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Mitteroecker P, Fischer B. Evolution of the human birth canal. Am J Obstet Gynecol 2024; 230:S841-S855. [PMID: 38462258 DOI: 10.1016/j.ajog.2022.09.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 09/07/2022] [Accepted: 09/07/2022] [Indexed: 03/12/2024]
Abstract
It seems puzzling why humans have evolved such a small and rigid birth canal that entails a relatively complex process of labor compared with the birth canal of our closest relatives, the great apes. This study reviewed insights into the evolution of the human birth canal from recent theoretical and empirical studies and discussed connections to obstetrics, gynecology, and orthopedics. Originating from the evolution of bipedality and the large human brain million years ago, the evolution of the human birth canal has been characterized by complex trade-off dynamics among multiple biological, environmental, and sociocultural factors. The long-held notion that a wider pelvis has not evolved because it would be disadvantageous for bipedal locomotion has not yet been empirically verified. However, recent clinical and biomechanical studies suggest that a larger birth canal would compromise pelvic floor stability and increase the risk of incontinence and pelvic organ prolapse. Several mammals have neonates that are equally large or even larger than human neonates compared to the size of the maternal birth canal. In these species, the pubic symphysis opens widely to allow successful delivery. Biomechanical and developmental constraints imposed by bipedality have hindered this evolutionary solution in humans and led to the comparatively rigid pelvic girdle in pregnant women. Mathematical models have shown why the evolutionary compromise to these antagonistic selective factors inevitably involves a certain rate of fetopelvic disproportion. In addition, these models predict that cesarean deliveries have disrupted the evolutionary equilibrium and led to new and ongoing evolutionary changes. Different forms of assisted birth have existed since the stone age and have become an integral part of human reproduction. Paradoxically, by buffering selection, they may also have hindered the evolution of a larger birth canal. Many of the biological, environmental, and sociocultural factors that have influenced the evolution of the human birth canal vary globally and are subject to ongoing transitions. These differences may have contributed to the global variation in the form of the birth canal and the difficulty of labor, and they likely continue to change human reproductive anatomy.
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Affiliation(s)
- Philipp Mitteroecker
- Unit for Theoretical Biology, Department of Evolutionary Biology, University of Vienna, Vienna, Austria.
| | - Barbara Fischer
- Unit for Theoretical Biology, Department of Evolutionary Biology, University of Vienna, Vienna, Austria
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Smith TD, Santana SE, Eiting TP. Ecomorphology and sensory biology of bats. Anat Rec (Hoboken) 2023; 306:2660-2669. [PMID: 37656052 DOI: 10.1002/ar.25314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 09/02/2023]
Abstract
This special issue of The Anatomical Record is inspired by and dedicated to Professor Kunwar P. Bhatnagar, whose lifelong interests in biology, and long career studying bats, inspired many and advanced our knowledge of the world's only flying mammals. The 15 articles included here represent a broad range of investigators, treading topics familiar to Prof. Bhatnagar, who was interested in seemingly every aspect of bat biology. Key topics include broad themes of bat development, sensory systems, and specializations related to flight and diet. These articles paint a complex picture of the fascinating adaptations of bats, such as rapid fore limb development, ear morphologies relating to echolocation, and other enhanced senses that allow bats to exploit niches in virtually every part of the world. In this introduction, we integrate and contextualize these articles within the broader story of bat ecomorphology, providing an overview of each of the key themes noted above. This special issue will serve as a springboard for future studies both in bat biology and in the broader world of mammalian comparative anatomy and ecomorphology.
