Publications by authors named "Matthew W Tocheri"

25 Publications

  • Page 1 of 1

Mitogenomics of macaques (Macaca) across Wallace's Line in the context of modern human dispersals.

J Hum Evol 2020 09 8;146:102852. Epub 2020 Aug 8.

Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103, Leipzig, Germany.

Wallace's Line demarcates a biogeographical boundary between the Indomalaya and Australasian ecoregions. Most placental mammalian genera, for example, occur to the west of this line, whereas most marsupial genera occur to the east. However, macaque monkeys are unusual because they naturally occur on both western and eastern sides. To further explore this anomalous distribution, we analyzed 222 mitochondrial genomes from ∼20 macaque species, including new genomes from 60 specimens. These comprise a population sampling of most Sulawesi macaques, Macaca fascicularis (long-tailed macaques) specimens that were collected by Alfred R. Wallace and specimens that were recovered during archaeological excavations at Liang Bua, a cave on the Indonesian island of Flores. In M. fascicularis, three mitochondrial lineages span the southernmost portion of Wallace's Line between Bali and Lombok, and divergences within these lineages are contemporaneous with, and possibly mediated by, past dispersals of modern human populations. Near the central portion of Wallace's Line between Borneo and Sulawesi, a more ancient dispersal of macaques from mainland Asia to Sulawesi preceded modern human colonization, which was followed by rapid dispersal of matrilines and was subsequently influenced by recent interspecies hybridization. In contrast to previous studies, we find no strong signal of recombination in most macaque mitochondrial genomes. These findings further characterize macaque evolution before and after modern human dispersal throughout Southeast Asia and point to possible effects on biodiversity of ancient human cultural diasporas.
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http://dx.doi.org/10.1016/j.jhevol.2020.102852DOI Listing
September 2020

Combined organic biomarker and use-wear analyses of stone artefacts from Liang Bua, Flores, Indonesia.

Sci Rep 2019 11 26;9(1):17553. Epub 2019 Nov 26.

Centre for Archaeological Science, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, New South Wales, 2522, Australia.

Organic biomarker and lithic use-wear analyses of archaeological implements manufactured and/or used by hominins in the past offers a means of assessing how prehistoric peoples utilised natural resources. Currently, most studies focus on one of these techniques, rather than using both in sequence. This study aims to assess the potential of combining both methods to analyse stone artefacts, using a set of 69 stones excavated from the cave site of Liang Bua (Flores, Indonesia). Prior to chemical analysis, an initial inspection of the artefacts revealed potential use-wear traces but no visible residues. Gas chromatography mass spectrometry (GC-MS) analysis, including the targeting of 86 lipids, terpenes, terpenoids, alkanes and their analogues, found compounds with plant or animal origin on 27 of the 69 stones. The artefacts were subsequently cleaned, and use-wear analysis identified traces of use on 43 artefacts. Use-wear analysis confirmed traces of use on 23 of the 27 artefacts with potential use-residues that were determined by GC-MS. The GC-MS results were broadly consistent with the functional classes identified in the later use-wear analysis. This inclusive approach for stone artefact analysis strengthens the identifications made through multiple lines of enquiry. There remain conflicts and uncertainties in specific cases, suggesting the need for further refinement and analyses of the relationships between use-wear and residues.
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http://dx.doi.org/10.1038/s41598-019-53782-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6879511PMC
November 2019

Temporal shifts in the distribution of murine rodent body size classes at Liang Bua (Flores, Indonesia) reveal new insights into the paleoecology of Homo floresiensis and associated fauna.

J Hum Evol 2019 05 14;130:45-60. Epub 2019 Mar 14.

Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, University of Adelaide, Adelaide, South Australia 5005, Australia; School of Biological Sciences, Environment Institute, and Centre for Applied Conservation Science, University of Adelaide, Adelaide, South Australia 5005 Australia.

