fragmentary pelvic remains recovered align more closely with specimens attributed to the species Australopithecus afarensis and Australopithecus africanus than they do with those of most (but not all) known species of the genus Homo. As with A. afarensis and A. africanus, H. naledi appears to have had marked lateral iliac flare and either a weakly developed or non-existent acetabulocristal buttress or a distinct, albeit weakly developed, acetabulospinous buttress. At the same time, H. naledi has robust superior pubic and ischiopubic rami and a short ischium with a narrow tuberoacetabular sulcus, similar to those found in modern humans. The fragmentary nature of the Dinaledi pelvic assemblage makes the attribution of sex and developmental age to individual specimens difficult, which in turn diminishes our ability to identify the number of individuals represented in the assemblage. At present, we can only confidently say that the pelvic fossils from Rising Star represent at least four individuals based on the presence of four overlapping right ischial fossils (whereas a minimum of 15 individuals can be identified from the Dinaledi dental assemblage). A primitive, early Australopithecus-like false pelvis combined with a derived Homo-like true pelvis is morphologically consistent with evidence from the lower ribcage and proximal femur of H. naledi. The overall similarity of H. naledi ilia to those of australopiths supports the inference, drawn from the observation of primitive pelvic morphology in the extinct species Homo floresiensis, that there is substantial variation in pelvic form within the genus Homo. In the light of these findings, we urge caution in making taxonomic attributions-even at the genus level-of isolated fossil ossa coxae.


Assuntos
Fósseis/anatomia & histologia , Hominidae/anatomia & histologia , Pelve/anatomia & histologia , Animais , Cavernas , África do Sul
9.
J Hum Evol ; 115: 65-77, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28476281

RESUMO

Body mass is an ecologically and biomechanically important variable in the study of hominin biology. Regression equations derived from recent human samples allow for the reasonable prediction of body mass of later, more human-like, and generally larger hominins from hip joint dimensions, but potential differences in hip biomechanics across hominin taxa render their use questionable with some earlier taxa (i.e., Australopithecus spp.). Morphometric prediction equations using stature and bi-iliac breadth avoid this problem, but their applicability to early hominins, some of which differ in both size and proportions from modern adult humans, has not been demonstrated. Here we use mean stature, bi-iliac breadth, and body mass from a global sample of human juveniles ranging in age from 6 to 12 years (n = 530 age- and sex-specific group annual means from 33 countries/regions) to evaluate the accuracy of several published morphometric prediction equations when applied to small humans. Though the body proportions of modern human juveniles likely differ from those of small-bodied early hominins, human juveniles (like fossil hominins) often differ in size and proportions from adult human reference samples and, accordingly, serve as a useful model for assessing the robustness of morphometric prediction equations. Morphometric equations based on adults systematically underpredict body mass in the youngest age groups and moderately overpredict body mass in the older groups, which fall in the body size range of adult Australopithecus (∼26-46 kg). Differences in body proportions, notably the ratio of lower limb length to stature, influence predictive accuracy. Ontogenetic changes in these body proportions likely influence the shift in prediction error (from under- to overprediction). However, because morphometric equations are reasonably accurate when applied to this juvenile test sample, we argue these equations may be used to predict body mass in small-bodied hominins, despite the potential for some error induced by differing body proportions and/or extrapolation beyond the original reference sample range.


Assuntos
Antropologia Física/métodos , Peso Corporal , Hominidae/fisiologia , Animais , Criança , Feminino , Humanos , Masculino
10.
J Hum Evol ; 111: 119-138, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28874266

RESUMO

Homo erectus and later humans have enlarged body sizes, reduced sexual dimorphism, elongated lower limbs, and increased encephalization compared to Australopithecus, together suggesting a distinct ecological pattern. The mosaic expression of such features in early Homo, including Homo habilis, Homo rudolfensis, and some early H. erectus, suggests that these traits do not constitute an integrated package. We examined the evidence for body mass, stature, limb proportions, body size and dental size dimorphism, and absolute and relative brain size in Homo naledi as represented in the Dinaledi Chamber sample. H. naledi stature and body mass are low compared to reported values for H. erectus, with the exception of some of the smaller bodied Dmanisi H. erectus specimens, and overlap with larger Australopithecus and early Homo estimates. H. naledi endocranial volumes (465-560 cc) and estimates of encephalization quotient are also similar to Australopithecus and low compared to all Homo specimens, with the exception of Homo floresiensis (LB1) and the smallest Dmanisi H. erectus specimen (D4500). Unlike Australopithecus, but similar to derived members of genus Homo, the Dinaledi assemblage of H. naledi exhibits both low levels of body mass and dental size variation, with an estimated body mass index of sexual dimorphism less than 20%, and appears to have an elongated lower limb. Thus, the H. naledi bauplan combines features not typically seen in Homo species (e.g., small brains and bodies) with those characteristic of H. erectus and more recent Homo species (e.g., reduced mass dimorphism, elongated lower limb).


