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Csanády A, Krišovský P. Sex differences in pelvic and sacral size in wildcat from the Western Carpathians. ANIM BIOL 2022. [DOI: 10.1163/15707563-bja10091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Sexual differences in the wildcat were evaluated on 15 variables in 49 pelvic and 38 sacral bones in wildcat from the Western Carpathians. Our data confirmed a male-biased sexual size dimorphism (SSD) in the pelvic and sacral bones. The effect size was very large for two pelvic (SB, smallest width of the shaft of the ilium; and LAR, length of the acetabulum) and two sacral traits (GB, greatest width across the wings; and BFcr, greatest width of the cranial articular surface). Our different allometric patterns in pelvic and sacral measures in both sexes may also be important in mode of locomotion. These findings highlight the need for morphometric analysis of species at the regional as well global level.
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Affiliation(s)
- Alexander Csanády
- University of Prešov, Faculty of Humanities and Natural Sciences, Department of Biology, 17. novembra 1, SK-080 01 Prešov, Slovakia
| | - Peter Krišovský
- East Slovak Museum Košice, Námestie Maratónu Mieru 2, SK-040 01 Košice, Slovakia
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2
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Tavares WC, Pessôa LM. Pelvic sexual dimorphism and its association with cranial morphology in Neotropical spiny rats (Rodentia, Echimyidae). J MAMM EVOL 2022. [DOI: 10.1007/s10914-022-09625-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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3
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Cox SL. A geometric morphometric assessment of shape variation in adult pelvic morphology. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 176:652-671. [PMID: 34528241 DOI: 10.1002/ajpa.24399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 06/13/2021] [Accepted: 07/29/2021] [Indexed: 12/16/2022]
Abstract
OBJECTIVES In humans, the pelvis is the most sexually dimorphic skeletal element and is often utilized in aging and sexing remains. The pelvis has become greatly relied upon in anthropological research (e.g., forensics, demographics, obstetrics, evolutionary history); however, pelvis morphology is highly variable, and very little is known about the nature, sources, patterning, and interpretation of this variation. This study aims to quantify pelvis shape variation, document sexual shape variation, and estimate the plasticity of morphology. This will ultimately give greater ability to interpret modern, archaeological, and evolutionary patterns to gain deeper insight into processes which shape human anatomy. MATERIALS AND METHODS Using a sample of 129 Medieval Danish skeletons, shape variation is documented in the greater sciatic notch (GSN), iliac crest (IC), arcuate line (AL), and sub-pubic angle (SPA) using 3D geometric morphometrics. The landmarking method applied here has the advantage of being applicable to fragmentary remains, rather than requiring whole bones. This allows it to be easily applied to archaeological samples and for the interpretation of separate bone features. Differences in shape were statistically analyzed by principle component analysis, linear discriminate analysis, and morphological disparity. Relationships between maximum femur length, body mass, and shape centroid size were also test by allometric regression. RESULTS Results quantify the sexual dimorphism and shape variation present in these features. The GSN shape is the most variable, while the AL is the least. Similarly, the IC is the only feature which shows almost no dimorphism in shape, and instead best reflects lifestyle/activity patterns. Evidence of dimorphism in the IC is likely a result of cultural labor patterns rather than genetic and hormonal influence. Finally, the shapes of the GSN, AL, and SPA are more related to body mass than to femur length, such that individuals with increased mass exhibit more classically "male" shapes and those with less mass have more "female" shapes. DISCUSSION The results have important implications for the evolution of pelvic anatomy, and sexual dimorphism, but also highlight the plasticity inherent in pelvic morphology. Analyzing pelvis features separately in a clearly defined, relatively genetically homogenous population gives insight into the determinants of bone morphology, which are not readily observable by other means. The relationship between body mass and shape suggests dimorphism in body size and composition may affect bone shape.
