High conservation of the dental plaque microbiome across populations with differing subsistence strategies and levels of market integration.

Industrialization-including urbanization, participation in the global food chain and consumption of heavily processed foods-is thought to drive substantial shifts in the human microbiome. While diet strongly influences stool microbiome composition, the influence of diet on the oral microbiome is largely speculative. Multiple ecologically distinct surfaces in the mouth, each harbouring a unique microbial community, pose a challenge to assessing changes in the oral microbiome in the context of industrialization, as the results depend on the oral site under study. Here, we investigated whether microbial communities of dental plaque, the dense biofilm on non-shedding tooth surfaces, are distinctly different across populations with dissimilar subsistence strategies and degree of industrialized market integration. Using a metagenomic approach, we compared the dental plaque microbiomes of Baka foragers and Nzime subsistence agriculturalists in Cameroon (n = 46) with the dental plaque and calculus microbiomes of highly industrialized populations in North America and Europe (n = 38). We found that differences in microbial taxonomic composition between populations were minimal, with high conservation of abundant microbial taxa and no significant differences in microbial diversity related to dietary practices. Instead, we find that the major source of variation in dental plaque microbial species composition is related to tooth location and oxygen availability, which may be influenced by toothbrushing or other dental hygiene measures. Our results support that dental plaque, in contrast to the stool microbiome, maintains an inherent stability against ecological perturbations in the oral environment.

Indigenous peoples' health: Culturally grounded evidence from the Baka, Southeastern Cameroon.

Indigenous Peoples are exposed to the impacts of the climatic, ecological and socioeconomic changes, yet there is a need for a better understanding of their health and higher involvement of Indigenous Peoples in health promotion design and implementation. Our study brings empirical data on the healthcare system of the Baka, forager-horticulturalists from Cameroon. Using a mixed methods approach, we explored the health issues they encounter, the emic determinants of health and healthcare system, and the different threats towards their healthcare system. We conducted focus group discussions, interviews with experts, and self-reported health recalls with 302 individuals living in two settlements from southeastern Cameroon during two fieldwork periods between June and November 2022. Our insights highlight the prevalence of respiratory and children's digestive issues, and the occurrence of illnesses implying a combination of symptoms that would deserve further Western biomedical attention. The Baka's healthcare relies on medicinal plants, knowledge experts, and on the social cohesion of the community, all largely affected by the local social-ecological impacts of global change. Exposure to the market and health facilities does not seem to relate to Baka's health state and practices but might affect their perception of health. Deforestation, poor water quality, and alcohol (ab)use were reported and observed threats to the Baka's health and healthcare system. Our work supplies empirical evidence for a better understanding of Baka's health and healthcare system, helpful in designing health prevention and policies adapted to their reality and culture. Further research and interventions on health should consider the current threats to Baka's local ecosystems and cultural knowledge. These insights contribute to a higher recognition of the Baka's, and most broadly, the Indigenous Peoples' emic perspective on health, and on culturally grounded indicators of the resilience of their healthcare system to current and future challenges.

The gut microbiome of Baka forager-horticulturalists from Cameroon is optimized for wild plant foods.

The human gut microbiome is losing biodiversity, due to the "microbiome modernization process" that occurs with urbanization. To keep track of it, here we applied shotgun metagenomics to the gut microbiome of the Baka, a group of forager-horticulturalists from Cameroon, who combine hunting and gathering with growing a few crops and working for neighboring Bantu-speaking farmers. We analyzed the gut microbiome of individuals with different access to and use of wild plant and processed foods, to explore the variation of their gut microbiome along the cline from hunter-gatherer to agricultural subsistence patterns. We found that 26 species-level genome bins from our cohort were pivotal for the degradation of the wild plant food substrates. These microbes include Old Friend species and are encoded for genes that are no longer present in industrialized gut microbiome. Our results highlight the potential relevance of these genes to human biology and health, in relation to lifestyle.

Reproductive seasonality in the Baka Pygmies, environmental factors and climatic changes.

Reproductive seasonality is a phenomenon common to human and animal populations and driven by, among others, climatic variables. Given the currently changing climate and its impacts on both the environment and human lives, the question arises of its potential effects on reproductive seasonality. Few studies have specifically explored the seasonality of reproduction among hunter-gatherers and anyone investigated how current climate change might affect this phenomenon. In this study we addressed reproductive seasonality in the Baka Pygmy living in African rain forests. Since reproductive seasonality can be linked to weather patterns, we explore this possibility. However, climatic variables driving weather patterns have changed over the years, so we assessed whether this has influenced the Baka reproductive pattern. Based on 34 years of written birth records and oral questionnaires from 13 years of systematic fieldwork, we observed a bimodal birth pattern with two birth peaks at 6-month intervals. Our results demonstrate that precipitation at conception or at birth potentially has effects, respectively negative and positive on the monthly number of births; and temperature has a role in controlling other variables that do affect the reproductive pattern. Changing weather patterns appear to be affecting the reproductive seasonality in the Baka, suggesting that attention needs to be given to the influence of global climate change on forager societies.

