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This chapter examines the role of selection in driving certain aspects of pelvic morphology, particularly the differences between mediolateral breadths and anteroposterior breadths. The chapter is divided into three sections, representing the three key selection pressures researchers have spent the most time on – namely, obstetrics, locomotion and thermoregulation. Data for the role of each of these on pelvic morphology are considered, as is discussion of the myriad ways human populations have mixed and matched morphological traits to manage these selection pressures. Clearly, there is not a single strategy for handling the interactive nature of these pressures.
In this chapter, we discuss evidence about the evolutionary forces that have shaped the evolution of the human pelvis, both in its entirety as well as portions of the pelvis, focusing on studies that have investigated pelvic evolution using experimental and quantitative genetic methods. These methods are tied to information from Chapter 4 about pelvis development, with emphasis placed on the importance of understanding the difficulty of tying development and growth with evolutionary processes. Special attention is placed on the concept of the palimpsest. Further, we review these findings in light of three principal hypotheses broadly offered about the processes that selected for pelvic shape (as reviewed in Chapters 2 and 3): locomotion, obstetric sufficiency and thermoregulation. We show from multiple studies that the human pelvis evolved in response to natural selection as well as through neutral evolutionary processes (e.g. genetic drift). A key conclusion from these studies is that parts of the pelvis evolved in different manners in response to these (and other) selection factors; thus, the shape of the human pelvis reflects a modular response to various sources of selection.
This chapter provides an overview of the anatomy of the primate pelvis, with a particular focus on the features of the hominoid (ape) and human pelvic morphologies. Underlying sources of morphological variation such as phylogenetic signals, sexual dimorphism and obstetric function are examined, as well as general patterns of pelvic anatomical variation within Homo sapiens.
In light of the various sources of evidence presented in the preceding chapters, we are left to conclude that the human (in the broadest sense of recent humans and their ancestors) pelvis represents various experiments in evolution. A diversity in pelvic sizes and shapes has marked hominin history, as each population and each species responded to selection pressures in sometimes unique and sometimes convergent ways. These were situated in the distinctive population histories of each of these groups, creating a mosaic of patterns underlain both by responses to evolution and changing patterns of covariance within development. To understand the diversity we observe among fossils, as well as variation within recent humans, we must therefore cultivate a multidisciplinary expertise in biomechanics, kinematics, fossil evidence, developmental biology and evolutionary theory. This book represents an attempt at bringing together these various sources of evidence to better understand the factors, patterns and potential processes that shaped the evolution of the pelvis.
Even before the focus on bipedalism as the ‘hallmark’ of the human lineage (Robinson, 1972), interest in the pelvis was stimulated by discussions across different disciplines, including the growing field of obstetrics (see review in Walrath, 2003), as well as by multiple fossil discoveries (Pycraft, 1930; Dart, 1949). It was also clear at the outset that the pelvis was going to serve as a crucial part of the evolutionary history of humans, given that it had obvious functional implications in its role in locomotion, which included dramatic differences between other species grouped with humans taxonomically and then phylogenetically, including the African and Asian apes.
To investigate pelvis evolution and to understand the sources of its variation, we must comprehend its development. We review developmental processes that form the pelvis from three perspectives: cell layers and tissues, genomic information and overall growth. At tissue level, the pelvis forms largely from lateral plate mesoderm as well as from somites. The os coxa forms from cartilaginous precursor tissues that grow and ossify, especially in two major regions that become the ischiopubis and the ilium. The sacrum and coccyx form from multiple ossification centres. Numerous secondary ossification centres form, with the last fusing by the mid-twenties. The importance of multiple genes and molecular factors are discussed, including interactions among and differences in timing and locations of expression, emphasising Islet1, Emx2, Pbx and Hox. We review the importance of differences in timing of ossification among skeletal elements, their interactions with mechanical loading and sex hormones, and environmental factors affecting individual growth. These processes are linked to morphological integration and are the origins of the morphological variation on which evolutionary forces act.
