Casey J. Roulette

Explaining Human Recreational Use of ‘pesticides’: The Neurotoxin Regulation Model of Substance Use vs. the Hijack Model and Implications for Age and Sex Differences in Drug Consumption

Most globally popular drugs are plant neurotoxins or their close chemical analogs. These compounds evolved to deter, not reward or reinforce, consumption. Moreover, they reliably activate virtually all toxin defense mechanisms, and are thus correctly identified by human neurophysiology as toxins. Acute drug toxicity must therefore play a more central role in drug use theory. We accordingly challenge the popular idea that the rewarding and reinforcing properties of drugs “hijack” the brain, and propose instead that the brain evolved to carefully regulate neurotoxin consumption to minimize fitness costs and maximize fitness benefits. This perspective provides a compelling explanation for the dramatic changes in substance use that occur during the transition from childhood to adulthood, and for pervasive sex differences in substance use: because nicotine and many other plant neurotoxins are teratogenic, children, and to a lesser extent women of childbearing age, evolved to avoid ingesting them. However, during the course of human evolution many adolescents and adults reaped net benefits from regulated intake of plant neurotoxins.

Teaching in hunter–gatherer infancy

A debate exists as to whether teaching is part of human nature and central to understanding culture or whether it is a recent invention of Western, Educated, Industrial, Rich, Democratic cultures. Some social–cultural anthropologists and cultural psychologists indicate teaching is rare in small-scale cultures while cognitive psychologists and evolutionary biologists indicate it is universal and key to understanding human culture. This study addresses the following questions: Does teaching of infants exist in hunter–gatherers? If teaching occurs in infancy, what skills or knowledge is transmitted by this process, how often does it occur and who is teaching? The study focuses on late infancy because cognitive psychologists indicate that one form of teaching, called natural pedagogy, emerges at this age. Videotapes of Aka hunter–gatherer infants were used to evaluate whether or not teaching exists among Aka hunter–gatherers of central Africa. The study finds evidence of multiple forms of teaching, including natural pedagogy, that are used to enhance learning of a variety of skills and knowledge.

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.

High prevalence of cannabis use among Aka foragers of the Congo Basin and its possible relationship to helminthiasis

Little is known about cannabis use in hunter‐gatherers. Therefore, we investigated cannabis use in the Aka, a population of foragers of the Congo Basin. Because cannabis contains anthelminthic compounds, and the Aka have a high prevalence of helminthiasis, we also tested the hypothesis that cannabis use might be an unconscious form of self‐medication against helminths.

A Biocultural Investigation of Gender Differences in Tobacco Use in an Egalitarian Hunter-Gatherer Population

In the developing world, the dramatic male bias in tobacco use is usually ascribed to pronounced gender disparities in social, political, or economic power. This bias might also reflect under-reporting by woman and/or over-reporting by men. To test the role of gender inequality on gender differences in tobacco use we investigated tobacco use among the Aka, a Congo Basin foraging population noted for its exceptionally high degree of gender equality. We also tested a sexual selection hypothesis—that Aka men’s tobacco use is related to risk taking. Tobacco use, income, tobacco purchases, tobacco sharing, reasons for using tobacco, risk taking, and other variables were measured using structured surveys and peer reports. Tobacco use was verified by testing for salivary cotinine, a nicotine metabolite. Contrary to expectations, we found a very large male bias in tobacco use. Low levels of use among females appeared to be explained by aversions to tobacco, concerns over its negative effects on fetal health, and a desire to attract husbands, who prefer nonsmoking wives. High male use appeared to be related to a desire to enhance hunting abilities and attract and/or retain wives, who prefer husbands that smoke. We conclude that low levels of smoking by Aka women are better explained by the hypothesis that women evolved to avoid plant toxins to protect their fetuses and nursing infants. High male use might be better explained by sexual selection. We also highlight the important role that recreational drugs appear to play in hunter-gatherer sharing relationships.

Medicinal foods and beverages among Maasai agro-pastoralists in northern Tanzania

ETHNOPHARMACOLOGICAL RELEVANCE Pastoralist Maasai populations of east Africa use several different wild plants as dietary and medicinal additives in beverages (soups and teas), yet little is known about how the plants used and the rationales for use compare and contrast across different Maasai beverages, including how gender specific dietary and health concerns structure patterns of intake. AIM OF THE STUDY We investigated three Maasai beverages: almajani (tea or herbal infusion); motorí (traditional soup); and okiti (psychoactive herbal tea). In order to build knowledge about the cultural functions of these Maasai food-medicines and their incidence of use we also investigated use rationales and self-reported frequencies of use. We conclude by examining gender differences and the possible pharmacological antimicrobial activity of the most frequently used plants. MATERIALS AND METHODS Research was conducted in 2015, with a population of semi-nomadic agropastoralist Maasai residing in northern Tanzania. Data were collected using key informant interviews, plant collections, n = 32 structured surveys, and n = 40 freelist interviews followed by a literature review to determine the known antimicrobial activity of the most used plants. RESULTS We identified 20 plants that Maasai add to soup, 11 in tea, and 11 in the psychoactive tea, for a total of 24 herbal additives. Seven plant species were used in all three Maasai beverages, and these clustered with 10 common ailments. Based on self-reports, women use the beverages less frequently and in smaller amounts than men. There were also several gender differences in the plants that Maasai add to motorí and their associated use rationales. CONCLUSIONS There are several intersections concerning the plant species used and their associated rationales for use in almajani, motori, and okiti. Moving outward, Maasai beverages and their additives increasingly involve gender specific concerns. Female use of food-medicines, relative to men, is structured by concerns over pregnancy, birth, and lactation. The frequent consumption of herbal additives, many of which contain antimicrobial compounds, potentially helps modulate infections, but could have other unintentional effects as well.

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.

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.

Teaching and Overimitation Among Aka Hunter-Gatherers

Cognitive psychologists indicate that teaching, language, and accurate imitation are distinct features of human cognition that enable rapid and precise acquisition of cultural beliefs and practices. This chapter examines two of the three proposed cognitive mechanisms that hypothetically enabled pronounced cultural diversity and complexity—teaching and accurate imitation. Both are either rare or do not exist in great apes but are hypothesized by researchers to be part of human nature and therefore universal. A limitation of most existing studies on these topics is that they have been conducted with Western children in laboratory settings. No studies on these topics have been conducted with active hunter-gatherers. This chapter describes two systematic studies with Aka hunter-gatherers of the Central African Republic. Videotapes of Aka 1-year-olds in naturalistic settings are used to evaluate whether or not one type of teaching, called natural pedagogy (NP), exists among foragers. The second study uses a standardized puzzle box with 4- to 7-year-old children to consider whether or not one form of accurate imitation, called overimitation, occurs at this age among the Aka, as it does among 90 % of Western children. Aka data supported the natural pedagogy hypothesis, but found that natural pedagogy was shaped by cultural context and that many other forms of teaching existed in infancy. The overimitation study questioned the age at which it is hypothesized to emerge in human children. Most Aka children used emulation rather than overimitation with the puzzle box, while most Aka adults used overimitation. Again, hunter-gatherer cultural context is suggested to impact the timing of its emergence in human development.