Liang Bua, the type locality of Homo floresiensis, is a limestone cave located in the western part of the Indonesian island of Flores. The relatively continuous stratigraphic sequence of the site spans the past ∼190 kyr and contains ∼275,000 taxonomically identifiable vertebrate skeletal elements, ∼80% of which belong to murine rodent taxa (i.e., rats). Six described genera are present at Liang Bua (Papagomys, Spelaeomys, Hooijeromys, Komodomys, Paulamys, and Rattus), one of which, Hooijeromys, is newly recorded in the site deposits, being previously known only from Early to Middle Pleistocene sites in central Flores. Measurements of the proximal femur (n = 10,212) and distal humerus (n = 1186) indicate five murine body size classes ranging from small (mouse-sized) to giant (common rabbit-sized) are present. The proportions of these five classes across successive stratigraphic units reveal two major changes in murine body size distribution due to significant shifts in the abundances of more open habitat-adapted medium-sized murines versus more closed habitat-adapted smaller-sized ones. One of these changes suggests a modest increase in available open habitats occurred ∼3 ka, likely the result of anthropogenic changes to the landscape related to farming by modern human populations. The other and more significant change occurred ∼60 ka suggesting a rapid shift from more open habitats to more closed conditions at this time. The abrupt reduction of medium-sized murines, along with the disappearance of H. floresiensis, Stegodon florensis insularis (an extinct proboscidean), Varanus komodoensis (Komodo dragon), Leptoptilos robustus (giant marabou stork), and Trigonoceps sp. (vulture) at Liang Bua ∼60-50 ka, is likely the consequence of these animals preferring and tracking more open habitats to elsewhere on the island. If correct, then the precise timing and nature of the extinction of H. floresiensis and its contemporaries must await new discoveries at Liang Bua or other as yet unexcavated sites on Flores.
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http://dx.doi.org/10.1016/j.jhevol.2019.02.002DOI Listing
May 2019

The spatio-temporal distribution of archaeological and faunal finds at Liang Bua (Flores, Indonesia) in light of the revised chronology for Homo floresiensis.

J Hum Evol 2018 11 31;124:52-74. Epub 2018 Aug 31.

Centre for Archaeological Science, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales 2522, Australia.

Liang Bua, the type site of Homo floresiensis, is a limestone cave on the Indonesian island of Flores with sedimentary deposits currently known to range in age from about 190 thousand years (ka) ago to the present. Recent revision of the stratigraphy and chronology of this depositional sequence suggests that skeletal remains of H. floresiensis are between ∼100 and 60 ka old, while cultural evidence of this taxon occurs until ∼50 ka ago. Here we examine the compositions of the faunal communities and stone artifacts, by broad taxonomic groups and raw materials, throughout the ∼190 ka time interval preserved in the sequence. Major shifts are observed in both the faunal and stone artifact assemblages that reflect marked changes in paleoecology and hominin behavior, respectively. Our results suggest that H. floresiensis and Stegodon florensis insularis, along with giant marabou stork (Leptoptilos robustus) and vulture (Trigonoceps sp.), were likely extinct by ∼50 ka ago. Moreover, an abrupt and statistically significant shift in raw material preference due to an increased use of chert occurs ∼46 thousand calibrated radiocarbon (C) years before present (ka cal. BP), a pattern that continues through the subsequent stratigraphic sequence. If an increased preference for chert does, in fact, characterize Homo sapiens assemblages at Liang Bua, as previous studies have suggested (e.g., Moore et al., 2009), then the shift observed here suggests that modern humans arrived on Flores by ∼46 ka cal. BP, which would be the earliest cultural evidence of modern humans in Indonesia.
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http://dx.doi.org/10.1016/j.jhevol.2018.07.001DOI Listing
November 2018

Evolution and function of the hominin forefoot.

Proc Natl Acad Sci U S A 2018 08 13;115(35):8746-8751. Epub 2018 Aug 13.

Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794.

The primate foot functions as a grasping organ. As such, its bones, soft tissues, and joints evolved to maximize power and stability in a variety of grasping configurations. Humans are the obvious exception to this primate pattern, with feet that evolved to support the unique biomechanical demands of bipedal locomotion. Of key functional importance to bipedalism is the morphology of the joints at the forefoot, known as the metatarsophalangeal joints (MTPJs), but a comprehensive analysis of hominin MTPJ morphology is currently lacking. Here we present the results of a multivariate shape and Bayesian phylogenetic comparative analyses of metatarsals (MTs) from a broad selection of anthropoid primates (including fossil apes and stem catarrhines) and most of the early hominin pedal fossil record, including the oldest hominin for which good pedal remains exist, Results corroborate the importance of specific bony morphologies such as dorsal MT head expansion and "doming" to the evolution of terrestrial bipedalism in hominins. Further, our evolutionary models reveal that the MT1 of shifts away from the reconstructed optimum of our last common ancestor with apes, but not necessarily in the direction of modern humans. However, the lateral rays of are transformed in a more human-like direction, suggesting that they were the digits first recruited by hominins into the primary role of terrestrial propulsion. This pattern of evolutionary change is seen consistently throughout the evolution of the foot, highlighting the mosaic nature of pedal evolution and the emergence of a derived, modern hallux relatively late in human evolution.
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http://dx.doi.org/10.1073/pnas.1800818115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6126759PMC
August 2018

Late Pleistocene songbirds of Liang Bua (Flores, Indonesia); the first fossil passerine fauna described from Wallacea.