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Affiliation(s)
- Samantha L Cox
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Physical Anthropology, Penn Museum, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,University of Cambridge, Department of Archaeology, Cambridge, UK
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4
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Pelvic bone morphometric analysis in the dugong (Dugong dugon). Sci Rep 2020; 10:19350. [PMID: 33168870 PMCID: PMC7652886 DOI: 10.1038/s41598-020-76545-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/29/2020] [Indexed: 11/09/2022] Open
Abstract
The dugong (Dugong dugon Müller) is recognized as an endangered marine mammal. There is limited available anatomical data on the dugong's skeletal system, while what is available has not been well established due to the limited number of archived samples and limited access to them. Importantly, there are certain key questions that should be answered when examining the bones and/or remains of animals such as; what kind of bone is it?; what species does it belong to?; what sex was the animal?; how old was the animal? or how big was it?, etc. In this study, we have focused on the pelvic bone of the dugong by asserting the hypothesis that pelvic bone morphology is related to age, sex, and body size. Here, we have established certain morphometric data encompassing 8 parameters and 5 indexes to analyze the morphology of the pelvic bones obtained from 88 specimens (45 dugongs). We will present three main findings: (1) the pelvic bone in mature male subjects is larger than it is in female subjects, (2) a high rate of accuracy can be established for sex identification using morphometric data obtained from the pelvic bone, and (3) the pelvic bone has the highest degree of correlation with body length, followed by body weight and age. Notably, the important data on the pelvic bone of the dugong acquired in this study can be reliable and extremely useful in sex identification and body size estimation.
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5
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Handelsman DJ, Hirschberg AL, Bermon S. Circulating Testosterone as the Hormonal Basis of Sex Differences in Athletic Performance. Endocr Rev 2018; 39:803-829. [PMID: 30010735 PMCID: PMC6391653 DOI: 10.1210/er.2018-00020] [Citation(s) in RCA: 229] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 06/18/2018] [Indexed: 12/22/2022]
Abstract
Elite athletic competitions have separate male and female events due to men's physical advantages in strength, speed, and endurance so that a protected female category with objective entry criteria is required. Prior to puberty, there is no sex difference in circulating testosterone concentrations or athletic performance, but from puberty onward a clear sex difference in athletic performance emerges as circulating testosterone concentrations rise in men because testes produce 30 times more testosterone than before puberty with circulating testosterone exceeding 15-fold that of women at any age. There is a wide sex difference in circulating testosterone concentrations and a reproducible dose-response relationship between circulating testosterone and muscle mass and strength as well as circulating hemoglobin in both men and women. These dichotomies largely account for the sex differences in muscle mass and strength and circulating hemoglobin levels that result in at least an 8% to 12% ergogenic advantage in men. Suppression of elevated circulating testosterone of hyperandrogenic athletes results in negative effects on performance, which are reversed when suppression ceases. Based on the nonoverlapping, bimodal distribution of circulating testosterone concentration (measured by liquid chromatography-mass spectrometry)-and making an allowance for women with mild hyperandrogenism, notably women with polycystic ovary syndrome (who are overrepresented in elite athletics)-the appropriate eligibility criterion for female athletic events should be a circulating testosterone of <5.0 nmol/L. This would include all women other than those with untreated hyperandrogenic disorders of sexual development and noncompliant male-to-female transgender as well as testosterone-treated female-to-male transgender or androgen dopers.
