Landscape disturbance impacts on Attalea butyracea palm distribution in central Panama.

BACKGROUND: Increased Attalea butyracea palm propagation, notable for its role as key habitat for the primary Chagas disease vector in Panama, has been linked to landscape disturbance in single-palm observations in this region. Close proximity of these palms to human dwellings is proposed to increase risk of Chagas disease transmission from sylvatic transmission cycles to domestic transmission involving human populations. This study examines the relationship between landscape disturbance and mature A. butyracea spatial distribution, density, and proximity to human populations and vector and reservoir species' movement corridors at a regional scale in a 300 km2 heterogeneous tropical landscape in central Panama. METHODS: We remotely identified the locations of over 50,000 mature A. butyracea palms using high-resolution WorldView2 satellite imagery. A local Getis-Ord Gi* spatial analysis identified significant clusters of aggregated palms. Associations between palm and cluster abundance and a landscape disturbance gradient, derived from official Panama land cover data, were tested using Chi-square tests for Homogeneity and Z-test for proportions. Kruskall-Wallis non-parametric analysis of variance tests were run to assess whether palm cluster area varied by disturbance level, or whether disturbance was associated with proximity of palms and palm clusters to susceptible populations or vector movement corridors. RESULTS: Our findings indicate a regional relationship between landscape disturbance and A. butyracea occurrence. We observe a significant increase in both individual and clustered A. butyracea in secondary forest, but a reduction of palms in agricultural settings. We do not detect evidence of any reduction in abundance of palms in residential settings. The majority of residential and commercial buildings in our study area are within vector flight distance of potential vector habitat in palm crowns. CONCLUSIONS: We observe probable anthropogenic elimination of A. butyracea palms in agricultural, but not residential, settings. Even in heavily deforested regions, significant concentrations of mature palms remain in close proximity to human establishments.

Age-related decline in urine concentration may not be universal: Comparative study from the U.S. and two small-scale societies.

OBJECTIVES: Evidence from industrialized populations suggests that urine concentrating ability declines with age. However, lifestyle factors including episodic protein intake and low hypertension may help explain differences between populations. Whether this age-related decline occurs among small-scale populations with active lifestyles and non-Western diets is unknown. We test the universality of age-related urine concentration decline. MATERIALS AND METHODS: We used urine specific gravity (Usg) and urine osmolality (Uosm) data from 15,055 U.S. nonpregnant adults without kidney failure aged 18-80 in 2007-2012 participating in the National Health and Nutrition Examination Survey (NHANES). We tested the relationship of age on urine concentration biomarkers with multiple linear regressions using survey commands. We compared results to longitudinal data on Usg from 116 Tsimane' forager-horticulturalists (266 observations) adults aged 18-83 in 2013-2014 from Lowland Bolivia, and to 38 Hadza hunter-gatherers (156 observations) aged 18-75 in 2010-2015 from Tanzania using random-effects panel linear regressions. RESULTS: Among U.S. adults, age was significantly negatively associated with Usg (Adjusted beta [B] = -0.0009 g/mL/10 years; SE = 0.0001; p < 0.001) and Uosm (B = -28.1 mOsm/kg/10 yr; SE = 2.4; p < 0.001). In contrast, among Tsimane' (B = 0.0003 g/mL/10 yr; SE = 0.0002; p = 0.16) and Hadza (B = -0.0004 g/mL/10 yr; SE = 0.0004; p = 0.29) age was not associated with Usg. Older Tsimane' and Hadza exhibited similar within-individual variability in Usg equivalent to younger adults. DISCUSSION: While U.S. adults exhibited age-related declines in urine concentration, Tsimane' and Hadza adults did not exhibit the same statistical decline in Usg. Mismatches between evolved physiology and modern environments in lifestyle may affect kidney physiology and disease risk.

Birth seasons and heights among girls and boys below 12 years of age: lasting effects and catch-up growth among native Amazonians in Bolivia.

