Human capital, wealth, and nutrition in the Bolivian Amazon

We analyze anthropometric variables of a society of forager-horticulturalists in the Bolivian Amazon (Tsimane') in 2001-2002. Community variables (e.g., inequality, social capital) explain little of the variance in anthropometric indices of nutritional status, but individual-level variables (schooling, wealth) are positively correlated with nutritional status. Dietary quality (foods high in animal proteins), access to foraging technology, and traditional knowledge of medicinal plants are related to better anthropometric indices.     

Assortative mating and offspring well-being: theory and empirical findings from a native Amazonian society in Bolivia

Mate choice matters for inclusive fitness, household economic efficiency, assimilation, stratification, and economic inequalities in society. In positive assortative mating, people pair with someone who resembles them along a trait, whereas in negative assortative mating, people pair with someone who differs from them along a trait. In industrial nations, people tend to follow positive assortative mating for fundamental demographic dimensions (e.g., age, schooling) and might practice negative assortative mating for economic outcomes (e.g., earnings). Research on assortative mating has focused on industrial nations, generally compared only one trait between couples, and paid scant attention to the effects of assortative mating for offspring well-being. If assortative mating enhances inclusive fitness, it might also enhance offspring well-being. Drawing on data from a farming–foraging society in the Bolivian Amazon (Tsimane') that practices preferential cross-cousin marriage, we (a) identify six parental traits (age, knowledge, wealth, schooling, height, and smiles) for which Tsimane' might practice assortative mating and (b) test the hypothesis that assortative mating enhances offspring well-being. Proxies for offspring well-being include height and school attainment. Tsimane' resemble people of industrial nations in practicing mostly positive assortative mating. Pairwise, mother–father and Pearson correlations of age, schooling, and earnings among Tsimane' resemble correlations of industrial nations. Correlation coefficients for the six parental traits were far higher than correlations that might happened just by chance. We found weak support for the hypothesis that assortative mating improves offspring well-being.     

The Role of Community and Individuals in the Formation of Social Capital

Because social capital shapes many desirable socioeconomic outcomes, we ask what incentives drive private investments in social capital. We estimate the association between private investments in social capital (outcome variable) and the following explanatory variables: (a) individual-level variables from an optimal investment model, (b) spillovers from group social capital, (c) village income inequality, and (d) market openness. We draw on information from Tsimane’, a native Amazonian society of foragers and farmers in Bolivia, and equate social capital with gifts, help given, and communal labor offered by the household. Age bore an inverted U-shaped and income bore a positive association with social capital, but geographic mobility, wealth, and schooling bore no significant association with social capital. We found strong group-level associations even after instrumenting social capital; the association probably stems from strong kinship ties which tend to blur the line between the group and the individual. Village measures of social capital were positively and significantly associated with private investments in social capital. We found some evidence that village income inequality and market openness were negatively associated with private investments in social capital.     

Human capital, schooling and health

A consensus has been forged in the last decade that recent periods of sustained growth in total factor productivity and reduced poverty are closely associated with improvements in a population's child nutrition, adult health, and schooling, particularly in low-income countries. Estimates of the productive returns from these three forms of human capital investment are nonetheless qualified by a number of limitations in our data and analytical methods. This paper reviews the problems that occupy researchers in this field and summarizes accumulating evidence of empirical regularities. Social experiments must be designed to assess how randomized policy interventions motivate families and individuals to invest in human capital, and then measure the changed wage opportunities of those who have been induced to make these investments. Statistical estimation of wage functions that seek to represent the relationship between wage rates and a variety of human capital stocks may yield biased estimates of private rates of return from these investments for a variety of reasons. The paper summarizes several of these problems and illustrates how data and statistical methods can be used to deal with some of them. The measures of labor productivity and the proxies specified for schooling and adult health are first discussed, and then the functional relationships between human capital and wages are described. Three types of estimation problem are discussed: (1) bias due to omitted variables, such as ability or frailty; (2) bias due to the measurement of an aggregation of multiple sources of human capital, e.g. genetic and socially reproducible variation, which may contribute to different gains in worker productivity; and (3) errors in measurement of the human capital stocks. Empirical examples and illustrative estimates are surveyed.     