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Affiliation(s)
- David J Handelsman
- ANZAC Research Institute, University of Sydney, Concord, New South Wales, Australia.,Department of Andrology, Concord Hospital, Sydney, New South Wales, Australia
| | - Angelica L Hirschberg
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.,Department of Gynecology and Reproductive Medicine, Karolinska University Hospital, Stockholm, Sweden
| | - Stephane Bermon
- Laboratoire Motricité Humaine, Education, Sport, Santé, Université Côte d'Azur, Nice, France.,Health and Science Department, International Association of Athletics Federations, Monaco
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6
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Adam CL, Marochi MZ, Masunari S. Ontogenetic shape changes and sexual dimorphism in Aegla marginata Bond-Buckup and Buckup, 1994. AN ACAD BRAS CIENC 2018; 90:1521-1532. [PMID: 29768572 DOI: 10.1590/0001-3765201820170441] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 12/08/2017] [Indexed: 11/22/2022] Open
Abstract
A study on relative growth, sexual dimorphism and ontogenetic trajectory was carried out in a population of the aeglidAegla marginata coming from Barrinha River, Iguape River Basin, Tunas do Paraná, Paraná State, Brazil. The size the of morphological sexual maturity was estimated for males and females. The analysis of sexual dimorphism and ontogenetic trajectory were performed using geometric morphometric technique. Males reach maturity with 10.58 mm of carapace length (CL) and females with 10.38 mm CL. Sexual size dimorphism was only visible among adults, with males reaching larger sizes. This is probably related to the reproductive strategy of males. However, sexual shape dimorphism was found for both juveniles and adults: the posterior region of the carapace was wider in females. As the contrast of this feature was stronger in adults, it can be considered that large abdomen is advantageous for egg incubation. The allometric trajectories of juveniles presented similar directions, becoming divergent during the adult phase. The shape variation inA. marginataoccurred gradually throughout its development, with no abrupt transformation upon reaching sexual maturity. The reproductive adaptation is the main reason for the morphological variation within populations ofA. marginata.
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Affiliation(s)
- Carolina L Adam
- Departamento de Zoologia, Universidade Federal do Paraná, Avenida Coronel Francisco Heráclito dos Santos, 100, 81531-980 Curitiba, PR, Brazil
| | - Murilo Z Marochi
- Departamento de Zoologia, Universidade Federal do Paraná, Avenida Coronel Francisco Heráclito dos Santos, 100, 81531-980 Curitiba, PR, Brazil
| | - Setuko Masunari
- Departamento de Zoologia, Universidade Federal do Paraná, Avenida Coronel Francisco Heráclito dos Santos, 100, 81531-980 Curitiba, PR, Brazil
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7
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Orbach DN, Hedrick B, Würsig B, Mesnick SL, Brennan PLR. The evolution of genital shape variation in female cetaceans. Evolution 2017; 72:261-273. [PMID: 29134627 DOI: 10.1111/evo.13395] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/05/2017] [Indexed: 12/31/2022]
Abstract
Male genital diversification is likely the result of sexual selection. Female genital diversification may also result from sexual selection, although it is less well studied and understood. Female genitalia are complex among whales, dolphins, and porpoises, especially compared to other vertebrates. The evolutionary factors affecting the diversity of vaginal complexity could include ontogeny, allometry, phylogeny, sexual selection, and natural selection. We quantified shape variation in female genitalia using 2D geometric morphometric analysis, and validated the application of this method to study soft tissues. We explored patterns of variation in the shape of the cervix and vagina of 24 cetacean species (n = 61 specimens), and found that genital shape varies primarily in the relative vaginal length and overall aspect ratio of the reproductive tract. Extensive genital shape variation was partly explained by ontogenetic changes and evolutionary allometry among sexually mature cetaceans, whereas phylogenetic signal, relative testis size, and neonate size were not significantly associated with genital shape. Female genital shape is diverse and evolves rapidly even among closely related species, consistent with predictions of sexual selection models and with findings in invertebrate and vertebrate taxa. Future research exploring genital shape variation in 3D will offer new insights into evolutionary mechanisms because internal vaginal structures are variable and can form complex spirals.
