Tobacco use vs. helminths in Congo basin hunter-gatherers: self-medication in humans?

Evolutionary perspectives on substance and behavioural addictions: Distinct and shared pathways to understanding, prediction and prevention

Addiction poses significant social, health, and criminal issues. Its moderate heritability and early-life impact, affecting reproductive success, poses an evolutionary paradox: why are humans predisposed to addictive behaviours? This paper reviews biological and psychological mechanisms of substance and behavioural addictions, exploring evolutionary explanations for the origin and function of relevant systems. Ancestrally, addiction-related systems promoted fitness through reward-seeking, and possibly self-medication. Today, psychoactive substances disrupt these systems, leading individuals to neglect essential life goals for immediate satisfaction. Behavioural addictions (e.g. video games, social media) often emulate ancestrally beneficial behaviours, making them appealing yet often irrelevant to contemporary success. Evolutionary insights have implications for how addiction is criminalised and stigmatised, propose novel avenues for interventions, anticipate new sources of addiction from emerging technologies such as AI. The emerging potential of glucagon-like peptide 1 (GLP-1) agonists targeting obesity suggest the satiation system may be a natural counter to overactivation of the reward system.

Homo medicus: The transition to meat eating increased pathogen pressure and the use of pharmacological plants in Homo

The human lineage transitioned to a more carnivorous niche 2.6 mya and evolved a large body size and slower life history, which likely increased zoonotic pathogen pressure. Evidence for this increase includes increased zoonotic infections in modern hunter-gatherers and bushmeat hunters, exceptionally low stomach pH compared to other primates, and divergence in immune-related genes. These all point to change, and probably intensification, in the infectious disease environment of Homo compared to earlier hominins and other apes. At the same time, the brain, an organ in which immune responses are constrained, began to triple in size. We propose that the combination of increased zoonotic pathogen pressure and the challenges of defending a large brain and body from pathogens in a long-lived mammal, selected for intensification of the plant-based self-medication strategies already in place in apes and other primates. In support, there is evidence of medicinal plant use by hominins in the middle Paleolithic, and all cultures today have sophisticated, plant-based medical systems, add spices to food, and regularly consume psychoactive plant substances that are harmful to helminths and other pathogens. We propose that the computational challenges of discovering effective plant-based treatments, the consequent ability to consume more energy-rich animal foods, and the reduced reliance on energetically-costly immune responses helped select for increased cognitive abilities and unique exchange relationships in Homo. In the story of human evolution, which has long emphasized hunting skills, medical skills had an equal role to play.

Monks: A Population at Risk for Liver Fluke and Skin-Penetrating Helminths

Monks cannot cook received raw meat dishes and should walk barefoot while working. This population lacks both a survey of parasitic infection and a proper prevention and control policy. Five hundred and fourteen monks from the Ubolratana, Ban Haet, and Ban Phai Districts of Kh on Kaen Province were enrolled in this study. A stool container and questionnaire were collected from each study participant. Stool samples were processed by formalin ethyl acetate concentration and agar plate culture techniques. We then analyzed the results and risk factors to demonstrate associations. The prevalence of overall parasites, liver flukes, and skin-penetrating helminths were 28.8%, 11.1%, and 19.3%, respectively. Raw fish dish offerings were associated with opisthorchiasis (ORcrude 3.32; 95% CI 1.53–7.20). The risk factors for skin-penetrating helminths were older age (ORcrude 5.02; 95% CI 2.2–11.17), being a long-term ordinate (ORcrude 3.28; 95% CI 1.15–9.34), smoking (ORcrude 2.03; 95% CI 1.23–3.36), and chronic kidney disease with other underlying disease (ORcrude 20.7; 95% CI 2.54–190.1). The protective factors for skin-penetrating helminths were secular education above primary education (ORcrude 0.41; 95% CI 0.25–0.65) and having received health education about parasitic infection (ORcrude 0.47; 95% CI 0.28–0.80). Wearing shoes at times other than alms work does not show a protective effect against skin-penetrating helminths (ORcrude 0.86; 95% CI 0.51–1.46). These findings support the recommendation for a strict Rule of Discipline regarding raw meat ingestion and allowing shoes to be worn for protection against skin-penetrating helminths in high-risk situations.

Higher blood nicotine concentrations following smokeless tobacco (pituri) and cigarette use linked to adverse pregnancy outcomes for Central Australian Aboriginal pregnancies

Background

In central Australia, Aboriginal women use wild tobacco plants, Nicotiana spp. (locally known as pituri) as a chewed smokeless tobacco, with this use continuing throughout pregnancy and lactation. Our aim was to describe the biological concentrations of nicotine and metabolites in samples from mothers and neonates and examine the relationships between maternal self-reported tobacco use and maternal and neonatal outcomes.

