Publicação

A life course approach to skeletal stress markers and minor congenital defects in a modern (19th-20th century) skeletal collection from Lisbon

Detalhes bibliográficos
Resumo:	Anthropology, through a life course approach, provides a crossover of biological, social and cultural perspectives and approaches on health and disease, with an outstanding potential to provide data that might not be obtained by any other field of knowledge, intertwining in the multidirectional association between cultural, social, historical, political, economic and biological processes. This work focus on the effect caused by environmental stress on human health and longevity, using the life course model, through the study of a sample of skeletons from the Lisbon Identified Skeletal Collection (aka Luís Lopes Collection), referring to the early-19th to mid-20th centuries, deposited at the National Museum of Natural History and Science, University of Lisbon, Portugal - 679 subadults and adults born between 1806 and 1958 and died at Lisbon between 1880 and 1970 were available for study. Life course approach emphasizes the effect of environmental stress on the skeleton at different stages of life, by analyzing the interruption of normal development and growth of skeletal injuries, currently called stress markers. The information obtained in this analysis provides evidence to identify how and when environmental stress affects the skeleton, with more or less severity and how the skeleton reacts or recovers, and how it affects patterns of morbidity and mortality in later stages of life. As a way of establishing the connection between environmental stressors and the skeleton, several minor congenital defects of the sternum, vertebral column and skull base, cribra orbitalia, size of the neuro-vertebral canal and length of the femur and tibia are analyzed. This study is the first to test the association between vertebral neural canal size and age-at-death in a collection of Portuguese skeletons, of individuals with known sex, age-at death, year of birth and cause of death. Age-at-death is negatively associated with the size of the neural vertebral canal in several cervical, thoracic and lumbar vertebrae. However, this association ceases to exist when the confounding variables: year of birth and cause of death are added to the models as covariates. The results appear to be consistent with the plasticity and constraint model before the introduction of covariates and with the predictive adaptive response model after the inclusion of covariates in the analysis. The predictive adaptive response model defends that, in the womb, the organism makes a prediction about the environment in which it will be inserted later in life, according to the clues it receives, and adapts itself to this future environment, not only for its immediate survival, but also to be better prepared for later living conditions. Later in life, when there is a mismatch between predictions made in the womb and conditions in real life, it will result in greater susceptibility to certain chronic diseases. In the plasticity and constraint model, uterine changes resulting from environmental stress factors have the sole function of immediate survival, and will have harmful effects on morbidity and mortality in more advanced stages of life, regardless of whether or not there is an environment similar to that the organism had in the womb. None of the birth defects of the sternum and spine analyzed in this study has a statistically significant relationship with sex and age-at-death. Sex differences in the characteristics studied are not very common; therefore, the absence of statistically significant differences between sexes was expected. The absence of differences in age-at-death is also consistent with other studies. The absence of statistically significant differences in sex and age-at-death between individuals with and without these birth defects, makes them useful for biological distance studies, but not as suitable as stress markers. It would be expected that individuals with birth defects would have been exposed to any type of stressful event (for example, exposure to toxic substances, inadequate consumption of nutrients) during embryogenesis, which would affect life-long morbidity and mortality. Still, even if these defects do not affect longevity, it does not necessarily mean that they are not markers of stress. If the predictive adaptive response theory is correct, then individuals subject to stressful events early in life are better prepared to deal with stressful events later in life, which would counteract the expected effect of decreasing longevity. The study of a possible association between congenital defects of the sternum, vertebral column and skull base with cribra orbitalia, vertebral neural canal sizes and femur and tibia length, presents more promising results, regarding the possibility of using some of these defects as stress markers. Hyperplasia of the sternum is related to the antero-posterior and transverse diameters of the neuro-vertebral channels of the thoracic vertebrae in men, but each of these correlations has an opposite direction. Men with sternum hyperplasia have narrower anteroposterior diameters and wider transverse diameters. A narrower anteroposterior diameter may be associated with a hostile environment early in life leading to the presence of sternal hyperplasia, whereas a wider transverse diameter may be linked to an improvement in the environment during late childhood and adolescence, allowing growth recover. Therefore, the use of sternum hyperplasia as a stress marker may be defensible, although further studies are needed to corroborate this association. The double hypoglossal canal is related to the transverse diameters in the thoracic vertebrae in women. Women with a double hypoglossal canal tend to have narrower transverse diameters. Of all the birth defects analyzed, the double hypoglossal canal is the most promising for use as a stress marker. Sex differences can be explained by considering that males, during growth, are culturally more protected from adverse conditions than females. Finally, an exhaustive analysis of the entire collection is made regarding the presence and variability of the hypoglossal canal. The gross prevalence of double hypoglossal canal fits within the normal parameters of variation of this characteristic when compared with results from other collections. However the gross prevalence of global variants in the hypoglossal canal (partial bridging, double and triple hypoglossal canal) is 32.4%. None of the variants of the hypoglossal canal shows any difference in sex or laterality. The main findings of this study allow to infer that environmental stress is negatively associated with age-at-death, even though the association of stress and skeletal markers is not always straightforward, possibly hindered by phenomenon such as catch-up-growth associated with slight improvements in socio-economic status during childhood and adolescence. Some minor congenital defects might have the potential to be used as stress markers, namely sternum hyperplasia and double hypoglossal canal.
Autores principais:	Amoroso, Paula Alexandra da Silva Pegado Santos
Assunto:	Stress markers minor congenital defects neuro-vertebral canal life course Luis Lopes Collection Marcadores de stresse defeitos congénitos canais neuro-vertebrais cribra orbitalia crescimento história de vida Coleção Luís Lopes
Ano:	2021
País:	Portugal
Tipo de documento:	tese de doutoramento
Tipo de acesso:	acesso restrito
Instituição associada:	Universidade de Lisboa
Idioma:	inglês
Origem:	Repositório da Universidade de Lisboa