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Affiliation(s)
- Dara N Orbach
- Department of Biology, Dalhousie University, Life Science Center, 1355 Oxford Street, Halifax, NS B3H 4R2, Canada.,Department of Biological Sciences, Mount Holyoke College, Amherst, Massachusetts
| | - Brandon Hedrick
- Department of Biological Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts
| | - Bernd Würsig
- Department of Marine Biology, Texas A&M University at Galveston, Galveston, Texas
| | - Sarah L Mesnick
- Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, California
| | - Patricia L R Brennan
- Department of Biological Sciences, Mount Holyoke College, Amherst, Massachusetts.,Department of Biological Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts
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8
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Matysiak A, Malecha AW, Jakubowski H, Sadowska ET, Koteja P, Tryjanowski P. Sexual dimorphism, asymmetry, and the effect of reproduction on pelvis bone in the bank vole, Myodes glareolus. MAMMAL RES 2017. [DOI: 10.1007/s13364-017-0317-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Moffett EA. Dimorphism in the Size and Shape of the Birth Canal Across Anthropoid Primates. Anat Rec (Hoboken) 2017; 300:870-889. [DOI: 10.1002/ar.23572] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 09/13/2016] [Accepted: 12/19/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Elizabeth A. Moffett
- Department of Pathology and Anatomical Sciences; University of Missouri; Columbia Missouri
- Department of Anthropology; Stony Brook University; Stony Brook New York
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10
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Zollikofer CP, Scherrer M, Ponce de León MS. Development of Pelvic Sexual Dimorphism in Hylobatids: Testing the Obstetric Constraints Hypothesis. Anat Rec (Hoboken) 2017; 300:859-869. [DOI: 10.1002/ar.23556] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/29/2016] [Accepted: 09/03/2016] [Indexed: 11/06/2022]
Affiliation(s)
| | - Marc Scherrer
- Anthropological Institute and Museum; University of Zurich; Zurich CH-8057 Switzerland
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11
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Mahakkanukrauh P, Ruengdit S, Tun SM, Case DT, Sinthubua A. Osteometric sex estimation from the os coxa in a Thai population. Forensic Sci Int 2016; 271:127.e1-127.e7. [PMID: 28062152 DOI: 10.1016/j.forsciint.2016.11.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 11/29/2016] [Accepted: 11/30/2016] [Indexed: 11/29/2022]
Abstract
The coxal bone shows a very high degree of sexual dimorphism both morphologically and metrically. However, despite a number of recent studies on sex estimation from the skeleton in Thailand, no osteometric methods of sexing the Thai os coxa have been proposed. Therefore, the aim of this study was to develop a standard sex estimation method for a Thai population by examining the efficacy of six coxal bone measurements and eight indices obtained from 200 Thai skeletons. Independent samples t-tests revealed statistically significant differences between males and females for all but one of the measurements. The equation with the highest correct allocation accuracy was based on four measurements (pubis length, ischium length, total height and acetabulum diameter) and had a predicted and cross-validated accuracy of 96.9% and a tested accuracy of 97.5% on a holdout sample of 40 individuals. The single variable equation with the highest correct allocation accuracy of 94.4% and a tested accuracy of 97.5% was for the ischiopubic index, which is calculated from ischium length and pubis length. Percentage accuracies in predicting sex from these equations were higher than many previous studies, suggesting high levels of sexual dimorphism in the Thai os coxa.
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Affiliation(s)
- Pasuk Mahakkanukrauh
- Forensic Osteology Research Center, Faculty of Medicine, Chiang Mai University, 50200, Thailand; Excellence in Osteology Research and Training Center (ORTC), Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Anatomy, Faculty of Medicine, Chiang Mai University, 50200, Thailand.
| | - Sittiporn Ruengdit
- Forensic Osteology Research Center, Faculty of Medicine, Chiang Mai University, 50200, Thailand.
| | - Saw Myint Tun
- Forensic Science Graduate Programme, Faculty of Science, Mahidol University, 10200, Thailand.
| | - D Troy Case
- Department of Sociology & Anthropology, NC State University, Campus Box 8107, Raleigh, NC 27695-8107, USA.
| | - Apichat Sinthubua
- Forensic Osteology Research Center, Faculty of Medicine, Chiang Mai University, 50200, Thailand; Excellence in Osteology Research and Training Center (ORTC), Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Anatomy, Faculty of Medicine, Chiang Mai University, 50200, Thailand.