PeerJ 2017 17;5:e3676. Epub 2017 Aug 17.

Ornithological Section, Senckenberg Research Institute, Frankfurt am Main, Germany.

Background: Passerines (Aves: Passeriformes) dominate modern terrestrial bird communities yet their fossil record is limited. Liang Bua is a large cave on the Indonesian island of Flores that preserves Late Pleistocene-Holocene deposits (∼190 ka to present day). Birds are the most diverse faunal group at Liang Bua and are present throughout the stratigraphic sequence.

Methods: We examined avian remains from the Late Pleistocene deposits of Sector XII, a 2 × 2 m area excavated to about 8.5 m depth. Although postcranial passerine remains are typically challenging to identify, we found several humeral characters particularly useful in discriminating between groups, and identified 89 skeletal elements of passerines.

Results: At least eight species from eight families are represented, including the Large-billed Crow ( cf. ) the Australasian Bushlark () a friarbird ( sp.), and the Pechora Pipit ( cf. )

Discussion: These remains constitute the first sample of fossil passerines described in Wallacea. Two of the taxa no longer occur on Flores today; a large sturnid (cf. ) and a grassbird ( sp.). Palaeoecologically, the songbird assemblage suggests open grassland and tall forests, which is consistent with conditions inferred from the non-passerine fauna at the site. cf. , found in the -bearing layers, was likely part of a scavenging guild that fed on carcasses of alongside vultures ( sp.), giant storks (), komodo dragons (), and probably as well.
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http://dx.doi.org/10.7717/peerj.3676DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5563437PMC
August 2017

New fossil remains of from the Lesedi Chamber, South Africa.

Elife 2017 05 9;6. Epub 2017 May 9.

Evolutionary Studies Institute, University of the Witwatersrand, Wits, South Africa.

The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to . 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 . 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 , and evidence of from both recovery localities shows a consistent pattern of differentiation from other hominin species.
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http://dx.doi.org/10.7554/eLife.24232DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5423776PMC
May 2017

Revised stratigraphy and chronology for Homo floresiensis at Liang Bua in Indonesia.

Nature 2016 Apr 30;532(7599):366-9. Epub 2016 Mar 30.

Centre for Archaeological Science, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia.

Homo floresiensis, a primitive hominin species discovered in Late Pleistocene sediments at Liang Bua (Flores, Indonesia), has generated wide interest and scientific debate. A major reason this taxon is controversial is because the H. floresiensis-bearing deposits, which include associated stone artefacts and remains of other extinct endemic fauna, were dated to between about 95 and 12 thousand calendar years (kyr) ago. These ages suggested that H. floresiensis survived until long after modern humans reached Australia by ~50 kyr ago. Here we report new stratigraphic and chronological evidence from Liang Bua that does not support the ages inferred previously for the H. floresiensis holotype (LB1), ~18 thousand calibrated radiocarbon years before present (kyr cal. BP), or the time of last appearance of this species (about 17 or 13-11 kyr cal. BP). Instead, the skeletal remains of H. floresiensis and the deposits containing them are dated to between about 100 and 60 kyr ago, whereas stone artefacts attributable to this species range from about 190 to 50 kyr in age. Whether H. floresiensis survived after 50 kyr ago--potentially encountering modern humans on Flores or other hominins dispersing through southeast Asia, such as Denisovans--is an open question.
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http://dx.doi.org/10.1038/nature17179DOI Listing
April 2016

The evolutionary origin and population history of the grauer gorilla.

Am J Phys Anthropol 2016 Jan;159(Suppl 61):S4-S18

Department of Anatomical Sciences, Stony Brook University Medical Center, Stony Brook, NY, 11794, USA.