BACKGROUND: Seasons affect many social, economic, and biological outcomes, particularly in low-resource settings, and some studies suggest that birth season affects child growth. AIM: To study a predictor of stunting that has received limited attention: birth season. SUBJECTS AND METHODS: This study uses cross-sectional data collected during 2008 in a low-resource society of horticulturists-foragers in the Bolivian Amazon, Tsimane'. It estimates the associations between birth months and height-for-age Z-scores (HAZ) for 562 girls and 546 boys separately, from birth until age 11 years or pre-puberty, which in this society occurs ∼13-14 years. RESULTS: Children born during the rainy season (February-May) were shorter, while children born during the end of the dry season and the start of the rainy season (August-November) were taller, both compared with their age-sex peers born during the rest of the year. The correlations of birth season with HAZ were stronger for boys than for girls. Controlling for birth season, there is some evidence of eventual partial catch-up growth, with the HAZ of girls or boys worsening until ∼ age 4-5 years, but improving thereafter. By age 6 years, many girls and boys had ceased to be stunted, irrespective of birth season. CONCLUSION: The results suggest that redressing stunting will require attention to conditions in utero, infancy and late childhood.

Percutaneous implant retention of a nasal prosthesis.

This report describes an approach to the simultaneous retention of a nasal prosthesis and an intraoral prosthesis for a patient who had undergone a total rhinectomy with resection of the upper lip and premaxilla. At the time of the nasal resection, 2 dental implants were placed adjacent to the resection margins in the first premolar positions. These were used to anchor an intraoral, milled titanium bar and overdenture to replace the missing anterior teeth and provide support for the upper lip, which had been reconstructed with a vascularized radial forearm free-flap. The titanium bar also incorporated a connection for a tissue-penetrating percutaneous nasal extension, which pierced the radial forearm flap near the junction with the hard palate. Magnetic attachments screwed to the nasal extension retained a nasal prosthesis. The predictable and straightforward implementation of this novel concept with digital design and manufacture of the titanium components and guided placement of the nasal extension was made possible with software planning.

Catch-up growth and growth deficits: Nine-year annual panel child growth for native Amazonians in Bolivia.

BACKGROUND: Childhood growth stunting is negatively associated with cognitive and health outcomes, and is claimed to be irreversible after age 2. AIM: To estimate growth rates for children aged 2-7 who were stunted (sex-age standardised z-score [HAZ] <-2), marginally-stunted (-2 ≤ HAZ ≤-1) or not-stunted (HAZ >-1) at baseline and tracked annually until age 11; frequency of movement among height categories; and variation in height predicted by early childhood height. SUBJECTS AND METHODS: This study used a 9-year annual panel (2002-2010) from a native Amazonian society of horticulturalists-foragers (Tsimane'; n = 174 girls; 179 boys at baseline). Descriptive statistics and random-effect regressions were used. RESULTS: This study found some evidence of catch-up growth in HAZ, but persistent height deficits. Children stunted at baseline improved 1 HAZ unit by age 11 and had higher annual growth rates than non-stunted children. Marginally-stunted boys had a 0.1 HAZ units higher annual growth rate than non-stunted boys. Despite some catch up, ∼ 80% of marginally-stunted children at baseline remained marginally-stunted by age 11. The height deficit increased from age 2 to 11. Modest year-to-year movement was found between height categories. CONCLUSIONS: The prevalence of growth faltering among the Tsimane' has declined, but hurdles still substantially lock children into height categories.

Water from fruit or the river? Examining hydration strategies and gastrointestinal illness among Tsimane' adults in the Bolivian Amazon.

