Thesis (Ph.D.)--Indiana University, Dept. of Anthropology, 2008. / Title from PDF t.p. (viewed on Jul 23, 2009). Source: Dissertation Abstracts International, Volume: 69-11, Section: A, page: 4382. Adviser: Christopher S. Peebles.

Thesis (Ph.D.)--Indiana University, Dept. of Anthropology, 2006. / "Title from dissertation home page (viewed July 16, 2007)." Source: Dissertation Abstracts International, Volume: 67-10, Section: A, page: 3878. Advisers: Travis R. Pickering; Kevin D. Hunt.

abstract: The bony pelvis is a pivotal component of the locomotor system, as it links the hindlimb with the trunk and serves as anchorage for the primary propulsive musculature. Its shape is therefore expected to be adapted to the biomechanical demands of habitual locomotor behavior. However, because the relationship between locomotor mechanics and pelvic morphology is not well understood, the adaptive significance of particular pelvic traits and overall pelvic shape remains unclear. This study used an integrative, dual approach to elucidate the relationship between form and function in the primate pelvis. A biomechanical cylinder model of pelvic stress resistance was tested using in vitro strain analysis of monkey and ape cadaver specimens. These results were used to refine adaptive hypotheses relating pelvic form to locomotor mechanics. Hypotheses of adaptation were then tested via univariate and geometric morphometric methods using a taxonomically broad, comparative sample of 67 primate taxa. These results suggest that the pelvis exhibits some iliac and ischial adaptations to stress resistance that are associated with the biomechanical demands of habitual locomotor loading and of body size. The ilium and ischium exhibit relatively low levels of strain during experimental loading as well as adaptations that increase strength. The pubis exhibits relatively high strains during loading and does not vary as predicted with locomotion. This integrated study clarifies the relationship between strain and adaptation; these results support the hypothesis that bones adapted to stress resistance exhibit low strains during typical loading. In general, the cylinder model of pelvic biomechanics is unsupported. While the predictions of loading regimes were generally rejected, the inability of these methods to test the possible occurrence of overlapping loading regimes precludes outright rejection of the cylinder model. However, the lack of support for predicted global responses to applied loading regimes suggests that pelvic stress resistance may be better explained by a model that accounts for local, functional subunits of pelvic structure. The coalescence of a localized model of pelvic biomechanics and comparative morphometrics has great potential to shed light on the evolution of the complex, multi-functional structure of the pelvis. / Dissertation/Thesis / Ph.D. Anthropology 2010

Diverse climates, infectious agents, and subsistence patterns drove humans to adapt metabolically to different environments since the migration out of Africa 100,000 years ago. In this dissertation, I review current literature on the genetic underpinnings, and the molecular and physiological manifestations of these metabolic adaptations in diverse human populations. Then, I develop a theory regarding pregnancy as a critical period in life history that mediated recent selection on human metabolism. Finally, I investigate the function and evidence for selection of derived genetic variants at increased frequency in East Asian populations. I find multiple standing variants that increase expression of the gene IVD and increase the efficiency of leucine catabolism, which lie on positively selected haplotypes in East Asians. I use this research process as a model for how to develop and study novel hypotheses of human metabolic adaptation. Such adaptations often impact health in the modern environment, so more evolutionary research will provide useful guidance to the medical community in how to treat people from diverse ethnicities. / Human Evolutionary Biology

This dissertation explores the relationships between maternal energetic condition, four bioactive compounds in milk, and infant health and growth outcomes through the lens of human life history theory. Research was conducted among the Toba of Barrio Namqom in Formosa, Argentina. This is among the first of studies to apply a life history biology lens to the dynamics of cortisol, insulin-like growth factor 1 (IGF-1), lactoferrin, and secretory immunoglobulin A (sIgA) in human milk. First, the role of maternal energetic condition as a predictor of the concentration of these four compounds in milk is explored. Several interesting relationships emerge, including significantly lower milk cortisol and IGF-1 among women with higher body mass index, and significantly higher milk cortisol among primiparous mothers. Next, the relationships between infant symptoms of illness and the two milk immunofactors, lactoferrin and sIgA, are investigated. Lactoferrin is found to exhibit a positive association with symptoms of illness, and sIgA shows a negative association. Finally, associations between concentration of milk bioactives and infant growth rate are tested, as well as associations between infant illness and growth rate, and maternal energetic condition and growth rate. Milk IGF-1 is found to positively associate with infant linear growth rate. Maternal parity is found to negatively associate with linear growth rate. First-born status is associated with significantly greater gains in length and mass over a four-month period. These and other results are discussed through the lens of life history biology and avenues for future research at the intersection of life history biology and public health are identified. / Human Evolutionary Biology

