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Griebel U, Oller DK. From emotional signals to symbols. Front Psychol 2024; 15:1135288. [PMID: 38629043 PMCID: PMC11020113 DOI: 10.3389/fpsyg.2024.1135288] [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: 12/31/2022] [Accepted: 03/13/2024] [Indexed: 04/19/2024] Open
Abstract
The quest for the origins of language is a diverse enterprise, where research from a variety of disciplines brings area-specific ideas and area-specific terminology to bear. This variety often results in misunderstandings and misconceptions about communication in various species. In the present paper, we argue for focus on emotional systems as the primary motivators for social signals in animals in general. This focus can help resolve discrepancies of interpretation among different areas of inquiry and can illuminate distinctions among different social signals as well as their phylogenetic origins in animals and especially in humans. We advocate, following Jaak Panksepp, a view wherein the Seeking System, the endogenous tendency to search and explore, is the most fundamental emotional motivation. The Seeking System forms the basis for flexible, voluntary, and exploratory control of motor systems and makes much of learning possible. The relative lack of vocal learning and expression in nonhuman primates contrasted with extensive vocal learning and expression in humans began, we propose, with the evolution in ancient hominins of a necessary foundation for the many subsequent capabilities required for language. That foundation was, according to the reasoning, naturally selected in the form of neurological connections between the Seeking System and mechanisms of glottal/phonatory control. The new connections allowed ancient hominins to develop flexible, endogenous vocal fitness signals produced at very high rates and including large numbers of discrete syllables, recombinable to form syllable combinations with many prosodic variations. The increasing sociality of hominins supported evolution of massive expansion in the utilization of these flexible vocal forms to allow development of words and sentences.
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Affiliation(s)
- Ulrike Griebel
- School of Communication Sciences and Disorders, The University of Memphis, Memphis, TN, United States
- The Institute for Intelligent Systems, University of Memphis, Memphis, TN, United States
- The Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
| | - D. Kimbrough Oller
- School of Communication Sciences and Disorders, The University of Memphis, Memphis, TN, United States
- The Institute for Intelligent Systems, University of Memphis, Memphis, TN, United States
- The Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
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2
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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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Wells JCK, Desoye G, Leon DA. Reconsidering the developmental origins of adult disease paradigm: The 'metabolic coordination of childbirth' hypothesis. Evol Med Public Health 2024; 12:50-66. [PMID: 38380130 PMCID: PMC10878253 DOI: 10.1093/emph/eoae002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 12/18/2023] [Indexed: 02/22/2024] Open
Abstract
In uncomplicated pregnancies, birthweight is inversely associated with adult non-communicable disease (NCD) risk. One proposed mechanism is maternal malnutrition during pregnancy. Another explanation is that shared genes link birthweight with NCDs. Both hypotheses are supported, but evolutionary perspectives address only the environmental pathway. We propose that genetic and environmental associations of birthweight with NCD risk reflect coordinated regulatory systems between mother and foetus, that evolved to reduce risks of obstructed labour. First, the foetus must tailor its growth to maternal metabolic signals, as it cannot predict the size of the birth canal from its own genome. Second, we predict that maternal alleles that promote placental nutrient supply have been selected to constrain foetal growth and gestation length when fetally expressed. Conversely, maternal alleles that increase birth canal size have been selected to promote foetal growth and gestation when fetally expressed. Evidence supports these hypotheses. These regulatory mechanisms may have undergone powerful selection as hominin neonates evolved larger size and encephalisation, since every mother is at risk of gestating a baby excessively for her pelvis. Our perspective can explain the inverse association of birthweight with NCD risk across most of the birthweight range: any constraint of birthweight, through plastic or genetic mechanisms, may reduce the capacity for homeostasis and increase NCD susceptibility. However, maternal obesity and diabetes can overwhelm this coordination system, challenging vaginal delivery while increasing offspring NCD risk. We argue that selection on viable vaginal delivery played an over-arching role in shaping the association of birthweight with NCD risk.
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Affiliation(s)
- Jonathan C K Wells
- Population, Policy and Practice Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Gernot Desoye
- Department of Obstetrics and Gynaecology, Medical University of Graz, Auenbruggerplatz 14, 8036 Graz, Austria
| | - David A Leon
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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Nishikawa S, Miki M, Chigusa Y, Furuta M, Kido A, Kawamura Y, Ueda Y, Mandai M, Mogami H. Obstetric pelvimetry by three-dimensional computed tomography in non-pregnant Japanese women: a retrospective single-center study. J Matern Fetal Neonatal Med 2023; 36:2190444. [PMID: 36927362 DOI: 10.1080/14767058.2023.2190444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
OBJECTIVE While a basic understanding of pelvic size and typology is still important for obstetricians, pelvic measurement data for Japanese women are very scarce. To our best knowledge, no large-scale pelvimetry studies of Japanese women have been made for the past 50 years. This study aimed to investigate the accurate size, particularly the obstetric conjugate (OC) and transverse diameter of the pelvic inlet (TD), of modern Japanese women, using three-dimensional (3D) computed tomography (CT), and to obtain their reference values. METHODS This retrospective, single-center observational study enrolled Japanese non-pregnant women aged between 20 and 40 years, who underwent pelvic CT examination from 2016 to 2021. CT was performed for various reasons, including acute abdomen, search for cancer metastases, and follow-up of existing disease. However, no cases were taken for pelvic measurements. Pelvimetry was performed retrospectively using a 3D workstation. The OC was measured on a strict lateral view and the TD was measured on an axial-oblique view. Other clinical data, such as age, height, and weight, were also extracted from the medical charts and analyzed. RESULTS A total of 1,263 patients were enrolled, with the mean age of 32.7 years (standard deviation [SD] 6.2). The mean height, weight, and body mass index were 158.8 cm (SD 5.8), 54.8 kg (SD 11.7), and 21.7 kg/m2 (SD 4.4), respectively. The mean OC length was 127.0 mm (SD 9.5, 95% confidence interval [CI] 126.5-127.5), while the mean TD length was 126.8 mm (SD 7.5, 95% CI 126.4-127.2). Both values were normally distributed. Height was significantly associated with OC (regression coefficient = 0.75 [95% CI 0.66-0.84], p < .001) and TD (regression coefficient = 0.63 [95% CI 0.56-0.70], p < .001). Age showed a weak but statistically significant positive association with TD (regression coefficient = 0.14 [95% CI 0.07-0.20], p < .001) and OC (regression coefficient = -0.10 [95% CI -0.18 to -0.01], p = .026). CONCLUSION The 3D CT pelvimetry in 1,263 non-pregnant Japanese women of childbearing age revealed the mean OC and TD of 127.0 mm, and 126.8 mm, which were 11.8 mm and 4.3 mm larger, respectively, than those in the survey in 1972. Our data will be referred to in clinical practice as the standard pelvic measurement values for the Japanese population.
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Affiliation(s)
- Shoko Nishikawa
- Department of Gynecology and Obstetrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masayo Miki
- Department of Gynecology and Obstetrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yoshitsugu Chigusa
- Department of Gynecology and Obstetrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Marie Furuta
- Department of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Aki Kido
- Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yosuke Kawamura
- Department of Gynecology and Obstetrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yusuke Ueda
- Department of Gynecology and Obstetrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masaki Mandai
- Department of Gynecology and Obstetrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Haruta Mogami
- Department of Gynecology and Obstetrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Cordey C, Webb NM, Haeusler M. Take it to the limit: The limitations of energetic explanations for birth timing in humans. Evol Med Public Health 2023; 11:415-428. [PMID: 38022799 PMCID: PMC10644907 DOI: 10.1093/emph/eoad035] [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: 02/19/2023] [Revised: 10/18/2023] [Indexed: 12/01/2023] Open
Abstract
A hallmark of modern humans is that our newborns are neurologically immature compared to other primates. It is disputed whether this so-called secondary altriciality evolved due to remodelling of the pelvis associated with bipedal locomotion, as suggested by the obstetrical dilemma hypothesis, or from maternal energetic limitations during pregnancy. Specifically, the 'Energetics of Gestation and Growth' (EGG) hypothesis posits that birth is initiated when foetal energy requirements exceed the maximum sustained maternal metabolic rate during pregnancy at around 2.1 × basal metabolic rate (BMR) of the non-pregnant, non-lactating condition (NPNL). However, the metabolic threshold argued under the EGG framework is derived from one study with a small sample size of only 12 women from the UK. Accordingly, we performed a meta-analysis of all published studies on metabolic scopes during pregnancy to better account for variability. After excluding 3 studies with methodological issues, a total of 12 studies with 303 women from 5 high- and 3 low-income countries were analysed. On average, pregnancy was found to be less metabolically challenging than previously suggested. The studies revealed substantial variation in metabolic scope during pregnancy, which was not reflected by variation in birth timing. Further, in a third of the studies, the metabolic rates exceeded 2.1 × BMRNPNL. Our simulation of foetal energy requirements demonstrated that this metabolic threshold of 2.1 × BMRNPNL cannot realistically be crossed by the foetus around the time of birth. These findings imply that metabolic constraints are not the main limiting factor dictating gestation length.
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Affiliation(s)
- Cédric Cordey
- Institute of Evolutionary Medicine, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Nicole M Webb
- Institute of Evolutionary Medicine, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Department of Palaeoanthropology, Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325, Frankfurt am Main, Germany
| | - Martin Haeusler
- Institute of Evolutionary Medicine, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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Wall-Scheffler C, Kurki H. Beyond sex, gender, and other dilemmas: Human pelvic morphology from an integrative context. Evol Anthropol 2023; 32:293-305. [PMID: 37609957 DOI: 10.1002/evan.22001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 05/30/2023] [Accepted: 08/01/2023] [Indexed: 08/24/2023]
Abstract
Recent research on the pelvis has clarified the flexibility of pelvic bones to manage nearly infinite possibilities in terms of selection and drift, while still maintaining excellent bipedalism. Despite this work, and the studies outlining the diversity of pelvic morphology across the hominin lineage, conversations continue to be stymied by distractions related to purported trade-offs that the different functions the pelvis must either allow for (e.g., parturition) or directly perform (e.g., attachment sites of muscles). Here we show that tight constraints on morphology are not evident in the pelvic variation of multiple human populations. We thus provide further evidence that human pelves are not geometrically similar and that pelvic morphology successfully balances the intersection of population history, active selective, and drift.
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Affiliation(s)
- Cara Wall-Scheffler
- Department of Biology, Seattle Pacific University, Seattle, Washington, USA
- Department of Anthropology, University of Washington, Seattle, Washington, USA
| | - Helen Kurki
- Department of Anthropology, University of Victoria, Victoria, British Columbia, Canada
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Warrener A. The multifactor pelvis: An alternative to the adaptationist approach of the obstetrical dilemma. Evol Anthropol 2023; 32:260-274. [PMID: 37527355 DOI: 10.1002/evan.21997] [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: 07/31/2022] [Revised: 02/23/2023] [Accepted: 07/08/2023] [Indexed: 08/03/2023]
Abstract
The obstetrical dilemma describes the competing demands that a bipedally adapted pelvis and a large-brained neonate place on human childbirth and is the predominant model within which hypotheses about the evolution of the pelvis are framed. I argue the obstetrical dilemma follows the adaptationist program outlined by Gould and Lewontin in 1979 and should be replaced with a new model, the multifactor pelvis. This change will allow thorough consideration of nonadaptive explanations for the evolution of the human pelvis and avoid negative social impacts from considering human childbirth inherently dangerous. First, the atomization of the pelvis into discrete traits is discussed, after which current evidence for both adaptive and nonadaptive hypotheses is evaluated, including childbirth, locomotion, shared genetics with other traits under selection, evolutionary history, genetic drift, and environmental and epigenetic influences on the pelvis.