Methods

Central Australian Aboriginal mothers (and their neonates) who planned to birth at the Alice Springs Hospital (Northern Territory, Australia) provided biological samples: maternal blood, arterial and venous cord blood, amniotic fluid, maternal and neonatal urine, and breast milk. These were analysed for concentrations of nicotine and five metabolites.

Results

A sample of 73 women were enrolled who self-reported: no-tobacco use (n = 31), tobacco chewing (n = 19), or smoking (n = 23). Not all biological samples were obtained from all mothers and neonates. In those where samples were available, higher total concentrations of nicotine and metabolites were found in the maternal plasma, urine, breast milk, cord bloods and Day 1 neonatal urine of chewers compared with smokers and no-tobacco users. Tobacco-exposed mothers (chewers and smokers) with elevated blood glucose had higher nicotine and metabolite concentrations than tobacco-exposed mothers without elevated glucose, and this was associated with increased neonatal birthweight. Neonates exposed to higher maternal nicotine levels were more likely to be admitted to Special Care Nursery. By Day 3, urinary concentrations in tobacco-exposed neonates had reduced from Day 1, although these remained higher than concentrations from neonates in the no-tobacco group.

Conclusions

This research provides the first evidence that maternal pituri chewing results in high nicotine concentrations in a wide range of maternal and neonatal biological samples and that exposure may be associated with adverse maternal and neonatal outcomes. Screening for the use of all tobacco and nicotine products during pregnancy rather than focusing solely on smoking would provide a more comprehensive assessment and contribute to a more accurate determination of tobacco and nicotine exposure. This knowledge will better inform maternal and foetal care, direct attention to targeted cessation strategies and ultimately improve long-term clinical outcomes, not only in this vulnerable population, but also for the wider population.

Note to readers

In this research, the central Australian Aboriginal women chose the term ‘Aboriginal’ to refer to themselves, and ‘Indigenous’ to refer to the broader group of Australian First Peoples. That choice has been maintained in the reporting of the research findings.

Central Australian Aboriginal women's pregnancy, labour and birth outcomes following maternal smokeless tobacco (pituri) use, cigarette use or no-tobacco use: a prospective cohort study

BACKGROUND

Outcomes related to maternal smoked tobacco (cigarette) use have been substantially examined over the past 50 years with resultant public health education targeted towards the reduction of use during pregnancy. However, worldwide the effects of maternal smokeless tobacco use have been less well explored and in Australia, there has been no examination of maternal outcomes in relation to the use of Australian Nicotiana spp. (tobacco plant) as a smokeless tobacco, colloquially known as pituri. The aim of this study is to describe the maternal outcomes of a group of central Australian Aboriginal women in relation to their self-reported tobacco use.

METHODS

Eligible participants were > 18 years of age, with a singleton pregnancy, > 28 weeks gestation, and who planned to birth at the Alice Springs Hospital (the major regional hospital for central Australia, in the Northern Territory, Australia). The sample consisted of 73 conveniently recruited women categorized by tobacco-use status as no-tobacco users (n = 31), pituri chewers (n = 19), and smokers (n = 23).

RESULTS

There were differences in the groups in relation to teenage pregnancies; 35% of no-tobacco users, compared with 5% of pituri users, and 13% of smokers were <  20 years of age. The chewers had a higher rate (48%) of combined pre-existing and pregnancy-related elevated glucose concentrations compared with smokers (22%) and no-tobacco users (16%).The pituri chewers had the lowest rate (14%) of clinically significant post-partum hemorrhage (> 1000 ml) compared with 22% of smokers and 36% of the no-tobacco users.

CONCLUSIONS

This is the first research to examine pituri use in pregnancy and the findings indicate possible associations with a range of adverse maternal outcomes. The use of smokeless tobacco needs to be considered in maternal healthcare assessment to inform antenatal, intrapartum and postpartum care planning.

IMPLICATIONS FOR PUBLIC HEALTH

Female smokeless tobacco use is a global phenomenon and is particularly prevalent in low and middle income countries and in Indigenous populations. The findings contribute to the developing knowledge around maternal smokeless tobacco use and maternal outcomes. Maternal screening for a broader range of tobacco and nicotine products is required.

NOTE TO READERS

In this research, the central Australian Aboriginal women chose the term 'Aboriginal' to refer to themselves, and 'Indigenous' to refer to the broader First Peoples. That choice has been maintained in the reporting of the research findings.

Exploring biocultural models of chewing tobacco and paan among reproductive-aged women: Self-medication, protection, or gender inequality?

