Tomás Huanca

Cultural, Practical, and Economic Value of Wild Plants: a Quantitative Study in the Bolivian Amazon

Researchers have developed several indices to estimate the significance of plant species for humans. We build on previous methods in ethnobotany and anthropology to develop a new way to value plant species along three dimensions: cultural, practical, and economic. We used interview and observational data on the use of wild plants by the Tsimane’, a foraging-horticultural society in the Bolivian Amazon. We calculated the cultural, practical, economic, and total values of 114 plant species from 46 families. We found a low correlation between the practical and the cultural values of species: some species rarely used were frequently mentioned in interviews, whereas some species frequently used were rarely mentioned in interviews. Indices of cultural, practical, and economic value measure different dimensions of the importance of plant species to society. The combination of the three indices offers a more comprehensive valuation of the significance of plants for humans than the use of only one index.

Local financial benefits of rain forests: Comparative evidence from Amerindian societies in Bolivia and Honduras

Researchers generally express the local value of tropical rain forests in dollars/ha/year. The approach is problematic because it produces low values to local users, underestimating the importance of the forest expressed as a share of household consumption or earnings. Here we contribute to valuation studies of rain forests by estimating the financial importance of the forest measured in three ways: (1) the contribution of forests to annual household consumption and (2) earnings; and (3) the value of a hectare of rain forest to villagers measured through the biological goods consumed and sold. We collected panel data on consumption and earnings from 81 households in four villages of two Amerindian societies in two nations (Tsimane’, Bolivia; Tawahka, Honduras). Analyses suggest: (1) forests account for a large share of household consumption (median 38.5%; range 14.65–53.11%); (2) forests contribute more to household consumption than to household earnings (median 22.69%; range 16.56–44.81%); (3) the relative

Maintenance versus growth: Investigating the costs of immune activation among children in lowland Bolivia

Immune function is a central component of maintenance effort, and it provides critical protection against the potentially life threatening effects of pathogens. However, immune defenses are energetically expensive, and the resources they consume are not available to support other activities related to growth and/or reproduction. In our study we use a life history theory framework to investigate tradeoffs between maintenance effort and growth among children in a remote area of Amazonian Bolivia. Baseline concentrations of C-reactive protein (CRP) were measured in 309 2- to 10-year olds as an indicator of immune activation, and height was measured at baseline and three months later. Elevated CRP at baseline predicts smaller gains in height over the subsequent three months, with the costs to growth particularly high for 2- to 4-year olds and for those with low energy reserves (in the form of body fat) at the time of immunostimulation. These results provide evidence for a significant tradeoff between investment in immunity and growth in humans, and highlight an important physiological mechanism through which maintenance effort may have lasting effects on child growth and development.

Influence of Helminth Infections on Childhood Nutritional Status in Lowland Bolivia

Infectious disease, such as diarrheal disease, respiratory infections, and parasitic infections, are an important source of nutritional and energetic stress in many populations. Inspired by the research and methodological innovations of A. Roberto Frisancho, this work considers the impact of childhood environment and local disease ecology on child health and nutritional patterns among an indigenous group in lowland Bolivia. Specifically, we examine the association between soil‐transmitted helminth infection, especially hookworm species, and anthropometric markers of short‐ and long‐term nutritional status. Fecal samples, anthropometric dimensions, and health interviews were collected for 92 children ranging in age from 2.0 to 10.9 years. Microscopic examination revealed high levels of parasitic infection, with 76% of children positive for hookworm species infections (77% of girls and 74% of boys). Less common infections included Ascaris lumbricoides, Trichurius trichiura, and Strongyloides stercoralis with only 15% of children positive for multiple‐species infections. After adjusting for sex and age, no statistically significant associations were observed between helminth infections and the frequency of reported illness or anthropometric measures of nutritional status. These data demonstrate the difficulty of assessing nutritional impacts of endemic infections. Am. J. Hum. Biol., 2009.

Evaluating indices of traditional ecological knowledge: a methodological contribution

BackgroundNew quantitative methods to collect and analyze data have produced novel findings in ethnobiology. A common application of quantitative methods in ethnobiology is to assess the traditional ecological knowledge of individuals. Few studies have addressed reliability of indices of traditional ecological knowledge constructed with different quantitative methods.MethodsWe assessed the associations among eight indices of traditional ecological knowledge from data collected from 650 native Amazonians. We computed Spearman correlations, Chronbachs alpha, and principal components factor analysis for the eight indices.ResultsWe found that indices derived from different raw data were weakly correlated (rho<0.5), whereas indices derived from the same raw data were highly correlated (rho>0.5; p < 0.001). We also found a relatively high internal consistency across data from the eight indices (Chronbachs alpha = 0.78). Last, results from a principal components factor analysis of the eight indices suggest that the eight indices were positively related, although the association was low when considering only the first factor.ConclusionA possible explanation for the relatively low correlation between indices derived from different raw data, but relatively high internal consistency of the eight indices is that the methods capture different aspects of an individuals traditional ecological knowledge. To develop a reliable measure of traditional ecological knowledge, researchers should collect raw data using a variety of methods and then generate an aggregated measure that contains data from the various components of traditional ecological knowledge. Failure to do this will hinder cross-cultural comparisons.