Does obesity influence labour market outcomes among working-age adults? Evidence from Canadian longitudinal data

Although a negative association between obesity and labour market outcomes is commonly reported in many studies, the causal nature of this relationship remains unclear. Using nationally representative longitudinal data from the last six confidential master files (2000/2001–2010/2011) of the National Population Health Survey, we examine the association between obesity and employment participation and earnings among working-age adults in Canada. After controlling for demographic and socioeconomic characteristics, lifestyle factors and time-invariant individual heterogeneity, our results show that obesity is not significantly associated with employment participation but is associated with reduced hourly wage rate and annual income among women by about 4% and 4.5%, respectively. The corresponding results for men show that obesity is associated with about 2% reduction in wage rate and income, but significant at 10% level. However, after controlling for the potential reverse causality bias using the lagged measure of obesity, the effect of obesity on wage rate and income became positive or statistically non-significant. Our findings suggest that obesity is not causally associated with negative labour market outcomes among working-age men in Canada. For working-age women, we find limited evidence of negative labour market outcomes.     

Effect of number and position of siblings on child and adult outcomes

This paper develops a theoretical model of the effects of family size and birth order on educational attainment and earnings. The parental utility maximization model allows the development of closed-form expressions for the within-family ratios of schooling and earnings. A reduced form demand function for each child's schooling and earnings also can be obtained. Each of these functions depends on the exogenous variables of the price of education divided by the price of parental consumption, parental income, the child's endowment, and the parameters of the utility and the production function. Application of this model to empirical data from the Twin and Adult Offspring Sample confirmed both birth order and family size effects for schooling even when parental age, income, education, and father's religion were controlled. The effects were larger for daughters than sons. The difference in educational attainment between 1st and 5th-born was 0.7 years for males and 1.4 years for females. Family size further reduces parental contribution to college education and encourages working, loans, and scholarships. The earnings data do not display birth order effects once family background and sibship size are controlled.     

Health and social cohesion: why care about income inequality?

Throughout the world, wealth and income are becoming more concentrated. Growing evidence suggests that the distribution of income-in addition to the absolute standard of living enjoyed by the poor-is a key determinant of population health. A large gap between rich people and poor people leads to higher mortality through the breakdown of social cohesion. The recent surge in income inequality in many countries has been accompanied by a marked increase in the residential concentration of poverty and affluence. Residential segregation diminishes the opportunities for social cohesion. Income inequality has spillover effects on society at large, including increased rates of crime and violence, impeded productivity and economic growth, and the impaired functioning of representative democracy. The extent of inequality in society is often a consequence of explicit policies and public choice. Reducing income inequality offers the prospect of greater social cohesiveness and better population health.     

Schooling,Local Knowledge and Working Memory: A Study among Three Contemporary Hunter-Gatherer Societies

Researchers have analysed whether school and local knowledge complement or substitute each other, but have paid less attention to whether those two learning models use different cognitive strategies. In this study, we use data collected among three contemporary hunter-gatherer societies with relatively low levels of exposure to schooling yet with high levels of local ecological knowledge to test the association between i) schooling and ii) local ecological knowledge and verbal working memory. Participants include 94 people (24 Baka, 25 Punan, and 45 Tsimane’) from whom we collected information on 1) schooling and school related skills (i.e., literacy and numeracy), 2) local knowledge and skills related to hunting and medicinal plants, and 3) working memory. To assess working memory, we applied a multi-trial free recall using words relevant to each cultural setting. People with and without schooling have similar levels of accurate and inaccurate recall, although they differ in their strategies to organize recall: people with schooling have higher results for serial clustering, suggesting better learning with repetition, whereas people without schooling have higher results for semantic clustering, suggesting they organize recall around semantically meaningful categories. Individual levels of local ecological knowledge are not related to accurate recall or organization recall, arguably due to overall high levels of local ecological knowledge. While schooling seems to favour some organization strategies this might come at the expense of some other organization strategies.     

Physical stature of adult Tsimane’ Amerindians, Bolivian Amazon in the 20th century

We examine the association between exposure to the market and Western society on the height of adult Tsimane', a foraging-farming society in the Bolivian Amazon. As with other contemporary native peoples, we find little evidence of a significant secular change in height during 1920-1980. Female height bore a positive association with own schooling and fluency in spoken Spanish and with maternal modern human capital (schooling, writing ability, and fluency in spoken Spanish), but male heights bore no association with parental height or with modern human capital. The absence of a secular change likely reflects the persistence of traditional forms of social organization and production that protect health.     

