Aaron D Blackwell
Biographic Data
| ID | 83301 |
|---|---|
| NAME | Aaron D Blackwell |
| GIVEN NAMES | Aaron D |
| FAMILY NAME | Blackwell |
| SIGNATURE | BLACKWELL A D |
| AFFILIATIONS | Washington State University |
| ORCID | 0000-0002-5871-9865 |
| VERIFIED | Yes |
| TOTAL WORKS | 29 |
| TOTAL CITATIONS | 126 |
| AUTHOR COUNT | 29 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 2009 |
| LATEST PUBLICATION YEAR | 2026 |
| H-INDEX | 6 |
Market Integration and Reproductive Transitions Among Indigenous Shuar and Neighboring Nonindigenous Ecuadorians in Amazonian Ecuador
OBJECTIVE: Global reproductive transitions are well documented, yet less is known about how neighboring populations with divergent histories and exposure to market integration (MI) experience them. This study examines how sociocultural and economic proxies of MI predict variation in reproductive outcomes among indigenous Shuar and nonindigenous Ecuadorian mestizos (Colonos) from Amazonian Ecuador, focusing on menarcheal age, age at first birth, p…
Circulating Epstein–Barr Virus Antibody Levels as a Biomarker of Socioecological Adversity in Amazonian Ecuador
OBJECTIVES: Circulating Epstein-Barr virus antibodies (EBV-Ab) are used as a biomarker of chronic stress in high-income settings, but their relevance in environments with a high burden of infectious disease, nutritional constraints, and limited resources is less clear. We investigated EBV-Ab as a biomarker of adversity in a setting where local ecology and economy may affect immune development differently than in wealthy countries. METHODS: We mea…
The Natural History of Child Signals of Need in Utila, Honduras
Trayectorias hormonales asociadas con la edad a la menarca y el aumento de peso en niñas originarias Qom/Toba
In this exploratory study, we analyzed the hormonal and growth trajectories of 61 Qom/Toba girls aged 8 to 14 years from a peri-urban community in Formosa, Argentina. Monthly measurements of weight and height were taken, and eight urine samples were collected every three months until the menarche was reported or until the end of the study. The urine samples were analyzed using enzyme immunoassay to determine testosterone and C-peptide levels. Bay…
Human milk immune factors, maternal nutritional status, and infant sex
OBJECTIVES: Breastfeeding is an energetically costly and intense form of human parental investment, providing sole-source nutrition in early infancy and bioactive components, including immune factors. Given the energetic cost of lactation, milk factors may be subject to tradeoffs, and variation in concentrations have been explored utilizing the Trivers-Willard hypothesis. As human milk immune factors are critical to developing immune system and p…
Low prevalence of anemia among Shuar communities of Amazonian Ecuador
OBJECTIVE: Anemia is an important global health challenge. We investigate anemia prevalence among Indigenous Shuar of Ecuador to expand our understanding of population-level variation, and to test hypotheses about how anemia variation is related to age, sex, and market integration. METHODS: Hemoglobin levels were measured in a total sample of 1650 Shuar participants (ages 6 months to 86 years) from 46 communities between 2008 and 2017 to compare …
Age‐related patterns of cytomegalovirus antibodies accompanying Epstein‐Barr virus co‐infection
OBJECTIVE: Cytomegalovirus (CMV) infection is associated with age-related chronic disease, and co-infection with Epstein-Barr virus (EBV) may compound disease risk. We aimed to assess the frequency of CMV infection and its relationship with age among EBV seropositive individuals in an Indigenous Amazonian population. METHODS: We report concentrations of CMV and EBV antibodies in dried blood spot samples collected from 157 EBV positive Shuar parti…
Ecoimmunology in the field
The Ecoimmunology of Health and Disease
The original hygiene hypothesis proposed that certain diseases derive from low levels of early-life microbial exposure. Since then, the hypothesis has been applied to numerous inflammatory, autoimmune, and allergic conditions. The changes in hygiene linked to these diseases include numerous changes in biotic exposure and lifestyle. To this end, some scholars have called for abandonment of the term or have suggested alternate labels, e.g., the old…
Do computed tomography findings agree with traditional osteological examination? The case of porous cranial lesions
A field method for cryopreservation of whole blood from a finger prick for later analysis with flow cytometry
OBJECTIVES: Flow cytometry is a powerful tool for investigating immune function, allowing for the quantification of leukocytes by subtype. Yet it has not been used extensively for field work due to perishable reagents and the need for immediate analysis of samples. To make flow cytometry more accessible, we devise and evaluate a field protocol for freezing capillary blood. MATERIALS AND METHODS: We collected finger prick blood samples from 110 vo…
Old friends and friendly fire
OBJECTIVES: Despite public health concerns about hookworm infection in pregnancy, little is known about immune profiles associated with hookworm (Necator americanus and Ancylostoma duodenale) infection during pregnancy. Fetal tolerance requirements may constrain maternal immune response to hookworm, thereby increasing susceptibility to new infections or increasing hemoglobin loss. To explore this possibility, we study systemic immune response and…