OBJECTIVES

Tobacco and areca nut are two of the most widely used psychoactive plant substances worldwide, yet the biocultural factors that account for variation in use patterns are not well understood. Here we attempt to understand the high prevalence of, and variation in, tobacco and areca nut use among reproductive-aged women.

METHODS

Research was carried out in Mysore, Karnataka, India. First, we conducted a qualitative investigation where participants engaged in semistructured interviews and focus group discussions to uncover cultural norms of women's tobacco use. Findings informed the second stage of research which quantitatively tested three models of tobacco and areca nut use (N = 74).

RESULTS

The qualitative study found that women were more likely to chew "natural" forms of tobacco and areca nut products (kaddipudi and paan). Quantitative tests of our hypotheses revealed that kaddipudi and combined tobacco use were best explained by the self-medication model, with somatic and environmental stress as strong indicators of use. The presence of cotinine, our biological indicator of tobacco use, was best modeled by gender inequality. We also found that men and women reported approximately equal tobacco use, even though their preferred types of tobacco and areca nut products differed.

CONCLUSIONS

Findings did not support the protection hypothesis as it relates to plant toxins. Instead, this study suggests that women might exploit neurotoxins such as nicotine and arecoline to offset the cognitive and energetic costs associated with iron deficiency in stressful environments.

Reducing the health risks derived from exposure to addictive substances

PURPOSE OF REVIEW

To discuss the health risks due to exposure to alcohol, illegal drugs and nicotine and how these risks might be reduced.

RECENT FINDINGS

In 2016, worldwide, alcohol, illegal drugs and nicotine were responsible for some 10 million deaths. There is evolutionary and biological evidence that humans are predisposed to consuming alcohol, illegal drugs and nicotine - present-day problems are caused by high levels of potency, exposure and drug delivery systems. The two priority substances for action are alcohol and smoked cigarettes; their exposure can be reduced by price increases, setting minimum prices per product, regulating a shift form smoked cigarettes to electronic nicotine delivery devices and, theoretically, reducing the ethanol content of existing beverages. Legalization of cannabis requires a strict regulatory framework.

SUMMARY

Purposeful policy can reduce the harm done by alcohol, illegal drugs and nicotine. In particular, policy to reduce exposure to alcohol requires considerable strengthening.

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.

Shamanism and efficacious exceptionalism

Shamans can have efficacy at healing through botanical remedies and in observational and advisory functions through cognitive strengths, while shamanic acts of strangeness are likely honest signals of these qualities. Given this potential for shamanic practices to have true efficacy and the capacity for honest signaling, we expect efficacy will influence the spread, persistence, and loss of shamanic practices.

Reframing the science and policy of nicotine, illegal drugs and alcohol - conclusions of the ALICE RAP Project

In 2013, illegal drug use was responsible for 1.8% of years of life lost in the European Union, alcohol was responsible for 8.2% and tobacco for 18.2%, imposing economic burdens in excess of 2.5% of GDP. No single European country has optimal governance structures for reducing the harm done by nicotine, illegal drugs and alcohol, and existing ones are poorly designed, fragmented, and sometimes cause harm. Reporting the main science and policy conclusions of a transdisciplinary five-year analysis of the place of addictions in Europe, researchers from 67 scientific institutions addressed these problems by reframing an understanding of addictions.  A new paradigm needs to account for evolutionary evidence which suggests that humans are biologically predisposed to seek out drugs, and that, today, individuals face availability of high drug doses, consequently increasing the risk of harm.  New definitions need to acknowledge that the defining element of addictive drugs is 'heavy use over time', a concept that could replace the diagnostic artefact captured by the clinical term 'substance use disorder', thus opening the door for new substances to be considered such as sugar. Tools of quantitative risk assessment that recognize drugs as toxins could be further deployed to assess regulatory approaches to reducing harm. Re-designed governance of drugs requires embedding policy within a comprehensive societal well-being frame that encompasses a range of domains of well-being, including quality of life, material living conditions and sustainability over time; such a frame adds arguments to the inappropriateness of policies that criminalize individuals for using drugs and that continue to categorize certain drugs as illegal. A health footprint, modelled on the carbon footprint, and using quantitative measures such as years of life lost due to death or disability, could serve as the accountability tool that apportions responsibility for who and what causes drug-related harm.

In vitro antiprotozoal activity and cytotoxicity of extracts and isolated constituents from Greenwayodendron suaveolens

ETHNOPHARMACOLOGICAL RELEVANCE

The Nkundo people (Nkundo area of Bolongo, Mai-Ndombe district, Bandundu Province, DR Congo) use various plant parts of the tree Greenwayodendron suaveolens (Engl. & Diels) Verdc. (syn. Polyalthia suaveolens Engl. & Diels) (Annonaceae) against malaria, but its antiprotozoal constituents are not known.