OBJECTIVE: Water is an essential nutrient overlooked in many cross-cultural studies of human nutrition. The present article describes dietary water intake patterns among forager-horticulturalist adults in lowland Bolivia, compares daily intake with international references and examines if variation in how people acquire water relates to gastrointestinal illness. DESIGN: Cross-sectional observational study used survey, anthropometric and qualitative methods with Tsimane' adults selected by age and sex stratification sampling in one community. SETTING: Research occurred in one Tsimane' village in the Beni department, Bolivia with limited access to clean water. The 24 h diet and health recalls were conducted in July-August 2012 and qualitative interviews/ethnographic observation in September-October 2013. SUBJECTS: Forty-five Tsimane' household heads (49% men) took part in the first data collection and twenty-two Tsimane' (55% men) were included in the follow-up interviews. RESULTS: Men and women reported consuming 4·9 litres and 4·4 litres of water daily from all dietary sources, respectively. On average, water from foods represented 50 % of total water intake. Thirteen per cent of participants reported symptoms of gastrointestinal illness. In a logistic regression model adjusted for age, BMI, sex and raw water consumed, each percentage increase in water obtained from foods was associated with a reduced risk of gastrointestinal illness (OR=0·92; 95% CI 0·85, 0·99). CONCLUSIONS: Both total water intake and percentage of water from foods were higher than averages in industrialized countries. These findings suggest that people without access to clean water may rely on water-rich foods as a dietary adaptation to reduce pathogen exposures.

Health and disease: exploring the relation between parasitic infections, child nutrition status, and markets.

Research in bioarchaeology and among living people provides insight into the biological and biocultural consequences of subsistence, political, and economic transitions. Central to this effort is examining infectious disease, such as diarrheal disease, respiratory infections, and parasitic infections because they are an important source of nutritional and energetic stress in both past and current groups. Although infection may not always result in overt disease, frequent exposure results in biological stress with a negative effect on child growth and, by extension, health. The goal of this article is to examine the association between a common class of infectious disease, soil-transmitted helminth worms, and nutritional status among youth living in communities that vary with respect to their distance from a commercial center. In 2007, anthropometric measurements and parasitological surveys were collected for 338 2-14-year-old children and adolescents living in lowland Bolivia as part of the Tsimane' Amazonian Panel Study. Associations between the presence of helminth infections and markers of both short- and long-term nutritional status were overall weak. Youth living in communities distant from the commercial center were more likely to be positive for multiple parasite species than youth in near communities, but youth in mid-distance communities had lower infection rates. This article demonstrates the challenge of identifying associations between nutritional and disease stress when individual and household factors are nested in a larger context of socioeconomic and environmental change. Increased collaboration between bioarchaeology and human biology should continue to examine the connections between stress and disease across time.

The consequences of linear growth stunting: influence on body composition among youth in the Bolivian Amazon.

Stunting, or linear growth retardation, has been documented in up to half of all children in rural indigenous populations of South America. Stunting is well understood as a signal of adverse conditions during growth, and has been associated with developmentally induced modifications to body composition, including body fat and muscularity, that stem from early growth restriction. This article examines the relation between short stature and three anthropometric indicators of body composition during childhood and adolescence among a rural, indigenous population of forager-horticulturalists. Anthropometric data were collected annually from 483 Tsimane' youth, ages 2-10 years, in 13 communities in the Beni region of Bolivia for 6 consecutive years (2002-2007). Baseline height-for-age was used to indicate stunting (HAZ < -2.0) and compared with z-scores of body mass index (BMI), sum of two skinfolds, and arm muscle area. Multilevel regression models indicate baseline stunting is associated with lower BMI z-scores (B = -0.386; P < 0.001), body fatness (ZSkinfold, B = -0.164; P < 0.001), and arm muscularity (AMAZ, B = -0.580; P < 0.001) in youth across a period of 6 years. When split by sex, there was a stronger relation between baseline stunting and lower skinfold body fat scores among girls (B = -0.244; P < 0.001) than boys (B = -0.080; P = 0.087). In contrast, baseline stunting was associated with lower arm muscularity in both girls (B = -0.498; P < 0.001) and boys (B = -0.646; P < 0.001). The relation between linear growth restriction and indicators of body composition persist into adolescence, providing additional insight into the influence of adverse conditions during growth.

