Quinn, Dr. Elizabeth Anne, Washington U., St. Louis, MO - To aid research on 'Milk with Altitude: Investigations Into Milk Composition and Physiology Among Tibetans'
DR. ELIZABETH A. QUINN, Washington University, St. Louis, Missouri, received funding in April 2013 to aid research on 'Milk with Altitude: Investigations into Milk Composition and Physiology among Tibetans.' This project was designed to specifically investigate the hypotheses that altitude would have an effect on milk composition among high altitude adapted ethnic Tibetans living in Nepal. Milk samples were collected from 130 mothers, with detailed anthropometrics collected on both mothers and infants. As predicted, there was no association between altitude and milk macronutrients or energy, although milk fat was much higher than reported by previous studies. Milk adiponectin did show a dose dependent association with altitude but not maternal body composition, while maternal body fat predicted milk leptin content. Older infants and toddlers in Nubri had significantly lower weight for age z-scores compared to toddlers in Kathmandu (-1.85 vs. -0.36). There were no associations between milk leptin or adiponectin and infant weight for age z-score in Nubri, but both leptin and adiponectin were inversely associated with weight for age z-score in Kathmandu. It appears that the ecological pressures of altitude (hypoxia, marginal nutrition, thermal stress, radiation stress) may have significantly stronger influences on infant weight among high altitude living populations than hormonal signals in milk. In Kathmandu, with many of these external stressors removed, the associations between these hormones and weight for age are present.
Barta, Dr. Jodi Lynn, U. of Toronto, Mississauga, Canada - To aid research on 'The Relationship Between Skin Pigmentation and Vitamin D Insufficiency in Northern Latitudes'
DR. JODI LYNN BARTA, University of Toronto, Mississauga, Canada, received funding in October 2007 to aid research on 'The Relationship between Skin Pigmentation and Vitamin D Insufficiency in Northern Latitudes.' This project examined the effects that changes in season have on vitamin D concentrations in individuals with varying levels of melanin in their skin in order to clarify the relationship between constitutive pigmentation and vitamin D status in otherwise healthy young adults of diverse ancestry living in northern latitudes. Preliminary data collected show that those with higher levels of melanin in their skin are at consistently higher risk of vitamin D insufficiency and deficiency, thus supporting the UVR hypothesis and highlighting the evolutionary significance of skin pigmentation as it relates to geographic origins and the importance of maintaining adequate vitamin D levels. Given the profound effects that vitamin D insufficiency and deficiency have on the human body, it was surprising that mean vitamin D concentrations in all ancestry groups were below adequate (75 nmol/L) regardless of season, despite the fact that mean vitamin D intakes in both late summer (296.72 IU) and winter (281.54 IU) were above current recommended adequate intake for adults (200 IU/day). Further research is necessary to precisely determine the vitamin D requirements of individuals of diverse ancestry living in northern latitudes and address the need for higher vitamin D intakes through supplementation and/or improved food fortification strategies to meet requirements and improve overall public health.
Hodges-Simeon, Carolyn Randolph, U. of California, Santa Barbara, CA - To aid research on 'Life History Trade-offs Affecting the Development of Human Sexual Dimorphism,' supervised by Dr. Steven J. Gaulin
CAROLYN R. HODGES-SIMEON, then a student at University of California, Santa Barbara, California, was awarded a grant in October 2010 to aid research on 'Life History Trade-Offs Affecting the Development of Human Sexual Dimorphism,' supervised by Dr. Steven J. Gaulin. The human vocal voice is sexually dimorphic in two primary ways: males have lower 'fundamental frequency' (F0, the perceptual correlate of which is 'pitch') and more closely spaced 'formant position' (Pf; also termed 'resonance'). These characteristics exhibit a pronounced and abrupt change during adolescence, marking the advancement of puberty. Research and data gathering target the developmental associations between dimorphic vocal characteristics (F0 and Pf), testosterone, immune functioning (secretory IgA and CRP), and energetic status (BMI and height) in adolescent boys in a non-industrialized population: the Tsimane' of lowland Bolivia. In doing so, this project uses the ontogeny of male vocal characteristics as a model system for examining two major theories in human evolutionary biology: 1) Life history theory (by examining trade-offs between reproductive and somatic investment); and 2) Immunocompetence handicap theory of sexual selection (by investigating whether sexually dimorphic signals are honest indicators of immunocompetence). Results indicate that males in better condition -- with better energetic and immune investment -- have higher testosterone levels, which are associated with lower voices. This research presents the first evidence that male vocal features are linked with condition, and that this association is mediated by testosterone.