How do humans generate and resist repetitive impact forces beneath the heel during walking and heel strike running? Due to the evolution of long day ranges and larger body sizes in the hominin lineage modern human hunter-gatherers must resist millions of high magnitude impact forces per foot per year. As such, impact forces may have been a selective pressure on many aspects of human morphology, including skeletal structure. This thesis therefore examines how humans generate impact forces under a variety of conditions and how variation in skeletal structure influences impact resistance. This thesis includes four studies that can be separated into two parts. In the first part, I test two models of how variation in the stiffness and height of footwear affect the generation of impact peaks during walking and heel strike running. The first model predicts that variation in the stiffness of footwear introduces tradeoffs between three crucial impact force related variables: impact loading rate, vertical impulse and effective mass. The prediction of the second model is that higher heels have the same effects on impact forces as do footwear of lower stiffness. These hypotheses were tested using 3D motion data and force data in human walkers and runners wearing a variety of footwear. Experimental results show that soft footwear introduces tradeoffs between impact loading rate, vertical impulse and effective mass, and that high heeled shoes influence impact duration, loading rate and vertical impulse in predictable ways. In the second part of this thesis, I document variation in hominoid skeletal structure and experimentally test how this variation affects function during impact forces. In particular, I examine trabecular bone volume fraction in the calcaneus of gorillas, chimpanzees and several H. sapiens populations that vary widely in geologic age and subsistence strategy. I then develop and test a model of how variation in trabecular bone volume fraction affects several mechanical properties of trabecular bone tissue, including the stiffness, strength and energy dissipation. The comparative data indicates that trabecular bone volume fraction in the human calcaneus has declined after the Pleistocene. The experimental data shows that larger trabecular bone volume fraction results in increased stiffness and strength but reduced energy dissipation of trabecular bone tissue. A final examination of the comparative data relative to the experimental data suggests that the human calcaneus resists impacts by being stiff strong rather than by dissipating mechanical energy. The results of this thesis suggest that way in which impacts are both generated and resisted has changed in recent human history, as modern footwear alters impact loading rate and vertical impulse and decline in trabecular bone volume fraction negatively influence trabecular bone strength. These results also have implications for how bones evolve to resist impacts, suggesting that bone structures than favor stiffness and strength are favored to cope with impacts. Finally, the results of this thesis are important for understanding the etiology of osteoarthritis, and musculoskeletal disease that has been linked to both repetitive impact forces during human locomotion and to variation in trabecular bone volume fraction. / Human Evolutionary Biology

Life history theory assumes that organisms allocate energetic resources (i.e., calories) to primary life functions such as maintenance, growth, reproduction, and physical activity in a manner that maximizes fitness. Under this conceptual framework, energy is limited, resource allocation is dynamic, and functional tradeoffs between competing metabolic processes are expected to occur. Life history tradeoffs have been invoked to explain biological variation across a range of species and ecological contexts. However, few studies have examined patterns of energy allocation and tradeoffs during human development, restricting fundamental understandings of human life history, phenotypic plasticity, and health. This dissertation investigates human energy allocation and life history tradeoffs in the context of physical growth among the Shuar, a small-scale indigenous population from Amazonian Ecuador. Mixed-longitudinal anthropometric data were collected from 2,553 Shuar between the ages of 0-29 years. Additional market integration (i.e., production for and consumption from a market-based economy) and immune activity (i.e., finger-prick blood biomarker) data were obtained from a subset of children and adolescents. Analysis was performed to explore variation in physical growth at the population, regional, household, and individual levels. Results demonstrate that, as a population, the Shuar grow significantly more slowly than international references and experience several unique developmental characteristics that may be explained by energetic life history tradeoffs. Between-individual variation in Shuar growth, however, is substantial. A large portion of this variation is explained by household-level market integration factors associated with differences in diet, lifestyle, and pathogen exposure. Among Shuar children, linear growth is negatively related to several diverse biomarkers of immune function, such that growth is reduced by as much as 83% during intermittent periods of elevated immune activity. These tradeoffs occur over timeframes as short as one week and are typically avoided by children with adequate energy reserves (i.e., high levels of subcutaneous body fat). Taken together, these findings provide evidence for an important role of energetic tradeoffs in shaping patterns of human ontogeny and health. / Human Evolutionary Biology

This dissertation examines the mortality experiences of two emerging industrial cities, Northampton and Holyoke, in the Connecticut River Valley of western Massachusetts, during the period from 1850 through 1910, and the processes that delayed the transition to lower mortality levels in New England. This was a period in which these two towns, and many others in New England, grew rapidly due to early industrialization and urbanization. Death rates rose after the middle of the nineteenth century and stabilized at high levels, only falling again after the turn of the twentieth century. This work is an anthropological enquiry into why life seems to have been more precarious in the emergent cities of New England as mortality was declining throughout western Europe. Some characteristics of these towns, for example, changing occupational, ethnic and age composition, can be ascertained from decennial census data. However, in order to analyze the relationship of mortality to changing population characteristics I use linked individual-level census and death records from 1850 to 1912 to analyze mortality across panels defined by the timing of decennial censuses. I also look at how individuals might have attempted to mitigate the risks of mortality through strategies of household formation and household economies. The use of individual-level linked census-death data in these communities supports detailed analyses of the changing risks of mortality over the emergence and eventual maturation of these industrializing urban centers. I find that the mortality experiences of Holyoke and Northampton were shaped by the processes that formed these unique communities: a large population of young adults, influxes of poorly-paid immigrant labor, densely crowded living and working conditions, and delays in adequate infrastructure, particularly clean water and sanitary sewerage. During the period mortality rose and the most vulnerable groups experienced the worst life chances. Over time, the communities matured. The population aged, growth slowed, outlying areas became accessible to industrial workers through a regional trolley system, and public works were better able to keep pace with population. Death from infectious and parasitic disease became less frequent, and death from chronic or degenerative disease more prevalent.

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