Assuntos
Tamanho Corporal , Encéfalo/anatomia & histologia , Fósseis/anatomia & histologia , Hominidae/anatomia & histologia , Caracteres Sexuais , Animais , Evolução Biológica , Humanos , Úmero/anatomia & histologia , Tamanho do Órgão , Tíbia/anatomia & histologia , Dente/anatomia & histologia
11.
Elife ; 62017 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-28483039

RESUMO

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.


Assuntos
Fósseis , Hominidae , Animais , Cavernas , África do Sul
12.
J Hum Evol ; 104: 32-49, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28317555

RESUMO

Cervical vertebrae are rare in the early hominin fossil record, presenting a challenge for understanding the evolution of the neck and head carriage in hominin evolution. Here, we examine the cervical vertebrae of Australopithecus sediba, which unlike other South African taxa is known from associated cervical vertebrae. The A. sediba cervical vertebrae exhibit human-like values for wedging, pedicle cross-sectional areas, and articular facet heights, indicating reduced ventral loading relative to African apes. These features combine with a pattern of vertebral body bone distribution and caudally progressive size expansion suggesting a mode of cervical lordosis, load mitigation, and head carriage similar to humans and distinct from the cantilevered mode of head carriage of the extant African great apes. Yet these derived features in A. sediba are accompanied by ape-like vertebral body and dorsal pillar sizes, articular facet orientation, and uncinate process morphology signaling reduced lateral and rotational coupled movements between vertebral elements and indicate a considerably stiffer neck than in humans. A primitively long and horizontally-oriented C7 spinous process is likely related to a prognathic viscerocranium, although the complimentary C3 spinous process is short, implying large moments emanating from scapular and shoulder elevators rather than large muscles of head stabilization. Cross-sectional spinous process shape and robust anterior tubercles similarly signal increased arm elevation consistent with climbing behavior in corroboration with arboreal signatures previously observed in the shoulder, arms, and hand of A. sediba. Spinal canal shape and size suggests that A. sediba lacked the cervical spinal cord enlargement of Homo that confers humans with enhanced motor control to the upper limbs. The cervical spine of A. sediba thus presents a mosaic of primitive and derived characters, with anatomical features relating to neck posture and head carriage mirroring humans juxtaposed with most other aspects of functional anatomy that resemble chimpanzees.


Assuntos
Vértebras Cervicais/anatomia & histologia , Fósseis/anatomia & histologia , Hominidae/anatomia & histologia , Animais , Feminino , Masculino , África do Sul
13.
J Hum Evol ; 104: 136-154, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28094004

RESUMO

Hominin evolution featured shifts from a trunk shape suitable for climbing and housing a large gut to a trunk adapted to bipedalism and higher quality diets. Our knowledge regarding the tempo, mode, and context in which these derived traits evolved has been limited, based largely on a small-bodied Australopithecus partial skeleton (A.L. 288-1; "Lucy") and a juvenile Homo erectus skeleton (KNM-WT 15000; "Turkana Boy"). Two recent discoveries, of a large-bodied Australopithecus afarensis (KSD-VP-1/1) and two Australopithecus sediba partial skeletons (MH1 and MH2), have added to our understanding of thorax evolution; however, little is known about thorax morphology in early Homo. Here we describe hominin vertebrae, ribs, and sternal remains from the Dinaledi chamber of the Rising Star cave system attributed to Homo naledi. Although the remains are highly fragmented, the best-preserved specimens-two lower thoracic vertebrae and a lower rib-were found in association and belong to a small-bodied individual. A second lower rib may belong to this individual as well. All four of these individual elements are amongst the smallest known in the hominin fossil record. H. naledi is characterized by robust, relatively uncurved lower ribs and a relatively large spinal canal. We expect that the recovery of additional material from Rising Star Cave will clarify the nature of these traits and shed light on H. naledi functional morphology and phylogeny.