Looking through the lens of social science approaches: A scoping review of leishmaniases and Chagas disease research.

Scholars have called for increased attention to sociocultural, economic, historical, and political processes shaping Neglected Tropical Diseases (NTDs) ecology. We conducted a scoping review to identify major research themes and the knowledge gaps in social science literature in leishmaniases or Chagas disease (CD). Following the scoping review protocol, we first determined the focus of the review to be centered on identifying research that approaches leishmaniases and CD from social science perspective and was indexed by large, biomedically focused databases. We then searched PubMed and Web of Science using "Leishmaniasis" and "Chagas disease" with "social science" or "anthropology" as search terms. We analyzed 199 articles (123 on leishmaniases and 76 on CD), categorizing them into three main research themes. Sociocultural dimensions of the diseases (leishmaniases=60.2 %; CD=68.4 %) primarily focused on individuals' knowledge, practices, and behaviors, barriers to accessing healthcare (especially in endemic regions), psychosocial effects, stigma, and traditional treatments. Research focused on socioeconomic dimensions of the diseases (leishmaniases=29.3 %; CD=19.7 %) included topics like household characteristics, social capital, and infrastructure access. A final theme, the historical and political contexts of the diseases (Leishmaniases=10.5 %; CD=11.9 %) was less common than other themes. Here, studies consider civil war and the (re)emergence of leishmaniasis, as well as the significance of CD discovery for scientific and public health in Brazil, which is the most common country for research on both leishmaniases and CD that draws on social science approaches. Future directions for research include focusing on how social institutions and economic factors shape diseases education, control measures, healthcare access, and quality of life of people affected by NTDs. Greater attention to social sciences can help mitigate and undo the ways that structural biases have infiltrated biomedicine.

Computer guided surgery for implant placement and dental rehabilitation in a patient undergoing sub-total mandibulectomy and microvascular free flap reconstruction.

A 58-year-old patient presented with an extensive, destructive, recurrent pleomorphic adenoma occupying the mandibular body and the soft tissues of the mouth and neck. Resection of the mandible from right ramus to left condylar process, and implant rehabilitation in both jaws with fixed bridgework was planned. Comprehensive presurgical prosthetic work up was carried out to record the existing dental relationship and guide all stages of the reconstruction. The jaw was first grafted with a segmented, fibular microvascular free-flap, which was fixed in place with a fixation plate prebent on a Rapid Prototype Anatomical Model of the jaw. Reconstruction with implant supported fixed partial dentures took place to the dental scheme planned preresection, using a computer guided approach to implant placement in the complex and unfamiliar anatomy of the extensively grafted mandible. This approach facilitated and expedited implant surgery such that treatment could take place using a minimally invasive approach relatively soon after surgery, prior to commencement of radiotherapy, and highlights the importance of a multidisciplinary approach to treatment for patients having extensive surgery to the jaws. The patient's personal assessment 2 years post surgery was recorded using 1999 University of Washington Quality of Life Questionnaire.

Diurnal cortisol rhythms and child growth: exploring the life history consequences of HPA activation among the Tsimane'.

OBJECTIVE: Although psychosocial stress has also been implicated as a contributor to growth failure by imposing energetic constraints during development, the direct physiological pathways by which these life history trade-offs are imposed are not well understood. This study explores associations between diurnal cortisol rhythms and differential patterns of linear child growth among the Tsimane, a horticulturalist and foraging society in the Bolivian Amazon. METHODS: Waking and bedtime salivary cortisol samples (n = 243) were collected from 53 Tsimane' children ages 1.6-6 over 3 days as part of a larger study of developmental trajectories in hypothalamic-pituitary-adrenal axis dynamics. Anthropometric measurements and survey data were collected in conjunction with the Tsimane' Amazonian panel study (TAPS). RESULTS: Among children under the age of 6, diurnal rhythms in stunted versus nonstunted children vary dramatically: stunted children display elevated cortisol at both the AM (P = 0.03) and PM (P = 0.02) collection points. Multilevel regression analysis demonstrates an inverse relationship between cortisol and height-for-age z-score status (P = 0.00), which is mediated, in part, by infection (P = 0.00), and is strongest among male children (n.s.). Moreover, the poorest statural growth is exhibited among children with high cortisol living in more acculturated Tsimane' communities, a proxy for a more adverse developmental milieu. CONCLUSIONS: This study reports a small, but significant, life history cost of elevated diurnal cortisol rhythms on linear growth among Tsimane' children, and provides critical insight into the developmental origins of health differentials among an indigenous Amazonian population experiencing rapid lifestyle changes.