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Affiliation(s)
- Anna Warrener
- Department of Anthropology, University of Colorado Denver, Denver, Colorado, USA
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Grunstra NDS, Betti L, Fischer B, Haeusler M, Pavlicev M, Stansfield E, Trevathan W, Webb NM, Wells JCK, Rosenberg KR, Mitteroecker P. There is an obstetrical dilemma: Misconceptions about the evolution of human childbirth and pelvic form. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023; 181:535-544. [PMID: 37353889 PMCID: PMC10952510 DOI: 10.1002/ajpa.24802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 05/27/2023] [Accepted: 06/11/2023] [Indexed: 06/25/2023]
Abstract
Compared to other primates, modern humans face high rates of maternal and neonatal morbidity and mortality during childbirth. Since the early 20th century, this "difficulty" of human parturition has prompted numerous evolutionary explanations, typically assuming antagonistic selective forces acting on maternal and fetal traits, which has been termed the "obstetrical dilemma." Recently, there has been a growing tendency among some anthropologists to question the difficulty of human childbirth and its evolutionary origin in an antagonistic selective regime. Partly, this stems from the motivation to combat increasing pathologization and overmedicalization of childbirth in industrialized countries. Some authors have argued that there is no obstetrical dilemma at all, and that the difficulty of childbirth mainly results from modern lifestyles and inappropriate and patriarchal obstetric practices. The failure of some studies to identify biomechanical and metabolic constraints on pelvic dimensions is sometimes interpreted as empirical support for discarding an obstetrical dilemma. Here we explain why these points are important but do not invalidate evolutionary explanations of human childbirth. We present robust empirical evidence and solid evolutionary theory supporting an obstetrical dilemma, yet one that is much more complex than originally conceived in the 20th century. We argue that evolutionary research does not hinder appropriate midwifery and obstetric care, nor does it promote negative views of female bodies. Understanding the evolutionary entanglement of biological and sociocultural factors underlying human childbirth can help us to understand individual variation in the risk factors of obstructed labor, and thus can contribute to more individualized maternal care.
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Affiliation(s)
- N. D. S. Grunstra
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
- Mammal CollectionNatural History Museum ViennaViennaAustria
| | - L. Betti
- School of Life and Health SciencesUniversity of RoehamptonLondonUK
| | - B. Fischer
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
| | - M. Haeusler
- Institute of Evolutionary MedicineUniversity of ZurichZurichSwitzerland
| | - M. Pavlicev
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
| | - E. Stansfield
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
| | - W. Trevathan
- School for Advanced ResearchSanta FeNew MexicoUSA
| | - N. M. Webb
- Institute of Evolutionary MedicineUniversity of ZurichZurichSwitzerland
- Institute of Archaeological Sciences, Senckenberg Centre for Human Evolution and PalaeoenvironmentEberhard‐Karls University of TübingenTübingenGermany
| | - J. C. K. Wells
- UCL Great Ormond Street Institute of Child Health, Population, Policy and Practice Research and Teaching ProgrammeChildhood Nutrition Research CentreLondonUK
| | - K. R. Rosenberg
- Department of AnthropologyUniversity of DelawareNewarkDelawareUSA
| | - P. Mitteroecker
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
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Kubicka AM. Changes in plasticity of the pelvic girdle from infancy to late adulthood in Homo sapiens. Sci Rep 2023; 13:9698. [PMID: 37322042 PMCID: PMC10272276 DOI: 10.1038/s41598-023-36703-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 06/08/2023] [Indexed: 06/17/2023] Open
Abstract
Previous research on the effects of body mass on the pelvic girdle focused mostly on adult females and males. Because the ontogenetic plasticity level in the pelvis remains largely unknown, this study investigated how the association between body mass index (BMI) and pelvic shape changes during development. It also assessed how the large variation in pelvic shape could be explained by the number of live births in females. Data included CT scans of 308 humans from infancy to late adulthood with known age, sex, body mass, body stature, and the number of live births (for adult females). 3D reconstruction and geometric morphometrics was used to analyze pelvic shape. Multivariate regression showed a significant association between BMI and pelvic shape in young females and old males. The association between the number of live births and pelvic shape in females was not significant. Less plasticity in pelvic shape in adult females than during puberty, perhaps reflects adaptation to support the abdominopelvic organs and the fetus during pregnancy. Non-significant susceptibility to BMI in young males may reflect bone maturation accelerated by excessive body mass. Hormonal secretion and biomechanical loading associated with pregnancy may not have a long-term effect on the pelvic morphology of females.
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Affiliation(s)
- Anna Maria Kubicka
- Department of Zoology, Poznań University of Life Sciences, Wojska Polskiego 71C, 60-625, Poznań, Poland.
- PaleoFED Team, Département Homme et Environnement, Muséum National d'Histoire Naturelle. Musée de l'Homme, UMR 7194, CNRS, Place du Trocadéro 17, 75016, Paris, France.
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Gonzalez-Cabrera I. A lineage explanation of human normative guidance: the coadaptive model of instrumental rationality and shared intentionality. SYNTHESE 2022; 200:493. [PMID: 36438177 PMCID: PMC9681693 DOI: 10.1007/s11229-022-03925-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
This paper aims to contribute to the existing literature on normative cognition by providing a lineage explanation of human social norm psychology. This approach builds upon theories of goal-directed behavioral control in the reinforcement learning and control literature, arguing that this form of control defines an important class of intentional normative mental states that are instrumental in nature. I defend the view that great ape capacities for instrumental reasoning and our capacity (or family of capacities) for shared intentionality coadapted to each other and argue that the evolution of this capacity has allowed the representation of social norms and the emergence of our capacity for normative guidance.
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Affiliation(s)
- Ivan Gonzalez-Cabrera
- Institute of Philosophy, University of Bern, Länggassstrasse 49, 3012 Bern, Switzerland
- Department of Psychology, University of Konstanz, Konstanz, Germany
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Decrausaz S, Shirley MK, Stock JT, Williams JE, Fewtrell MS, Clark CA, Arthurs OJ, Wells JCK. Evaluation of dual-energy X-ray absorptiometry compared to magnetic resonance imaging for collecting measurements of the human bony pelvis. Am J Hum Biol 2022; 34:e23753. [PMID: 35460113 PMCID: PMC9541267 DOI: 10.1002/ajhb.23753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 04/05/2022] [Accepted: 04/08/2022] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVES Imaging methods to measure the human pelvis in vivo provide opportunities to better understand pelvic variation and adaptation. Magnetic resonance imaging (MRI) provides high-resolution images, but is more expensive than dual-energy X-ray absorptiometry (DXA). We sought to compare pelvic breadth measurements collected from the same individuals using both methods, to investigate if there are systematic differences in pelvic measurement between these imaging methods. METHODS Three pelvic breadth dimensions (bi-iliac breadth, bi-acetabular breadth, medio-lateral inlet breadth) were collected from MRI and DXA scans of a cross-sectional sample of healthy, nulliparous adult women of South Asian ancestry (n = 63). Measurements of MRI and DXA pelvic dimensions were collected four times in total, with one baseline data collection session and three replications. Data collected from these sessions were averaged, used to calculate technical error of measurement and entered into a Bland-Altman analysis. Linear regression models were fitted with a given MRI pelvic measurement regressed on the same measurement collected from DXA scans, as well as MRI mean bias regressed on DXA mean bias. RESULTS Technical error of measurement was higher in DXA measurements of bi-iliac breadth and medio-lateral pelvic inlet breadth and higher for MRI measurements of bi-acetabular breadth. Bland Altman analyses showed no statistically significant relationship between the mean bias of MRI and DXA, and the differences between MRI and DXA pelvic measurements. CONCLUSIONS DXA measurements of pelvic breadth are comparable to MRI measurements of pelvic breadth. DXA is a less costly imaging technique than MRI and can be used to collect measurements of skeletal elements in living people.
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Affiliation(s)
- Sarah‐Louise Decrausaz
- Department of ArchaeologyUniversity of CambridgeCambridgeUK,Department of AnthropologyUniversity of VictoriaVictoriaCanada
| | - Meghan K. Shirley
- Population, Policy, and Practice Research and Teaching DepartmentChildhood Nutrition Research Centre, UCL Great Ormond Street Institute of Child HealthLondonUK,Division of GI, Hepatology and NutritionThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Jay T. Stock
- Department of ArchaeologyUniversity of CambridgeCambridgeUK,Department of AnthropologyWestern UniversityLondonCanada,Department of ArchaeologyMax Planck Centre for the Science of Human HistoryJenaGermany
| | - Jane E. Williams
- Population, Policy, and Practice Research and Teaching DepartmentChildhood Nutrition Research Centre, UCL Great Ormond Street Institute of Child HealthLondonUK
| | - Mary S. Fewtrell
- Population, Policy, and Practice Research and Teaching DepartmentChildhood Nutrition Research Centre, UCL Great Ormond Street Institute of Child HealthLondonUK
| | - Chris A. Clark
- Population, Policy, and Practice Research and Teaching DepartmentChildhood Nutrition Research Centre, UCL Great Ormond Street Institute of Child HealthLondonUK
| | - Owen J. Arthurs
- Population, Policy, and Practice Research and Teaching DepartmentChildhood Nutrition Research Centre, UCL Great Ormond Street Institute of Child HealthLondonUK
| | - Jonathan C. K. Wells
- Population, Policy, and Practice Research and Teaching DepartmentChildhood Nutrition Research Centre, UCL Great Ormond Street Institute of Child HealthLondonUK
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Maggiulli O, Rufo F, Johns SE, Wells JC. Food taboos during pregnancy: meta-analysis on cross cultural differences suggests specific, diet-related pressures on childbirth among agriculturalists. PeerJ 2022; 10:e13633. [PMID: 35846875 PMCID: PMC9281602 DOI: 10.7717/peerj.13633] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 06/03/2022] [Indexed: 01/17/2023] Open
Abstract
Pregnancy is the most delicate stage of human life history as well as a common target of food taboos across cultures. Despite puzzling evidence that many pregnant women across the world reduce their intake of nutritious foods to accomplish cultural norms, no study has provided statistical analysis of cross-cultural variation in food taboos during pregnancy. Moreover, antenatal practices among forager and agriculturalists have never been compared, despite subsistence mode being known to affect staple foods and lifestyle directly. This gap hinders to us from understanding the overall threats attributed to pregnancy, and their perceived nutritional causes around the world. The present study constitutes the first cross-cultural meta-analysis on food taboos during pregnancy. We examined thirty-two articles on dietary antenatal restrictions among agricultural and non-agricultural societies, in order to: (i) identify cross-culturally targeted animal, plant and miscellaneous foods; (ii) define major clusters of taboo focus; (iii) test the hypothesis that food types and clusters of focus distribute differently between agricultural and non-agricultural taboos; and (iv) test the hypothesis that food types distribute differently across the clusters of taboo focus. All data were analysed in SPSS and RStudio using chi-squared tests and Fisher's exact tests. We detected a gradient in taboo focus that ranged from no direct physiological interest to the fear of varied physiological complications to a very specific concern over increased birth weight and difficult delivery. Non-agricultural taboos were more likely to target non-domesticated animal foods and to be justified by concerns not directly linked to the physiological sphere, whereas agricultural taboos tended to targed more cultivated and processed products and showed a stronger association with concerns over increased birth weight. Despite some methodological discrepancies in the existing literature on food taboos during pregnancy, our results illustrate that such cultural traits are useful for detecting perception of biological pressures on reproduction across cultures. Indeed, the widespread concern over birth weight and carbohydrate rich foods overlaps with clinical evidence that obstructed labor is a major threat to maternal life in Africa, Asia and Eurasia. Furthermore, asymmetry in the frequency of such concern across subsistence modes aligns with the evolutionary perspective that agriculture may have exacerbated delivery complications. This study highlights the need for the improved understanding of dietary behaviors during pregnancy across the world, addressing the role of obstructed labor as a key point of convergence between clinical, evolutionary and cultural issues in human behavior.