Assuntos
Fósseis/anatomia & histologia , Hominidae/anatomia & histologia , Costelas/anatomia & histologia , Coluna Vertebral/anatomia & histologia , Animais , Evolução Biológica , África do Sul
14.
J Hum Evol ; 104: 174-204, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27855981

RESUMO

This paper describes the 108 femoral, patellar, tibial, and fibular elements of a new species of Homo (Homo naledi) discovered in the Dinaledi chamber of the Rising Star cave system in South Africa. Homo naledi possesses a mosaic of primitive, derived, and unique traits functionally indicative of a bipedal hominin adapted for long distance walking and possibly running. Traits shared with australopiths include an anteroposteriorly compressed femoral neck, a mediolaterally compressed tibia, and a relatively circular fibular neck. Traits shared with Homo include a well-marked linea aspera, anteroposteriorly thick patellae, relatively long tibiae, and gracile fibulae with laterally oriented lateral malleoli. Unique features include the presence of two pillars on the superior aspect of the femoral neck and a tubercular distal insertion of the pes anserinus on the tibia. The mosaic morphology of the H. naledi thigh and leg appears most consistent with a species intermediate between Australopithecus spp. and Homo erectus and, accordingly, may offer insight into the nature of the earliest members of genus Homo. These fossils also expand the morphological diversity of the Homo lower limb, perhaps indicative of locomotor diversity in our genus.


Assuntos
Fósseis/anatomia & histologia , Hominidae/anatomia & histologia , Ossos da Perna/anatomia & histologia , Animais , Evolução Biológica , África do Sul
15.
J Hum Evol ; 104: 155-173, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27839696

RESUMO

The evolutionary transition from an ape-like to human-like upper extremity occurred in the context of a behavioral shift from an upper limb predominantly involved in locomotion to one adapted for manipulation. Selection for overarm throwing and endurance running is thought to have further shaped modern human shoulder girdle morphology and its position about the thorax. Homo naledi (Dinaledi Chamber, Rising Star Cave, Cradle of Humankind, South Africa) combines an australopith-like cranial capacity with dental characteristics akin to early Homo. Although the hand, foot, and lower limb display many derived morphologies, the upper limb retains many primitive traits. Here, we describe the H. naledi upper extremity (excluding the hand) in detail and in a comparative context to evaluate the diversity of clavicular, scapular, humeral, radial, and ulnar morphology among early hominins and later Homo. Homo naledi had a scapula with a markedly cranially-oriented glenoid, a humerus with extremely low torsion, and an australopith-like clavicle. These traits indicate that the H. naledi scapula was situated superiorly and laterally on the thorax. This shoulder girdle configuration is more similar to that of Australopithecus and distinct from that of modern humans, whose scapulae are positioned low and dorsally about the thorax. Although early Homo erectus maintains many primitive clavicular and humeral features, its derived scapular morphology suggests a loss of climbing adaptations. In contrast, the H. naledi upper limb is markedly primitive, retaining morphology conducive to climbing while lacking many of the derived features related to effective throwing or running purported to characterize other members of early Homo.


Assuntos
Ossos do Braço/anatomia & histologia , Fósseis/anatomia & histologia , Hominidae/anatomia & histologia , Animais , Evolução Biológica , África do Sul
16.
Nat Commun ; 6: 8431, 2015 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-26441219

RESUMO

A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, South Africa. Based on associated hominin material, the bones of this hand are attributed to Homo naledi. This hand reveals a long, robust thumb and derived wrist morphology that is shared with Neandertals and modern humans, and considered adaptive for intensified manual manipulation. However, the finger bones are longer and more curved than in most australopiths, indicating frequent use of the hand during life for strong grasping during locomotor climbing and suspension. These markedly curved digits in combination with an otherwise human-like wrist and palm indicate a significant degree of climbing, despite the derived nature of many aspects of the hand and other regions of the postcranial skeleton in H. naledi.


