1
|
Le Maître A, Guy F, Merceron G, Kostopoulos DS. Morphology of the Bony Labyrinth Supports the Affinities of Paradolichopithecus with the Papionina. INT J PRIMATOL 2022; 44:209-236. [PMID: 36817734 PMCID: PMC9931825 DOI: 10.1007/s10764-022-00329-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/26/2022] [Indexed: 10/14/2022]
Abstract
Discoveries in recent decades indicate that the large papionin monkeys Paradolipopithecus and Procynocephalus are key members of the Late Pliocene - Early Pleistocene mammalian faunas of Eurasia. However, their taxonomical status, phylogenetic relationships, and ecological profile remain unclear. Here we investigate the two latter aspects through the study of the inner ear anatomy, as revealed by applying micro-CT scan imaging techniques on the cranium LGPUT DFN3-150 of Paradolichopithecus from the lower Pleistocene (2.3 Ma) fossil site Dafnero-3 in Northwestern Greece. Using geometric morphometric methods, we quantified shape variation and the allometric and phylogenetic signals in extant cercopithecines (n = 80), and explored the morphological affinities of the fossil specimen with extant taxa. LGPUT DFN3-150 has a large centroid size similar to that of baboons and their relatives. It shares several shape features with Macacina and Cercopithecini, which we interpret as probable retention of a primitive morphology. Overall, its inner ear morphology is more consistent with a stem Papionini more closely related to Papionina than Macacina, or to a basal crown Papionina. Our results, along with morphometrical and ecological features from previous studies, call into question the traditional hypothesis of a Paradolichopithecus-Macacina clade, and provide alternative perspectives in the study of Eurasian primate evolution during the late Neogene-Quaternary. Supplementary Information The online version contains supplementary material available at 10.1007/s10764-022-00329-4.
Collapse
Affiliation(s)
- Anne Le Maître
- Department of Evolutionary Biology, University of Vienna, Djerassiplatz 1, 1030 Vienna, Austria
- PALEVOPRIM - UMR 7262 CNRS INEE, Université de Poitiers, Poitiers, France
| | - Franck Guy
- PALEVOPRIM - UMR 7262 CNRS INEE, Université de Poitiers, Poitiers, France
| | - Gildas Merceron
- PALEVOPRIM - UMR 7262 CNRS INEE, Université de Poitiers, Poitiers, France
| | - Dimitris S Kostopoulos
- Laboratory of Geology and Palaeontology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| |
Collapse
|
2
|
New fossils from Kromdraai and Drimolen, South Africa, and their distinctiveness among Paranthropus robustus. Sci Rep 2022; 12:13956. [PMID: 35977986 PMCID: PMC9385619 DOI: 10.1038/s41598-022-18223-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/08/2022] [Indexed: 11/08/2022] Open
Abstract
Most fossil hominin species are sampled with spatial, temporal or anatomical biases that can hinder assessments of their paleodiversity, and may not yield genuine evolutionary signals. We use new fossils from the Kromdraai (Unit P) and Drimolen sites (South Africa) to provide insights into the paleodiversity of the Lower Pleistocene robust australopith, Paranthropus robustus. Our focus is the morphology of the temporal bone and the relationships between size and shape (allometry) of the semi-circular canals (SCC), an aspect that has not yet been investigated among southern African australopiths. We find significant size and shape SCC differences between P. robustus from Kromdraai, Drimolen and Swartkrans. This site-related variation is consistent with other differences observed on the temporal bone. P. robustus from Kromdraai Unit P is distinctive because of its smaller temporal bone and SCC, and its proportionally less developed posterior SCC, independently of age and sex. We emphasize the importance of allometry to interpret paleodiversity in P. robustus as either the consequence of differences in body size, or as yet unknown factors. Some features of the inner ear of P. robustus represent directional selection soon after its origin, whereas the size and shape variations described here may result from evolutionary changes.