Gorillas living in western central Africa (Gorilla gorilla) are morphologically and genetically distinguishable from those living in eastern central Africa (Gorilla beringei). Genomic analyses show eastern gorillas experienced a significant reduction in population size during the Pleistocene subsequent to geographical isolation from their western counterparts. However, how these results relate more specifically to the recent biogeographical and evolutionary history of eastern gorillas remains poorly understood. Here we show that two rare morphological traits are present in the hands and feet of both eastern gorilla subspecies at strikingly high frequencies (>60% in G. b. graueri; ∼28% in G. b. beringei) in comparison with western gorillas (<1%). The intrageneric distribution of these rare traits suggests that they became common among eastern gorillas after diverging from their western relatives during the early to middle Pleistocene. The extremely high frequencies observed among grauer gorillas-which currently occupy a geographic range more than ten times the size of that of mountain gorillas-imply that grauers originated relatively recently from a small founding population of eastern gorillas. Current paleoenvironmental, geological, and biogeographical evidence supports the hypothesis that a small group of eastern gorillas likely dispersed westward from the Virungas into present-day grauer range in the highlands just north of Lake Kivu, either immediately before or directly after the Younger Dryas interval. We propose that as the lowland forests of central Africa expanded rapidly during the early Holocene, they became connected with the expanding highland forests along the Albertine Rift and enabled the descendants of this small group to widely disperse. The descendant populations significantly expanded their geographic range and population numbers relative to the gorillas of the Virunga Mountains and the Bwindi-Impenetrable Forest, ultimately resulting in the grauer gorilla subspecies recognized today. This founder-effect hypothesis offers some optimism for modern conservation efforts to save critically endangered eastern gorillas from extinction.
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http://dx.doi.org/10.1002/ajpa.22900DOI Listing
January 2016

The hand of Homo naledi.

Nat Commun 2015 Oct 6;6:8431. Epub 2015 Oct 6.

Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa.

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.
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http://dx.doi.org/10.1038/ncomms9431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4597335PMC
October 2015

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

Elife 2015 Sep 10;4. Epub 2015 Sep 10.

Evolutionary Studies Institute and Centre of Excellence in PalaeoSciences, University of the Witwatersrand, Johannesburg, South Africa.

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.
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http://dx.doi.org/10.7554/eLife.09560DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4559886PMC
September 2015

Functional aspects of metatarsal head shape in humans, apes, and Old World monkeys.

J Hum Evol 2015 Sep 12;86:136-46. Epub 2015 Aug 12.

Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USA.

Modern human metatarsal heads are typically described as "dorsally domed," mediolaterally wide, and dorsally flat. Despite the apparent functional importance of these features in forefoot stability during bipedalism, the distinctiveness of this morphology has not been quantitatively evaluated within a broad comparative framework. In order to use these features to reconstruct fossil hominin locomotor behaviors with any confidence, their connection to human bipedalism should be validated through a comparative analysis of other primates with different locomotor behaviors and foot postures, including species with biomechanical demands potentially similar to those of bipedalism (e.g., terrestrial digitigrady). This study explores shape variation in the distal metatarsus among humans and other extant catarrhines using three-dimensional geometric morphometrics (3 DGM). Shape differences among species in metatarsal head morphology are well captured by the first two principal components of Procrustes shape coordinates, and these two components summarize most of the variance related to "dorsal doming" and "dorsal expansion." Multivariate statistical tests reveal significant differences among clades in overall shape, and humans are reliably distinguishable from other species by aspects of shape related to a greater degree of dorsal doming. Within quadrupeds, terrestrial species also trend toward more domed metatarsal heads, but not to the extent seen in humans. Certain aspects of distal metatarsus shape are likely related to habitual dorsiflexion of the metatarsophalangeal joints, but the total morphological pattern seen in humans is distinct. These comparative results indicate that this geometric morphometric approach is useful to characterize the complexity of metatarsal head morphology and will help clarify its relationship with function in fossil primates, including early hominins.
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http://dx.doi.org/10.1016/j.jhevol.2015.06.005DOI Listing
September 2015

Exploring phylogenetic and functional signals in complex morphologies: the hamate of extant anthropoids as a test-case study.

Anat Rec (Hoboken) 2015 Jan;298(1):212-29

Department of Anatomical Sciences, Stony Brook University School of Medicine, Stony Brook, New York; Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Edifici Z (ICTA-ICP), campus de la UAB, c/ de les Columnes, s/n., 08193 Cerdanyola del Vallès, Barcelona, Spain; NYCEP Morphometrics Group.