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Affiliation(s)
| | | | | | - Jonathan C.K. Wells
- University College London Great Ormond Street Institute of Child Health, London, United Kingdom
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Murray AA. Variability and the form-function framework in evolutionary biomechanics and human locomotion. EVOLUTIONARY HUMAN SCIENCES 2022; 4:e29. [PMID: 37588899 PMCID: PMC10426129 DOI: 10.1017/ehs.2022.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The form-function conceptual framework, which assumes a strong relationship between the structure of a particular trait and its function, has been crucial for understanding morphological variation and locomotion among extant and fossil species across many disciplines. In biological anthropology, it is the lens through which many important questions and hypotheses have been tackled with respect to relationships between morphology and locomotor kinematics, energetics and performance. However, it is becoming increasingly evident that the morphologies of fossil hominins, apes and humans can confer considerable locomotor diversity and flexibility, and can do so with a range of kinematics depending on soft tissue plasticity and environmental and cultural factors. This complexity is not built into traditional biomechanical or mathematical models of relationships between structure and kinematics or energetics, limiting our interpretation of what bone structure is telling us about behaviour in the past. The nine papers presented in this Special Collection together address some of the challenges that variation in the relationship between form and function pose in evolutionary biomechanics, to better characterise the complexity linking structure and function and to provide tools through which we may begin to incorporate some of this complexity into our functional interpretations.
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Affiliation(s)
- Alison A. Murray
- Department of Anthropology, University of Victoria, Cornett Building Room B228, 3800 Finnerty Road, Victoria, BC, CanadaV8P 5C2
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14
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Gorman J, Roberts CA, Newsham S, Bentley GR. Squatting, pelvic morphology and a reconsideration of childbirth difficulties. Evol Med Public Health 2022; 10:243-255. [PMID: 35663511 PMCID: PMC9154243 DOI: 10.1093/emph/eoac017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 04/19/2022] [Indexed: 11/14/2022] Open
Abstract
Childbirth is commonly viewed as difficult in human females, encompassed by the 'Obstetrical Dilemma' (OD) described by early palaeoanthropologists as an evolved trade-off between a narrow pelvis necessitated by bipedalism and a large-brained fetal head. The OD has been challenged on several grounds. We add to these challenges by suggesting humans likely squatted regularly during routine tasks prior to the advent of farming societies and use of seats. We suggest that habitual squatting, together with taller stature and better nutrition of ancestral hunter-gatherers compared with later Neolithic and industrial counterparts, obviated an OD. Instead, difficulties with parturition may have arisen much later in our history, accompanying permanent settlements, poorer nutrition, greater infectious disease loads and negligible squatting in daily life. We discuss bioarchaeological and contemporary data that support these viewpoints, suggest ways in which this hypothesis might be tested further and consider its implications for obstetrical practice. Lay Summary Human childbirth is viewed as universally difficult. Evidence from physical therapies/engineering and studies of living and ancestral humans illustrates habitual squatting widens the pelvis and could improve childbirth outcomes. Obstetrical difficulties emerged late in prehistory accompanying settled agriculture, poorer nutrition and less squatting. Specific physical exercises could improve obstetrical practice.
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Affiliation(s)
- John Gorman
- Independent Scholar, Greenhead, Brampton, Northumberland CA8 7HX, UK
| | - Charlotte A Roberts
- Department of Archaeology, Durham University, Dawson Building, South Road, Durham DH1 3LE, UK
| | - Sally Newsham
- Department of Gynaecology, North Cumbria Integrated Care NHS Foundation Trust, Cumbria CA2 7HY, UK
| | - Gillian R Bentley
- Department of Anthropology, Durham University, Dawson Building, South Road, Durham DH1 3LE, UK
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15
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VanSickle C, Liese KL, Rutherford JN. Textbook typologies: Challenging the myth of the perfect obstetric pelvis. Anat Rec (Hoboken) 2022; 305:952-967. [PMID: 35202515 PMCID: PMC9303659 DOI: 10.1002/ar.24880] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 01/18/2022] [Accepted: 01/22/2022] [Indexed: 12/03/2022]
Abstract
Medical education's treatment of obstetric-related anatomy exemplifies historical sex bias in medical curricula. Foundational obstetric and midwifery textbooks teach that clinical pelvimetry and the Caldwell-Moloy classification system are used to assess the pelvic capacity of a pregnant patient. We describe the history of these techniques-ostensibly developed to manage arrested labors-and offer the following criticisms. The sample on which these techniques were developed betrays the bias of the authors and does not represent the sample needed to address their interest in obstetric outcomes. Caldwell and Moloy wrote as though the size and shape of the bony pelvis are the primary causes of "difficult birth"; today we know differently, yet books still present their work as relevant. The human obstetric pelvis varies in complex ways that are healthy and normal such that neither individual clinical pelvimetric dimensions nor the artificial typologies developed from these measurements can be clearly correlated with obstetric outcomes. We critique the continued inclusion of clinical pelvimetry and the Caldwell-Moloy classification system in biomedical curricula for the racism that was inherent in the development of these techniques and that has clinical consequences today. We call for textbooks, curricula, and clinical practices to abandon these outdated, racist techniques. In their place, we call for a truly evidence-based practice of obstetrics and midwifery, one based on an understanding of the complexity and variability of the physiology of pregnancy and birth. Instead of using false typologies that lack evidence, this change would empower both pregnant people and practitioners.
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Affiliation(s)
- Caroline VanSickle
- Department of AnatomyA.T. Still University, Kirksville College of Osteopathic MedicineKirksvilleMissouriUSA
| | - Kylea L. Liese
- Department of Human Development Nursing Science, College of NursingUniversity of Illinois ChicagoChicagoIllinoisUSA
| | - Julienne N. Rutherford
- Department of Human Development Nursing Science, College of NursingUniversity of Illinois ChicagoChicagoIllinoisUSA
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16
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Pany‐Kucera D, Spannagl‐Steiner M, Desideri J, Rebay‐Salisbury K. Indicators of motherhood? Sacral preauricular extensions and notches in identified skeletal collections. INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY 2022; 32:64-74. [PMID: 35874189 PMCID: PMC9293283 DOI: 10.1002/oa.3044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 08/30/2021] [Accepted: 09/23/2021] [Indexed: 06/15/2023]
Abstract
The sacral preauricular extension (SPE) and sacral preauricular notch (SPN) are morphological changes at the ventral apex of the sacrum. We recently specified their shapes and appearances and suggested a scoring system based on prehistoric Austrian skeletal assemblages. We hypothesized that these specific pelvic changes relate to past pregnancies and parturitions, a hypothesis that we now tested on a subsample of individuals from the Simon Identified Skeletal collection in Geneva (n = 62) and the Christ Church, Spitalfields collection in London (n = 27) linked to historical information on deliveries. We found SPE and SPN in low frequencies and only in female individuals with at least two children in both collections, and a significant association between the emergence of SPE and first births by 25 years. SPN was found only in two females in the Simon collection, but both with a very high number of recorded parturitions including twin births. Based on these results, we are confident in our assumption that at least SPE, and possibly also SPN, result from increased compression forces at the sacroiliac joint, and especially at the ventrosuperior margin, in recurring (complicated) birth events, the interaction of enhanced pelvic joint mobility that is highest up to age 25, and postural changes related to weight gain during pregnancy. Pelvic shape, dimensions, body proportions, biomechanical issues and hormonal levels may also play a role in their emergence.
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Affiliation(s)
- Doris Pany‐Kucera
- Austrian Archaeological InstituteAustrian Academy of SciencesViennaAustria
- Department of AnthropologyNatural History MuseumViennaAustria
| | - Michaela Spannagl‐Steiner
- Austrian Archaeological InstituteAustrian Academy of SciencesViennaAustria
- Department of AnthropologyNatural History MuseumViennaAustria
| | - Jocelyne Desideri
- Department F.‐A. Forel for Environmental and Aquatic Sciences, Laboratory of Prehistoric Archaeology and AnthropologyUniversity of GenevaGenevaSwitzerland
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17
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Childbirth and Infant Care in Early Human Ancestors: What the Bones Tell Us. EVOLUTIONARY PSYCHOLOGY 2022. [DOI: 10.1007/978-3-030-76000-7_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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18
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Long HL, Ramsay G, Griebel U, Bene ER, Bowman DD, Burkhardt-Reed MM, Oller DK. Perspectives on the origin of language: Infants vocalize most during independent vocal play but produce their most speech-like vocalizations during turn taking. PLoS One 2022; 17:e0279395. [PMID: 36584126 PMCID: PMC9803194 DOI: 10.1371/journal.pone.0279395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 12/07/2022] [Indexed: 12/31/2022] Open
Abstract
A growing body of research emphasizes both endogenous and social motivations in human vocal development. Our own efforts seek to establish an evolutionary and developmental perspective on the existence and usage of speech-like vocalizations ("protophones") in the first year of life. We evaluated the relative occurrence of protophones in 40 typically developing infants across the second-half year based on longitudinal all-day recordings. Infants showed strong endogenous motivation to vocalize, producing vastly more protophones during independent vocal exploration and play than during vocal turn taking. Both periods of vocal play and periods of turn-taking corresponded to elevated levels of the most advanced protophones (canonical babbling) relative to periods without vocal play or without turn-taking. Notably, periods of turn taking showed even more canonical babbling than periods of vocal play. We conclude that endogenous motivation drives infants' tendencies to explore and display a great number of speech-like vocalizations, but that social interaction drives the production of the most speech-like forms. The results inform our previously published proposal that the human infant has been naturally selected to explore protophone production and that the exploratory inclination in our hominin ancestors formed a foundation for language.