Does exposure to parasites modify relationships between diurnal cortisol and leukocytes among Honduran women
BACKGROUND: Altered hypothalamic-pituitary-adrenal (HPA) function and related changes in circulating glucocorticoids have been implicated in the pathogenesis of numerous diseases that involve dysregulated immune function. Glucocorticoid hormones have both direct and indirect modulatory effects on both pro- and anti-inflammatory aspects of the immune system, including granulocytic and lymphocytic leukocyte subsets. However, past findings are compl…
Testosterone is positively and estradiol negatively associated with mucosal immunity in Amazonian adolescents
Objectives A core assumption of life history theory and the immunocompetence handicap hypothesis (ICHH) is that testosterone (T) upregulates energetic investment in mating effort at the expense of immunity. This tenet, along with observed positive relationships between estrogens and immunity, may contribute to the higher observed morbidity and mortality of males. In the present study, we examine the association between sex steroid hormones and mu…
Methodological differences cannot explain associations between health, anthropometrics, and excess resting metabolic rate
"We appreciate Ocobock's interest in methodological rigor. We largely agree with her commentary, which suggests that departures from standard protocols might have contributed to the high resting metabolic rate (RMR) measured for Tsimane. Indeed, our paper acknowledges many of the key departures from gold-standard indirect calorimetry methods of RMR assessment and attempts to adjust for several of these (Gurven et al., 2016). Bringing standard cli…
A matter of perception
OBJECTIVES: Numerous studies link low objective and subjective socioeconomic status (SES) to chronic activation of the hypothalamic pituitary adrenal (HPA) axis. Here, we examine associations between objective and subjective SES and diurnal salivary cortisol, a primary HPA component, as well as demographic and ecological predictors associated with SES perceptions and changes in diurnal cortisol. METHODS: Participants were residents (age 18-79, n …
Adrenal maturation, nutritional status, and mucosal immunity in Bolivian youth
OBJECTIVES: Humans-and several other apes-exhibit a unique pattern of post-natal adrenal maturation; however, the causes and consequences of variation in adrenal development are not well understood. In this study, we examine developmental and age-related maturation of the adrenal gland (measured via dehydroepiandrosterone-sulfate [DHEA-S]) for potential life-history associations with growth and mucosal immunity in a rural population of immune-cha…
The Tsimane Health and Life History Project
The Tsimane Health and Life History Project, an integrated bio‐behavioral study of the human life course, is designed to test competing hypotheses of human life‐history evolution. One aim is to understand the bidirectional connections between life history and social behavior in a high‐fertility, kin‐based context lacking amenities of modern urban life (e.g. sanitation, banks, electricity). Another aim is to understand how a high pathogen burden i…
Physical growth of the shuar
OBJECTIVES: Information concerning physical growth among small-scale populations remains limited, yet such data are critical to local health efforts and to foster basic understandings of human life history and variation in childhood development. Using a large dataset and robust modeling methods, this study aims to describe growth from birth to adulthood among the indigenous Shuar of Amazonian Ecuador. METHODS: Mixed-longitudinal measures of heigh…
Immune function in Amazonian horticulturalists
Tsimane ecology leads to lymphocyte repertoires and immunoglobulin profiles that differ from those observed in industrialised populations. These differences have consequences for disease susceptibility and co-vary with patterns of other life history traits, such as growth and reproduction
Associations between male testosterone and immune function in a pathogenically stressed forager‐horticultural population
OBJECTIVES: Despite well-known fitness advantages to males who produce and maintain high endogenous testosterone levels, such phenotypes may be costly if testosterone-mediated investment in reproductive effort trade-off against investment in somatic maintenance. Previous studies of androgen-mediated trade-offs in human immune function find mixed results, in part because most studies either focus on a few indicators of immunity, are confounded by …
High resting metabolic rate among Amazonian forager‐horticulturalists experiencing high pathogen burden
OBJECTIVES: Resting metabolic rate (RMR) reflects energetic costs of homeostasis and accounts for 60 to 75% of total energy expenditure (TEE). Lean mass and physical activity account for much RMR variability, but the impact of prolonged immune activation from infection on human RMR is unclear in naturalistic settings. We evaluate the effects of infection on mass-corrected RMR among Bolivian forager-horticulturalists, and assess whether RMR declin…
Growth references for Tsimane forager‐horticulturalists of the Bolivian Amazon