Three-dimensional geometric morphometrics (3DGM) is a powerful tool for capturing and visualizing the "pure" shape of complex structures. However, these shape differences are sometimes difficult to interpret from a functional viewpoint, unless specific approaches (mostly based on biomechanical modeling) are employed. Here, we use 3DGM to explore the complex shape variation of the hamate, the disto-ulnar wrist bone, in anthropoid primates. Major trends of shape variation are explored using principal components analysis along with analyses of shape and size covariation. We also evaluate the phylogenetic patterning of hamate shape by plotting an anthropoid phylogenetic tree onto the shape space (i.e., phylomorphospace) and test against complete absence of phylogenetic signal using posterior permutation. Finally, the covariation of hamate shape and locomotor categories is explored by means of 2-block partial least squares (PLS) using shape coordinates and a matrix of data on arboreal locomotor behavior. Our results show that 3DGM is a valuable and versatile tool for characterizing the shape of complex structures such as wrist bones in anthropoids. For the hamate, a significant phylogenetic pattern is found in both hamate shape and size, indicating that closely related taxa are typically the most similar in hamate form. Our allometric analyses show that major differences in hamate shape among taxa are not a direct consequence of differences in hamate size. Finally, our PLS indicates a significant covariation of hamate shape and different types of arboreal locomotion, highlighting the relevance of this approach in future 3DGM studies seeking to capture a functional signal from complex biological structures.
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http://dx.doi.org/10.1002/ar.23079DOI Listing
January 2015

Three-dimensional geometric morphometric analysis of talar morphology in extant gorilla taxa from highland and lowland habitats.

Anat Rec (Hoboken) 2015 Jan;298(1):277-90

Evolutionary Anthropology Lab, Department of Anthropology, University of Minnesota, Minneapolis, Minnesota.

Western gorillas (Gorilla gorilla) are known to climb significantly more often than eastern gorillas (Gorilla beringei), a behavioral distinction attributable to major differences in their respective habitats (i.e., highland vs. lowland). Genetic evidence suggests that the lineages leading to these taxa began diverging from one another between approximately 1 and 3 million years ago. Thus, gorillas offer a special opportunity to examine the degree to which morphology of recently diverged taxa may be "fine-tuned" to differing ecological requirements. Using three-dimensional (3D) geometric morphometrics, we compared talar morphology in a sample of 87 specimens including western (lowland), mountain (highland), and grauer gorillas (lowland and highland populations). Talar shape was captured with a series of landmarks and semilandmarks superimposed by generalized Procrustes analysis. A between-group principal components analysis of overall talar shape separates gorillas by ecological habitat and by taxon. An analysis of only the trochlea and lateral malleolar facet identifies subtle variations in trochlear shape between western lowland and lowland grauer gorillas, potentially indicative of convergent evolution of arboreal adaptations in the talus. Lastly, talar shape scales differently with centroid size for highland and lowland gorillas, suggesting that ankle morphology may track body-size mediated variation in arboreal behaviors differently depending on ecological setting. Several of the observed shape differences are linked biomechanically to the facilitation of climbing in lowland gorillas and to stability and load-bearing on terrestrial substrates in the highland taxa, providing an important comparative model for studying morphological variation in groups known only from fossils (e.g., early hominins).
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http://dx.doi.org/10.1002/ar.23069DOI Listing
January 2015

Ecological divergence and talar morphology in gorillas.

Am J Phys Anthropol 2014 Apr 21;153(4):526-41. Epub 2013 Dec 21.

Department of Anatomy, Des Moines University, Des Moines, IA, 50312.

Gorillas occupy a variety of habitats from the west coast to eastern central Africa. These habitats differ considerably in altitude, which has a pronounced effect on forest ecology. Although all gorillas are obligate terrestrial knuckle-walking quadrupeds, those that live in lowland habitats eat fruits and climb more often than do those living in highland habitats. Here we test the hypothesis that gorilla talus morphology falls along a morphocline that tracks locomotor function related to a more inverted or everted foot set. This proposed morphocline predicts that gorillas living in lowland habitats may have a talocrural joint configured to facilitate a more medially oriented foot during climbing, suggesting that they may be more adaptively committed to arboreality than gorillas living in highland habitats. To quantify the relative set of the foot in gorillas, we chose two three-dimensional measurements of the talocrural joint: mediolateral curvature of the trochlea and relative surface area of the lateral malleolus. Our results show that, in comparison to their eastern counterparts, western gorillas have talar features that reflect a more medially directed sole of the foot. This morphology likely facilitates foot placement in a wider range of positions and minimization of shearing stresses across the joint when the foot is loaded on more curved or vertically oriented substrates as occurs during climbing and other arboreal behaviors. In contrast, eastern gorilla talar morphology is consistent with habitual placement of the foot with the sole directed more inferiorly, suggesting more effective loading during plantigrade push-off on terrestrial substrates.
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http://dx.doi.org/10.1002/ajpa.22451DOI Listing
April 2014

Early Pleistocene third metacarpal from Kenya and the evolution of modern human-like hand morphology.