Collapse
|
3
|
Cárdenas-Serna M, Jeffery N. Human semicircular canal form: Ontogenetic changes and variation of shape and size. J Anat 2022; 240:541-555. [PMID: 34674260 PMCID: PMC8819049 DOI: 10.1111/joa.13576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 10/04/2021] [Accepted: 10/08/2021] [Indexed: 11/29/2022] Open
Abstract
The semicircular canals (SCCs) transduce angular acceleration of the head into neuronal signals, and their morphology has been used to infer function. Once formed, the bony labyrinth, that surrounds the canals, is tightly regulated and has a very low bone turnover. However, relaxed postnatal inhibition of bone remodelling later in ontogeny may allow for some organised adjustments of shape and size or for greater stochastic variation. In the present study, we test the hypotheses that after birth, the shape and size of the bony canal changes or becomes more variable, or both. We study microCT scans of human perinatal and adult temporal bones using a combination of geometric morphometric analysis and cross-sectional measures. Results revealed marginal differences of size (<5%), of cross-sectional shape and of measurement variability. Geometry of the three canals together and their cross-sectional areas were, however, indistinguishable between perinates and adults. These mixed findings are indicative of diminutive levels of relaxed inhibition superimposed over a constrained template of SCC morphology.
Collapse
Affiliation(s)
- Marcela Cárdenas-Serna
- Department of Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Nathan Jeffery
- Department of Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| |
Collapse
|
4
|
Pollak L, Gilad R, Michael T. Unilateral mimicking bilateral BPPV- a forgotten entity? Characteristics of a large cohort of patients, comparison with posterior canal BPPV and clinical implications. J Otol 2021; 16:252-257. [PMID: 34548872 PMCID: PMC8438632 DOI: 10.1016/j.joto.2021.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/16/2021] [Accepted: 06/16/2021] [Indexed: 12/02/2022] Open
Abstract
Objective Unilateral mimicking bilateral benign paroxysmal positional vertigo (umb-BPPV) was attributed to inappropriate head positioning during testing of the posterior canal. Despite its inclusion in the Diagnostic criteria for the classification of vestibular disorders of the Bárány Society, the clinical characteristics and treatment responsiveness of this BPPV subtype have not been intensively studied. Methods Records of patients with BPPV seen at a single outpatient dizziness clinic during the years 2000–2020 were reviewed. Eighty seven patients with umb-BPPV and 86 random patients with posterior canal BPPV (p-BPPV) were retrieved. Their demographics and BPPV characteristics were analyzed. Results Patients' and BPPV characteristics were similar in umb- and p-BPPV except for the prevalence of males in the umb-BPPV group. No differences were found between treatment responsiveness and recurrences in both groups. The recurrence rate of umb-BPPV was not influenced by age, gender, BPPV side, duration of symptoms or treatment responsiveness during the first attack. Conclusions In accordance with our hypothesis about mixed canalo- and cupulolithiasis as the underlying mechanism of umb-BPPV, patients did not differ in characteristics and treatment responsiveness from p-BPPV patients. Recognition of umb-BPPV is important since inappropriate treatment can cause an unnecessary delay in therapy success.
