Mark Caudell

Resource Availability, Mortality, and Fertility: A Path Analytic Approach to Global Life-History Variation

Abstract Humans exhibit considerable diversity in timing and rate of reproduction. Life-history theory (LHT) suggests that ecological cues of resource richness and survival probabilities shape human phenotypes across populations. Populations experiencing high extrinsic mortality due to uncertainty in resources should exhibit faster life histories. Here we use a path analytic (PA) approach informed by LHT to model the multiple pathways between resources, mortality rates, and reproductive behavior in 191 countries. Resources that account for the most variance in population mortality rates are predicted to explain the most variance in total fertility rates. Results indicate that resources (e.g., calories, sanitation, education, and health-care expenditures) influence fertility rates in paths through communicable and noncommnunicable diseases. Paths acting through communicable disease are more strongly associated with fertility than are paths through noncommunicable diseases. These results suggest that a PA approach may help disaggregate extrinsic and intrinsic mortality factors in cross-cultural analyses. Such knowledge may be useful in developing targeted policies to decrease teenage pregnancy, total fertility rates, and thus issues associated with overpopulation.

Informal lending networks in rural Ethiopia

Abstract Economic development in emergent nations is tied to smallholder subsistence populations whose livelihoods are vulnerable to exogenous shocks. When shocks occur, individuals often rely on resources embedded within informal insurance networks. Resource access is related to network position and reflected in properties such as centrality and reachability. We analyze a complete informal lending network (188 nodes, 295 ties) among the Sidama, an agro-pastoralist population in southwestern Ethiopia. Results indicate that culturally salient indicators of wealth, such as cattle ownership and gender, largely account for network structure. Analysis of a complete network further allows us to discuss the impact of global network properties, such as overall typology, on a communities response to different types of shocks (covariate and idiosyncratic). These findings extend our understanding of how individuals and communities engage informal lending networks in response to exogenous shocks.

VULNERABILITY AND RESILIENCE OF SIDAMA ENSET AND MAIZE FARMS IN SOUTHWESTERN ETHIOPIA

Abstract Enset (Ensete ventricosum) is the traditional staple food of Sidama people who live in Rift Valley lowlands to highlands in southwest Ethiopia. Enset is drought resistant, but it matures slowly, requires substantial manure inputs from cattle, and intensive processing. Maize, introduced to Sidamaland in the mid-twentieth century, is common in midlands and lowlands. Maize matures rapidly and provides more kcal/kg than enset, but it is prone to failure in dry years and requires chemical fertilizer, which is subject to global market price fluctuations. We compare cultural ecology, productivity, failure, and resilience of enset and maize in 410 farms across four Sidama ecological zones. The risks and benefits of enset and maize are complexly associated with variable local environments. Enset offers drought-resistant produce that, with sufficient manure inputs, is adequate for subsistence in the wet highlands, but its performance is more variable elsewhere. Fertilized, maize yields larger harvests than enset, but vulnerability to rainfall and global processes create special challenges. Maize and enset appear to be in different adaptive cycle phases: maize grows quickly and maize farms rebounded from crop loss within four years. Only half of enset farms recovered within six years after crop failure, complicating farming decisions in an environment with tremendous localized variation. In general, the Sidama zone shows a pattern of regional diversity with local specialization for maize only, enset only, or mixed maize and enset cultivation. In some areas maize has become a preferred crop and food for younger people.

Antimicrobial use and veterinary care among agro-pastoralists in Northern Tanzania

Frequent and unregulated use of antimicrobials (AM) in livestock requires public health attention as a likely selection pressure for resistant bacteria. Studies among small-holders, who own a large percentage of the world’s livestock, are vital for understanding how practices involving AM use might influence resistance. We present a cultural-ecological mixed-methods analysis to explore sectors of veterinary care, loosely regulated AM use, and human exposure to AMs through meat and milk consumption across three rural to peri-urban Tanzanian ethnic groups (N = 415 households). Reported use of self-administered AMs varied by ethnic group (Maasai: 74%, Arusha: 21%, Chagga: 1%) as did consultation with professional veterinarians (Maasai: 36%, Arusha: 45%, Chagga: 96%) and observation of withdrawal of meat and milk from consumption during and following AM treatment (Maasai: 7%, Arusha: 72%, Chagga: 96%). The antibiotic oxytetracycline was by far the most common AM in this sample. Within ethnic groups, herd composition differences, particularly size of small-stock and cattle herds, were most strongly associated with differences in lay AM use. Among the Arusha, proxies for urbanization, including owning transportation and reliance on “zero-grazing” herds had the strongest positive associations with veterinarian consultation, while distance to urban centers was negatively associated. For Maasai, consultation was negatively associated with use of traditional healers or veterinary drug-shops. Observation of withdrawal was most strongly associated with owning technology among Maasai while Arusha observance displayed seasonal differences. This “One-Health” analysis suggests that livelihood and cultural niche factors, through their association with practices in smallholder populations, provide insight into the selection pressures that may contribute to the evolution and dissemination of antimicrobial resistance.