Martin, Melanie Ann, U. of California, Santa Barbara, CA - To aid research on 'Maternal Factors Influencing Variation in Infant Feeding Practices in a Natural Fertility Population,' supervised by Dr. Michael Gurven
MELANIE A. MARTIN, then a student at University of California, Santa Barbara, California, was awarded funding in April 2012 to aid research on 'Maternal Factors Influencing Variation in Infant Feeding Practices in a Natural Fertility Population,' supervised by Dr. Michael Gurven. Exclusive breastfeeding for six months and continued breastfeeding for two years or longer promote optimal infant health and growth. Globally, however, many mothers introduce complementary foods and wean earlier than recommended. This study examined factors associated with variation in infant feeding practices in an indigenous population, the Tsimane of Bolivia. During 2012-2013, interviews and anthropometric measurements were collected from 147 Tsimane mothers and infants aged 0-36 months, with 47 mother-infant pairs visited repeatedly over eight months. Half of Tsimane infants were introduced to complementary foods by four months of age, although 75 percent were still breastfed at two years. On average, male infants were exclusively breastfed longer and weaned later than females. No other maternal, infant, or household factors measured influenced the duration of exclusive breastfeeding duration. Age at weaning, however, was increased by the number of family members over the age of 10, and decreased by a mother's subsequent pregnancy and total number of living offspring. Poor growth was evident in only two percent of infants aged 0-6 months, but increased markedly after twelve months. Earlier weaning and/or the quantity or quality of complementary foods may more significantly impact Tsimane infant growth and health outcomes than does early complementary feeding.
Robins, Tara C., U. of Oregon, Eugene, OR - To aid research on 'Social Change, Parasite Exposure, and Autoimmunity among Shuar Forager- Horticulturalists of Amazonia: An Evolutionary Medicine Approach,' supervised by Dr. J. Josh Snodgrass
TARA C. ROBINS, then a graduate student at University of Oregon, Eugene, Oregon, was awarded funding in April 2012 to aid research on 'Social Change, Parasite Exposure, and Autoimmunity among Shuar Forager-Horticulturalists of Amazonia: An Evolutionary Medicine Approach,' supervised by Dr. J. Josh Snodgrass. The Hygiene Hypothesis and the Disappearing Microbiota Hypothesis posit that decreases in parasite and bacterial exposure in developed nations are responsible for immune dysregulation associated with the development of allergies and autoimmune disorders. These hypotheses explore the co-evolutionary relationship between humans and pathogens that led to the development of the human immune system. While these hypotheses have been tested in clinical and laboratory settings in developed nations, very few studies have tried to capture these relationships among populations undergoing the transition from traditional to more market-based lifestyles. This study tests these hypotheses among the Shuar forager-horticulturalists of Amazonian Ecuador who are undergoing rapid (though varied) social and economic changes associated with increased market participation. Using stool samples to assess parasite and microbial diversity, blood spot markers of immune dysregulation, and interviews to evaluate level of market integration, this study documents a decrease in parasite exposure with market participation/increased hygiene and a related increase in inflammatory marker C-reactive protein. Findings suggest that parasites, specifically intestinal parasitic worms may provide immune stimulation necessary to decrease inflammation, suggesting that the altered intestinal microflora in developed nations may be, in part, responsible for the development of allergy and autoimmunity.
Bekelman, Traci Allison, U. of Colorado, Boulder, CO - To aid research on 'Using the Protein Leverage Hypothesis to Understand Socioeconomic Variation in Diet and Body Size,' supervised by Dr. Darna Dufour
TRACI A. BEKELMAN, while a graduate student at the University of Colorado, Boulder, Colorado, was awarded a grant in October 2013 to aid research on 'Using the Protein Leverage Hypothesis to Understand Socioeconomic Variation in Diet and Body Size,' supervised by Dr. Darna Dufour. Guided by the Protein Leverage Hypothesis the grantee examined an explanation for the inverse relationship between socioeconomic status (SES) and obesity: limited access to dietary protein among low-SES women leads to consumption of a lower proportion of protein in the diet, which in turn drives higher energy intake and hence obesity. The project examined the prevalence of obesity, diet, the perceived cost and desirability of different sources of protein and shopping habits in 140 women of low-, middle- and high-SES. As expected, high-SES women had the lowest obesity levels. Protein intake (as a proportion of energy intake) was positively associated with SES, and inversely associated with energy intake. Also as expected, protein intake (in grams) did not vary by SES. These finding are consistent with the Protein Leverage Hypothesis. Contrary to expectations, there was not an inverse relationship between SES and energy intake nor was there a difference in the frequency of desirable protein consumption across SES groups. These findings are inconsistent with the Protein Leverage Hypothesis. In conclusion, obesity is inversely associated with SES in Costa Rican women and protein intake may play a role in this relationship.