Proc Natl Acad Sci U S A 2014 Jan 16;111(1):121-4. Epub 2013 Dec 16.

Integrative Anatomy Program, Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, MO 65212.

Despite discoveries of relatively complete hands from two early hominin species (Ardipithecus ramidus and Australopithecus sediba) and partial hands from another (Australopithecus afarensis), fundamental questions remain about the evolution of human-like hand anatomy and function. These questions are driven by the paucity of hand fossils in the hominin fossil record between 800,000 and 1.8 My old, a time interval well documented for the emergence and subsequent proliferation of Acheulian technology (shaped bifacial stone tools). Modern and Middle to Late Pleistocene humans share a suite of derived features in the thumb, wrist, and radial carpometacarpal joints that is noticeably absent in early hominins. Here we show that one of the most distinctive features of this suite in the Middle Pleistocene to recent human hand, the third metacarpal styloid process, was present ∼1.42 Mya in an East African hominin from Kaitio, West Turkana, Kenya. This fossil thus provides the earliest unambiguous evidence for the evolution of a key shared derived characteristic of modern human and Neandertal hand morphology and suggests that the distinctive complex of radial carpometacarpal joint features in the human hand arose early in the evolution of the genus Homo and probably in Homo erectus sensu lato.
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http://dx.doi.org/10.1073/pnas.1316014110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3890866PMC
January 2014

New wrist bones of Homo floresiensis from Liang Bua (Flores, Indonesia).

J Hum Evol 2013 Feb 4;64(2):109-29. Epub 2013 Jan 4.

Department of Anatomical Sciences, Stony Brook University, Health Sciences Center T-8 040, Stony Brook, NY 11794-8081, USA.

The carpals from the Homo floresiensis type specimen (LB1) lack features that compose the shared, derived complex of the radial side of the wrist in Neandertals and modern humans. This paper comprises a description and three-dimensional morphometric analysis of new carpals from at least one other individual at Liang Bua attributed to H. floresiensis: a right capitate and two hamates. The new capitate is smaller than that of LB1 but is nearly identical in morphology. As with capitates from extant apes, species of Australopithecus, and LB1, the newly described capitate displays a deeply-excavated nonarticular area along its radial aspect, a scaphoid facet that extends into a J-hook articulation on the neck, and a more radially-oriented second metacarpal facet; it also lacks an enlarged palmarly-positioned trapezoid facet. Because there is no accommodation for the derived, palmarly blocky trapezoid that characterizes Homo sapiens and Neandertals, this individual most likely had a plesiomorphically wedge-shaped trapezoid (like LB1). Morphometric analyses confirm the close similarity of the new capitate and that of LB1, and are consistent with previous findings of an overall primitive articular geometry. In general, hamate morphology is more conserved across hominins, and the H. floresiensis specimens fall at the far edge of the range of variation for H. sapiens in a number of metrics. However, the hamate of H. floresiensis is exceptionally small and exhibits a relatively long, stout hamulus lacking the oval-shaped cross-section characteristic of human and Neandertal hamuli (variably present in australopiths). Documentation of a second individual with primitive carpal anatomy from Liang Bua, along with further analysis of trapezoid scaling relative to the capitate in LB1, refutes claims that the wrist of the type specimen represents a modern human with pathology. In total, the carpal anatomy of H. floresiensis supports the hypothesis that the lineage leading to the evolution of this species originated prior to the cladogenetic event that gave rise to modern humans and Neandertals.
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http://dx.doi.org/10.1016/j.jhevol.2012.10.003DOI Listing
February 2013

Early brain growth cessation in wild Virunga mountain gorillas (Gorilla beringei beringei).

Am J Primatol 2013 May 3;75(5):450-63. Epub 2012 Dec 3.

Department of Anthropology, Center for the Advanced Study of Hominid Paleobiology, The George Washington University, Washington, DC 20052, USA.