Medical pluralism and livestock health: ethnomedical and biomedical veterinary knowledge among East African agropastoralists

BackgroundHuman and animal health are deeply intertwined in livestock dependent areas. Livestock health contributes to food security and can influence human health through the transmission of zoonotic diseases. In low-income countries diagnosis and treatment of livestock diseases is often carried out by household members who draw upon both ethnoveterinary medicine (EVM) and contemporary veterinary biomedicine (VB). Expertise in these knowledge bases, along with their coexistence, informs treatment and thus ultimately impacts animal and human health. The aim of the current study was to determine how socio-cultural and ecological differences within and between two livestock-keeping populations, the Maasai of northern Tanzania and Koore of southwest Ethiopia, impact expertise in EVM and VB and coexistence of the two knowledge bases.MethodsAn ethnoveterinary research project was conducted to examine dimensions of EVM and VB knowledge among the Maasai (N = 142 households) and the Koore (N = 100). Cultural consensus methods were used to quantify expertise and the level of agreement on EVM and VB knowledge. Ordinary least squares regression was used to model patterns of expertise and consensus across groups and to examine associations between knowledge and demographic/sociocultural attributes.ResultsMaasai and Koore informants displayed high consensus on EVM but only the Koore displayed consensus on VB knowledge. EVM expertise in the Koore varied across gender, herd size, and level of VB expertise. EVM expertise was highest in the Maasai but was only associated with age. The only factor associated with VB expertise was EVM expertise in the Koore.ConclusionsVariation in consensus and the correlates of expertise across the Maassi and the Koore are likely related to differences in the cultural transmission of EVM and VB knowledge. Transmission dynamics are established by the integration of livestock within the socioecological systems of the Maasai and Koore and culture historical experiences with livestock disease. Consideration of the nature and coexistence of EVM and VB provides insight into the capacity of groups to cope with disease outbreaks, pharmaceutical use patterns, and the development of community health interventions.

Culture and Psychological Responses to Environmental Shocks: Cultural Ecology of Sidama Impulsivity and Niche Construction in Southwest Ethiopia

Sidama people occupy a subsistence niche partitioned between traditional enset agropastoralism and transitional maize farming. Enset production is low risk and requires multiple years for cultivation and processing. Maize farming is high risk and high yield, requiring one growing season from planting to harvest. Contrasting enset and maize farming, we examine effects of crop loss and social shocks on Sidama impulsivity. We argue that impulsivity is a psychological process that is differentially activated by environmental shocks in the stable, traditional enset regime and unstable, transitional maize regime. Using a robust psychometric model derived from Barratt impulsiveness scale items, we demonstrate two dimensions of Sidama impulsivity: careful control (CC) and acts without thinking (AWT). Both dimensions are associated with environmental shocks, but the associations are moderated by social-ecological regimes. In the enset regime, effects of shocks on impulsivity are muted. However, increased impulsivity is significantly associated with shocks in the global market–dependent maize regime. Effects on CC were significant for social shocks but not crop loss, while AWT was associated with crop loss and social shocks. Results may indicate domain-specific aspects of impulsivity in response to environmental perturbation. Impulsivity may be adaptive in the context bidirectional predictive processing in active cultural niche construction.

Greater wealth inequality, less polygyny: rethinking the polygyny threshold model

Monogamy appears to have become the predominant human mating system with the emergence of highly unequal agricultural populations that replaced relatively egalitarian horticultural populations, challenging the conventional idea—based on the polygyny threshold model—that polygyny should be positively associated with wealth inequality. To address this polygyny paradox, we generalize the standard polygyny threshold model to a mutual mate choice model predicting the fraction of women married polygynously. We then demonstrate two conditions that are jointly sufficient to make monogamy the predominant marriage form, even in highly unequal societies. We assess if these conditions are satisfied using individual-level data from 29 human populations. Our analysis shows that with the shift to stratified agricultural economies: (i) the population frequency of relatively poor individuals increased, increasing wealth inequality, but decreasing the frequency of individuals with sufficient wealth to secure polygynous marriage, and (ii) diminishing marginal fitness returns to additional wives prevent extremely wealthy men from obtaining as many wives as their relative wealth would otherwise predict. These conditions jointly lead to a high population-level frequency of monogamy.