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12
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Developmental evidence for obstetric adaptation of the human female pelvis. Proc Natl Acad Sci U S A 2016; 113:5227-32. [PMID: 27114515 DOI: 10.1073/pnas.1517085113] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The bony pelvis of adult humans exhibits marked sexual dimorphism, which is traditionally interpreted in the framework of the "obstetrical dilemma" hypothesis: Giving birth to large-brained/large-bodied babies requires a wide pelvis, whereas efficient bipedal locomotion requires a narrow pelvis. This hypothesis has been challenged recently on biomechanical, metabolic, and biocultural grounds, so that it remains unclear which factors are responsible for sex-specific differences in adult pelvic morphology. Here we address this issue from a developmental perspective. We use methods of biomedical imaging and geometric morphometrics to analyze changes in pelvic morphology from late fetal stages to adulthood in a known-age/known-sex forensic/clinical sample. Results show that, until puberty, female and male pelves exhibit only moderate sexual dimorphism and follow largely similar developmental trajectories. With the onset of puberty, however, the female trajectory diverges substantially from the common course, resulting in rapid expansion of obstetrically relevant pelvic dimensions up to the age of 25-30 y. From 40 y onward females resume a mode of pelvic development similar to males, resulting in significant reduction of obstetric dimensions. This complex developmental trajectory is likely linked to the pubertal rise and premenopausal fall of estradiol levels and results in the obstetrically most adequate pelvic morphology during the time of maximum female fertility. The evidence that hormones mediate female pelvic development and morphology supports the view that solutions of the obstetrical dilemma depend not only on selection and adaptation but also on developmental plasticity as a response to ecological/nutritional factors during a female's lifetime.
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13
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Kurki HK, Decrausaz SL. Shape variation in the human pelvis and limb skeleton: Implications for obstetric adaptation. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 159:630-8. [PMID: 26699269 DOI: 10.1002/ajpa.22922] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/26/2015] [Accepted: 11/28/2015] [Indexed: 12/22/2022]
Abstract
OBJECTIVES Under the obstetrical dilemma (OD) hypothesis, selection acts on the human female pelvis to ensure a sufficiently sized obstetric canal for birthing a large-brained, broad shouldered neonate, while bipedal locomotion selects for a narrower and smaller pelvis. Despite this female-specific stabilizing selection, variability of linear dimensions of the pelvic canal and overall size are not reduced in females, suggesting shape may instead be variable among females of a population. Female canal shape has been shown to vary among populations, while male canal shape does not. Within this context, we examine within-population canal shape variation in comparison with that of noncanal aspects of the pelvis and the limbs. MATERIALS AND METHODS Nine skeletal samples (total female n = 101, male n = 117) representing diverse body sizes and shapes were included. Principal components analysis was applied to size-adjusted variables of each skeletal region. A multivariate variance was calculated using the weighted PC scores for all components in each model and F-ratios used to assess differences in within-population variances between sexes and skeletal regions. RESULTS Within both sexes, multivariate canal shape variance is significantly greater than noncanal pelvis and limb variances, while limb variance is greater than noncanal pelvis variance in some populations. Multivariate shape variation is not consistently different between the sexes in any of the skeletal regions. DISCUSSION Diverse selective pressures, including obstetrics, locomotion, load carrying, and others may act on canal shape, as well as genetic drift and plasticity, thus increasing variation in morphospace while protecting obstetric sufficiency.