Understanding the life history correlates of ontogenetic differences in hominoid brain growth requires information from multiple species. At present, however, data on how brain size changes over the course of development are only available from chimpanzees and modern humans. In this study, we examined brain growth in wild Virunga mountain gorillas using data derived from necropsy reports (N = 34) and endocranial volume (EV) measurements (N = 86). The youngest individual in our sample was a 10-day-old neonatal male with a brain mass of 208 g, representing 42% of the adult male average. Our results demonstrate that Virunga mountain gorillas reach maximum adult-like brain mass by 3-4 years of age; adult-sized EV is reached by the time the first permanent molars emerge. This is in contrast to the pattern observed in chimpanzees, which despite their smaller absolute brain size, reportedly attain adult brain mass approximately 1 year later than Virunga mountain gorillas. Our findings demonstrate that brain growth is completed early in Virunga mountain gorillas compared to other great apes studied thus far, in a manner that appears to be linked with other life history characteristics of this population.
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http://dx.doi.org/10.1002/ajp.22100DOI Listing
May 2013

Ecological divergence and medial cuneiform morphology in gorillas.

J Hum Evol 2011 Feb 19;60(2):171-84. Epub 2010 Nov 19.

Human Origins Program, Department of Anthropology, National Museum of Natural History, Smithsonian Institution, 10th and Constitution Avenue NW, Washington, DC 20013-7012, USA.

Gorillas are more closely related to each other than to any other extant primate and are all terrestrial knuckle-walkers, but taxa differ along a gradient of dietary strategies and the frequency of arboreality in their behavioral repertoire. In this study, we test the hypothesis that medial cuneiform morphology falls on a morphocline in gorillas that tracks function related to hallucial abduction ability and relative frequency of arboreality. This morphocline predicts that western gorillas, being the most arboreal, should display a medial cuneiform anatomy that reflects the greatest hallucial abduction ability, followed by grauer gorillas, and then by mountain gorillas. Using a three-dimensional methodology to measure angles between articular surfaces, relative articular and nonarticular areas, and the curvatures of the hallucial articular surface, the functional predictions are partially confirmed in separating western gorillas from both eastern gorillas. Western gorillas are characterized by a more medially oriented, proportionately larger, and more mediolaterally curved hallucial facet than are eastern gorillas. These characteristics follow the predictions for a more prehensile hallux in western gorillas relative to a more stable, plantigrade hallux in eastern gorillas. The characteristics that distinguish eastern gorilla taxa from one another appear unrelated to hallucial abduction ability or frequency of arboreality. In total, this reexamination of medial cuneiform morphology suggests differentiation between eastern and western gorillas due to a longstanding ecological divergence and more recent and possibly non-adaptive differences between eastern taxa.
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http://dx.doi.org/10.1016/j.jhevol.2010.09.002DOI Listing
February 2011

The Olduvai Hominid 8 foot: adult or subadult?

J Hum Evol 2010 May 22;58(5):418-23. Epub 2010 Apr 22.

Department of Anthropology, Boston University, Boston, MA 02215, USA.

Olduvai Hominid 8 (OH 8), an articulating set of fossil hominin tarsal and metatarsal bones, is critical to interpretations of the evolution of hominin pedal morphology and bipedal locomotion. It has been suggested that OH 8 may represent the foot of a subadult and may be associated with the OH 7 mandible, the type specimen of Homo habilis. This assertion is based on the presence of what may be unfused distal metatarsal epiphyses. Accurately assessing the skeletal maturity of the OH 8 foot is important for interpretations of the functional morphology and locomotor behavior of Plio-Pleistocene hominins. In this study, we compare metatarsal fusion patterns and internal bone morphology of the lateral metatarsals among subadult hominines (85 modern humans, 48 Pan, and 25 Gorilla) to assess the likelihood that OH 8 belonged to either an adult or subadult hominin. Our results suggest that if OH 8 is indeed from a subadult, then it displays a metatarsal developmental pattern that is unobserved in our comparative sample. In OH 8, the fully fused base of the first metatarsal and the presence of trabecular bone at the distal ends of the second and third metatarsal shafts make it highly improbable that it belonged to a subadult, let alone a subadult that matches the developmental age of the OH 7 mandible. In total, the results of this study suggest that the OH 8 foot most likely belonged to an adult hominin.
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http://dx.doi.org/10.1016/j.jhevol.2010.03.004DOI Listing
May 2010

The evolutionary history of the hominin hand since the last common ancestor of Pan and Homo.