International references for BMI-for-age and WFH are likely appropriate for Tsimane, but differences in height-for-age and weight-for-age suggest Tsimane specific references may be useful for these measures
Heterogeneous effects of market integration on sub-adult body size and nutritional status among the Shuar of Amazonian Ecuador
This study provides novel insight into the complex socio-ecological pathways linking MI, physical growth and health among the Shuar and other indigenous Amazonian populations
Patterns of senescence in human cardiovascular fitness
OBJECTIVES: This study explores whether cardiovascular fitness levels and senescent decline are similar in the Tsimane of Bolivia and Canadians, as well as other subsistence and industrialized populations. Among Tsimane, we examine whether morbidity predicts lower levels and faster decline of cardiovascular fitness, or whether their lifestyle (e.g., high physical activity) promotes high levels and slow decline. Alternatively, high activity levels…
Implications of market integration for cardiovascular and metabolic health among an indigenous Amazonian Ecuadorian population
This study provides evidence that MI among Shuar is not a uniformly negative process but instead produces complex cardiovascular and metabolic health outcomes
Heterogeneous effects of market integration on sub-adult body size and nutritional status among the Shuar of Amazonian Ecuador
This study provides novel insight into the complex socio-ecological pathways linking MI, physical growth and health among the Shuar and other indigenous Amazonian populations
Growth references for Tsimane forager‐horticulturalists of the Bolivian Amazon
International references for BMI-for-age and WFH are likely appropriate for Tsimane, but differences in height-for-age and weight-for-age suggest Tsimane specific references may be useful for these measures
High resting metabolic rate among Amazonian forager‐horticulturalists experiencing high pathogen burden
OBJECTIVES: Resting metabolic rate (RMR) reflects energetic costs of homeostasis and accounts for 60 to 75% of total energy expenditure (TEE). Lean mass and physical activity account for much RMR variability, but the impact of prolonged immune activation from infection on human RMR is unclear in naturalistic settings. We evaluate the effects of infection on mass-corrected RMR among Bolivian forager-horticulturalists, and assess whether RMR declin…
Associations between male testosterone and immune function in a pathogenically stressed forager‐horticultural population
OBJECTIVES: Despite well-known fitness advantages to males who produce and maintain high endogenous testosterone levels, such phenotypes may be costly if testosterone-mediated investment in reproductive effort trade-off against investment in somatic maintenance. Previous studies of androgen-mediated trade-offs in human immune function find mixed results, in part because most studies either focus on a few indicators of immunity, are confounded by …
The Ecoimmunology of Health and Disease
The original hygiene hypothesis proposed that certain diseases derive from low levels of early-life microbial exposure. Since then, the hypothesis has been applied to numerous inflammatory, autoimmune, and allergic conditions. The changes in hygiene linked to these diseases include numerous changes in biotic exposure and lifestyle. To this end, some scholars have called for abandonment of the term or have suggested alternate labels, e.g., the old…
A field method for cryopreservation of whole blood from a finger prick for later analysis with flow cytometry
OBJECTIVES: Flow cytometry is a powerful tool for investigating immune function, allowing for the quantification of leukocytes by subtype. Yet it has not been used extensively for field work due to perishable reagents and the need for immediate analysis of samples. To make flow cytometry more accessible, we devise and evaluate a field protocol for freezing capillary blood. MATERIALS AND METHODS: We collected finger prick blood samples from 110 vo…
The Natural History of Child Signals of Need in Utila, Honduras
Does exposure to parasites modify relationships between diurnal cortisol and leukocytes among Honduran women
BACKGROUND: Altered hypothalamic-pituitary-adrenal (HPA) function and related changes in circulating glucocorticoids have been implicated in the pathogenesis of numerous diseases that involve dysregulated immune function. Glucocorticoid hormones have both direct and indirect modulatory effects on both pro- and anti-inflammatory aspects of the immune system, including granulocytic and lymphocytic leukocyte subsets. However, past findings are compl…
Growth and market integration in Amazonia
We describe and compare the growth of three groups of juveniles, aged 0–18, who experience different degrees of market integration and acculturation in the Ecuadorian Amazon. These include 1,384 indigenous Shuar from the Upano Valley of Ecuador and surrounding areas, 570 nonindigenous colono (or colonist) children from the same area, and 42 Shiwiar from the interior of Ecuador. We use differences between these populations in National Health and N…
Life history, immune function, and intestinal helminths
Objectives. Infection with helminths is associated with shifts in host immunity, including increased production of immunoglobulin E (IgE) and reduced inflammation. Given limited energy budgets, these shifts may involve changes in energy allocation toward competing demands. Here we test for potential trade‐offs between growth, IgE, and the inflammatory marker C‐reactive protein (CRP). Methods. Dried blood spots and anthropometrics were collected f…