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Affiliation(s)
- Helen K Kurki
- Department of Anthropology, University of Victoria, Victoria, BC, V8P 5C2, Canada
| | - Sarah-Louise Decrausaz
- Division of Biological Anthropology, Department of Archaeology and Anthropology, University of Cambridge, Cambridge, CB2 3QG
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14
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Betti L. Sexual dimorphism in the size and shape of the os coxae and the effects of microevolutionary processes. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 153:167-77. [DOI: 10.1002/ajpa.22410] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 09/16/2013] [Accepted: 10/13/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Lia Betti
- Division of Biological Anthropology; Department of Archaeology and Anthropology; University of Cambridge; Cambridge CB2 3QG UK
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15
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Bilfeld MF, Dedouit F, Sans N, Rousseau H, Rougé D, Telmon N. Ontogeny of Size and Shape Sexual Dimorphism in the Ilium: A Multislice Computed Tomography Study by Geometric Morphometry. J Forensic Sci 2012; 58:303-10. [DOI: 10.1111/1556-4029.12037] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 01/19/2012] [Accepted: 02/02/2012] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Nicolas Sans
- Service de Radiologie; CHU Toulouse-Purpan; place du docteur Baylac; 31059; Toulouse Cedex 9; France
| | - Hervé Rousseau
- Service de Radiologie; CHU Toulouse-Rangueil; 1 avenue Professeur Jean Poulhès; 31059; Toulouse Cedex 9; France
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16
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Wells JCK, DeSilva JM, Stock JT. The obstetric dilemma: an ancient game of Russian roulette, or a variable dilemma sensitive to ecology? AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 149 Suppl 55:40-71. [PMID: 23138755 DOI: 10.1002/ajpa.22160] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The difficult birth process of humans, often described as the "obstetric dilemma," is commonly assumed to reflect antagonistic selective pressures favoring neonatal encephalization and maternal bipedal locomotion. However, cephalo-pelvic disproportion is not exclusive to humans, and is present in some primate species of smaller body size. The fossil record indicates mosaic evolution of the obstetric dilemma, involving a number of different evolutionary processes, and it appears to have shifted in magnitude between Australopithecus, Pleistocene Homo, and recent human populations. Most attention to date has focused on its generic nature, rather than on its variability between populations. We re-evaluate the nature of the human obstetric dilemma using updated hominin and primate literature, and then consider the contribution of phenotypic plasticity to variability in its magnitude. Both maternal pelvic dimensions and fetal growth patterns are sensitive to ecological factors such as diet and the thermal environment. Neonatal head girth has low plasticity, whereas neonatal mass and maternal stature have higher plasticity. Secular trends in body size may therefore exacerbate or decrease the obstetric dilemma. The emergence of agriculture may have exacerbated the dilemma, by decreasing maternal stature and increasing neonatal growth and adiposity due to dietary shifts. Paleodemographic comparisons between foragers and agriculturalists suggest that foragers have considerably lower rates of perinatal mortality. In contemporary populations, maternal stature remains strongly associated with perinatal mortality in many populations. Long-term improvements in nutrition across future generations may relieve the dilemma, but in the meantime, variability in its magnitude is likely to persist.
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Affiliation(s)
- Jonathan C K Wells
- Childhood Nutrition Research Centre, UCL Institute of Child Health, London WC1N 1EH, UK.