The effect of income on the extraction of non-timber tropical forest products: Model,hypotheses, and preliminary findings from the Sumu Indians of Nicaragua

We use microeconomic theory to frame hypotheses about the effects of income on the use of non-timber rain forest products. We hypothesize that an increase in income: (a) encourages foraging specialization, resulting in the extraction of fewer goods; (b) increases the share of household income from occupations besides foraging; (c) produces a yearly value from the extraction of nontimber forest goods of about $50 per hectare; and (d) produces depletion of forest goods entering commercial channels and sustainable extraction of goods facing cheaper industrial substitutes. To examine these hypotheses we present worldwide ethnographic information and preliminary findings from field work carried out among the Sumu Indians of Nicaragua. Field work suggests that higher income produces: (a) foraging specialization with animals rather than with plants; (b) a decline in the economic importance of forest goods in household income; (c) and a rise in the value of non-timber goods removed from the forest to about $35/ha/year. We did not have time to test hypothesis d.     

Do Markets Worsen Economic Inequalities? Kuznets in the Bush

Integration into a market economy or economic development can erode the quality of life of indigenous people by, for example, increasing income inequalities. The Kuznets hypothesis predicts that the link between income inequality and income (a proxy for economic development) resembles an inverted U. We test the hypothesis using a survey of 511 households from 59 villages of Tsimane' Amerindians, a horticultural-foraging society in the tropical rain forest of Bolivia. We measure village inequalities of three economic outcomes: income, imputed annual value of rice production, and wealth. We used three indices of inequality: the coefficient of variation, the standard deviation of the logarithm, and the Gini coefficient. Explanatory variables include either income and income squared, wealth and wealth squared, or imputed annual rice production and production squared. We used village-to-town distance as a control. We find little evidence that integration to the market increases inequalities of economic outcomes, with two exceptions: Wealth bore the predicted inverted U-shaped relation with wealth inequalities, and imputed rice production bore a U-shaped relation to inequality, but only when (a) using adult equivalents to express household size and (b) the Gini coefficient and the coefficient of variation to measure inequality; in no case were results robust to different econometric specifications. We advance several explanations for why economic development might not accentuate economic inequalities among relatively autarkic rural economies.     

Snakes allocate amino acids acquired during vitellogenesis to offspring: are capital and income breeding consequences of variable foraging success?

Reproductive allocation strategies have been historically described as lying on a continuum between capital and income breeding. Capital breeders have been defined as species that allocate stored reserves to reproduction, whereas income breeders have been defined as species that allocate relatively recently‐ingested food resources to reproduction. Snakes are considered capital breeders because they efficiently store large amounts of nutrients and energy, potentially enough to support an entire reproductive bout without feeding. We examined the abilities of five viviparous snake species to allocate income to follicles during vitellogenesis. We fed ¹⁵N‐labelled L‐leucine to experimental females of each species during vitellogenesis, whereas control females were fed unlabelled meals. After ovulation, we measured yolk ¹⁵N p.p.m. using mass spectrometry. Maternal scale samples taken before labelling were used to estimate endogenous ¹⁵N concentrations, which should represent ‘capital’. Scale samples taken at ovulation were used to determine whether snakes assimilated ¹⁵N‐labelled‐leucine from labelled diets. Yolks and post‐ovulatory scales of labelled females were significantly more enriched in ¹⁵N than those of unlabelled females in all species, indicating significant assimilation and allocation of income‐derived amino acids to the yolk during vitellogenesis. The lack of among‐species differences suggests that all species allocated income amino acids to vitellogenesis. The results obtained in the present study suggest that proportional utilization of income or capital depends on the frequency and timing of foraging success during reproductive events. Therefore, capital and income breeding may be consequences of both life‐history and environmental constraints on foraging success, rather than strategies of reproductive allocation. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 390–404.     

Does the Functional Form of the Association Between Education and Mortality Differ by U.S. Region?