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Affiliation(s)
- Helen L. Long
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
| | - Gordon Ramsay
- Marcus Autism Center, Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Center for Translational Social Neuroscience, Emory University, Atlanta, Georgia, United States of America
| | - Ulrike Griebel
- Institute for Intelligent Systems, University of Memphis, Memphis, Tennessee, United States of America
- School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America
- Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
| | - Edina R. Bene
- School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America
| | - Dale D. Bowman
- Institute for Intelligent Systems, University of Memphis, Memphis, Tennessee, United States of America
- Department of Mathematics, University of Memphis, Memphis, Tennessee, United States of America
| | - Megan M. Burkhardt-Reed
- School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America
| | - D. Kimbrough Oller
- Institute for Intelligent Systems, University of Memphis, Memphis, Tennessee, United States of America
- School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America
- Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
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19
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Miller FA, Marphatia AA, Wells JC, Cortina-Borja M, Manandhar DS, Saville NM. Associations between early marriage and preterm delivery: Evidence from lowland Nepal. Am J Hum Biol 2021; 34:e23709. [PMID: 34862821 DOI: 10.1002/ajhb.23709] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVES Preterm delivery (<37 weeks gestation) is the largest cause of child mortality worldwide. Marriage and pregnancy during adolescence have been associated with an increased risk of preterm delivery. We investigate independent associations of age at marriage and age at first pregnancy with preterm delivery in a cohort of women from rural lowland Nepal. METHODS We analyzed data from 17 974 women in the Low Birth Weight South Asia Trial. Logistic regression models tested associations of age at marriage and age at first pregnancy with preterm delivery, for primigravida (n = 6 243) and multigravida (n = 11 731) women. Models were adjusted for maternal education, maternal caste, and household asset score. RESULTS Ninety percent of participants had married at <18 years and 58% had their first pregnancy at <18 years. 20% of participants delivered preterm. Primigravida participants married at ≤14 years had higher odds of preterm delivery than those married ≥18 years, when adjusting for study design (adjusted odds ratio (aOR) 1.45, 95% CI: 1.15-1.83), confounders (aOR 1.28: 1.01-1.62) and confounders + age at pregnancy (aOR 1.29: 1.00-1.68). Associations were insignificant for multigravida women. No significant associations were observed between age at first pregnancy and preterm delivery. DISCUSSION In this population, early marriage, rather than pregnancy, is a risk factor for preterm delivery. We hypothesize that psychological stress, a driver of preterm delivery which is increased among those marrying young, rather than physiological immaturity, drives this association. Further research into the psychological consequences of child marriage in Nepal is needed.
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Affiliation(s)
- Faith A Miller
- Institute for Global Health (IGH), University College London (UCL), London, UK
| | - Akanksha A Marphatia
- Department of Geography, University of Cambridge, Cambridge, UK.,Population, Policy and Practice Research and Teaching Department, Great Ormond Street Institute of Child Health (ICH), University College London (UCL), London, UK
| | - Jonathan C Wells
- Population, Policy and Practice Research and Teaching Department, Great Ormond Street Institute of Child Health (ICH), University College London (UCL), London, UK
| | - Mario Cortina-Borja
- Population, Policy and Practice Research and Teaching Department, Great Ormond Street Institute of Child Health (ICH), University College London (UCL), London, UK
| | | | - Naomi M Saville
- Institute for Global Health (IGH), University College London (UCL), London, UK
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20
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Uy J, Laudicina NM. Assessing the role of the pelvic canal in supporting the gut in humans. PLoS One 2021; 16:e0258341. [PMID: 34634091 PMCID: PMC8504728 DOI: 10.1371/journal.pone.0258341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 09/25/2021] [Indexed: 11/19/2022] Open
Abstract
The human pelvic canal (true pelvis) functions to support the abdominopelvic organs and serves as a passageway for reproduction (females). Previous research suggests that these two functions work against each other with the expectation that the supportive role results in a narrower pelvic midplane, while fetal passage necessitates a larger opening. In this research, we examine how gut size relates to the size and shape of the true pelvis, which may have implications on how gut size can influence pelvic floor integrity. Pelves and in vivo gut volumes were measured from CT scans of 92 adults (48 female, 44 male). The true pelvis was measured at three obstetrical planes (inlet, midplane, outlet) using 11 3D landmarks. CT volumetry was used to obtain an individual’s gut size. Gut volume was compared to the pelvic planes using multiple regression to evaluate the relationship between gut size and the true pelvis. We find that, in males, larger gut sizes are associated with increased mediolateral canal dimensions at the inlet and midplane. In females, we find that larger gut sizes are associated with more medially-projecting ischial spines and an anteroposteriorly longer outlet. We hypothesize that the association of larger guts with increased canal width in males and increased outlet length in females are adaptations to create adequate space for the gut, while more medially projecting ischial spines reduce the risk of pelvic floor disorders in females, despite its possible spatial consequences for fetal passage.
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Affiliation(s)
- Jeanelle Uy
- Anthropology, California State University Long Beach, Long Beach, California, United States of America
- * E-mail:
| | - Natalie M. Laudicina
- Biomedical Sciences, Grand Valley State University, Allendale, Michigan, United States of America
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21
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Stansfield E, Fischer B, Grunstra NDS, Pouca MV, Mitteroecker P. The evolution of pelvic canal shape and rotational birth in humans. BMC Biol 2021; 19:224. [PMID: 34635119 PMCID: PMC8507337 DOI: 10.1186/s12915-021-01150-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 09/09/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND The human foetus typically needs to rotate when passing through the tight birth canal because of the complex shape of the pelvis. In most women, the upper part, or inlet, of the birth canal has a round or mediolaterally oval shape, which is considered ideal for parturition, but it is unknown why the lower part of the birth canal has a pronounced anteroposteriorly oval shape. RESULTS Here, we show that the shape of the lower birth canal affects the ability of the pelvic floor to resist the pressure exerted by the abdominal organs and the foetus. Based on a series of finite element analyses, we found that the highest deformation, stress, and strain occur in pelvic floors with a circular or mediolaterally oval shape, whereas an anteroposterior elongation increases pelvic floor stability. CONCLUSIONS This suggests that the anteroposterior oval outlet shape is an evolutionary adaptation for pelvic floor support. For the pelvic inlet, by contrast, it has long been assumed that the mediolateral dimension is constrained by the efficiency of upright locomotion. But we argue that the mediolateral elongation has evolved because of the limits on the anteroposterior diameter imposed by upright posture. We show that an anteroposteriorly deeper inlet would require greater pelvic tilt and lumbar lordosis, which compromises spine health and the stability of upright posture. These different requirements of the pelvic inlet and outlet likely have led to the complex shape of the pelvic canal and to the evolution of rotational birth characteristic of humans.
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Affiliation(s)
- Ekaterina Stansfield
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria.
| | - Barbara Fischer
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
| | - Nicole D S Grunstra
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
- Konrad Lorenz Institute for Evolution and Cognition Research, Martinstrasse 12, 3400, Klosterneuburg, Austria
- Mammal Collection, Natural History Museum Vienna, Burgring 7, 1010, Vienna, Austria
| | - Maria Villa Pouca
- Faculty of Engineering of University of Porto (FEUP), Rua Dr. Roberto Frias, s/n, 4200-465, Porto, Portugal
- Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI/LAETA), Rua Dr. Roberto Frias, 400, 4200-465, Porto, Portugal
| | - Philipp Mitteroecker
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria.
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22
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Haeusler M, Grunstra ND, Martin RD, Krenn VA, Fornai C, Webb NM. The obstetrical dilemma hypothesis: there's life in the old dog yet. Biol Rev Camb Philos Soc 2021; 96:2031-2057. [PMID: 34013651 PMCID: PMC8518115 DOI: 10.1111/brv.12744] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 05/06/2021] [Accepted: 05/10/2021] [Indexed: 12/17/2022]
Abstract
The term 'obstetrical dilemma' was coined by Washburn in 1960 to describe the trade-off between selection for a larger birth canal, permitting successful passage of a big-brained human neonate, and the smaller pelvic dimensions required for bipedal locomotion. His suggested solution to these antagonistic pressures was to give birth prematurely, explaining the unusual degree of neurological and physical immaturity, or secondary altriciality, observed in human infants. This proposed trade-off has traditionally been offered as the predominant evolutionary explanation for why human childbirth is so challenging, and inherently risky, compared to that of other primates. This perceived difficulty is likely due to the tight fit of fetal to maternal pelvic dimensions along with the convoluted shape of the birth canal and a comparatively low degree of ligamentous flexibility. Although the ideas combined under the obstetrical dilemma hypothesis originated almost a century ago, they have received renewed attention and empirical scrutiny in the last decade, with some researchers advocating complete rejection of the hypothesis and its assumptions. However, the hypothesis is complex because it presently captures several, mutually non-exclusive ideas: (i) there is an evolutionary trade-off resulting from opposing selection pressures on the pelvis; (ii) selection favouring a narrow pelvis specifically derives from bipedalism; (iii) human neonates are secondarily altricial because they are born relatively immature to ensure that they fit through the maternal bony pelvis; (iv) as a corollary to the asymmetric selection pressure for a spacious birth canal in females, humans evolved pronounced sexual dimorphism of pelvic shape. Recently, the hypothesis has been challenged on both empirical and theoretical grounds. Here, we appraise the original ideas captured under the 'obstetrical dilemma' and their subsequent evolution. We also evaluate complementary and alternative explanations for a tight fetopelvic fit and obstructed labour, including ecological factors related to nutrition and thermoregulation, constraints imposed by the stability of the pelvic floor or by maternal and fetal metabolism, the energetics of bipedalism, and variability in pelvic shape. This reveals that human childbirth is affected by a complex combination of evolutionary, ecological, and biocultural factors, which variably constrain maternal pelvic form and fetal growth. Our review demonstrates that it is unwarranted to reject the obstetrical dilemma hypothesis entirely because several of its fundamental assumptions have not been successfully discounted despite claims to the contrary. As such, the obstetrical dilemma remains a tenable hypothesis that can be used productively to guide evolutionary research.