J Anat 2008 Apr;212(4):544-62

Human Origins Program, Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington DC, USA.

Molecular evidence indicates that the last common ancestor of the genus Pan and the hominin clade existed between 8 and 4 million years ago (Ma). The current fossil record indicates the Pan-Homo last common ancestor existed at least 5 Ma and most likely between 6 and 7 Ma. Together, the molecular and fossil evidence has important consequences for interpreting the evolutionary history of the hand within the tribe Hominini (hominins). Firstly, parsimony supports the hypothesis that the hand of the last common ancestor most likely resembled that of an extant great ape overall (Pan, Gorilla, and Pongo), and that of an African ape in particular. Second, it provides a context for interpreting the derived changes to the hand that have evolved in various hominins. For example, the Australopithecus afarensis hand is likely derived in comparison with that of the Pan-Homo last common ancestor in having shorter fingers relative to thumb length and more proximo-distally oriented joints between its capitate, second metacarpal, and trapezium. This evidence suggests that these derived features evolved prior to the intensification of stone tool-related hominin behaviors beginning around 2.5 Ma. However, a majority of primitive features most likely present in the Pan-Homo last common ancestor are retained in the hands of Australopithecus, Paranthropus/early Homo, and Homo floresiensis. This evidence suggests that further derived changes to the hands of other hominins such as modern humans and Neandertals did not evolve until after 2.5 Ma and possibly even later than 1.5 Ma, which is currently the earliest evidence of Acheulian technology. The derived hands of modern humans and Neandertals may indicate a morphological commitment to tool-related manipulative behaviors beyond that observed in other hominins, including those (e.g. H. floresiensis) which may be descended from earlier tool-making species.
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http://dx.doi.org/10.1111/j.1469-7580.2008.00865.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2409097PMC
April 2008

The primitive wrist of Homo floresiensis and its implications for hominin evolution.

Science 2007 Sep;317(5845):1743-5

Human Origins Program, Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA.

Whether the Late Pleistocene hominin fossils from Flores, Indonesia, represent a new species, Homo floresiensis, or pathological modern humans has been debated. Analysis of three wrist bones from the holotype specimen (LB1) shows that it retains wrist morphology that is primitive for the African ape-human clade. In contrast, Neandertals and modern humans share derived wrist morphology that forms during embryogenesis, which diminishes the probability that pathology could result in the normal primitive state. This evidence indicates that LB1 is not a modern human with an undiagnosed pathology or growth defect; rather, it represents a species descended from a hominin ancestor that branched off before the origin of the clade that includes modern humans, Neandertals, and their last common ancestor.
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http://dx.doi.org/10.1126/science.1147143DOI Listing
September 2007

Reconstructing infant weaning histories at Roman period Kellis, Egypt using stable isotope analysis of dentition.

Am J Phys Anthropol 2007 Sep;134(1):63-74

Department of Anthropology, University of Central Florida, Orlando, FL 32816, USA.

Studies of infant feeding and weaning patterns in past populations that rely on a cross-sectional approach must make the assumption that no infant mortality bias exists. Previous investigations of infant weaning patterns at the Dakhleh Oasis, Egypt, relied on cross-sectional isotope data. In this study, we re-examine this weaning pattern, using a simulated longitudinal approach, which does not require any assumptions regarding potential infant mortality biases. This involves examining the dental isotopic signatures of individuals who survived the weaning process. Stable isotope signatures from juveniles and adults (102 individuals, 297 teeth) were examined to reconstruct the weaning history of those that survived the weaning process. Both deciduous and permanent teeth were sampled. Homogenized enamel and dentin samples were isolated from each tooth and analyzed for delta(13)C(ap) and delta(18)O(ap) from the enamel and delta(15)N(coll) and delta(13)C(coll) from dentin collagen. We investigate differences between in utero versus postbirth, preweaning versus postweaning, and juvenile versus adult stable isotope values as reflected in the dentition. A random permutation procedure was used to test for statistically significant differences in stable isotope values between tooth types. Statistically significant differences were observed in all stable isotopes between permanent and deciduous teeth, and between early and later forming permanent teeth in delta(13)C(ap) and delta(15)N(coll) isotopes. These results indicate dietary change between in utero and postbirth, and changes occurring during the weaning period. These results provide a more comprehensive picture of infant weaning practices at Kellis and provide further support that complete weaning occurred by 3 years of age.
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http://dx.doi.org/10.1002/ajpa.20639DOI Listing
September 2007