To understand the education–mortality association among U.S. adults, recent studies have documented its national functional form. However, the functional form of education–mortality relationship may vary across geographic contexts. The four U.S. Census regions differ considerably in their social and economic policies, employment opportunities, income levels, and other factors that may affect how education lowers the risk of mortality. Thus, we documented regional differences in the functional form of the education–mortality association and examined the role of employment and income in accounting for regional differences. We used data on non-Hispanic white adults (2,981,672, person years) aged 45–84 in the 2000–2009 National Health Interview Survey, with Linked Mortality File through 2011 (37,598 deaths) and estimated discrete-time hazard models. The functional form of education and adult mortality was best characterized by credentialism in the Midwest, Northeast, and for Western men. For Western women, the association was linear, consistent with the human capital model. In the South, we observed a combination of mechanisms, with mortality risk declining with each year of schooling and a step change with high school graduation, followed by steeper decline thereafter. Our work adds to the increasing body of research that stresses the importance of contexts in shaping the education–mortality relationship.     

Fertility decline and the changing dynamics of wealth,status and inequality

In the course of demographic transitions (DTs), two large-scale trends become apparent: (i) the broadly positive association between wealth, status and fertility tends to reverse, and (ii) wealth inequalities increase and then temporarily decrease. We argue that these two broad patterns are linked, through a diversification of reproductive strategies that subsequently converge as populations consume more, become less self-sufficient and increasingly depend on education as a route to socio-economic status. We examine these links using data from 22 mid-transition communities in rural Poland. We identify changing relationships between fertility and multiple measures of wealth, status and inequality. Wealth and status generally have opposing effects on fertility, but these associations vary by community. Where farming remains a viable livelihood, reproductive strategies typical of both pre- and post-DT populations coexist. Fertility is lower and less variable in communities with lower wealth inequality, and macro-level patterns in inequality are generally reproduced at the community level. Our results provide a detailed insight into the changing dynamics of wealth, status and inequality that accompany DTs at the community level where peoples'' social and economic interactions typically take place. We find no evidence to suggest that women with the most educational capital gain wealth advantages from reducing fertility, nor that higher educational capital delays the onset of childbearing in this population. Rather, these patterns reflect changing reproductive preferences during a period of profound economic and social change, with implications for our understanding of reproductive and socio-economic inequalities in transitioning populations.     

Human Body-mass Index (Weight in kg/stature in m2) as a Useful Proxy to Assess the Relation between Income and Wildlife Consumption in Poor Rural Societies

There is growing interest in assessing how income influences the consumption of wildlife in poor rural areas of developing nations. The interest stems from the possibility of using income to contribute to the conservation of wildlife. Though promising, efforts have been hampered by the difficulty of obtaining accurate measures of income. We propose using human body-mass index (BMI: weight in kilograms/physical stature in m²), an indicator of short-term nutritional status, as a proxy variable for monetary income to estimate income elasticities of wildlife consumption (income elasticity: percent change in wildlife consumption/one-percent change income). The advantages of BMI over monetary income include a positive association with monetary income, ease of measurement, and absence of zero values. The assessment procedure was tested among Tsimane’ Amerindians, a society of foragers and farmers in the Bolivian Amazon. The population over 15 years of age (350 men and 322 women) in 13 villages was surveyed for five consecutive quarters (August 2002–November 2003). Income elasticities of wildlife consumption using BMI as a proxy for income ranged from −0.84 to −1.20. The estimates suggest that wildlife is a food item whose consumption declines with increasing income. Estimates of income elasticity of wildlife consumption using conventional indices of monetary income are negative, but lower and indistinguishable from zero owing to classical measurement errors of monetary income. The use of BMI to estimate income elasticities of wildlife consumption is promising, but requires further validation in different settings.     