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Affiliation(s)
- Martin Haeusler
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
| | - Nicole D.S. Grunstra
- Konrad Lorenz Institute (KLI) for Evolution and Cognition ResearchMartinstrasse 12Klosterneuburg3400Austria
- Department of Evolutionary BiologyUniversity of ViennaUniversity Biology Building (UBB), Carl Djerassi Platz 1Vienna1030Austria
- Mammal CollectionNatural History Museum ViennaBurgring 7Vienna1010Austria
| | - Robert D. Martin
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
- The Field Museum1400 S Lake Shore DrChicagoIL60605U.S.A.
| | - Viktoria A. Krenn
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
- Department of Evolutionary AnthropologyUniversity of ViennaUniversity Biology Building (UBB), Carl Djerassi Platz 1Vienna1030Austria
| | - Cinzia Fornai
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
- Department of Evolutionary AnthropologyUniversity of ViennaUniversity Biology Building (UBB), Carl Djerassi Platz 1Vienna1030Austria
| | - Nicole M. Webb
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
- Senckenberg Research Institute and Natural History Museum FrankfurtSenckenberganlage 25Frankfurt am Main60325Germany
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23
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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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24
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Wells JCK, Pomeroy E, Stock JT. Evolution of Lactase Persistence: Turbo-Charging Adaptation in Growth Under the Selective Pressure of Maternal Mortality? Front Physiol 2021; 12:696516. [PMID: 34497534 PMCID: PMC8419441 DOI: 10.3389/fphys.2021.696516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 07/30/2021] [Indexed: 11/13/2022] Open
Abstract
The emergence of the capacity to digest milk in some populations represents a landmark in human evolution, linking genetic change with a component of niche construction, namely dairying. Alleles promoting continued activity of the enzyme lactase through the life-course (lactase persistence) evolved in several global regions within the last 7,000 years. In some European regions, these alleles underwent rapid selection and must have profoundly affected fertility or mortality. Elsewhere, alleles spread more locally. However, the functional benefits underlying the rapid spread of lactase persistence remain unclear. Here, we set out the hypothesis that lactase persistence promoted skeletal growth, thereby offering a generic rapid solution to childbirth complications arising from exposure to ecological change, or to new environments through migration. Since reduced maternal growth and greater neonatal size both increase the risk of obstructed labour, any ecological exposure impacting these traits may increase maternal mortality risk. Over many generations, maternal skeletal dimensions could adapt to new ecological conditions through genetic change. However, this adaptive strategy would fail if ecological change was rapid, including through migration into new niches. We propose that the combination of consuming milk and lactase persistence could have reduced maternal mortality by promoting growth of the pelvis after weaning, while high calcium intake would reduce risk of pelvic deformities. Our conceptual framework provides locally relevant hypotheses to explain selection for lactase persistence in different global regions. For any given diet and individual genotype, the combination of lactase persistence and milk consumption would divert more energy to skeletal growth, either increasing pelvic dimensions or buffering them from worsening ecological conditions. The emergence of lactase persistence among dairying populations could have helped early European farmers adapt rapidly to northern latitudes, East African pastoralists adapt to sudden climate shifts to drier environments, and Near Eastern populations counteract secular declines in height associated with early agriculture. In each case, we assume that lactase persistence accelerated the timescale over which maternal skeletal dimensions could change, thus promoting both maternal and offspring survival. Where lactase persistence did not emerge, birth weight was constrained at lower levels, and this contributes to contemporary variability in diabetes risk.
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Affiliation(s)
- Jonathan C K Wells
- Childhood Nutrition Research Centre, Population Policy and Practice Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Emma Pomeroy
- Department of Archaeology, University of Cambridge, Cambridge, United Kingdom
| | - Jay T Stock
- Department of Anthropology, University of Western Ontario, London, ON, Canada.,Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany
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Moffett EA. Sexual dimorphism in the size and shape of the non-obstetric pelvis across anthropoids. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 176:402-421. [PMID: 34453450 DOI: 10.1002/ajpa.24398] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 04/26/2021] [Accepted: 07/20/2021] [Indexed: 11/06/2022]
Abstract
OBJECTIVES The presence of sexual dimorphism in the birth canals of anthropoid primates is well documented, and birth canal dimorphism tends to be especially robust among species that give birth to relatively large neonates. However, it is less clear whether birth canal dimorphism is accompanied by dimorphism in parts of the pelvis not directly under selection for birth, particularly including bi-iliac breadth, biactetabular breadth, lengths of the ischium and ilium, and 3D shape. This study investigates the patterns of dimorphism among anthropoid primates in those parts of the pelvis which do not directly contribute to the bony birth canal, here termed the non-obstetric pelvis. METHODS 3D landmark data were collected on the bony pelves of 899 anthropoid primates. Specifically, landmark data were collected on parts of the pelvis not thought to be directly involved in selection for parturition, including portions of the posterior and superior ilium, acetabulum, and lateral ischium. Principal components analysis and Euclidean distance matrix analysis were used to ascertain sexual dimorphism in pelvic sizes and shapes within each species. RESULTS Results show that dimorphism in non-obstetric pelvic size and shape exists across anthropoids, just as is seen in the birth canal. However, the magnitude of dimorphism in non-obstetric pelvic shape tends to be greater among anthropoid species that give birth to relatively large neonates compared with those birthing smaller neonates relative to maternal pelvic size. CONCLUSIONS Though all anthropoids included in the study show some degree of sexual dimorphism in non-obstetric pelvic size and/or shape, species which give birth to large neonates relative to maternal pelvic size have the highest levels of dimorphism in pelvic shape. Moreover, the magnitude of dimorphism in certain parts of the non-obstetric pelvis mirrors patterns seen in the birth canal. The results of this study are promising for ascertaining pelvic dimorphism and relative neonate size in fossil primates, particularly in fragmentary remains which do not preserve a complete bony birth canal.
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Affiliation(s)
- Elizabeth A Moffett
- Department of Clinical Anatomy and Osteopathic Principles, Rocky Vista University, Parker, Colorado, USA
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Lassek WD, Gaulin SJC. Does Nubility Indicate More Than High Reproductive Value? Nubile Primiparas' Pregnancy Outcomes in Evolutionary Perspective. EVOLUTIONARY PSYCHOLOGY 2021; 19:14747049211039506. [PMID: 34524917 PMCID: PMC10355305 DOI: 10.1177/14747049211039506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 11/16/2022] Open
Abstract
The idea that human males are most strongly attracted to traits that peak in women in the nubile age group raises the question of how well women in that age group contend with the potential hazards of a first pregnancy. Using data for 1.7 million first births from 1990 U.S. natality and mortality records, we compared outcomes for women with first births (primiparas) aged 16-20 years (when first births typically occur in forager and subsistence groups) with those aged 21-25 years. The younger primiparas had a much lower risk of potentially life-threatening complications of labor and delivery and, when evolutionarily novel risk factors were controlled, fetuses which were significantly more likely to survive despite lower birth weights. Thus, nubile primiparas were more likely to have a successful reproductive outcome defined in an evolutionarily relevant way (an infant of normal birth weight and gestation, surviving to one year, and delivered without a medically necessary cesarean delivery). This suggests that prior to the widespread availability of surgical deliveries, men who mated with women in the nubile age group would have reaped the benefit of having a reproductive partner more likely to have a successful first pregnancy.
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Affiliation(s)
- William D. Lassek
- Department of Anthropology, HSSB 2001, University of California, Santa Barbara, CA, USA
| | - Steven J. C. Gaulin
- Department of Anthropology, HSSB 2001, University of California, Santa Barbara, CA, USA
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Frémondière P, Thollon L, Marchal F. Pelvic and neonatal size correlations in light of evolutionary hypotheses. Am J Hum Biol 2021; 34:e23619. [PMID: 34028115 DOI: 10.1002/ajhb.23619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 04/26/2021] [Accepted: 05/03/2021] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE This study aimed to analyze the correlations between maternal size, neonatal size, and gestational variables. METHODS Our sample comprises 131 mother-infant dyads. We investigated correlations between five neonatal traits (gestational age, birthweight, head, suboccipito-brematic, and abdominal girths), three maternal traits (height, BMI, and uterus height), and three pelvic variables (conjugate, inter-spinous diameters, and sub-pubic angle) using computed tomography pelvimetry. RESULTS We found that the five neonatal traits were significantly intercorrelated. BMI was not correlated with neonatal traits while maternal height was correlated with birthweight, suboccipito-brematic, and abdominal girth. In the multiple regression models, gestational age was correlated with birthweight, head, and abdominal girth. Among the neonatal and pelvimetry correlations, conjugate diameter was slightly correlated with suboccipito-bregmatic girth, but inter-spinous and sub-pubic angle were not correlated with neonatal traits. Uterus height predicted all neonatal variables, but it was not correlated with gestational age. DISCUSSION Our results suggest that fetal growth is shaped by maternal phenotype rather than external ecological factors. The association of the inlet size with suboccipito-bregmatic girth reflects the tight fit between the neonatal brain and the maternal pelvis dimensions, an adaptation that would reduce the risk of cephalo-pelvic disproportion, while the absence of tight fit at the midplane and outlet could be due to the effect of the pelvic relaxation. Uterus distention is not the only mechanism involved in the initiation of parturition. Birth and pregnancy are complex processes and we suggest that maternal-neonatal associations are the result of a combination of multiple obstetric tradeoffs.
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Affiliation(s)
- Pierre Frémondière
- Aix Marseille Univ, School of Midwifery, Faculty of Medical and Paramedical Sciences, Marseille, France.,Aix Marseille Univ, CNRS, EFS, ADES, Marseille, France
| | - Lionel Thollon
- Applied Biomechanics Laboratory (UMR-T24), Marseille, France
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Oller DK, Griebel U. Functionally Flexible Signaling and the Origin of Language. Front Psychol 2021; 11:626138. [PMID: 33574785 PMCID: PMC7870697 DOI: 10.3389/fpsyg.2020.626138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 12/30/2020] [Indexed: 12/04/2022] Open
Abstract
At the earliest break of ancient hominins from their primate relatives in vocal communication, we propose a selection pressure on vocal fitness signaling by hominin infants. Exploratory vocalizations, not tied to expression of distress or immediate need, could have helped persuade parents of the wellness and viability of the infants who produced them. We hypothesize that hominin parents invested more in infants who produced such signals of fitness plentifully, neglecting or abandoning them less often than infants who produced the sounds less frequently. Selection for such exploratory vocalization provided a critically important inclination and capability relevant to language, we reason, because the system that encouraged spontaneous vocalization also made vocalization functionally flexible to an extent that has not been observed in any other animal. Although this vocal flexibility did not by itself create language, it provided an essential foundation upon which language would evolve through a variety of additional steps. In evaluating this speculation, we consider presumable barriers to evolving language that are thought to be implications of Darwinian Theory. It has been claimed that communication always involves sender self-interest and that self-interest leads to deceit, which is countered through clever detection by receivers. The constant battle of senders and receivers has been thought to pose an insuperable challenge to honest communication, which has been viewed as a requirement of language. To make communication honest, it has been proposed that stable signaling requires costly handicaps for the sender, and since language cannot entail high cost, the reasoning has suggested an insurmountable obstacle to the evolution of language. We think this presumed honesty barrier is an illusion that can be revealed by recognition of the fact that language is not inherently honest and in light of the distinction between illocutionary force and semantics. Our paper also considers barriers to the evolution of language (not having to do with honesty) that we think may have actually played important roles in preventing species other than humans from evolving language.
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Affiliation(s)
- D. Kimbrough Oller
- School of Communication Sciences and Disorders, The University of Memphis, Memphis, TN, United States
- Institute for Intelligent Systems, The University of Memphis, Memphis, TN, United States
- Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
| | - Ulrike Griebel
- School of Communication Sciences and Disorders, The University of Memphis, Memphis, TN, United States
- Institute for Intelligent Systems, The University of Memphis, Memphis, TN, United States
- Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
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Wells JCK, Marphatia AA, Cortina-Borja M, Manandhar DS, Reid AM, Saville N. Maternal physical, socioeconomic, and demographic characteristics and childbirth complications in rural lowland Nepal: Applying an evolutionary framework to understand the role of phenotypic plasticity. Am J Hum Biol 2021; 33:e23566. [PMID: 33452758 DOI: 10.1002/ajhb.23566] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVES Evolutionary perspectives on human childbirth have primarily focused on characteristics of our species in general, rather than variability within and between contemporary populations. We use an evolutionary framework to explore how physical and demographic characteristics of mothers shape the risks of childbirth complications in rural lowland Nepal, where childbearing typically commences in adolescence and chronic undernutrition is widespread, though maternal overweight is increasing in association with nutrition transition. METHODS We conducted secondary analyses of data from a cluster-randomized trial. Women aged 14-35 years were categorized by age, number of previous pregnancies, height, body mass index (BMI), husband's education, and household wealth. Multivariable logistic regression models tested whether these characteristics independently predicted risks of episiotomy and cesarean section (CS, n = 14 261), and obstructed labor (OL, n = 5185). RESULTS Risks were greatest among first-time adolescent mothers, though associations with age varied by outcome. Independent of age and parity, short stature and high BMI increased risks of CS and OL, whereas associations were weaker for episiotomy. Male offspring had increased risk of CS and OL but not episiotomy. Wealth was not associated with OL, but lower wealth and lower husband's education were associated with lower likelihood of episiotomy and CS. CONCLUSIONS At the individual level, the risk childbirth complications is shaped by trade-offs between fertility, growth, and survival. Some biological markers of disadvantage (early childbearing, short stature) increased the risk, whereas low socio-economic status was associated with lower risk, indicating reduced access to relevant facilities. Independent of these associations, maternal age showed complex effects.