Collapse
Affiliation(s)
- Lea Pollak
- Neurology and Dizziness Clinic, Kupat Cholim Macabi and the Ben Gurion, University of the Negev, Beer Sheva, Israel
| | - Ronit Gilad
- Neurology Department, Kaplan Medical Center, Rechovot, Affiliated to the Hebrew, University, Jerusalem, Israel
| | - Tal Michael
- The Faculty of Health Public, Ben Gurion University of the Negev, Beer, Sheva, Israel
| |
Collapse
|
5
|
Ward DL, Schroeder L, Pomeroy E, Roy JE, Buck LT, Stock JT, Martin-Gronert M, Ozanne SE, Silcox MT, Viola TB. Early life malnutrition and fluctuating asymmetry in the rat bony labyrinth. Anat Rec (Hoboken) 2021; 304:2645-2660. [PMID: 33586866 DOI: 10.1002/ar.24601] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/18/2021] [Accepted: 01/22/2021] [Indexed: 12/26/2022]
Abstract
Maternal malnutrition during gestation and lactation is known to have adverse effects on offspring. We evaluate the impact of maternal diet on offspring bony labyrinth morphology. The bony labyrinth develops early and is thought to be stable to protect vital sensory organs within. For these reasons, bony labyrinth morphology has been used extensively to assess locomotion, hearing function, and phylogeny in primates and numerous other taxa. While variation related to these parameters has been documented, there is still a component of intraspecific variation that is unexplained. Although the labyrinthine developmental window is small, it may provide the opportunity for developmental instability to produce corresponding shape differences, as measured by fluctuating asymmetry (FA). We hypothesized that (a) offspring with poor maternal diet would exhibit increased FA, but (b) no unilateral shape difference. To test these hypotheses, we used two groups of rats (Rattus norvegicus; Crl:WI[Han] strain), one control group and one group exposed to a isocaloric, protein-restricted maternal diet during gestation and suckling. Individuals were sampled at weaning, sexual maturity, and old age. A Procrustes analysis of variance identified statistically significant FA in all diet-age subgroups. No differences in level of FA were identified among the subgroups, rejecting our first hypothesis. A principal components analysis identified no unilateral shape differences, supporting our second hypothesis. These results indicate that bony labyrinth morphology is remarkably stable and likely protected from a poor maternal diet during development. In light of this result, other factors must be explored to explain intraspecific variation in labyrinthine shape.
Collapse
Affiliation(s)
- Devin L Ward
- Department of Anthropology, University of Toronto, Toronto, Ontario, Canada
| | - Lauren Schroeder
- Department of Anthropology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Emma Pomeroy
- Department of Archaeology, University of Cambridge, Cambridge, UK
| | - Jocelyn E Roy
- Department of Anthropology, University of Toronto, Toronto, Ontario, Canada
| | - Laura T Buck
- Department of Archaeology, University of Cambridge, Cambridge, UK
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| | - Jay T Stock
- Department of Anthropology, Western University, London, Ontario, Canada
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany
| | - Malgorzata Martin-Gronert
- Metabolic Research Laboratories and MRC Metabolic Diseases Unit, University of Cambridge, Cambridge, UK
| | - Susan E Ozanne
- Metabolic Research Laboratories and MRC Metabolic Diseases Unit, University of Cambridge, Cambridge, UK
| | - Mary T Silcox
- Department of Anthropology, University of Toronto Scarborough, Scarborough, Ontario, Canada
| | - T Bence Viola
- Department of Anthropology, University of Toronto, Toronto, Ontario, Canada
- Institute for Archaeology and Ethnography, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russian Federation
| |
Collapse
|
6
|
Reassessment of the phylogenetic relationships of the late Miocene apes Hispanopithecus and Rudapithecus based on vestibular morphology. Proc Natl Acad Sci U S A 2021; 118:2015215118. [PMID: 33495351 DOI: 10.1073/pnas.2015215118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Late Miocene great apes are key to reconstructing the ancestral morphotype from which earliest hominins evolved. Despite consensus that the late Miocene dryopith great apes Hispanopithecus laietanus (Spain) and Rudapithecus hungaricus (Hungary) are closely related (Hominidae), ongoing debate on their phylogenetic relationships with extant apes (stem hominids, hominines, or pongines) complicates our understanding of great ape and human evolution. To clarify this question, we rely on the morphology of the inner ear semicircular canals, which has been shown to be phylogenetically informative. Based on microcomputed tomography scans, we describe the vestibular morphology of Hispanopithecus and Rudapithecus, and compare them with extant hominoids using landmark-free deformation-based three-dimensional geometric morphometric analyses. We also provide critical evidence about the evolutionary patterns of the vestibular apparatus in living and fossil hominoids under different phylogenetic assumptions for dryopiths. Our results are consistent with the distinction of Rudapithecus and Hispanopithecus at the genus rank, and further support their allocation to the Hominidae based on their derived semicircular canal volumetric proportions. Compared with extant hominids, the vestibular morphology of Hispanopithecus and Rudapithecus most closely resembles that of African apes, and differs from the derived condition of orangutans. However, the vestibular morphologies reconstructed for the last common ancestors of dryopiths, crown hominines, and crown hominids are very similar, indicating that hominines are plesiomorphic in this regard. Therefore, our results do not conclusively favor a hominine or stem hominid status for the investigated dryopiths.