Turning Pests into Profits: Introduced Buffalo Provide Multiple Benefits to Indigenous People of Northern Australia

Introduced species are a major driver of negative ecological change, but some introduced species can potentially offer positive benefits to society. Asian swamp buffalo (Bubalus bubalis) were introduced to the northern Australian mainland in 1827 and have since become a serious pest. However, buffalo have also supported various profitable industries, including harvesting for hides, meat, and live export. We investigate an indigenous wildlife-based enterprise that harvests wild buffalo from indigenous-held lands in remote northern Australia. We used ecological modelling and social research techniques to quantify the buffalo dynamics and to examine their contributions to sustainable livelihoods in a remote Aboriginal community. Results suggest that the current harvest rate will not drive the species to extinction and it is thus unlikely that the population size of buffalo will be reduced enough to alleviate ecological damage. This enterprise is profitable and provides regular royalty payments to traditional land owners and wage income for employees, along with several additional non-financial capital assets. We demonstrate that the commercial exploitation of introduced species can provide additional or alternative sources of protein and income to promote economic development for indigenous people. This type of enterprise could be expanded to more communities using harvest rates above maximum sustainable yield to provide greater positive social and ecological outcomes for indigenous communities.     

The evolutionary origins of human patience: temporal preferences in chimpanzees, bonobos, and human adults

To make adaptive choices, individuals must sometimes exhibit patience, forgoing immediate benefits to acquire more valuable future rewards [1-3]. Although humans account for future consequences when making temporal decisions [4], many animal species wait only a few seconds for delayed benefits [5-10]. Current research thus suggests a phylogenetic gap between patient humans and impulsive, present-oriented animals [9, 11], a distinction with implications for our understanding of economic decision making [12] and the origins of human cooperation [13]. On the basis of a series of experimental results, we reject this conclusion. First, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes) exhibit a degree of patience not seen in other animals tested thus far. Second, humans are less willing to wait for food rewards than are chimpanzees. Third, humans are more willing to wait for monetary rewards than for food, and show the highest degree of patience only in response to decisions about money involving low opportunity costs. These findings suggest that core components of the capacity for future-oriented decisions evolved before the human lineage diverged from apes. Moreover, the different levels of patience that humans exhibit might be driven by fundamental differences in the mechanisms representing biological versus abstract rewards.     

Socioeconomic differentials among single-race and multi-race Japanese Americans

Using data from the 2000 US Census, this study investigates various groups of single-race and multi-race Japanese Americans in terms of their schooling and wages. The results indicate that all categories of Japanese Americans tend to have higher schooling than whites. Single-race Japanese Americans tend to have higher schooling than multi-race Japanese Americans, and 1.5-generation Japanese Americans tend to have higher schooling than native-born Japanese Americans. With the exception of foreign-educated, immigrant Japanese Americans, most of the wage differentials are explained by schooling and a few other demographic characteristics. These results are rather inconsistent with traditional assimilation theory which posits rising socioeconomic attainments with increasing acculturation. Instead, the findings suggest a reverse pattern by which the groups that are more closely related to Japan tend to have higher levels of educational attainment which then become translated into higher wages.     

Biosocial Conservation: Integrating Biological and Ethnographic Methods to Study Human–Primate Interactions

Biodiversity conservation is one of the grand challenges facing society. Many people interested in biodiversity conservation have a background in wildlife biology. However, the diverse social, cultural, political, and historical factors that influence the lives of people and wildlife can be investigated fully only by incorporating social science methods, ideally within an interdisciplinary framework. Cultural hierarchies of knowledge and the hegemony of the natural sciences create a barrier to interdisciplinary understandings. Here, we review three different projects that confront this difficulty, integrating biological and ethnographic methods to study conservation problems. The first project involved wildlife foraging on crops around a newly established national park in Gabon. Biological methods revealed the extent of crop loss, the species responsible, and an effect of field isolation, while ethnography revealed institutional and social vulnerability to foraging wildlife. The second project concerned great ape tourism in the Central African Republic. Biological methods revealed that gorilla tourism poses risks to gorillas, while ethnography revealed why people seek close proximity to gorillas. The third project focused on humans and other primates living alongside one another in Morocco. Incorporating shepherds in the coproduction of ecological knowledge about primates built trust and altered attitudes to the primates. These three case studies demonstrate how the integration of biological and social methods can help us to understand the sustainability of human–wildlife interactions, and thus promote coexistence. In each case, an integrated biosocial approach incorporating ethnographic data produced results that would not otherwise have come to light. Research that transcends conventional academic boundaries requires the openness and flexibility to move beyond one’s comfort zone to understand and acknowledge the legitimacy of “other” kinds of knowledge. It is challenging but crucial if we are to address conservation problems effectively.