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Affiliation(s)
- Jonathan C K Wells
- Population, Policy and Practice Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK
| | | | - Mario Cortina-Borja
- Population, Policy and Practice Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK
| | | | - Alice M Reid
- Department of Geography, University of Cambridge, Cambridge, UK
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31
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Waxenbaum EB, Feiler ME. Influence of climatic stress on nonmetric sexually dimorphic features of the skull and pelvis. Am J Hum Biol 2020; 33:e23559. [PMID: 33377211 DOI: 10.1002/ajhb.23559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 11/05/2020] [Accepted: 12/11/2020] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVES Human sexual dimorphism is frequently assessed through skull and pelvic size and shape. Researchers suggest that climatic variation and the associated stress may be significant factors in sexual dimorphism's etiology. However, little research has specifically investigated climatic effects on nonmetric skeletal indicators of sex. To further appreciate the plasticity of human biology, a comparative study of standard skull and pelvic nonmetric sex indicators is presented. METHODS A Native Alaskan archeological sample (n = 104) and a component of the Terry collection (n = 99) represent populations originating from different climatic environments in recent history. These sex-balanced groups are compared through Tukey-Kramer's method and Greene's t-test to determine any variation in degree of sexual dimorphism within and between samples. RESULTS The results reinforce the complex and multifaceted relationship between climate and sexual dimorphism. The Terry sample demonstrated a greater degree of sexual dimorphism with statistically significant differences in robusticity of the mastoid process and nuchal crest compared with the Native Alaskans. A more "male" morphotype and reduced dimorphism are appreciated in the pelves of Native Alaskans than the Terry sample. CONCLUSIONS This research highlights a reduction in sexual dimorphism in populations under greater climatic stress and contributes to the production of more accurate skeletal assessments in future investigations. Discussion of confounding factors suggest more research is necessary to untangle climate and human morphology's complex relationship. This study contributes to a greater appreciation of human biological plasticity, ecogeographic variation, and the evolution of modern human diversity.
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Affiliation(s)
- Erin B Waxenbaum
- Department of Anthropology, Northwestern University, Evanston, Illinois, USA
| | - Maria E Feiler
- Department of Anthropology, Northwestern University, Evanston, Illinois, USA
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Adegboyega MT, Stamos PA, Hublin JJ, Weaver TD. Virtual reconstruction of the Kebara 2 Neanderthal pelvis. J Hum Evol 2020; 151:102922. [PMID: 33360685 DOI: 10.1016/j.jhevol.2020.102922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/17/2020] [Accepted: 11/18/2020] [Indexed: 12/01/2022]
Abstract
The paucity of well-preserved pelvises in the hominin fossil record has hindered robust analyses of shifts in critical biological processes throughout human evolution. The Kebara 2 pelvis remains one of the best preserved hominin pelvises, providing a rare opportunity to assess Neanderthal pelvic morphology and function. Here, we present two new reconstructions of the Kebara 2 pelvis created from CT scans of the right hip bone and sacrum. For both reconstructions, we proceeded as follows. First, we virtually reconstructed the right hip bone and the sacrum by repositioning the fragments of the hip bone and sacrum. Then, we created a mirrored copy of the right hip bone to act as the left hip bone. Next, we 3D printed the three bones and physically articulated them. Finally, we used fiducial points collected from the physically articulated models to articulate the hip bones and sacrum in virtual space. Our objectives were to (1) reposition misaligned fragments, particularly the ischiopubic ramus; (2) create a 3D model of a complete pelvis; and (3) assess interobserver reconstruction variation. These new reconstructions show that, in comparison with previous measurements, Kebara 2 possessed a higher shape index (maximum anteroposterior length/maximum mediolateral width) for the pelvic inlet and perhaps the outlet and a more anteriorly positioned sacral promontory and pubic symphysis relative to the acetabula. The latter differences result in a lower ratio between the distances anterior and posterior to the anterior margins of the acetabula. Generally, the new reconstructions tend to accentuate features of the Kebara 2 pelvis--the long superior pubic ramus and anteriorly positioned pelvic inlet--that have already been discussed for Kebara 2 and other Neanderthals.
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Affiliation(s)
- Mayowa T Adegboyega
- Department of Anthropology, University of California, 1 Shields Avenue, Davis, CA, 95616, USA.
| | - Peter A Stamos
- Department of Anthropology, University of California, 1 Shields Avenue, Davis, CA, 95616, USA; Department of Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th Street / Anatomy 201, Chicago, IL, 60637, USA
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany
| | - Timothy D Weaver
- Department of Anthropology, University of California, 1 Shields Avenue, Davis, CA, 95616, USA; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany
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Powell CD, Wilson WM, Olesaningo G, Manyama M, Jamniczky H, Spritz R, Cross JC, Lukowiak K, Hallgrimsson B, Gonzalez PN. Lack of head sparing following third-trimester caloric restriction among Tanzanian Maasai. PLoS One 2020; 15:e0237700. [PMID: 32966295 PMCID: PMC7510984 DOI: 10.1371/journal.pone.0237700] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 08/02/2020] [Indexed: 12/31/2022] Open
Abstract
The reduction of food intake during pregnancy is part of many cultural and religious traditions around the world. The impact of such practices on fetal growth and development are poorly understood. Here, we examined the patterns of diet intake among Maasai pregnant women and assessed their effect on newborn morphometrics. We recruited 141 mother-infant pairs from Ngorongoro Conservation Area (NCA) in Northern Tanzania and quantified dietary intake and changes in maternal diet during pregnancy. We obtained measurements of body weight (BW) and head circumference (HC) at birth. We found that Maasai women significantly reduced their dietary intake during the third trimester, going from an average of 1601 kcal/day during the first two trimesters to 799 kcal/day in the final trimester. The greatest proportion of nutrient reduction was in carbohydrates. Overall, 40% of HC Z-scores of the NCA sample were more than 2 standard deviations below the WHO standard. Nearly a third of neonates classify as low birth weight (< 2500g). HC was smaller relative to BW in this cohort than predicted using the WHO standard. This contrasts markedly to a Tanzanian birth cohort obtained at the same time in an urban context in which only 12% of infants exhibited low weight, only two individuals had HC Z-scores < 2 and HC's relative to birth weight were larger than predicted using the WHO standards. The surprising lack of head sparing in the NCA cohort suggests that the impact of third trimester malnutrition bears further investigation in both animal models and human populations, especially as low HC is negatively associated with long term health outcomes.
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Affiliation(s)
- Christopher D. Powell
- Department of Cell Biology & Anatomy, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Warren M. Wilson
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Alberta, Canada
| | | | - Mange Manyama
- Catholic University of Health and Allied Sciences, Mwanza, Tanzania
- Division of Medical Education, Weill Cornell Medicine, Qatar
| | - Heather Jamniczky
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Alberta, Canada
- McCaig Bone and Joint Institute, University of Calgary, Calgary, Alberta, Canada
| | - Richard Spritz
- Department of Pediatrics and Human Medical Genetics and Genomics Program, University of Colorado School of Medicine, Denver, Colorado
| | - James C. Cross
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, and the Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Department Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada
| | - Kenneth Lukowiak
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Benedikt Hallgrimsson
- Department of Cell Biology & Anatomy, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Paula N. Gonzalez
- Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos (CONICET-Hospital El Cruce Dr. Nestor Kirchner-Uiversidad Nacional Arturo Jauretche), Buenos Aires, Argentina
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Halcrow S, Warren R, Kushnick G, Nowell A. Care of Infants in the Past: Bridging evolutionary anthropological and bioarchaeological approaches. EVOLUTIONARY HUMAN SCIENCES 2020; 2:e47. [PMID: 37588386 PMCID: PMC10427473 DOI: 10.1017/ehs.2020.46] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The importance of care of infants and children in palaeoanthropological and human behavioural ecological research on the evolution of our species is evident in the diversity of research on human development, alloparental care, and learning and social interaction. There has been a recent surge of interest in modelling the social implications of care provision for people with serious disabilities in bioarchaeology. However, there is a lack of acknowledgement of infant and child care in bioarchaeology, despite the significant labour and resources that are required, and the implications this has for health outcomes within societies. Drawing on the recent proliferation of studies on infancy and childhood in evolutionary anthropology and bioarchaeology, this paper presents ways the subdisciplines may draw on research developments from each field to advance a more holistic understanding of the evolutionary, social and health significance of infant and children care in the past.
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Affiliation(s)
- Siân Halcrow
- Department of Anatomy, University of Otago, New Zealand
| | - Ruth Warren
- Department of Anatomy, University of Otago, New Zealand
| | - Geoff Kushnick
- School of Archaeology and Anthropology, Research School of Humanities and the Arts, ANU College of Arts and Social Sciences, Australian National University, Australia
| | - April Nowell
- Department of Anthropology, University of Victoria, Canada
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Covariation of fetal skull and maternal pelvis during the perinatal period in rhesus macaques and evolution of childbirth in primates. Proc Natl Acad Sci U S A 2020; 117:21251-21257. [PMID: 32817513 DOI: 10.1073/pnas.2002112117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A large brain combined with an upright posture in humans has resulted in a high cephalopelvic proportion and frequently obstructed labor. Fischer and Mitteroecker [B. Fischer, P. Mitteroecker, Proc. Natl. Acad. Sci. U.S.A. 112, 5655-5660 (2015)] proposed that the morphological covariations between the skull and pelvis could have evolved to ameliorate obstructed labor in humans. The availability of quantitative data of such covariation, especially of the fetal skull and maternal pelvis, however, is still scarce. Here, we present direct evidence of morphological covariations between the skull and pelvis using actual mother-fetus dyads during the perinatal period of Macaca mulatta, a species that exhibits cephalopelvic proportions comparable to modern humans. We analyzed the covariation of the three-dimensional morphology of the fetal skull and maternal pelvis using computed tomography-based models. The covariation was mostly observed at the pelvic locations related to the birth canal, and the forms of the birth canal and fetal skull covary in such a way that reduces obstetric difficulties. Therefore, cephalopelvic covariation could have evolved not only in humans, but also in other primate taxa in parallel, or it could have evolved already in the early catarrhines.