Collapse
|
7
|
Thompson NE. The biomechanics of knuckle-walking: 3-D kinematics of the chimpanzee and macaque wrist, hand and fingers. J Exp Biol 2020; 223:jeb224360. [PMID: 32554524 DOI: 10.1242/jeb.224360] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/05/2020] [Indexed: 08/26/2023]
Abstract
The origin and evolution of knuckle-walking has long been a key focus in understanding African ape, including human, origins. Yet, despite numerous studies documenting morphological characteristics potentially associated with knuckle-walking, little quantitative three-dimensional (3-D) data exist of forelimb motion during knuckle-walking. Nor do any comparative 3-D data exist for hand postures used during quadrupedalism in monkeys. This lack of data has limited the testability of proposed adaptations for knuckle-walking in African apes. This study presents the first 3-D kinematic data of the wrist, hand and metacarpophalangeal joints during knuckle-walking in chimpanzees and in macaques using digitigrade and palmigrade hand postures. These results clarify the unique characteristics of, and commonalities between, knuckle-walking and digitigrady/palmigrady in multiple planes of motion. Notably, chimpanzees utilized more wrist ulnar deviation than any macaque hand posture. Maximum extension of the chimpanzee wrist was slight (5-20 deg) and generally overlapped with macaque digitigrady. Metacarpophalangeal joint motion displayed distinct differences between digits in both species, likely related to the timing of force application. These data also reveal that maximum metacarpophalangeal extension angles during knuckle-walking (26-59 deg) were generally higher than previously considered. In macaques, maximum metacarpophalangeal extension during digitigrady and palmigrady overlapped for most digits, highlighting additional complexity in the interpretation of skeletal features that may be related to limiting metacarpophalangeal motion. Most importantly, however, these new 3-D data serve as a fundamental dataset with which evaluation of proposed musculoskeletal adaptations for knuckle-walking can be tested.
Collapse
Affiliation(s)
- Nathan E Thompson
- Department of Anatomy, NYIT College of Osteopathic Medicine, Old Westbury, NY 11568, USA
| |
Collapse
|
8
|
Morimoto N, Kunimatsu Y, Nakatsukasa M, Ponce de León MS, Zollikofer CPE, Ishida H, Sasaki T, Suwa G. Variation of bony labyrinthine morphology in Mio−Plio−Pleistocene and modern anthropoids. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 173:276-292. [DOI: 10.1002/ajpa.24098] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 03/06/2020] [Accepted: 05/17/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Naoki Morimoto
- Laboratory of Physical Anthropology Graduate School of Science, Kyoto University Kyoto Japan
| | - Yutaka Kunimatsu
- Faculty of Business Administration Ryukoku University Fushimi, Kyoto Japan
| | - Masato Nakatsukasa
- Laboratory of Physical Anthropology Graduate School of Science, Kyoto University Kyoto Japan
| | | | | | | | | | - Gen Suwa
- University Museum, University of Tokyo Hongo, Bunkyo‐ku, Tokyo Japan
| |
Collapse
|
9
|
Le Maître A, Grunstra NDS, Pfaff C, Mitteroecker P. Evolution of the Mammalian Ear: An Evolvability Hypothesis. Evol Biol 2020; 47:187-192. [PMID: 32801400 PMCID: PMC7399675 DOI: 10.1007/s11692-020-09502-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 05/12/2020] [Indexed: 11/29/2022]
Abstract
Encapsulated within the temporal bone and comprising the smallest elements of the vertebrate skeleton, the ear is key to multiple senses: balance, posture control, gaze stabilization, and hearing. The transformation of the primary jaw joint into the mammalian ear ossicles is one of the most iconic transitions in vertebrate evolution, but the drivers of this complex evolutionary trajectory are not fully understood. We propose a novel hypothesis: The incorporation of the bones of the primary jaw joint into the middle ear has considerably increased the genetic, regulatory, and developmental complexity of the mammalian ear. This increase in the number of genetic and developmental factors may, in turn, have increased the evolutionary degrees of freedom for independent adaptations of the different functional ear units. The simpler ear anatomy in birds and reptiles may be less susceptible to developmental instabilities and disorders than in mammals but also more constrained in its evolution. Despite the tight spatial entanglement of functional ear components, the increased "evolvability" of the mammalian ear may have contributed to the evolutionary success and adaptive diversification of mammals in the vast diversity of ecological and behavioral niches observable today. A brief literature review revealed supporting evidence for this hypothesis.