Physical activity in an indigenous Ecuadorian forager‐horticulturalist population as measured using accelerometry
OBJECTIVE: Minimal information on physical activity is available for non-Western populations undergoing the transition to a market economy. This is unfortunate given the importance of these data for understanding health issues such as the global obesity epidemic. We consider the utility of using accelerometry technology to examine activity patterns and energy use regulation among indigenous Shuar, an Ecuadorian forager-horticulturalist population…
Patterns of senescence in human cardiovascular fitness
OBJECTIVES: This study explores whether cardiovascular fitness levels and senescent decline are similar in the Tsimane of Bolivia and Canadians, as well as other subsistence and industrialized populations. Among Tsimane, we examine whether morbidity predicts lower levels and faster decline of cardiovascular fitness, or whether their lifestyle (e.g., high physical activity) promotes high levels and slow decline. Alternatively, high activity levels…
Implications of market integration for cardiovascular and metabolic health among an indigenous Amazonian Ecuadorian population
This study provides evidence that MI among Shuar is not a uniformly negative process but instead produces complex cardiovascular and metabolic health outcomes
Physical growth of the shuar
OBJECTIVES: Information concerning physical growth among small-scale populations remains limited, yet such data are critical to local health efforts and to foster basic understandings of human life history and variation in childhood development. Using a large dataset and robust modeling methods, this study aims to describe growth from birth to adulthood among the indigenous Shuar of Amazonian Ecuador. METHODS: Mixed-longitudinal measures of heigh…
Immune function in Amazonian horticulturalists
Tsimane ecology leads to lymphocyte repertoires and immunoglobulin profiles that differ from those observed in industrialised populations. These differences have consequences for disease susceptibility and co-vary with patterns of other life history traits, such as growth and reproduction
Associations between male testosterone and immune function in a pathogenically stressed forager‐horticultural population
OBJECTIVES: Despite well-known fitness advantages to males who produce and maintain high endogenous testosterone levels, such phenotypes may be costly if testosterone-mediated investment in reproductive effort trade-off against investment in somatic maintenance. Previous studies of androgen-mediated trade-offs in human immune function find mixed results, in part because most studies either focus on a few indicators of immunity, are confounded by …
High resting metabolic rate among Amazonian forager‐horticulturalists experiencing high pathogen burden
OBJECTIVES: Resting metabolic rate (RMR) reflects energetic costs of homeostasis and accounts for 60 to 75% of total energy expenditure (TEE). Lean mass and physical activity account for much RMR variability, but the impact of prolonged immune activation from infection on human RMR is unclear in naturalistic settings. We evaluate the effects of infection on mass-corrected RMR among Bolivian forager-horticulturalists, and assess whether RMR declin…
Growth references for Tsimane forager‐horticulturalists of the Bolivian Amazon
International references for BMI-for-age and WFH are likely appropriate for Tsimane, but differences in height-for-age and weight-for-age suggest Tsimane specific references may be useful for these measures
Heterogeneous effects of market integration on sub-adult body size and nutritional status among the Shuar of Amazonian Ecuador
This study provides novel insight into the complex socio-ecological pathways linking MI, physical growth and health among the Shuar and other indigenous Amazonian populations
A matter of perception
OBJECTIVES: Numerous studies link low objective and subjective socioeconomic status (SES) to chronic activation of the hypothalamic pituitary adrenal (HPA) axis. Here, we examine associations between objective and subjective SES and diurnal salivary cortisol, a primary HPA component, as well as demographic and ecological predictors associated with SES perceptions and changes in diurnal cortisol. METHODS: Participants were residents (age 18-79, n …
Adrenal maturation, nutritional status, and mucosal immunity in Bolivian youth
OBJECTIVES: Humans-and several other apes-exhibit a unique pattern of post-natal adrenal maturation; however, the causes and consequences of variation in adrenal development are not well understood. In this study, we examine developmental and age-related maturation of the adrenal gland (measured via dehydroepiandrosterone-sulfate [DHEA-S]) for potential life-history associations with growth and mucosal immunity in a rural population of immune-cha…
The Tsimane Health and Life History Project
The Tsimane Health and Life History Project, an integrated bio‐behavioral study of the human life course, is designed to test competing hypotheses of human life‐history evolution. One aim is to understand the bidirectional connections between life history and social behavior in a high‐fertility, kin‐based context lacking amenities of modern urban life (e.g. sanitation, banks, electricity). Another aim is to understand how a high pathogen burden i…