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Affiliation(s)
- Timothy D Smith
- School of Physical Therapy, Slippery Rock University, Slippery Rock, Pennsylvania, USA
| | - Sharlene E Santana
- Department of Biology, University of Washington, Seattle, Washington, USA
| | - Thomas P Eiting
- Department of Physiology and Pathology, Burrell College of Osteopathic Medicine, Las Cruces, New Mexico, USA
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Smith TD, Prufrock KA, DeLeon VB. How to make a vampire. Anat Rec (Hoboken) 2023; 306:2872-2887. [PMID: 36806921 DOI: 10.1002/ar.25179] [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: 01/07/2023] [Revised: 02/01/2023] [Accepted: 02/01/2023] [Indexed: 02/23/2023]
Abstract
Herein, we compared the developmental maturity of the cranium, limbs, and feeding apparatus in a perinatal common vampire bat relative to its mother. In addition, we introduce a method for combining two computed tomographic imaging techniques to three-dimensionally reconstruct endocasts in poorly ossified crania. The Desmodus specimens were scanned using microcomputed tomography (microCT) and diffusible iodine-based contrast-enhanced CT to image bone and soft tissues. Muscles of the jaw and limbs, and the endocranial cavity were segmented using imaging software. Endocranial volume (ECV) of the perinatal Desmodus is 74% of adult ECV. The facial skeletal is less developed (e.g., palatal length 60% of adult length), but volumes for alveolar crypts/sockets of permanent teeth are nearly identical. The forelimb skeleton is uniformly less ossified than the distal hind limb, with no secondary centers ossified and an entirely cartilaginous carpus. All epiphyseal growth zones are active in the brachium and antebrachium, with the distal radius exhibiting the greatest number of proliferating chondrocytes arranged in columns. The hind limb skeleton is precociously ossified from the knee distally. The musculature of the fore limb, temporalis, and masseter muscles appear weakly developed (6-11% of the adult volume). In contrast, the leg and foot musculature is better developed (23-25% of adult volume), possibly enhancing the newborn's capability to grip the mother's fur. Desmodus is born relatively large, and our results suggest they are born neurally and dentally precocious, with generally underdeveloped limbs, especially the fore limb.
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Affiliation(s)
- Timothy D Smith
- School of Physical Therapy, Slippery Rock University, Slippery Rock, Pennsylvania, USA
| | - Kristen A Prufrock
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Valerie B DeLeon
- Department of Anthropology, University of Florida, Gainesville, Florida, USA
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Smith TD, Ruf I, DeLeon VB. Ontogenetic transformation of the cartilaginous nasal capsule in mammals, a review with new observations on bats. Anat Rec (Hoboken) 2023. [PMID: 36647334 DOI: 10.1002/ar.25152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/15/2022] [Accepted: 12/20/2022] [Indexed: 01/18/2023]
Abstract
The nasal capsule, as the most rostral part of the chondrocranium, is a critical point of connection with the facial skeleton. Its fate may influence facial form, and the varied fates of cartilage may be a vehicle contributing to morphological diversity. Here, we review ontogenetic changes in the cartilaginous nasal capsule of mammals, and make new observations on perinatal specimens of two chiropteran species of different suborders. Our observations reveal some commonalities between Rousettus leschenaultii and Desmodus rotundus, such as perinatal ossification of the first ethmoturbinal. However, in Rousettus, ossification of turbinals is demonstrated as either perichondrial or endochondral. In Desmodus, perichondrial and endochondral ossification of the posterior nasal cupula is observed at birth, a part of the nasal capsule previously shown to persist as cartilage into infancy in Rousettus. Combined with prior findings on cranial cartilages we identify several diverse transformational mechanisms by which cartilage as a tissue type may contribute to morphological diversity of the cranium. First, cartilage differentiates in an iterative fashion to increase nasal complexity, but still retains the capacity for later elaboration via de novo bone emanating outward before or after cartilage ossifies. Second, cartilage acts as a driver of growth at growth centers, or via interstitial growth (e.g., septal cartilage). Finally, cartilage as a tissue may influence the timing of ossification and union of the facial and basicranial skeleton. In particular, cartilage at certain points of ontogeny may "model" via selective resorption, showing some similarity to bone.