HIV Stigma Reduction Interventions Among Health Care Providers and Students in Different Countries: A Systematic Review.

BACKGROUND: Health care providers' stigmatizing attitudes are obstacles to patients' well- being and quality of life. Dealing with HIV-related stigma and understanding the impact of feasible interventions on reducing stigmatizing attitudes among health care providers are considered important strategies to improve the quality of HIV care, patient-provider relationships, and provide supportive and safe care services. OBJECTIVE: The aim of this study was to systematically review interventions to reduce HIV-related stigma among health care providers. METHODS: This systematic review was performed using Medline, CINAHL, ERIC, and APA PsycInfo, Health Source: Nursing/Academic Edition to search for quasi-experimental studies and randomized controlled trials (RCTs) designed to reduce HIV stigma among health care providers. The quality of eligible research studies was independently appraised by two reviewers. RESULTS: A total of 774 studies were screened, 100 articles were assessed for eligibility, and 10 studies met the inclusion criteria. All interventions effectively reduced HIV-related stigma. Elements of successful interventions included knowledge modules, peer education, patients' testimonials, Photovoice-informed stigma reduction training, stigma-free space intervention, and popular opinion leaders. Interventions were assessed and compared in terms of contents, delivery modes, HIV stigma measurements, follow-up, and limitations. CONCLUSION: This systematic review supports the effectiveness of in-person educational interventions at reducing HIV-related stigma among health care providers across countries. Comparisons of delivery modes of interventions indicated that educational interventions delivered by patients' testimonials and peer education strategies are more promising than lecture-based teaching methods. Further studies are needed to assess the long-term effects of interventions on clinical behaviors and practices.

Cultural consonance and body morphology: estimates with longitudinal data from an Amazonian society.

Researchers have hypothesized that the degree to which an individual's actual behavior approximates the culturally valued lifestyle encoded in the dominant cultural model has consequences for physical and mental health. We contribute to this line of research by analyzing data from a longitudinal study composed of five annual surveys (2002-2006 inclusive) from 791 adults in one society of foragers-farmers in the Bolivian Amazon, the Tsimane'. We estimate the association between a standard measure of individual achievement of the cultural model, cultural consonance, and three indicators of body morphology. Drawing on research suggesting that in societies in the early stages of economic development an increase in socioeconomic status is associated with an increase in mean body mass, we expect to find a positive association between cultural consonance and three anthropometric measures. We found the expected positive association between cultural consonance and anthropometric measures-especially for men-only when using ordinary least square (OLS) regression models, but not when using fixed-effects regression models. The real magnitude of the association was low. The comparison of estimates from OLS and fixed-effect regression models suggests that previous findings on the effects of cultural consonance on body morphology using cross-sectional data should be read with caution because the association might be largely explained by fixed characteristics of individuals not accounted in OLS models.

Short but catching up: statural growth among native Amazonian Bolivian children.