Testosterone is positively and estradiol negatively associated with mucosal immunity in Amazonian adolescents
Objectives A core assumption of life history theory and the immunocompetence handicap hypothesis (ICHH) is that testosterone (T) upregulates energetic investment in mating effort at the expense of immunity. This tenet, along with observed positive relationships between estrogens and immunity, may contribute to the higher observed morbidity and mortality of males. In the present study, we examine the association between sex steroid hormones and mu…
Methodological differences cannot explain associations between health, anthropometrics, and excess resting metabolic rate
"We appreciate Ocobock's interest in methodological rigor. We largely agree with her commentary, which suggests that departures from standard protocols might have contributed to the high resting metabolic rate (RMR) measured for Tsimane. Indeed, our paper acknowledges many of the key departures from gold-standard indirect calorimetry methods of RMR assessment and attempts to adjust for several of these (Gurven et al., 2016). Bringing standard cli…
Old friends and friendly fire
OBJECTIVES: Despite public health concerns about hookworm infection in pregnancy, little is known about immune profiles associated with hookworm (Necator americanus and Ancylostoma duodenale) infection during pregnancy. Fetal tolerance requirements may constrain maternal immune response to hookworm, thereby increasing susceptibility to new infections or increasing hemoglobin loss. To explore this possibility, we study systemic immune response and…
Does exposure to parasites modify relationships between diurnal cortisol and leukocytes among Honduran women
BACKGROUND: Altered hypothalamic-pituitary-adrenal (HPA) function and related changes in circulating glucocorticoids have been implicated in the pathogenesis of numerous diseases that involve dysregulated immune function. Glucocorticoid hormones have both direct and indirect modulatory effects on both pro- and anti-inflammatory aspects of the immune system, including granulocytic and lymphocytic leukocyte subsets. However, past findings are compl…
Do computed tomography findings agree with traditional osteological examination? The case of porous cranial lesions
A field method for cryopreservation of whole blood from a finger prick for later analysis with flow cytometry
OBJECTIVES: Flow cytometry is a powerful tool for investigating immune function, allowing for the quantification of leukocytes by subtype. Yet it has not been used extensively for field work due to perishable reagents and the need for immediate analysis of samples. To make flow cytometry more accessible, we devise and evaluate a field protocol for freezing capillary blood. MATERIALS AND METHODS: We collected finger prick blood samples from 110 vo…
Low prevalence of anemia among Shuar communities of Amazonian Ecuador
OBJECTIVE: Anemia is an important global health challenge. We investigate anemia prevalence among Indigenous Shuar of Ecuador to expand our understanding of population-level variation, and to test hypotheses about how anemia variation is related to age, sex, and market integration. METHODS: Hemoglobin levels were measured in a total sample of 1650 Shuar participants (ages 6 months to 86 years) from 46 communities between 2008 and 2017 to compare …
Age‐related patterns of cytomegalovirus antibodies accompanying Epstein‐Barr virus co‐infection
OBJECTIVE: Cytomegalovirus (CMV) infection is associated with age-related chronic disease, and co-infection with Epstein-Barr virus (EBV) may compound disease risk. We aimed to assess the frequency of CMV infection and its relationship with age among EBV seropositive individuals in an Indigenous Amazonian population. METHODS: We report concentrations of CMV and EBV antibodies in dried blood spot samples collected from 157 EBV positive Shuar parti…
Ecoimmunology in the field
The Ecoimmunology of Health and Disease
The original hygiene hypothesis proposed that certain diseases derive from low levels of early-life microbial exposure. Since then, the hypothesis has been applied to numerous inflammatory, autoimmune, and allergic conditions. The changes in hygiene linked to these diseases include numerous changes in biotic exposure and lifestyle. To this end, some scholars have called for abandonment of the term or have suggested alternate labels, e.g., the old…
Human milk immune factors, maternal nutritional status, and infant sex
OBJECTIVES: Breastfeeding is an energetically costly and intense form of human parental investment, providing sole-source nutrition in early infancy and bioactive components, including immune factors. Given the energetic cost of lactation, milk factors may be subject to tradeoffs, and variation in concentrations have been explored utilizing the Trivers-Willard hypothesis. As human milk immune factors are critical to developing immune system and p…
Biology (23 works) · Medicine (22 works) · Ecology (13 works) · Population (13 works) · Immunology (12 works) · Demography (11 works) · Immune system (10 works) · Internal Medicine (10 works) · Indigenous Health and Education (9 works) · Geography (8 works)