Collapse
Affiliation(s)
- Anne Le Maître
- Department of Evolutionary Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
- Department of Palaeontology, University of Vienna, Vienna, Austria
- PALEVOPRIM - UMR 7262CNRS INEE, Université de Poitiers, Poitiers, France
| | - Nicole D. S. Grunstra
- Department of Evolutionary Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
- KLI Institute for Evolution and Cognition Research, Klosterneuburg, Austria
- Mammal Collection, Natural History Museum Vienna, Vienna, Austria
| | - Cathrin Pfaff
- Department of Palaeontology, University of Vienna, Vienna, Austria
| | - Philipp Mitteroecker
- Department of Evolutionary Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
- KLI Institute for Evolution and Cognition Research, Klosterneuburg, Austria
| |
Collapse
|
10
|
Urciuoli A, Zanolli C, Beaudet A, Dumoncel J, Santos F, Moyà-Solà S, Alba DM. The evolution of the vestibular apparatus in apes and humans. eLife 2020; 9:e51261. [PMID: 32122463 PMCID: PMC7054002 DOI: 10.7554/elife.51261] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 01/18/2020] [Indexed: 12/17/2022] Open
Abstract
Phylogenetic relationships among extinct hominoids (apes and humans) are controversial due to pervasive homoplasy and the incompleteness of the fossil record. The bony labyrinth might contribute to this debate, as it displays strong phylogenetic signal among other mammals. However, the potential of the vestibular apparatus for phylogenetic reconstruction among fossil apes remains understudied. Here we test and quantify the phylogenetic signal embedded in the vestibular morphology of extant anthropoids (monkeys, apes and humans) and two extinct apes (Oreopithecus and Australopithecus) as captured by a deformation-based 3D geometric morphometric analysis. We also reconstruct the ancestral morphology of various hominoid clades based on phylogenetically-informed maximum likelihood methods. Besides revealing strong phylogenetic signal in the vestibule and enabling the proposal of potential synapomorphies for various hominoid clades, our results confirm the relevance of vestibular morphology for addressing the controversial phylogenetic relationships of fossil apes.
Collapse
Affiliation(s)
- Alessandro Urciuoli
- Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Cerdanyola del VallèsBarcelonaSpain
| | - Clément Zanolli
- Laboratoire PACEA, UMR 5199 CNRS, Université de BordeauxPessacFrance
| | - Amélie Beaudet
- School of Geography, Archaeology and Environmental StudiesUniversity of the WitwatersrandJohannesburgSouth Africa
- Department of AnatomyUniversity of PretoriaPretoriaSouth Africa
| | - Jean Dumoncel
- Laboratoire AMIS, UMR 5288 CNRS, Université de ToulouseToulouseFrance
| | - Frédéric Santos
- Laboratoire PACEA, UMR 5199 CNRS, Université de BordeauxPessacFrance
| | - Salvador Moyà-Solà
- Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Cerdanyola del VallèsBarcelonaSpain
- Institució Catalana de Recerca i Estudis Avançats (ICREA)BarcelonaSpain
- Unitat d’Antropologia (Departament de Biologia Animal, Biologia Vegetal i Ecologia)Universitat Autònoma de Barcelona, Cerdanyola del VallèsBarcelonaSpain
| | - David M Alba
- Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Cerdanyola del VallèsBarcelonaSpain
| |
Collapse
|
11
|
Vasilopoulou-Kampitsi M, Goyens J, Van Damme R, Aerts P. The ecological signal on the shape of the lacertid vestibular system: simple versus complex microhabitats. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- M Vasilopoulou-Kampitsi
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - J Goyens
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - R Van Damme
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - P Aerts
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Antwerp, Belgium
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| |
Collapse
|
12
|
The bony labyrinth of StW 573 (“Little Foot”): Implications for early hominin evolution and paleobiology. J Hum Evol 2019; 127:67-80. [DOI: 10.1016/j.jhevol.2018.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 12/01/2018] [Accepted: 12/04/2018] [Indexed: 12/14/2022]
|
13
|
Abstract