Non-market Returns to Traditional Human Capital: Nutritional Status and Traditional Knowledge in a Native Amazonian Society

Abstract In industrial economies schooling produces positive non-market returns but do traditional forms of human capital also produce such returns, and do schooling and traditional human capital act as complements or substitutes in their association with well-being? Drawing on data from 450 adults (16+ years of age) from an indigenous Amazonian society in Bolivia, we estimate the association between traditional plant knowledge and nutritional status as measured by body-mass index. After conditioning for many covariates, we find that doubling an adults traditional knowledge is associated with a mean improvement in BMI of 6.3 per cent; the association is stronger for unschooled adults and for those living far from the market town. Though schooling bore a negative association with traditional knowledge, those two forms of human capital had independent associations with BMI. The analysis suggests that schooling does not necessarily undermine the accumulation of traditional knowledge.

Moving beyond a Snapshot to Understand Changes in the Well‐Being of Native Amazonians

Forces such as the opening of trade, globalization, multinational corporate resource extraction, urbanization, acculturation, and colonization catalyze economic, ecological, and sociocultural change, which can threaten the well‐being and habitat of native Amazonians. Understanding these forces is of paramount importance to improve the well‐being of native Amazonians and to foster the conservation of biological diversity, yet most analyses of these forces rely on cross‐sectional data. Though adequate to describe the association between variables at one point in time, cross‐sectional data do not allow one to estimate changes in well‐being over time. We collected data annually during five consecutive years (2002–2006, inclusive) from a foraging and farming society of native Amazonians in Bolivia (Tsimane’) to estimate annual rates of change for seven indicators of adult well‐being. Indicators encompassed both objective and subjective measures of well‐being that included economic, health, psychological, and social dimensions that overlap well with Tsimane’ notions of well‐being. The annual rate of change in the inflation‐adjusted (hereafter real) value of food consumption (+6.35%), body mass index (+0.71%), and incidence of anger (−10.40%) show significant improvements over time, but the annual rate of change in the self‐reported number of recent ailments (+7.35%) shows a significant deterioration. Trends in other indicators of well‐being (smiles, real wealth, social relations) show positive but insignificant rates of change. Results did not vary by sex and were consistent when using other indicators of well‐being.

Why Do Mothers Favor Girls and Fathers, Boys? A Hypothesis and a Test of Investment Disparity

Growing evidence suggests mothers invest more in girls than boys and fathers more in boys than girls. We develop a hypothesis that predicts preference for girls by the parent facing more resource constraints and preference for boys by the parent facing less constraint. We test the hypothesis with panel data from the Tsimane’, a foraging-farming society in the Bolivian Amazon. Tsimane’ mothers face more resource constraints than fathers. As predicted, mother’s wealth protected girl’s BMI, but father’s wealth had weak effects on boy’s BMI. Numerous tests yielded robust results, including those that controlled for fixed effects of child and household.

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.

Olfaction and environment: Tsimane' of Bolivian rainforest have lower threshold of odor detection than industrialized German people.

Olfactory sensitivity varies between individuals. However, data regarding cross-cultural and inter-group differences are scarce. We compared the thresholds of odor detection of the traditional society of Tsimane’ (native Amazonians of the Bolivian rainforest; n = 151) and people living in Dresden (Germany; n = 286) using “Sniffin’ Sticks” threshold subtest. Tsimane’ detected n-butanol at significantly lower concentrations than the German subjects. The distribution of thresholds of the Tsimane’ was very specific, with 25% of Tsimane’ obtaining better results in the olfactory test than any member of the German group. These data suggest that differences in olfactory sensitivity seem to be especially salient between industrialized and non-industrialized populations inhabiting different environmental conditions. We hypothesize that the possible sources of such differences are: (i) the impact of pollution which impairs the olfactory abilities of people from industrialized countries; (ii) better training of olfaction because of the higher importance of smell in traditional populations; (iii) environmental pressures shaping olfactory abilities in these populations.