Growing up in the Betsileo landscape: Children's wild edible plants knowledge in Madagascar.

Understanding local knowledge about wild edible plants (WEP) is essential for assessing plant services, reducing the risks of knowledge extinction, recognizing the rights of local communities, and improving biodiversity conservation efforts. However, the knowledge of specific groups such as women or children tends to be under-represented in local ecological knowledge (LEK) research. In this study, we explore how knowledge of WEP is distributed across gender and life stages (adults/children) among Betsileo people in the southern highlands of Madagascar. Using data from free listings with 42 adults and 40 children, gender-balanced, we show that knowledge on WEP differs widely across gender and life stage. In addition, we find that children have extended knowledge of WEP while reporting different species than adults. Women's knowledge specializes in herbaceous species (versus other plant life forms), while men's knowledge specializes in endemic species (versus native or introduced). Finally, we find that introduced species are more frequently cited by children, while adults cite more endemic species. We discuss the LEK differentiation mechanisms and the implications of acquiring life stage's knowledge in the highland landscapes of Madagascar. Given our findings, we highlight the importance of considering groups with under-represented knowledge repositories, such as children and women, into future research.

Alcohol, drugs and sexual abuse in Cameroon's rainforest.

Due to global socio-economical and ecological changes, indigenous societies are exposed to an increased risk of alcohol and substance abuse. Most research on this topic has been done on indigenous communities in Canada, Australia, the US, parts of Europe and New Zealand, leaving indigenous communities in other parts of the world largely unrepresented. This study focuses on alcohol and drug consumption among the Baka: a former hunter-gatherer society in southeastern Cameroon that has been facing drastic socio-ecological changes in the last five decades. During long-term fieldwork we collected ethnographic and empirical data by means of group and individual interviews among four Baka communities. By using a multivariable approach, we describe psychoactive substance use behaviors, its socio-cultural and political context, and consequences. Our findings show that 48% of men, 24% of women and 11% of children between five and 16 years old reported alcohol intake in the past 24 h. The use of Tramadol was also reported, including by children as young as five years old. Psychoactive substances were used for recreational purposes, as painkillers, and energy boosters. Substance abuse was related to health issues, especially problems with fertility, and to several household and social conflicts. Other factors related to substance abuse were Baka's marginalization and sexual exploitation of Baka women and girls. By discussing these matters, we hope to stimulate more research on similar problems in small-scale societies and to invite governments, human rights activists, and other important parties to take action.

The importance of choosing appropriate methods for assessing wild food plant knowledge and use: A case study among the Baka in Cameroon.

In tropical rainforests, access to and availability of natural resources are vital for the dietary diversity and food security of forest-dwelling societies. In the Congo Basin, these are challenged by the increasing exploitation of forests for bushmeat, commercial hardwood, mining, and large-scale agriculture. In this context, a balanced approach is needed between the pressures from forest exploitation, non-timber forest product trade and the livelihood and dietary behavior of rural communities. While there is a general positive association between tree cover and dietary diversity, the complex biocultural interactions between tropical forest food resources and the communities they sustain are still understudied. This research focuses on the knowledge and use of wild food plants by the forest-dwelling Baka people in southeast Cameroon. By using two different sets of methods, namely ex-situ interviews and in-situ surveys, we collected ethnographic and ethnobotanical data in two Baka settlements and explored the diversity of wild edible plants known, the frequency of their consumption, and potential conflicts between local diet and commercial trade in forest resources. Within a single Baka population, we showed that the in-situ walk-in-the-woods method resulted in more detailed information on wild food plant knowledge and use frequency than the ex-situ methods of freelisting and dietary recalls. Our in-situ method yielded 91 wild edible species, much more than the ex-situ freelisting interviews (38 spp.) and dietary recalls (12 spp.). Our results suggest that studies that are based only on ex-situ interviews may underestimate the importance of wild food plants for local communities. We discuss the limitations and strengths of these different methods for investigating the diversity of wild food plant knowledge and uses. Our analysis shows that future studies on wild food plants would profit from a mixed approach that combines in-situ and ex-situ methods.

Happy just because. A cross-cultural study on subjective wellbeing in three Indigenous societies.