A two-month follow-up evaluation testing interventions to limit the emergence and spread of antimicrobial resistant bacteria among Maasai of northern Tanzania

BackgroundIn sub-Saharan Africa, efforts to control antimicrobial resistance (AMR) are aggravated by unregulated drug sales and use, and high connectivity between human, livestock, and wildlife populations. Our previous research indicates that Maasai agropastoralists—who have high exposure to livestock and livestock products and self-administer veterinary antibiotics—harbor antibiotic resistant Escherichia coli (E. coli). Here, we report the results of a public health intervention project among Maasai aimed at reducing selection and transmission of E. coli bacteria.MethodsResearch was conducted in two Maasai communities in Northern Tanzania. Participants were provided with health knowledge and technological innovations to facilitate: 1) the prudent use of veterinary antibiotics (tape measures and dosage charts to calculate livestock weight for more accurate dosage), and, 2) the pasteurization of milk (thermometers), the latter of which was motivated by findings of high levels of resistant E. coli in Maasai milk. To determine knowledge retention and intervention adoption, we conducted a two-month follow-up evaluation in the largest of the two communities.ResultsRetention of antimicrobial knowledge was positively associated with retention of bacterial knowledge and, among men, retention of bacterial knowledge was associated with greater wealth. Bacterial and AMR knowledge were not, however, associated with self-reported use of the innovations. Among women, self-reported use of the thermometers was associated with having more children and greater retention of knowledge about the health benefits of the innovations. Whereas 70% of women used their innovations correctly, men performed only 18% of the weight-estimation steps correctly. Men’s correct use was associated with schooling, such that high illiteracy rates remain an important obstacle to the dissemination and diffusion of weight-estimation materials.ConclusionOur results indicate that dietary preferences for unboiled milk, concerns over child health, and a desire to improve the health of livestock are important cultural values that need to be incorporated in future AMR-prevention interventions that target Maasai populations. More generally, these findings inform future community-health interventions to limit AMR.

The Interplay of Mortality, Economics, and Female Empowerment in Fertility Transformations A Fixed Effects Analysis Across 40 Years and 167 Countries

Theoretical explanations for fertility transformations, such as the demographic transition, have primarily emphasized one of three influences: (a) decreasing mortality rates, (b) economic development, and (c) the transmission of female empowerment norms. Empirical tests suggest that the relative contribution of these factors on predicting fertility varies across populations and time periods. Identification of the factors underlying this variation will ultimately be aided by the pooling of cross-national and time-series data. To this end, the current study combines data from 167 countries across a 40-year time period (i.e., 1970-2010). A fixed effects model is specified to examine how the three factors predict within-country variability in adolescent and total fertility rates. Results indicate that all three variables are associated with fertility patterns in theoretically consistent ways, although the association is often non-linear. In addition, the level of association between economic development and female empowerment with fertility varies across levels of mortality. Results highlight that a “unified” theory of demography will develop through understanding how levels of the three factors may interact to transform global fertility patterns.

Children's Ethnobiological Notions of Contamination and Contagions among Maasai Agro-Pastoralists of Northern Tanzania

Abstract. Humans and other living organisms harbor disease-causing pathogenic microorganisms. These microorganisms are often transmitted through physical contact with contaminated objects, such as food, water, or other people. While some theoretical and empirical research examines the ontogeny of contamination and contagion beliefs, cross-cultural research on this topic is limited. To help remedy this paucity of data, we conducted an ethnobiological study of contagion and contamination beliefs among Maasai children (n = 42) in the Simanjiro district, Tanzania. Participants include 36 middle-aged schoolchildren and six four-year-olds. We contrast the childrens beliefs with those of 12 local adults. To measure childrens views of contagion and contamination, we developed sentence-framed yes/no elicitation tasks using three different stimuli—a fly, a cough, and a cough from someone with respiratory symptoms. Qualitative semi-structured interviews were conducted to further understand childrens ethnotheories of contamination and contagion. Children generally reported that coughs and flies are directly contaminating, whereas they offered mixed results for associational and indirect contamination. Children discussed time, psychological contagion, saliva, wind, and the supernatural/natural as key elements to their beliefs, reasons, and personal actions taken to minimize contamination/contagion risk. We found education to be significantly positively correlated with children reporting that flies and coughs were directly contaminating, while age had no effect. Although children were more likely than adults to associate flies with contamination, their general belief pattern differs little from adults. Local cultural-ecological factors and explanatory models of disease, as well as formal religious and education institutions, shape Maasai childrens ethnobiological beliefs of contagions and contamination.