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17
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Kurki HK. Pelvic dimorphism in relation to body size and body size dimorphism in humans. J Hum Evol 2011; 61:631-43. [DOI: 10.1016/j.jhevol.2011.07.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 07/22/2011] [Accepted: 07/31/2011] [Indexed: 10/17/2022]
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18
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Towal RB, Quist BW, Gopal V, Solomon JH, Hartmann MJZ. The morphology of the rat vibrissal array: a model for quantifying spatiotemporal patterns of whisker-object contact. PLoS Comput Biol 2011; 7:e1001120. [PMID: 21490724 PMCID: PMC3072363 DOI: 10.1371/journal.pcbi.1001120] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 03/10/2011] [Indexed: 11/18/2022] Open
Abstract
In all sensory modalities, the data acquired by the nervous system is shaped by the biomechanics, material properties, and the morphology of the peripheral sensory organs. The rat vibrissal (whisker) system is one of the premier models in neuroscience to study the relationship between physical embodiment of the sensor array and the neural circuits underlying perception. To date, however, the three-dimensional morphology of the vibrissal array has not been characterized. Quantifying array morphology is important because it directly constrains the mechanosensory inputs that will be generated during behavior. These inputs in turn shape all subsequent neural processing in the vibrissal-trigeminal system, from the trigeminal ganglion to primary somatosensory ("barrel") cortex. Here we develop a set of equations for the morphology of the vibrissal array that accurately describes the location of every point on every whisker to within ±5% of the whisker length. Given only a whisker's identity (row and column location within the array), the equations establish the whisker's two-dimensional (2D) shape as well as three-dimensional (3D) position and orientation. The equations were developed via parameterization of 2D and 3D scans of six rat vibrissal arrays, and the parameters were specifically chosen to be consistent with those commonly measured in behavioral studies. The final morphological model was used to simulate the contact patterns that would be generated as a rat uses its whiskers to tactually explore objects with varying curvatures. The simulations demonstrate that altering the morphology of the array changes the relationship between the sensory signals acquired and the curvature of the object. The morphology of the vibrissal array thus directly constrains the nature of the neural computations that can be associated with extraction of a particular object feature. These results illustrate the key role that the physical embodiment of the sensor array plays in the sensing process.
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Affiliation(s)
- R. Blythe Towal
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Brian W. Quist
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Venkatesh Gopal
- Department of Physics, Elmhurst College, Elmhurst, Illinois, United States of America
| | - Joseph H. Solomon
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Mitra J. Z. Hartmann
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
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19
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Oyhenart EE, Cesani MF, Castro LE, Quintero FA, Fucini MC, Luna ME, Guimarey LM. Bone growth and sexual dimorphism at birth in intrauterine-growth-retarded rats. Anat Sci Int 2010; 86:119-27. [PMID: 21153456 DOI: 10.1007/s12565-010-0098-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 10/03/2010] [Indexed: 11/24/2022]
Abstract
This paper addresses the effect of a reduction of uterine blood flow (RUB) on postcranial bone growth in rats. The objectives were: (1) to discover and characterize the changes evoked by growth retardation through a reduction in placental blood flow, (2) to see if the resulting growth retardation is different in each bone, and (3) to analyze any sex-specific features. RUB was induced by the partial bending of uterine vessels at day 1 of pregnancy. Control and sham-operated animals were also included. The animals were X-rayed at birth. The lengths and widths of the humerus, radius, and femur and pelvic length, interischial, interpubic, and pubic widths were measured. Data were analyzed by ANOVA and LSD post hoc tests. The intersubject analysis showed significant differences between groups and non-significant differences between sexes. In males, sham-operated and RUB showed significant differences in pelvic lengths and widths, and humeral, radial, femoral, and tibial widths. In females, there were significant differences only for humeral widths, radial lengths and widths, and femoral and tibial widths. We conclude that reduced blood flow delays appendicular bone growth as observed at birth. Pelvic length was more affected than that of the limbs. The widths of the pelvic and limbs bones, in turn, were more altered than the lengths, and the growth of the males more than that of the females. Partial bending of uterine vessels compromised postcranial growth, though under such disadvantageous circumstances the females proved to be more capable of growing and thus more resilient than the males.
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Affiliation(s)
- Evelia Edith Oyhenart
- Instituto de Genética Veterinaria ¨Ing. Fernando Noel Dulout¨ (IGEVET), Universidad Nacional de La Plata (UNLP)-CCT La Plata-CONICET, Buenos Aires, Argentina.
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Schutz H, Donovan ER, Hayes JP. Effects of parity on pelvic size and shape dimorphism inMus. J Morphol 2009; 270:834-42. [DOI: 10.1002/jmor.10723] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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SCHUTZ HEIDI, POLLY PDAVID, KRIEGER JONATHAND, GURALNICK ROBERTP. Differential sexual dimorphism: size and shape in the cranium and pelvis of grey foxes (Urocyon). Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2008.01132.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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