MATERIALS AND METHODS

The crude 80% ethanol extract from the fruits, leaves, root bark and stem bark and 16 fractions were assessed in vitro for their antiprotozoal activity against Trypanosoma brucei brucei, T. cruzi, Leishmania infantum and the chloroquine and pyrimethamine-resistant K1 strain of Plasmodium falciparum (Pf-K1). Their cytotoxic effects were evaluated against MRC-5 cells. Active constituents were isolated by chromatographic means, identified using spectroscopic methods, and evaluated in the same assays.

RESULTS

The root bark extract showed the highest activity against P. falciparum K1 (IC₅₀ 0.26µg/mL) along with the stem bark alkaloid fraction (IC₅₀ 0.27µg/mL). The root bark alkaloid fraction had a pronounced activity against all selected protozoa with IC₅₀ values <1µg/mL. The 90% methanol fractions of the different plant parts showed a pronounced activity against P. falciparum K1, with IC₅₀ values ranging between 0.36µg/mL and 0.69µg/mL. Four constituents were isolated: the triterpenes polycarpol, and dihydropolycarpol, the latter one being reported for the first time from nature, and the alkaloids polyalthenol and N-acetyl-polyveoline. They were active to a various degree against one or more protozoa, mostly accompanied by cytotoxicity. The highest selectivity was observed for N-acetyl-polyveoline against P. falciparum K1 (IC50 2.8µM, selectivity index 10.9).

CONCLUSIONS

These results may explain at least in part the traditional use of this plant species against parasitic diseases such as malaria in DR Congo.

Hunter-gatherer genomics: evolutionary insights and ethical considerations

Hunting and gathering societies currently comprise only a small proportion of all human populations. However, the geographic and environmental diversity of modern hunter-gatherer groups, their inherent dependence on ecological resources, and their connection to patterns of behavior and subsistence that represent the vast majority of human history provide opportunities for scientific research to deliver major insights into the evolutionary history of our species. We review recent evolutionary genomic studies of hunter-gatherers, focusing especially on those that identify and functionally characterize phenotypic adaptations to local environments. We also call attention to specific ethical issues that scientists conducting hunter-gatherer genomics research ought to consider, including potential social and economic tensions between traditionally mobile hunter-gatherers and the land ownership-based nation-states by which they are governed, and the implications of genomic-based evidence of long-term evolutionary associations with particular habitats.

Using Evolutionary Theory to Guide Mental Health Research

Evolutionary approaches to medicine can shed light on the origins and etiology of disease. Such an approach may be especially useful in psychiatry, which frequently addresses conditions with heterogeneous presentation and unknown causes. We review several previous applications of evolutionary theory that highlight the ways in which psychiatric conditions may persist despite and because of natural selection. One lesson from the evolutionary approach is that some conditions currently classified as disorders (because they cause distress and impairment) may actually be caused by functioning adaptations operating "normally" (as designed by natural selection). Such conditions suggest an alternative illness model that may generate alternative intervention strategies. Thus, the evolutionary approach suggests that psychiatry should sometimes think differently about distress and impairment. The complexity of the human brain, including normal functioning and potential for dysfunctions, has developed over evolutionary time and has been shaped by natural selection. Understanding the evolutionary origins of psychiatric conditions is therefore a crucial component to a complete understanding of etiology.

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

OBJECTIVES

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.

METHODS

We collected self- and peer-reports of cannabis use from all adult Aka in the Lobaye district of the Central African Republic (n = 379). Because female cannabis use was low, we restricted sample collection to men. Using an immunoassay for Δ9-tetrahydrocannabinol-11-oic acid (THCA), a urinary biomarker of recent cannabis consumption, we validated cannabis use in men currently residing in camps near a logging road (n = 62). We also collected stool samples to assay worm burden. A longitudinal reinfection study was conducted among a subsample of the male participants (n = 23) who had been treated with a commercial anthelmintic 1 year ago.

RESULTS

The prevalence of self- and peer-reported cannabis use was 70.9% among men and 6.1% among women, for a total prevalence of 38.6%. Using a 50 ng/ml threshold for THCA, 67.7% of men used cannabis. Cannabis users were significantly younger and had less material wealth than the non-cannabis users. There were significant negative associations between THCA levels and worm burden, and reinfection with helminths 1 year after treatment with a commercial anthelmintic.

CONCLUSIONS

The prevalence of cannabis use among adult Aka men was high when compared to most global populations. THCA levels were negatively correlated with parasite infection and reinfection, supporting the self-medication hypothesis.