While cross-cultural research on subjective well-being and its multiple drivers is growing, the study of happiness among Indigenous peoples continues to be under-represented in the literature. In this work, we measure life satisfaction through open-ended questionnaires to explore levels and drivers of subjective well-being among 474 adults in three Indigenous societies across the tropics: the Tsimane' in Bolivian lowland Amazonia, the Baka in southeastern Cameroon, and the Punan in Indonesian Borneo. We found that life satisfaction levels in the three studied societies are slightly above neutral, suggesting that most people in the sample consider themselves as moderately happy. We also found that respondents provided explanations mostly when their satisfaction with life was negative, as if moderate happiness was the normal state and explanations were only needed when reporting a different life satisfaction level due to some exceptionally good or bad occurrence. Finally, we also found that issues related to health and-to a lesser extent-social life were the more prominent explanations for life satisfaction. Our research not only highlights the importance to understand, appreciate and respect Indigenous peoples' own perspectives and insights on subjective well-being, but also suggests that the greatest gains in subjective well-being might be achieved by alleviating the factors that tend to make people unhappy.

"Hunting Otherwise" : Women's Hunting in Two Contemporary Forager-Horticulturalist Societies.

Although subsistence hunting is cross-culturally an activity led and practiced mostly by men, a rich body of literature shows that in many small-scale societies women also engage in hunting in varied and often inconspicuous ways. Using data collected among two contemporary forager-horticulturalist societies facing rapid change (the Tsimane' of Bolivia and the Baka of Cameroon), we compare the technological and social characteristics of hunting trips led by women and men and analyze the specific socioeconomic characteristics that facilitate or constrain women's engagement in hunting. Results from interviews on daily activities with 121 Tsimane' (63 women and 58 men) and 159 Baka (83 women and 76 men) show that Tsimane' and Baka women participate in subsistence hunting, albeit using different techniques and in different social contexts than men. We also found differences in the individual and household socioeconomic profiles of Tsimane' and Baka women who hunt and those who do not hunt. Moreover, the characteristics that differentiate hunter and non-hunter women vary from one society to the other, suggesting that gender roles in relation to hunting are fluid and likely to change, not only across societies, but also as societies change.

The life history of human foraging: Cross-cultural and individual variation.

Human adaptation depends on the integration of slow life history, complex production skills, and extensive sociality. Refining and testing models of the evolution of human life history and cultural learning benefit from increasingly accurate measurement of knowledge, skills, and rates of production with age. We pursue this goal by inferring hunters' increases and declines of skill from approximately 23,000 hunting records generated by more than 1800 individuals at 40 locations. The data reveal an average age of peak productivity between 30 and 35 years of age, although high skill is maintained throughout much of adulthood. In addition, there is substantial variation both among individuals and sites. Within study sites, variation among individuals depends more on heterogeneity in rates of decline than in rates of increase. This analysis sharpens questions about the coevolution of human life history and cultural adaptation.

Social Networks and Knowledge Transmission Strategies among Baka Children, Southeastern Cameroon.

The dynamics of knowledge transmission and acquisition, or how different aspects of culture are passed from one individual to another and how they are acquired and embodied by individuals, are central to understanding cultural evolution. In small-scale societies, cultural knowledge is largely acquired early in life through observation, imitation, and other forms of social learning embedded in daily experiences. However, little is known about the pathways through which such knowledge is transmitted, especially during middle childhood and adolescence. This study presents new empirical data on cultural knowledge transmission during childhood. Data were collected among the Baka, a forager-farmer society in southeastern Cameroon. We conducted structured interviews with children between 5 and 16 years of age (n = 58 children; 177 interviews, with children being interviewed 1-6 times) about group composition during subsistence activities. Children's groups were generally diverse, although children tended to perform subsistence activities primarily without adults and with same-sex companions. Group composition varied from one subsistence activity to another, which suggests that the flow of knowledge might also vary according to the activity performed. Analysis of the social composition of children's subsistence groups shows that vertical and oblique transmission of subsistence-related knowledge might not be predominant during middle childhood and adolescence. Rather, horizontal transmission appears to be the most common knowledge transmission strategy used by Baka children during middle childhood and adolescence, highlighting the importance of other children in the transmission of knowledge.

Local ecological knowledge among Baka children: a case of "children's culture" ?

Childhood is an extensive life period specific to the human species and a key stage for development. Considering the importance of childhood for cultural transmission, we test the existence of a 'children's culture', or child-specific knowledge and practices not necessarily shared with adults, among the Baka in Southeast Cameroon. Using structured questionnaires, we collected data among 69 children and 175 adults to assess the ability to name, identify, and conceptualize animals and wild edibles. We found that some of the ecological knowledge related to little mammals and birds reported by Baka children was not reported by adults. We also found similarities between children's and adult's knowledge, both regarding the content of knowledge and how knowledge is distributed. Thus, middle childhood children hold similar knowledge than adults, especially related to wild edibles. Moreover, as children age, they start shedding child-specific knowledge and holding more adult's knowledge. Additionally and echoing the gendered knowledge distribution present in adulthood, since middle childhood there are differences in the knowledge hold by boys and girls. We discuss our results highlighting the existence of specific ecological knowledge held by Baka children, the overlap between children's and adults' knowledge, and the changes in children's ecological knowledge as they move into adulthood.