Descrição
Resumo:	Anthropology, through a life course approach, provides a crossover of biological, social and cultural perspectives and approaches on health and disease, with an outstanding potential to provide data that might not be obtained by any other field of knowledge, intertwining in the multidirectional association between cultural, social, historical, political, economic and biological processes. This work focus on the effect caused by environmental stress on human health and longevity, using the life course model, through the study of a sample of skeletons from the Lisbon Identified Skeletal Collection (aka Luís Lopes Collection), referring to the early-19th to mid-20th centuries, deposited at the National Museum of Natural History and Science, University of Lisbon, Portugal - 679 subadults and adults born between 1806 and 1958 and died at Lisbon between 1880 and 1970 were available for study. Life course approach emphasizes the effect of environmental stress on the skeleton at different stages of life, by analyzing the interruption of normal development and growth of skeletal injuries, currently called stress markers. The information obtained in this analysis provides evidence to identify how and when environmental stress affects the skeleton, with more or less severity and how the skeleton reacts or recovers, and how it affects patterns of morbidity and mortality in later stages of life. As a way of establishing the connection between environmental stressors and the skeleton, several minor congenital defects of the sternum, vertebral column and skull base, cribra orbitalia, size of the neuro-vertebral canal and length of the femur and tibia are analyzed. This study is the first to test the association between vertebral neural canal size and age-at-death in a collection of Portuguese skeletons, of individuals with known sex, age-at death, year of birth and cause of death. Age-at-death is negatively associated with the size of the neural vertebral canal in several cervical, thoracic and lumbar vertebrae. However, this association ceases to exist when the confounding variables: year of birth and cause of death are added to the models as covariates. The results appear to be consistent with the plasticity and constraint model before the introduction of covariates and with the predictive adaptive response model after the inclusion of covariates in the analysis. The predictive adaptive response model defends that, in the womb, the organism makes a prediction about the environment in which it will be inserted later in life, according to the clues it receives, and adapts itself to this future environment, not only for its immediate survival, but also to be better prepared for later living conditions. Later in life, when there is a mismatch between predictions made in the womb and conditions in real life, it will result in greater susceptibility to certain chronic diseases. In the plasticity and constraint model, uterine changes resulting from environmental stress factors have the sole function of immediate survival, and will have harmful effects on morbidity and mortality in more advanced stages of life, regardless of whether or not there is an environment similar to that the organism had in the womb. None of the birth defects of the sternum and spine analyzed in this study has a statistically significant relationship with sex and age-at-death. Sex differences in the characteristics studied are not very common; therefore, the absence of statistically significant differences between sexes was expected. The absence of differences in age-at-death is also consistent with other studies. The absence of statistically significant differences in sex and age-at-death between individuals with and without these birth defects, makes them useful for biological distance studies, but not as suitable as stress markers. It would be expected that individuals with birth defects would have been exposed to any type of stressful event (for example, exposure to toxic substances, inadequate consumption of nutrients) during embryogenesis, which would affect life-long morbidity and mortality. Still, even if these defects do not affect longevity, it does not necessarily mean that they are not markers of stress. If the predictive adaptive response theory is correct, then individuals subject to stressful events early in life are better prepared to deal with stressful events later in life, which would counteract the expected effect of decreasing longevity. The study of a possible association between congenital defects of the sternum, vertebral column and skull base with cribra orbitalia, vertebral neural canal sizes and femur and tibia length, presents more promising results, regarding the possibility of using some of these defects as stress markers. Hyperplasia of the sternum is related to the antero-posterior and transverse diameters of the neuro-vertebral channels of the thoracic vertebrae in men, but each of these correlations has an opposite direction. Men with sternum hyperplasia have narrower anteroposterior diameters and wider transverse diameters. A narrower anteroposterior diameter may be associated with a hostile environment early in life leading to the presence of sternal hyperplasia, whereas a wider transverse diameter may be linked to an improvement in the environment during late childhood and adolescence, allowing growth recover. Therefore, the use of sternum hyperplasia as a stress marker may be defensible, although further studies are needed to corroborate this association. The double hypoglossal canal is related to the transverse diameters in the thoracic vertebrae in women. Women with a double hypoglossal canal tend to have narrower transverse diameters. Of all the birth defects analyzed, the double hypoglossal canal is the most promising for use as a stress marker. Sex differences can be explained by considering that males, during growth, are culturally more protected from adverse conditions than females. Finally, an exhaustive analysis of the entire collection is made regarding the presence and variability of the hypoglossal canal. The gross prevalence of double hypoglossal canal fits within the normal parameters of variation of this characteristic when compared with results from other collections. However the gross prevalence of global variants in the hypoglossal canal (partial bridging, double and triple hypoglossal canal) is 32.4%. None of the variants of the hypoglossal canal shows any difference in sex or laterality. The main findings of this study allow to infer that environmental stress is negatively associated with age-at-death, even though the association of stress and skeletal markers is not always straightforward, possibly hindered by phenomenon such as catch-up-growth associated with slight improvements in socio-economic status during childhood and adolescence. Some minor congenital defects might have the potential to be used as stress markers, namely sternum hyperplasia and double hypoglossal canal.