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Affiliation(s)
- Timothy D Smith
- School of Physical Therapy, Slippery Rock University, Slippery Rock, Pennsylvania, USA
| | - Irina Ruf
- Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, Frankfurt am Main, Germany
- Institut für Geowissenschaften, Goethe-Universität Frankfurt am Main, Frankfurt am Main, Germany
| | - Valerie B DeLeon
- Department of Anthropology, University of Florida, Gainesville, Florida, USA
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Ospina-Garcés SM, León-Paniagua L. Sexual dimorphism and geographic variation of the skull of the fishing bat Noctilio leporinus (Chiroptera: Noctilionidae) in Mexico. REV MEX BIODIVERS 2021. [DOI: 10.22201/ib.20078706e.2021.92.3518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Ponssa ML, Abdala V. Sesamoids in Caudata and Gymnophiona (Lissamphibia): absences and evidence. PeerJ 2021; 8:e10595. [PMID: 33384907 PMCID: PMC7751427 DOI: 10.7717/peerj.10595] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 11/26/2020] [Indexed: 11/30/2022] Open
Abstract
An integrative definition of sesamoid bones has been recently proposed, highlighting their relationship with tendons and ligaments, their genetic origin, the influence of epigenetic stimuli on their development, and their variable tissue composition. Sesamoid bones occur mainly associated with a large number of mobile joints in vertebrates, most commonly in the postcranium. Here, we present a survey of the distribution pattern of sesamoids in 256 taxa of Caudata and Gymnophiona and 24 taxa of temnospondyls and lepospondyls, based on dissections, high-resolution X-ray computed tomography from digital databases and literature data. These groups have a pivotal role in the interpretation of the evolution of sesamoids in Lissamphibia and tetrapods in general. Our main goals were: (1) to contribute to the knowledge of the comparative anatomy of sesamoids in Lissamphibia; (2) to assess the evolutionary history of selected sesamoids. We formally studied the evolution of the observed sesamoids by optimizing them in the most accepted phylogeny of the group. We identified only three bony or cartilaginous sesamoids in Caudata: the mandibular sesamoid, which is adjacent to the jaw articulation; one located on the mandibular symphysis; and one located in the posterior end of the maxilla. We did not observe any cartilaginous or osseous sesamoid in Gymnophiona. Mapping analyses of the sesamoid dataset of urodeles onto the phylogeny revealed that the very conspicuous sesamoid in the mandibular symphysis of Necturus beyeri and Amphiuma tridactylum is an independent acquisition of these taxa. On the contrary, the sesamoid located between the maxilla and the lower jaw is a new synapomorphy that supports the node of Hydromantes platycephalus and Karsenia coreana. The absence of a mandibular sesamoid is plesiomorphic to Caudata, whereas it is convergent in seven different families. The absence of postcranial sesamoids in salamanders might reveal a paedomorphic pattern that would be visible in their limb joints.
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Affiliation(s)
- María Laura Ponssa
- Área Herpetología, Unidad Ejecutora Lillo (UEL), CONICET-Fundación Miguel Lillo, San Miguel de Tucumán, Tucumán, Argentina
| | - Virginia Abdala
- Instituto de Biodiversidad Neotropical (IBN), UNT-CONICET. Cátedra de Biología General, Facultad de Ciencias Naturales e IML, UNT, Yerba Buena, Tucuman, Argentina
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Stanchak KE, Arbour JH, Santana SE. Anatomical diversification of a skeletal novelty in bat feet. Evolution 2019; 73:1591-1603. [DOI: 10.1111/evo.13786] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 05/05/2019] [Accepted: 05/18/2019] [Indexed: 12/30/2022]
Affiliation(s)
- Kathryn E. Stanchak
- Department of Biology and Burke Museum of Natural History and Culture University of Washington Seattle Washington 98195
| | - Jessica H. Arbour
- Department of Biology and Burke Museum of Natural History and Culture University of Washington Seattle Washington 98195
| | - Sharlene E. Santana
- Department of Biology and Burke Museum of Natural History and Culture University of Washington Seattle Washington 98195
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Grunstra NDS, Zachos FE, Herdina AN, Fischer B, Pavličev M, Mitteroecker P. Humans as inverted bats: A comparative approach to the obstetric conundrum. Am J Hum Biol 2019; 31:e23227. [PMID: 30810261 PMCID: PMC6492174 DOI: 10.1002/ajhb.23227] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 02/03/2019] [Accepted: 02/06/2019] [Indexed: 01/19/2023] Open
Abstract
OBJECTIVES The narrow human birth canal evolved in response to multiple opposing selective forces on the pelvis. These factors cannot be sufficiently disentangled in humans because of the limited range of relevant variation. Here, we outline a comparative strategy to study the evolution of human childbirth and to test existing hypotheses in primates and other mammals. METHODS We combined a literature review with comparative analyses of neonatal and female body and brain mass, using three existing datasets. We also present images of bony pelves of a diverse sample of taxa. RESULTS Bats, certain non-human primates, seals, and most ungulates, including whales, have much larger relative neonatal masses than humans, and they all differ in their anatomical adaptations for childbirth. Bats, as a group, are particularly interesting in this context as they give birth to the relatively largest neonates, and their pelvis is highly dimorphic: Whereas males have a fused symphysis, a ligament bridges a large pubic gap in females. The resulting strong demands on the widened and vulnerable pelvic floor likely are relaxed by roosting head-down. CONCLUSIONS Parturition has constituted a strong selective force in many non-human placentals. We illustrated how the demands on pelvic morphology resulting from locomotion, pelvic floor stability, childbirth, and perhaps also erectile function in males have been traded off differently in mammals, depending on their locomotion and environment. Exploiting the power of a comparative approach, we present new hypotheses and research directions for resolving the obstetric conundrum in humans.