The adaptive nature of culture. A cross-cultural analysis of the returns of local environmental knowledge in three indigenous societies.

Researchers have argued that the behavioral adaptations that explain the success of our species are partially cultural, i.e., cumulative and socially transmitted. Thus, understanding the adaptive nature of culture is crucial to understand human evolution. We use a cross-cultural framework and empirical data purposely collected to test whether culturally transmitted and individually appropriated knowledge provides individual returns in terms of hunting yields and health and, by extension, to nutritional status, a proxy for individual adaptive success. Data were collected in three subsistence-oriented societies: the Tsimane' (Amazon), the Baka (Congo Basin), and the Punan (Borneo). Results suggest that variations in individual levels of local environmental knowledge relate to individual hunting returns and to self-reported health, but not to nutritional status. We argue that this paradox can be explained through the prevalence of sharing: individuals achieving higher returns to their knowledge transfer them to the rest of the population, which explains the lack of association between knowledge and nutritional status. The finding is in consonance with previous research highlighting the importance of cultural traits favoring group success, but pushes it forward by elucidating the mechanisms through which individual and group level adaptive forces interact.

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.

Differences between Pygmy and Non-Pygmy Hunting in Congo Basin Forests.

We use data on game harvest from 60 Pygmy and non-Pygmy settlements in the Congo Basin forests to examine whether hunting patterns and prey profiles differ between the two hunter groups. For each group, we calculate hunted animal numbers and biomass available per inhabitant, P, per year (harvest rates) and killed per hunter, H, per year (extraction rates). We assess the impact of hunting of both hunter groups from estimates of numbers and biomass of prey species killed per square kilometre, and by examining the proportion of hunted taxa of low, medium and high population growth rates as a measure of their vulnerability to overhunting. We then map harvested biomass (kg-1P-1Yr-1) of bushmeat by Pygmies and non-Pygmies throughout the Congo Basin. Hunting patterns differ between Pygmies and non-Pygmies; Pygmies take larger and different prey and non-Pygmies sell more for profit. We show that non-Pygmies have a potentially more severe impact on prey populations than Pygmies. This is because non-Pygmies hunt a wider range of species, and twice as many animals are taken per square kilometre. Moreover, in non-Pygmy settlements there was a larger proportion of game taken of low population growth rate. Our harvest map shows that the non-Pygmy population may be responsible for 27 times more animals harvested than the Pygmy population. Such differences indicate that the intense competition that may arise from the more widespread commercial hunting by non-Pygmies is a far more important constraint and source of conflict than are protected areas.

Children's daily activities and knowledge acquisition: A case study among the Baka from southeastern Cameroon.

BACKGROUND: The acquisition of local knowledge occurs through complex interactions between individual and contextual characteristics: as context changes, so it changes the acquisition of knowledge. Contemporary small-scale societies facing rapid social-ecological change provide a unique opportunity to study the relation between social-ecological changes and the process of acquisition of local knowledge. In this work, we study children's involvement in subsistence related activities (i.e., hunting and gathering) in a context of social-ecological change and discuss how such involvement might condition the acquisition of local knowledge during childhood. METHODS: We interviewed 98 children from a hunter-gatherer society, the Baka, living in two different villages in southeastern Cameroon and assessed their involvement in daily activities. Using interviews, we collected self-reported data on the main activities performed during the previous 24 h. We describe the frequency of occurrence of daily activities during middle childhood and adolescence and explore the variation in occurrence according to the sex, the age group, and the village of residency of the child. We also explore variation according to the season in which the activity is conducted and to the predicted potential of the activity for the acquisition of local knowledge. RESULTS: Baka children and adolescents engage in subsistence-related activities (i.e., hunting and gathering) and playing more frequently than in other activities (i.e., traditional tales or schooling). Gender differences in children's subsistence activities emerge at an early age. Engagement in activities also varies with age, with adolescents spending more time in agricultural activities, modern leisure (i.e., going to bars), and socializing than younger children. When conducting similar activities, adolescents use more complex techniques than younger children. CONCLUSION: Subsistence activities, which present a high potential for transmission of local knowledge, continue to be predominant in Baka childhood. However, Baka children also engage in other, non-traditional activities, such as modern forms of leisure, or schooling, with a low potential for the transmission of local knowledge. Baka children's involvement in non-traditional activities might have unforeseen impacts on the acquisition of local knowledge.