Assuntos
Fósseis , Ossos da Mão/anatomia & histologia , Hominidae/anatomia & histologia , Polegar/anatomia & histologia , Punho/anatomia & histologia , Animais , Evolução Biológica , Gorilla gorilla/anatomia & histologia , Mãos/anatomia & histologia , Humanos , Homem de Neandertal/anatomia & histologia , Pan paniscus/anatomia & histologia , Pan troglodytes/anatomia & histologia
17.
Elife ; 42015 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-26354289

RESUMO

We describe the physical context of the Dinaledi Chamber within the Rising Star cave, South Africa, which contains the fossils of Homo naledi. Approximately 1550 specimens of hominin remains have been recovered from at least 15 individuals, representing a small portion of the total fossil content. Macro-vertebrate fossils are exclusively H. naledi, and occur within clay-rich sediments derived from in situ weathering, and exogenous clay and silt, which entered the chamber through fractures that prevented passage of coarser-grained material. The chamber was always in the dark zone, and not accessible to non-hominins. Bone taphonomy indicates that hominin individuals reached the chamber complete, with disarticulation occurring during/after deposition. Hominins accumulated over time as older laminated mudstone units and sediment along the cave floor were eroded. Preliminary evidence is consistent with deliberate body disposal in a single location, by a hominin species other than Homo sapiens, at an as-yet unknown date.


Assuntos
Fenômenos Químicos , Fósseis , Sedimentos Geológicos , Hominidae/classificação , Animais , Humanos , África do Sul
18.
Elife ; 42015 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-26354291

RESUMO

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.


Assuntos
Hominidae/anatomia & histologia , Hominidae/classificação , Animais , Antropometria , Humanos , Filogenia , África do Sul
19.
J Forensic Sci ; 60(1): 21-8, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25382679

RESUMO

Sex determination is critical for developing the biological profile of unidentified skeletal remains. When more commonly used elements (os coxa, cranium) for sexing are not available, methods utilizing other skeletal elements are needed. This study aims to assess the degree of sexual dimorphism of the lumbar vertebrae and develop discriminant functions for sex determination from them, using a sample of South African blacks from the Raymond A. Dart Collection (47 males, 51 females). Eleven variables at each lumbar level were subjected to univariate and multivariate discriminant function analyses. Univariate equations produced classification rates ranging from 57.7% to 83.5%, with the highest accuracies associated with dimensions of the vertebral body. Multivariate stepwise analysis generated classification rates ranging from 75.9% to 88.7%. These results are comparable to other methods for sexing the skeleton and indicate that measures of the lumbar vertebrae can be used as an effective tool for sex determination.


Assuntos
Vértebras Lombares/anatomia & histologia , Determinação do Sexo pelo Esqueleto/métodos , Análise Discriminante , Feminino , Antropologia Forense , Humanos , Masculino , África do Sul , Articulação Zigapofisária/anatomia & histologia
20.
Anat Rec (Hoboken) ; 298(1): 168-79, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25339238

RESUMO

Neandertals and Homo sapiens are known to differ in scapular glenoid fossa morphology. Functional explanations may be appropriate for certain aspects of glenoid fossa morphology; however, other factors--e.g., allometry, evolutionary development--must be addressed before functional morphology is considered. Using three-dimensional geometric morphometrics, shape of the scapular glenoid fossa was compared among Neandertals, early and recent modern humans, chimpanzees, orangutans, Australopithecus afarensis, and Au. sediba. Permutation analysis revealed that side, sex, and lifestyle did not correlate with shape. Of the features we found to differ between groups, anterior glenoid rim morphology and fossa curvature did not correlate with the aforementioned shape variables; thus, a functional explanation is appropriate for these components of glenoid fossa shape. Shared morphology among recent humans and chimpanzees (to the exclusion of Neandertals and orangutans) suggests independent forces contributing to these morphological configurations. Potential explanations include adaptations to habitual behavior and locomotor adaptations in the scapulae of recent humans and chimpanzees; these explanations are supported by clinical and experimental literature. The absence of these morphological features in Neandertals may support the lack of these selective forces on their scapular glenoid fossa morphology.


Assuntos
Evolução Biológica , Cavidade Glenoide/anatomia & histologia , Cavidade Glenoide/fisiologia , Matemática , Homem de Neandertal/anatomia & histologia , Homem de Neandertal/fisiologia , Adaptação Fisiológica/fisiologia , Animais , Fenômenos Biomecânicos/fisiologia , Humanos , Imageamento Tridimensional , Locomoção/fisiologia , Pan troglodytes/anatomia & histologia , Pan troglodytes/fisiologia , Pongo/anatomia & histologia , Pongo/fisiologia , Análise de Componente Principal
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