The ubiquity and consequences of childhood growth stunting (<-2 SD in height-for-age Z score, HAZ) in rural areas of low-income nations has galvanized research into the reversibility of stunting, but the shortage of panel data has hindered progress. Using panel data from a native Amazonian society of foragers-farmers in Bolivia (Tsimane'), we estimate rates of catch-up growth for stunted children. One hundred forty-six girls and 158 boys 2 < or = age < or = 7 were measured annually during 2002-2006. Annual Delta height in cm and in HAZ were regressed separately against baseline stunting and control variables related to attributes of the child, mother, household, and village. Children stunted at baseline had catch-up growth rates 0.11 SD/year higher than their nonstunted age and sex peers, with a higher rate among children farther from towns. The rate of catch up did not differ by the child's sex. A 10% rise in household income and an additional younger sibling lowered by 0.16 SD/year and 0.53 SD/year the rate of growth. Results were weaker when measuring Delta height in cm rather than in HAZ. Possible reasons for catch-up growth include (a) omitted variable bias, (b) parental reallocation of resources to redress growth faltering, particularly if parents perceive the benefits of redressing growth faltering for child school achievement, and (c) developmental plasticity during this period when growth rates are most rapid and linear growth trajectories have not yet canalized.

Cultural consonance and psychological well-being. Estimates using longitudinal data from an Amazonian society.

Researchers have hypothesized that the degree to which an individual's actual behavior approximates the culturally valued lifestyle encoded in the dominant cultural model has consequences for physical and mental health. We contribute to this line of research by analyzing data from a longitudinal study composed of five annual surveys (2002-2006 inclusive) of 791 adults in one society of foragers-farmers in the Bolivian Amazon, the Tsimane'. We estimate the association between a standard measure of individual achievement of the cultural model and (a) four indicators of psychological well-being (sadness, anger, fear and happiness) and (b) consumption of four potentially addictive substances (alcohol, cigarette, coca leaves and home-brewed beer) as indicators of stress behavior. After controlling for individual fixed effects, we found a negative association between individual achievement of the cultural model and psychological distress and a positive association between individual achievement of the cultural model and psychological well-being. Only the consumption of commercial alcohol bears the expected negative association with cultural consonance in material lifestyle, probably because the other substances analyzed have cultural values attached. Our work contributes to research on psychological health disparities by showing that a locally defined and culturally specific measure of lifestyle success is associated with psychological health.

Individual wealth rank, community wealth inequality, and self-reported adult poor health: a test of hypotheses with panel data (2002-2006) from native Amazonians, Bolivia.

Growing evidence suggests that economic inequality in a community harms the health of a person. Using panel data from a small-scale, preindustrial rural society, we test whether individual wealth rank and village wealth inequality affects self-reported poor health in a foraging-farming native Amazonian society. A person's wealth rank was negatively but weakly associated with self-reported morbidity. Each step up/year in the village wealth hierarchy reduced total self-reported days ill by 0.4 percent. The Gini coefficient of village wealth inequality bore a positive association with self-reported poor health that was large in size, but not statistically significant. We found small village wealth inequality, and evidence that individual economic rank did not change. The modest effects may have to do with having used subjective rather than objective measures of health, having small village wealth inequality, and with the possibly true modest effect of a person's wealth rank on health in a small-scale, kin-based society. Finally, we also found that an increase in mean individual wealth by village was related to worse self-reported health. As the Tsimane' integrate into the market economy, their possibilities of wealth accumulation rise, which may affect their well-being. Our work contributes to recent efforts in biocultural anthropology to link the study of social inequalities, human biology, and human-environment interactions.

Longitudinal Changes in Measures of Body Fat and Diet Among Adult Tsimane' Forager-Horticulturalists of Bolivia, 2002-2010.