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Long HL, Bowman DD, Yoo H, Burkhardt-Reed MM, Bene ER, Oller DK. Social and endogenous infant vocalizations. PLoS One 2020; 15:e0224956. [PMID: 32756591 PMCID: PMC7406057 DOI: 10.1371/journal.pone.0224956] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 07/20/2020] [Indexed: 12/04/2022] Open
Abstract
Research on infant vocal development has provided notable insights into vocal interaction with caregivers, elucidating growth in foundations for language through parental elicitation and reaction to vocalizations. A role for infant vocalizations produced endogenously, potentially providing raw material for interaction and a basis for growth in the vocal capacity itself, has received less attention. We report that in laboratory recordings of infants and their parents, the bulk of infant speech-like vocalizations, or "protophones", were directed toward no one and instead appeared to be generated endogenously, mostly in exploration of vocal abilities. The tendency to predominantly produce protophones without directing them to others occurred both during periods when parents were instructed to interact with their infants and during periods when parents were occupied with an interviewer, with the infants in the room. The results emphasize the infant as an agent in vocal learning, even when not interacting socially and suggest an enhanced perspective on foundations for vocal language.
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Affiliation(s)
- Helen L. Long
- Origins of Language Laboratory, School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America
| | - Dale D. Bowman
- Department of Mathematics, University of Memphis, Memphis, Tennessee, United States of America
| | - Hyunjoo Yoo
- Department of Communicative Disorders, College of Arts & Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Megan M. Burkhardt-Reed
- Origins of Language Laboratory, School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America
| | - Edina R. Bene
- Origins of Language Laboratory, School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America
| | - D. Kimbrough Oller
- Origins of Language Laboratory, School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America
- Institute for Intelligent Systems, University of Memphis, Memphis, Tennessee, United States of America
- Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
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Ricklan SJ, Decrausaz SL, Wells JCK, Stock JT. Obstetric dimensions of the female pelvis are less integrated than locomotor dimensions and show protective scaling patterns: Implications for the obstetrical dilemma. Am J Hum Biol 2020; 33:e23451. [PMID: 32567787 DOI: 10.1002/ajhb.23451] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 05/14/2020] [Accepted: 05/15/2020] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVES The "obstetrical dilemma" hypothesis assumes that the modern human female pelvis serves two discrete functions: obstetrics and locomotion. We investigate whether these differing functions create observable patterns of morphological covariation and whether those patterns differ by height, weight, and age. This allows evaluation of evidence for canalization and phenotypic plasticity relevant to obstetric and locomotor function among a living female population. METHODS Landmarks (N = 86) were collected and inter-landmark distances were calculated (N = 36) on the pelvis and proximal femur of CT scans of living women aged 20 to 90 years (M = 93) receiving a routine CT scan. Partial least squares and relative SD of eigenvalues analyses were used to evaluate integration overall and within locomotor and obstetric modules, respectively. Ordinary Least Squared regression was used to evaluate scaling relationships between inter-landmark distances and height, weight, and age. RESULTS The obstetric pelvis was significantly less internally integrated than the locomotor pelvis. Many obstetric measurements were constrained in absolute terms relative to height; shorter women had relatively larger birth canal dimensions, and several key obstetric dimensions showed relative freedom from height. Lower weight women had some relatively larger obstetric and locomotor dimensions. Regarding age, younger women showed a few relatively larger outlet dimensions. CONCLUSIONS This study suggests that the obstetric pelvis and the locomotor pelvis function are morphologically distinct, with the obstetric pelvis showing relatively greater flexibility. These relationships between relative constraints support the hypothesis that the modern female pelvis shows evidence of both canalization and phenotypic plasticity in obstetric and locomotor structures.
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Affiliation(s)
- Sarah J Ricklan
- Department of Archaeology, University of Cambridge, Cambridge, UK.,New York University Grossman School of Medicine, New York, New York, USA
| | - Sarah-Louise Decrausaz
- Department of Archaeology, University of Cambridge, Cambridge, UK.,Department of Anthropology, University of Victoria, Victoria, British Columbia, Canada
| | - Jonathan C K Wells
- Childhood Nutrition Research Centre, Population, Policy, and Practice Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Jay T Stock
- Department of Archaeology, University of Cambridge, Cambridge, UK.,Department of Anthropology, Western University, London, Ontario, Canada.,Department of Archaeology, Max Planck Centre for the Science of Human History, Jena, Germany
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Caesarean sections are associated with sonographic determined fetal size from the second trimester onwards. ANTHROPOLOGICAL REVIEW 2020. [DOI: 10.2478/anre-2020-0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Human birth represents a critical and life-threatening event in the life of mother and child and is therefore of special importance for anthropological as well as public health research.
Study aims: to analyze the association patterns between fetal biometry and delivery modes from the first trimester onwards.
In this electronic medical record-based study, a dataset of 3408 singleton term birth taking place at the Viennese Danube hospital in Austria. was analyzed. Fetal biometry was reconstructed by the results of three ultrasound examinations carried out at the 11th/12th, 20th/21th and 32th/33thweek of gestation. In detail, crown-rump length, biparietal diameter, fronto-occipital diameter, head circumference, abdominal trans-verse diameter, abdominal sagittal diameter, abdominal circumference, and femur length were determined. Birth weight, birth length and head circumference were measured immediately after birth. Four delivery modes were compared: spontaneous vaginal birth, instrumental vaginal birth, planned cesarean section and emergency cesarean section.
The total cesarean section rate was 10.2%. Fetal biometry and newborn size differed significantly between the four delivery modes. From the second trimester onward, head circumferences were significantly larger (p=0.005) among fetuses delivered by instrumental delivery or emergency cesarean section than among fetuses delivered by spontaneous vaginal birth. The fetal abdominal dimensions during the third trimester were significantly largest (p=0.001) among fetuses delivered by emergency cesarean section. In comparison to spontaneous vaginal delivery the risk to require instrumental delivery increased significantly with increasing fetal head dimensions at the second (p=0.019) and third trimester(p=0.032) independent of maternal somatic factors. The risk of emergency CS increased significantly with increasing head dimensions (p=0.030) as well as abdominal dimensions (p=0.001) at the third trimester and newborn size (p=0.002), also independently of maternal somatic factors.
In general, larger fetuses are on an increased risk of experiencing instrumental delivery or emergency caesarean section. This association between fetal size and delivery mode is detectable from the second trimester onwards.
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Affiliation(s)
- Cara Ocobock
- Department of Anthropology University Notre Dame Notre Dame IN 46556 USA
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40
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Uy J, Hawks J, VanSickle C. Sexual dimorphism of the relationship between the gut and pelvis in humans. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 173:130-140. [PMID: 32519366 DOI: 10.1002/ajpa.24084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 02/04/2020] [Accepted: 05/06/2020] [Indexed: 01/12/2023]
Abstract
OBJECTIVES Obstetric demands have long been considered in the evolution of the pelvis, yet consideration of the interaction of pregnancy, the pelvis, and the gastrointestinal tract (gut) is lacking. Here, we explore sex differences in the relationship of gut volume with body size and pelvic dimensions. MATERIALS AND METHODS Computed tomography (CT) scans of living adult Homo sapiens (46 females and 42 males) were obtained to measure in vivo gut volume (GV) and to extract 3D models of the pelvis. We collected 19 3D landmarks from each pelvis model to acquire pelvic measurements. We used ordinary least squares regression to explore relationships between GV and body weight, stature, and linear pelvic dimensions. RESULTS The gut-pelvis relationship differs between males and females. Females do not exhibit significant statistical correlations between GV and any variable tested. GV correlates with body size and pelvic outlet size in males. GV scales with negative allometry relative to body weight, stature, maximum bi-iliac breadth, inferior transverse outlet breadth, and bispinous distance in males. DISCUSSION The lack of association between GV and body size in females may be due to limits imposed by the anticipation of accommodating a gravid uterus and/or the increased plasticity of the pelvis. The pattern of relationship between GV and the pelvic outlet suggests the role of the bony pelvis in supporting the adominal viscera in females may be small relative to its role in childbirth. We conclude that gut size inference in fossil hominins from skeletal proxies is limited and confounded by sexual dimorphism.
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Affiliation(s)
- Jeanelle Uy
- Department of Anthropology, California State University, Long Beach, California, USA
| | - John Hawks
- Department of Anthropology, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg, South Africa
| | - Caroline VanSickle
- Department of Anatomy, A.T. Still University Kirksville College of Osteopathic Medicine, 800 W. Jefferson St., Kirksville, Missouri, USA
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Vieth R. Weaker bones and white skin as adaptions to improve anthropological "fitness" for northern environments. Osteoporos Int 2020; 31:617-624. [PMID: 31696275 PMCID: PMC7075826 DOI: 10.1007/s00198-019-05167-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/11/2019] [Indexed: 01/12/2023]
Abstract
The vitamin D paradox relates to the lower risk of osteoporosis in people of sub-Saharan African ancestry (Blacks) compared with people of European ancestry (Whites). The paradox implies that for bone health, Blacks require less vitamin D and calcium than Whites do. Why should populations that migrated northward out of Africa have ended up needing more vitamin D than tropical Blacks? Human skin color became lighter away from the tropics to permit greater skin penetration of the UVB light that generates vitamin D. Lack of vitamin D impairs intestinal calcium absorption and limits the amount of calcium that can deposit into the protein matrix of bone, causing rickets or osteomalacia. These can cause cephalopelvic disproportion and death in childbirth. Whiter skin was more fit for reproduction in UV-light restricted environments, but natural selection was also driven by the phenotype of bone per se. Bone formation starts with the deposition of bone-matrix proteins. Mineralization of the matrix happens more slowly, and it stiffens bone. If vitamin D and/or calcium supplies are marginal, larger bones will not be as fully mineralized as smaller bones. For the same amount of mineral, unmineralized or partially mineralized bone is more easily deformed than fully mineralized bone. The evidence leads to the hypothesis that to minimize the soft bone that causes pelvic deformation, a decrease in amount of bone, along with more rapid mineralization of osteoid improved reproductive fitness in Whites. Adaptation of bone biology for reproductive fitness in response to the environmental stress of limited availability of vitamin D and calcium came at the cost of greater risk of osteoporosis later in life.
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Affiliation(s)
- R Vieth
- Department of Laboratory Medicine and Pathobiology, and Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Medical Sciences Building, 5th Floor, Room 5253A 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
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Leongómez JD, Sánchez OR, Vásquez-Amézquita M, Valderrama E, Castellanos-Chacón A, Morales-Sánchez L, Nieto J, González-Santoyo I. Self-reported Health is Related to Body Height and Waist Circumference in Rural Indigenous and Urbanised Latin-American Populations. Sci Rep 2020; 10:4391. [PMID: 32152353 PMCID: PMC7062753 DOI: 10.1038/s41598-020-61289-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 02/12/2020] [Indexed: 11/08/2022] Open
Abstract
Body height is a life-history component. It involves important costs for its expression and maintenance, which may originate trade-offs on other costly components such as reproduction or immunity. Although previous evidence has supported the idea that human height could be a sexually selected trait, the explanatory mechanisms that underlie this selection are poorly understood. Despite extensive studies on the association between height and attractiveness, the role of immunity in linking this relation is scarcely studied, particularly in non-Western populations. Here, we tested whether human height is related to health measured by self-perception, and relevant nutritional and health anthropometric indicators in three Latin-American populations that widely differ in socioeconomic and ecological conditions: two urbanised populations from Bogota (Colombia) and Mexico City (Mexico), and one isolated indigenous population (Me'Phaa, Mexico). Results showed that self-reported health is best predicted by an interaction between height and waist circumference: the presumed benefits of being taller are waist-dependent, and affect taller people more than shorter individuals. If health and genetic quality cues play an important role in human mate-choice, and height and waist interact to signal health, its evolutionary consequences, including cognitive and behavioural effects, should be addressed in future research.