This chapter examines the fossil record of hominoid and hominin pelvic remains from the Miocene through to the Late Pleistocene. The interpretation of functional demands shaping hominin pelvic morphology including locomotion, obstetrics and thermoregulation are discussed, as well as evidence for pelvic sexual dimorphism in hominin species. The long-standing view of a relatively linear pattern of hominin pelvic evolution from Australopiths, through early Homo, to Neanderthals, broken only by the appearance of the somewhat divergent morphology of Homo sapiens is examined in light of recent fossil pelvis discoveries that point to greater diversity in the hominin pelvic morphology. These fossils add to evidence from elsewhere in the postcranium that indicate there were multiple ways to be a bipedal hominin.
There is a paucity of long-term prospective disaster studies of the psychological sequelae among survivors.
At 1½ and 25 years after the Spitak earthquake, 142 early adolescents from two cities were assessed: Gumri (moderate–severe exposure) and Spitak (very severe exposure). The Gumri group included treated and not-treated subjects, while the Spitak group included not-treated subjects. Instruments included: DSM-III-R PTSD-Reaction Index (PTSD-RI); DSM-5 PTSD-Checklist (PCL); Depression Self-Rating Scale (DSRS); and Center for Epidemiological Studies-Depression Scale (CES-D).
(1) Between 1½ and 25 years, PTSD rates and mean scores decreased significantly in the three groups (over 50%). However, at 25 years 9.1–22.4% met DSM-5 PTSD criteria. (2) At 1½ years, the Spitak group had higher PTSD-RI (p < 0.001) and DSRS scores (p < 0.001) compared to the Gumri-not-treated group. At 25 years, the Spitak group that had experienced fewer post-earthquake adversities (p < 0.03), had a greater decrease in PTSD-RI scores (p < 0.02), and lower CES-D scores (p < 0.01). (3) Before treatment, PTSD-RI and DSRS scores did not differ between the Gumri-treated and not-treated groups. At 25-years, the Gumri-treated group showed a greater decrease in PTSD-RI scores (p < 0.03), and lower mean PTSD-RI (p < 0.02), PCL (p < 0.02), and CES-D (p < 0.01) scores. (4) Predictors of PTSD symptom severity at 25-years included: home destruction, treatment, social support, post-earthquake adversities, and chronic medical illnesses.
Post-disaster PTSD and depressive symptoms can persist for decades. Trauma-focused treatment, alleviation of post-disaster adversities, improving the social ecology, and monitoring for chronic medical illnesses are essential components of recovery programs.
Prevention of Clostridioides difficile infection (CDI) is a national priority and may be facilitated by deployment of the Targeted Assessment for Prevention (TAP) Strategy, a quality improvement framework providing a focused approach to infection prevention. This article describes the process and outcomes of TAP Strategy implementation for CDI prevention in a healthcare system.
Hospital A was identified based on CDI surveillance data indicating an excess burden of infections above the national goal; hospitals B and C participated as part of systemwide deployment. TAP facility assessments were administered to staff to identify infection control gaps and inform CDI prevention interventions. Retrospective analysis was performed using negative-binomial, interrupted time series (ITS) regression to assess overall effect of targeted CDI prevention efforts. Analysis included hospital-onset, laboratory-identified C. difficile event data for 18 months before and after implementation of the TAP facility assessments.
The systemwide monthly CDI rate significantly decreased at the intervention (β2, −44%; P = .017), and the postintervention CDI rate trend showed a sustained decrease (β1 + β3; −12% per month; P = .008). At an individual hospital level, the CDI rate trend significantly decreased in the postintervention period at hospital A only (β1 + β3, −26% per month; P = .003).
This project demonstrates TAP Strategy implementation in a healthcare system, yielding significant decrease in the laboratory-identified C. difficile rate trend in the postintervention period at the system level and in hospital A. This project highlights the potential benefit of directing prevention efforts to facilities with the highest burden of excess infections to more efficiently reduce CDI rates.