The cavity system of the inner ear—the so-called bony labyrinth—houses the senses of balance and hearing. This structure is embedded in dense petrous bone, fully formed by birth and generally well preserved in human skeletal remains, thus providing a rich source of morphological information about past populations. Here we show that labyrinthine morphology tracks genetic distances and geography in an isolation-by-distance model with dispersal from Africa. Because petrous bones have become prime targets of ancient DNA recovery, we propose that all destructive studies first acquire high-resolution 3D computed-tomography data prior to any invasive sampling. Such data will constitute an important archive of morphological variation in past and present populations, and will permit individual-based genotype–phenotype comparisons. The dispersal of modern humans from Africa is now well documented with genetic data that track population history, as well as gene flow between populations. Phenetic skeletal data, such as cranial and pelvic morphologies, also exhibit a dispersal-from-Africa signal, which, however, tends to be blurred by the effects of local adaptation and in vivo phenotypic plasticity, and that is often deteriorated by postmortem damage to skeletal remains. These complexities raise the question of which skeletal structures most effectively track neutral population history. The cavity system of the inner ear (the so-called bony labyrinth) is a good candidate structure for such analyses. It is already fully formed by birth, which minimizes postnatal phenotypic plasticity, and it is generally well preserved in archaeological samples. Here we use morphometric data of the bony labyrinth to show that it is a surprisingly good marker of the global dispersal of modern humans from Africa. Labyrinthine morphology tracks genetic distances and geography in accordance with an isolation-by-distance model with dispersal from Africa. Our data further indicate that the neutral-like pattern of variation is compatible with stabilizing selection on labyrinth morphology. Given the increasingly important role of the petrous bone for ancient DNA recovery from archaeological specimens, we encourage researchers to acquire 3D morphological data of the inner ear structures before any invasive sampling. Such data will constitute an important archive of phenotypic variation in present and past populations, and will permit individual-based genotype–phenotype comparisons.
Collapse
|
14
|
Recent inner ear specialization for high-speed hunting in cheetahs. Sci Rep 2018; 8:2301. [PMID: 29396425 PMCID: PMC5797172 DOI: 10.1038/s41598-018-20198-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 01/15/2018] [Indexed: 11/30/2022] Open
Abstract
The cheetah, Acinonyx jubatus, is the fastest living land mammal. Because of its specialized hunting strategy, this species evolved a series of specialized morphological and functional body features to increase its exceptional predatory performance during high-speed hunting. Using high-resolution X-ray computed micro-tomography (μCT), we provide the first analyses of the size and shape of the vestibular system of the inner ear in cats, an organ essential for maintaining body balance and adapting head posture and gaze direction during movement in most vertebrates. We demonstrate that the vestibular system of modern cheetahs is extremely different in shape and proportions relative to other cats analysed (12 modern and two fossil felid species), including a closely-related fossil cheetah species. These distinctive attributes (i.e., one of the greatest volumes of the vestibular system, dorsal extension of the anterior and posterior semicircular canals) correlate with a greater afferent sensitivity of the inner ear to head motions, facilitating postural and visual stability during high-speed prey pursuit and capture. These features are not present in the fossil cheetah A. pardinensis, that went extinct about 126,000 years ago, demonstrating that the unique and highly specialized inner ear of the sole living species of cheetah likely evolved extremely recently, possibly later than the middle Pleistocene.
Collapse
|