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Affiliation(s)
- Juan David Leongómez
- Human Behaviour Lab, Faculty of Psychology, Universidad El Bosque, Bogota, Colombia.
| | - Oscar R Sánchez
- Human Behaviour Lab, Faculty of Psychology, Universidad El Bosque, Bogota, Colombia
| | | | - Eugenio Valderrama
- Human Behaviour Lab, Faculty of Psychology, Universidad El Bosque, Bogota, Colombia
- LH Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States of America
| | | | - Lina Morales-Sánchez
- Human Behaviour Lab, Faculty of Psychology, Universidad El Bosque, Bogota, Colombia
- Department of Psychology, Faculty of Social Sciences, Los Andes University, Bogota, Colombia
| | - Javier Nieto
- Laboratory of Learning and Adaptation, Faculty of Psychology, National Autonomous University of Mexico, Mexico City, Mexico
| | - Isaac González-Santoyo
- Neuroecology Lab, Faculty of Psychology, National Autonomous University of Mexico, Mexico City, Mexico.
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Zaffarini E, Mitteroecker P. Secular changes in body height predict global rates of caesarean section. Proc Biol Sci 2020; 286:20182425. [PMID: 30963921 DOI: 10.1098/rspb.2018.2425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The massive global variation in caesarean-section (C-section) rate is usually attributed to socio-economic, medical and cultural heterogeneity. Here, we show that a third of the global variance in current national C-section rate can be explained by the trends of adult body height from the 1970s to the 1990s. In many countries, living conditions have continually improved during the last century, which has led to an increase in both fetal and adult average body size. As the fetus is one generation ahead of the mother, the fetus is likely to experience better environmental conditions during development than the mother did, causing a disproportionately large fetus and an increased risk of obstructed labour. A structural equation model revealed that socio-economic development and access to healthcare affect C-section rate via multiple causal pathways, but the strongest direct effect on C-section rate was body height change. These results indicate that the historical trajectory of socio-economic development affects-via its influence on pre- and postnatal growth-the intergenerational relationship between maternal and fetal dimensions and thus the difficulty of labour. This sheds new light on historic and prehistoric transitions of childbirth and questions the World Health Organization (WHO) suggestion for a global 'ideal' C-section rate.
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Affiliation(s)
- Eva Zaffarini
- 1 Department of Theoretical Biology, University of Vienna , Althanstrasse 14, 1090 Vienna , Austria.,2 Department of Biotechnology and Bioscience, University of Milano-Bicocca , Piazza della Scienza 2, 20126 Milano , Italy
| | - Philipp Mitteroecker
- 1 Department of Theoretical Biology, University of Vienna , Althanstrasse 14, 1090 Vienna , Austria
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Moving Beyond the Obstetrical Dilemma Hypothesis: Birth, Weaning and Infant Care in the Plio-Pleistocene. THE MOTHER-INFANT NEXUS IN ANTHROPOLOGY 2020. [DOI: 10.1007/978-3-030-27393-4_10] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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45
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Nishi K, Saiki K, Oyamada J, Okamoto K, Ogami-Takamura K, Hasegawa T, Moriuchi T, Sakamoto J, Higashi T, Tsurumoto T, Manabe Y. Sex-based differences in human sacroiliac joint shape: a three-dimensional morphological analysis of the iliac auricular surface of modern Japanese macerated bones. Anat Sci Int 2019; 95:219-229. [PMID: 31792910 DOI: 10.1007/s12565-019-00513-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 11/25/2019] [Indexed: 11/30/2022]
Abstract
The human pelvis is one of the skeletons where sex differences are expressed, but few detailed studies have been conducted on sex-related differences in the sacroiliac joint morphology. Therefore, we conducted a three-dimensional morphological analysis evaluation of the sacroiliac joints to clarify the sex-related difference of the joint's morphology. Right-side macerated innominate bones of Japanese males (n = 100) and females (n = 70) whose ages at death were recorded were included in the study. Three-dimensional images were created from the subjects' iliac auricular surface images, and 16 measurement parameters were acquired on the basis of 11 defined measurement points. All measurement parameters were compared between the male and female groups. The values of the measurement parameters indicating the size of the iliac auricular surface were significantly larger in the male group than in the female group. In addition, the angle between the short and long arms of the auricular surface was larger in the male group. Furthermore, on the basis of the corrected values of the physical disparity, the long arm dimension of the iliac auricular surface was larger in the male group, while the short arm dimension was larger in the female group. The sex-based differences in the iliac auricular surface morphology that were confirmed in this study may reflect the sex-based differences in the sacroiliac joint function. The findings of this study may contribute to the elucidation of the pathophysiology of the sacroiliac joint dysfunction that frequently occurs in women.
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Affiliation(s)
- Keita Nishi
- Department of Oral Anatomy and Dental Anthropology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan.
| | - Kazunobu Saiki
- Department of Macroscopic Anatomy, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Joichi Oyamada
- Department of Oral Anatomy and Dental Anthropology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan
| | - Keishi Okamoto
- Department of Macroscopic Anatomy, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Keiko Ogami-Takamura
- Department of Macroscopic Anatomy, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Takashi Hasegawa
- Department of Community-Based Rehabilitation Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Takefumi Moriuchi
- Department of Occupational Therapy Science, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Junya Sakamoto
- Department of Physical Therapy Science, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Toshio Higashi
- Department of Community-Based Rehabilitation Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Toshiyuki Tsurumoto
- Department of Macroscopic Anatomy, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Yoshitaka Manabe
- Department of Oral Anatomy and Dental Anthropology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan
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Fatica LM, Almécija S, McFarlin SC, Hammond AS. Pelvic shape variation among gorilla subspecies: Phylogenetic and ecological signals. J Hum Evol 2019; 137:102684. [DOI: 10.1016/j.jhevol.2019.102684] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 09/23/2019] [Accepted: 09/24/2019] [Indexed: 01/28/2023]
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Wells JCK. Could consanguineous marriage provide a cultural alleviation for the obstetric dilemma? Med Hypotheses 2019; 134:109424. [PMID: 31654884 DOI: 10.1016/j.mehy.2019.109424] [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: 07/30/2019] [Revised: 09/27/2019] [Accepted: 10/09/2019] [Indexed: 11/18/2022]
Abstract
In placental mammals, a poor fit between the physical dimensions of the fetus and maternal pelvis increases the likelihood of obstructed labour. This problem is especially relevant to humans, as our species demonstrates both unique adaptations in pelvic shape and structure associated with bipedalism, and fetal encephalization. Natural selection is expected to have favoured adaptations that reduce the chances of such mismatch within individual mother-offspring dyads. Here, I hypothesise that the cultural practice of consanguineous marriage may have been favoured, on account of increasing the genetic similarity between mothers and offspring and hence the correlation between maternal and fetal physical dimensions. These benefits could be amplified if consanguineous marriage was accompanied by assortative mating for height. An additional benefit of consanguineous marriage for childbirth is the slight reduction in birth size of such offspring compared to non-consanguineous unions. Although the offspring of consanguineous unions have elevated risks of morbidity and mortality, these risks are moderate and the practice could still have been favoured by selection if the reduction in maternal mortality was greater than the increased mortality among individual offspring. This hypothesis could be tested directly by investigating whether rates of obstructed labour are lower in individuals and populations practising consanguineous marriage. At a broader level, phylogenetic analysis could be conducted to test whether consanguineous marriage appears to have originated in the areas where intensive agriculture was first practiced, as adult height typically fell in such populations, potentially exacerbating the risk of obstructed labour.
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Affiliation(s)
- Jonathan C K Wells
- Childhood Nutrition Research Centre, Population, Policy and Practice Research and Teaching Programme, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, WC, UK.
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48
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Infant funerary behavior and kinship in Pleistocene hunter-gatherers from Morocco. J Hum Evol 2019; 135:102637. [DOI: 10.1016/j.jhevol.2019.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 11/21/2022]
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49
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Wells JCK. The diabesity epidemic in the light of evolution: insights from the capacity-load model. Diabetologia 2019; 62:1740-1750. [PMID: 31451870 PMCID: PMC6731192 DOI: 10.1007/s00125-019-4944-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 05/21/2019] [Indexed: 12/21/2022]
Abstract
The global nutrition transition, which embraces major changes in how food is produced, distributed and consumed, is associated with rapid increases in the prevalence of obesity, but the implications for diabetes differ between populations. A simple conceptual model treats diabetes risk as the function of two interacting traits: 'metabolic capacity,' which promotes glucose homeostasis, and 'metabolic load', which challenges glucose homoeostasis. Population variability in diabetes prevalence is consistent with this conceptual model, indicating that the effect of obesity varies by ethnicity. Evolutionary life history theory can help explain why variability in metabolic capacity and metabolic load emerges. At the species level (hominin evolution), across human populations and within individual life courses, phenotypic variability emerges under selective pressure to maximise reproductive fitness rather than metabolic health. Those exposed to adverse environments may express or develop several metabolic traits that are individually beneficial for reproductive fitness, but which cumulatively increase diabetes risk. Public health interventions can help promote metabolic capacity, but there are limits to the benefits that can emerge within a single generation. This means that efforts to curb metabolic load (obesity, unhealthy lifestyles) must remain at the forefront of diabetes prevention. Such efforts should go beyond individuals and target the broader food system and socioeconomic factors, in order to maximise their efficacy.
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Affiliation(s)
- Jonathan C K Wells
- Childhood Nutrition Research Centre, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK.
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50
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Abstract
Hominin birth mechanics have been examined and debated from limited and often fragmentary fossil pelvic material. Some have proposed that birth in the early hominin genus Australopithecus was relatively easy and ape-like, while others have argued for a more complex, human-like birth mechanism in australopiths. Still others have hypothesized a unique birth mechanism, with no known modern equivalent. Preliminary work on the pelvis of the recently discovered 1.98 million-year-old hominin Australopithecus sediba found it to possess a unique combination of Homo and Australopithecus-like features. Here, we create a composite pelvis of Australopithecus sediba to reconstruct the birth process in this early hominin. Consistent with other hominin species, including modern humans, the fetus would enter the pelvic inlet in a transverse direction. However, unlike in modern humans, the fetus would not need additional rotations to traverse the birth canal. Further fetal rotation is unnecessary even with a Homo-like pelvic midplane expansion, not seen in earlier hominin species. With a birth canal shape more closely associated with specimens from the genus Homo and a lack of cephalopelvic or shoulder constraints, we therefore find evidence to support the hypothesis that the pelvic morphology of Australopithecus sediba is a result of locomotor, rather than strictly obstetric constraints.
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