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Affiliation(s)
- Nicole D. S. Grunstra
- Department of Theoretical BiologyUniversity of ViennaViennaAustria
- Mammal CollectionNatural History Museum ViennaViennaAustria
| | - Frank E. Zachos
- Mammal CollectionNatural History Museum ViennaViennaAustria
- Department of Integrative ZoologyUniversity of ViennaViennaAustria
| | | | - Barbara Fischer
- Konrad Lorenz Institute for Evolution and Cognition ResearchKlosterneuburgAustria
| | - Mihaela Pavličev
- Cincinnati Children's Hospital Medical CenterCincinnatiOhio
- Department of PediatricsUniversity of Cincinnati College of MedicineCincinnatiOhio
- Department of PhilosophyUniversity of CincinnatiCincinnatiOhio
| | - Philipp Mitteroecker
- Department of Theoretical BiologyUniversity of ViennaViennaAustria
- Konrad Lorenz Institute for Evolution and Cognition ResearchKlosterneuburgAustria
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López‐Aguirre C, Hand SJ, Koyabu D, Son NT, Wilson LAB. Prenatal allometric trajectories and the developmental basis of postcranial phenotypic diversity in bats (Chiroptera). JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2019; 332:36-49. [DOI: 10.1002/jez.b.22846] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/17/2019] [Accepted: 01/31/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Camilo López‐Aguirre
- PANGEA Research Centre School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney New South Wales Australia
| | - Suzanne J. Hand
- PANGEA Research Centre School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney New South Wales Australia
| | - Daisuke Koyabu
- Department of Curatorial Studies University Museum, University of Tokyo Tokyo Japan
- Department of Humanities and Sciences Musashino Art University Tokyo Japan
| | - Nguyen Truong Son
- Department of Vertebrate Zoology Institute of Ecology and Biological Resources, Vietnam Academy of Sciences and Technology Hanoi Vietnam
- Faculty of Ecology and Biological Resources Graduate University of Science and Technology Hanoi Vietnam
| | - Laura A. B. Wilson
- PANGEA Research Centre School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney New South Wales Australia
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Celeita JS, Reyes‐Amaya N, Jerez A. Comparative hindlimb bone morphology in noctilionid fisher bats (Chiroptera: Noctilionidae), with emphasis on
Noctilio leporinus
postnatal development. ACTA ZOOL-STOCKHOLM 2018. [DOI: 10.1111/azo.12276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Nicolás Reyes‐Amaya
- Unidad Ejecutora Lillo (CONICET – Fundación Miguel Lillo) San Miguel de Tucumán Argentina
| | - Adriana Jerez
- Laboratorio de Ecología Evolutiva, Departamento de BiologíaUniversidad Nacional de Colombia Bogotá Colombia
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Amador LI, Giannini NP, Simmons NB, Abdala V. Morphology and Evolution of Sesamoid Elements in Bats (Mammalia: Chiroptera). AMERICAN MUSEUM NOVITATES 2018. [DOI: 10.1206/3905.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Lucila Inés Amador
- Unidad Ejecutora Lillo: Fundación Miguel Lillo – CONICET, Tucumán, Argentina
| | - Norberto Pedro Giannini
- Unidad Ejecutora Lillo: Fundación Miguel Lillo – CONICET, Tucumán, Argentina
- Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, Tucumán, Argentina
- Division of Vertebrate Zoology (Mammalogy), American Museum of Natural History
| | - Nancy B. Simmons
- Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, Tucumán, Argentina
| | - Virginia Abdala
- Instituto de Biodiversidad Neotropical: Universidad Nacional de Tucumán – CONICET, Tucumán, Argentina
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