OBJECTIVE: This study examined changes in body fat and diet among Tsimane' forager-horticulturalists and assessed how dietary shifts relate to increases in adiposity between 2002 and 2010. METHODS: Longitudinal anthropometric and household-level dietary recall data from 365 men and 339 women aged ≥20 years in the Tsimane' Amazonian Panel Study were used. Multilevel mixed-effects models estimated how BMI, body fat percentage, waist circumference, skinfolds, and fat-free mass relate to household consumption of crops, hunted or fished foods, domesticated animal products, cooking oil, and refined grains and sugar. RESULTS: Women's prevalence of overweight and obesity increased from 22.6% and 2.4% in 2002 to 28.8% and 8.9% in 2010, respectively, and BMI increased by 0.60% ± 0.12% per year (P < 0.001). Increases in fat-free mass accounted for some of this observed weight gain among women. Men's prevalence of overweight and obesity increased from 16.2% and 0.7% to 25.0% and 2.2%, respectively, and BMI increased by 0.22% ± 0.09% per year (P = 0.009). Household use of cooking oil increased and was positively associated with female BMI. Consumption of domesticated animal products did not change significantly but was positively associated with female BMI and male waist circumference. CONCLUSIONS: Even small increases in energy-dense market-based foods can contribute to adiposity gains among a moderately active, subsistence-based population.

Social rank and adult male nutritional status: evidence of the social gradient in health from a foraging-farming society.

Research with humans and non-human primate species has found an association between social rank and individual health. Among humans, a robust literature in industrial societies has shown that each step down the rank hierarchy is associated with increased morbidity and mortality. Here, we present supportive evidence for the social gradient in health drawing on data from 289 men (18+ years of age) from a society of foragers-farmers in the Bolivian Amazon (Tsimane'). We use a measure of social rank that captures the locally perceived position of a man in the hierarchy of important people in a village. In multivariate regression analysis we found a positive and statistically significant association between social rank and three standard indicators of nutritional status: body mass index (BMI), mid-arm circumference, and the sum of four skinfolds. Results persisted after controlling for material and psychosocial pathways that have been shown to mediate the association between individual socioeconomic status and health in industrial societies. Future research should explore locally-relevant psychosocial factors that may mediate the association between social status and health in non-industrial societies.

Developmental changes in the relationship between leptin and adiposity among Tsimané children and adolescents.

Leptin is thought to signal energy stores, thus helping the body balance energy intake and expenditure. However, the strong relationship between leptin and adiposity in populations with adequate nutrition or common obesity is not universal across ecologic contexts, and leptin often correlates only weakly, or not at all, with adiposity in populations of lean or marginally-nourished males. To clarify whether the relationship between adiposity and leptin changes during development, this study examines leptin and body fat among children and adolescents of lowland Bolivia. Anthropometric measures of body composition and dried blood spot samples were collected from 487 Tsimane' ranging from 2 to 15 years of age. Leptin was assayed using an enzyme immunoassay protocol validated for use with blood spot samples. In this population, leptin concentrations were among the lowest reported in a human population (mean +/- SD: 1.26 +/- 0.5 and 0.57 +/- 0.3 in females and males). In addition, the relationship between leptin and adiposity follows distinct developmental trajectories in males and females. In males, leptin is weakly correlated with most measures of body composition at all ages investigated. However, in females, the level of body fat and the strength of the correlation between body fat and leptin (a measure of its strength as a signal of energy stores) both increase markedly with age. These findings suggest a more important role of leptin as a signal of energy stores among females as they approach reproductive maturity, while raising questions about the function of this hormone in lean males.

Ethnobotanical skills and clearance of tropical rain forest for agriculture: a case study in the lowlands of Bolivia.

Indigenous peoples are often considered potential allies in the conservation of biological diversity. Here we assess whether ethnobotanical skills of indigenous people contribute to a reduction in the clearance of tropical rain forest. We measured ethnobotanical skills of male household heads and area of rain forest cleared for agriculture among 128 households of Tsimane', a native Amazonian group in Bolivia. We used multivariate regressions to estimate the relation between ethnobotanical skills and area of rain forest cleared while controlling for schooling, health status, number of plots cleared, adults in household, and village of residency. We found that when the ethnobotanical skills of the male household head were doubled, the amount of tropical rain forest cleared per household was reduced by 25%. The association was stronger when the area of old-growth forest cleared was used as the dependent variable than when the area cleared from fallow forest was used as the dependent variable. People who use the forest for subsistence might place a higher value on standing forest than people who do not use it, and thus they may be more reluctant to cut down the forest.