This book provides a synthetic overview of all evidence concerning the evolution of the morphology of the human pelvis, including comparative anatomy, clinical and experimental studies, and quantitative evolutionary models. By integrating these lines of research, this is the first book to bring all sources of evidence together to develop a coherent statement about the current state of the art in understanding pelvic evolution. Second, and related to this, the volume is the first detailed assessment of existing paradigms about the evolution of the pelvis, especially the obstetric dilemma. The authors argue that there are many 'dilemmas', but these must be approached using a testable methodology, rather than on the proviso of a single paradigm. The volume clearly contributes to greater scientific knowledge about human variation and evolution, and has implications for clinicians working within reproductive health. A thought-provoking read for students, researchers and professionals in the fields of biological anthropology, human evolutionary anthropology, paleoanthropology, bioarchaeology, biology, developmental biology and obstetrics.
Aboriginal Australians experience higher rates of non-communicable chronic disease, injury, dementia, and mortality than non-Aboriginal Australians. Self-reported health is a holistic measure and may fit well with Aboriginal views of health and well-being. This study aimed to identify predictors of self-reported health in older Aboriginal Australians and determine acceptable research methodologies for future aging research.
Longitudinal, population-based study.
Five communities across New South Wales, Australia (two urban and three regional sites).
Aboriginal and Torres Strait Islander people (n = 227; 60–88 years, M = 66.06, SD = 5.85; 145 female).
Participants completed baseline (demographic, medical, cognitive, mental health, and social factors) and follow-up assessments (self-reported health quantified with 5-point scale; sharing thoughts on areas important for future research). Predictors of self-reported health were examined using logistic regression analyses.
Self-reported health was associated with sex, activities of daily living, social activity participation, resilience, alcohol use, kidney problems, arthritis, falls, and recent hospitalization. Arthritis, kidney problems, and resilience remained significant in multiple logistic regression models.
Perceived resilience and the absence of certain chronic age-related conditions predict older Aboriginal peoples’ self-reported health. Understanding these factors could inform interventions to improve well-being. Findings on acceptable research methodologies suggest that many older Aboriginal people would embrace a range of methodologies within long-standing research partnerships, which is an important consideration for Indigenous population research internationally.
Early detection and intervention strategies in patients at clinical high-risk (CHR) for syndromal psychosis have the potential to contain the morbidity of schizophrenia and similar conditions. However, research criteria that have relied on severity and number of positive symptoms are limited in their specificity and risk high false-positive rates. Our objective was to examine the degree to which measures of recency of onset or intensification of positive symptoms [a.k.a., new or worsening (NOW) symptoms] contribute to predictive capacity.
We recruited 109 help-seeking individuals whose symptoms met criteria for the Progression Subtype of the Attenuated Positive Symptom Psychosis-Risk Syndrome defined by the Structured Interview for Psychosis-Risk Syndromes and followed every three months for two years or onset of syndromal psychosis.
Forty-one (40.6%) of 101 participants meeting CHR criteria developed a syndromal psychotic disorder [mostly (80.5%) schizophrenia] with half converting within 142 days (interquartile range: 69–410 days). Patients with more NOW symptoms were more likely to convert (converters: 3.63 ± 0.89; non-converters: 2.90 ± 1.27; p = 0.001). Patients with stable attenuated positive symptoms were less likely to convert than those with NOW symptoms. New, but not worsening, symptoms, in isolation, also predicted conversion.
Results suggest that the severity and number of attenuated positive symptoms are less predictive of conversion to syndromal psychosis than the timing of their emergence and intensification. These findings also suggest that the earliest phase of psychotic illness involves a rapid, dynamic process, beginning before the syndromal first episode, with potentially substantial implications for CHR research and understanding the neurobiology of psychosis.