Fried, Ruby L., Northwestern U., Evanston, IL - To aid research on 'Intergenerational Impacts of Culture Change: Traditional Food and the Metabolic Functioning of Alaska Native Peoples,' supervised by Dr. Christopher Kawaza
Preliminary abstract: Anthropological studies conducted from Samoa to Siberia have demonstrated consequences of cultural change on human biological variation. Findings point to market integration, 'Westernization,' 'acculturation,' and other social transitions as determinants of changes in diet and lifestyle that lead to increased obesity and metabolic dysregulation in affected populations. While the majority of this research has focused on the direct impacts of such shifts on adult biology, recent work is focusing attention on early life critical periods when experiences can lead to durable biological changes that alter developmental biology and long-term health. As a recent manifestation of this idea, rising rates of maternal obesity, gestational weight gain (GWG), and high blood glucose and triglycerides may be creating an evolutionarily novel, gestational milieu that promotes faster fetal growth, higher birth weights, adiposity, and metabolic dysregulation in offspring. This emerging evidence supports a new hypothesis: the impacts of culture change on human biology do not end with the individual who directly experiences it, but may also be transmitted, via an altered in utero environment, to the next generation. The proposed study aims to test this model of an intergenerational impact of culture change among Alaska Native mother-infant dyads by comparing dietary intake (traditional vs. Western foods) with maternal obesity, GWG, pregnancy metabolism and fetal/infancy growth and adiposity in offspring. Recent and still ongoing cultural and dietary transitions among Alaska Native groups provide a valuable opportunity to evaluate maternal metabolism as a pathway linking rapid culture change with altered growth, body composition and health outcomes in offspring.
Hoke, Morgan Kathleen, Northwestern U., Evanston, IL - To aid research on 'Changing Economic Activity, Infant Feeding, and Early Growth among the Quechua of Nuñoa, Peru,' supervised by Dr. William Leonard
MORGAN K. HOKE, then a graduate student at Northwestern University, Evanston, Illinois, was awarded funding in April 2014 to aid research on 'Changing Economic Activity, Infant Feeding, and Early Growth among the Quechua of Nuñoa, Peru,' supervised by Dr. William Leonard. This project examines the major influences on infant feeding practices, nutrition, and early growth and health in the south-central highlands of Nuñoa, Peru. In particular, this research explores the way that ongoing economic changes in the area-including the development of a new dairying industry-affect how and what caretakers choose to feed infants. Two local women were trained and hired as research assistants to aid in administration of surveys and translation. Recruitment took place in July 2014, and 150 participants were recruited to the study, of which 143 completed the initial survey, 127 completed the survey with measurements, and 104 participants completed both rounds of the survey and health assessments. The first round of surveys and health assessments took place between July and September 2014. Interviews were conducted between September 2014 and January 2015 with mothers as well as health center staff and officials administering programs intended to improve early nutrition and health. Interviews revealed a number of significant insights that helped make sense of findings from the first survey and which allowed for modifications to the second round survey. The follow-up survey and health assessment occurred in February and March 2015. Data entry and interview transcription took place in May and June 2015.
Masterson, Erin Elizabeth, U. of Washington, Seattle, WA - To aid research on 'Putting Teeth into the Developmental Origins Hypothesis: Early Childhood Ecology, Enamel Defects and Adolescent Growth,' supervised by Dr. Daniel Eisenberg
Preliminary abstract: Like a window into the past, adult teeth may reflect early childhood ecology. Dental enamel on the permanent maxillary incisors calcifies incrementally during early childhood (0-5 years of age), is highly-sensitive to biological stress, and doesn't repair over the life course. Developmental defects in the enamel (DDE) are caused by metabolic disruption during development, including micronutrient deficiency, gastrointestinal disturbance, and bacterial and viral infections. According to developmental origins of health and disease (DOHaD) research findings and evolutionary theory, these factors may also influence chronic disease risk later in life. Bioarcheological findings have indicated an association exists between DDEs in the permanent dentition and increased morbidity and early mortality among skeletal remains, suggesting that dental enamel may be a retrospective marker of early childhood ecology. However, the association between DDEs and long-term health consequences has never been tested in a contemporary population. The purpose of the proposed project is to assess whether DDEs -- developed during the first five years of life -- is a marker of early childhood ecology and predictor of adolescent growth in a contemporary population. Based on evolutionary theory, we hypothesize that enamel defects mark a physiologically-stressful early childhood that predicts unhealthy growth in adolescence. We expect our study to provide the scientific community more confidence in interpretations of DDEs, and to introduce a new measure of early childhood ecology that may enable widespread study of the DOHaD and improve the sensitivity of these studies.