Functional aspects of the use of plants and animals in local medical systems and their implications for resilience

Can socioeconomic factors and the availability of medicinal plant resources influence people's perception of risk in relation to diseases?

BACKGROUND

This study explores how socioeconomic factors and the availability of medicinal plant resources influence the perception of disease risk in a local medical system. It addresses the role of traditional knowledge and the care and prevention practices used by the community, highlighting the interactions between cultural, social and environmental aspects.

METHODS

The research was conducted in the community of Serra Grande, Lagoa do Ouro, Pernambuco, with 95 participants. Semi-structured interviews were conducted to collect data on socioeconomic factors, perceived risk of disease (using ranking and Likert scale), and perceived availability of medicinal plants. The data were analyzed with Generalized Linear Models using R software.

RESULTS

Age was the only socioeconomic factor with a significant influence on the perception of risk of disease, being higher among individuals aged between 51 and 70. In addition, the results indicated that the perception of risk of disease is negatively influenced by the availability of medicinal plant resources, i.e., a lower availability of plants is associated with a higher perception of risk. 117 species of medicinal plants used by the community were identified, with the Fabaceae and Lamiacae families standing out.

CONCLUSIONS

The study highlights the complexity of risk perception in rural communities, influenced by social, cultural and environmental factors. Effective public health policies must integrate these dynamics, creating adaptive strategies that strengthen community resilience and preserve traditional knowledge and resources essential for health.

Barcoding and traditional health practitioner perspectives are informative to monitor and conserve frogs and reptiles traded for traditional medicine in urban South Africa

Previous literature suggests that Indigenous cultural practices, specifically traditional medicine, are commonplace among urban communities contrary to the general conception that such practices are restricted to rural societies. We reviewed previous literature for records of herptiles (frog and reptile species) sold by traditional health practitioners in urban South Africa, then used visual confirmation surveys, DNA barcoding and folk taxonomy to identify the herptile species that were on sale. Additionally, we interviewed 11 IsiZulu and SePedi speaking traditional health practitioners to document details of the collection and pricing of herptile specimens along with the practitioners' views of current conservation measures for traditional medicine markets. The 34 herptile species recorded in previous literature on traditional medicine markets included endangered and non-native species. Spectrophotometry measurements of the DNA we extracted from the tissue of herptiles used in traditional medicine were an unreliable predictor of whether those extractions would be suitable for further experimental work. From our initial set of 111 tissue samples, 81 sequencing reactions were successful and 55 of those sequences had species-level matches to COI reference sequences on the NCBI GenBank and/or BOLD databases. Molecular identification revealed that traditional health practitioners correctly labelled 77% of the samples that we successfully identified with DNA barcoding in this study. Our mixed methodology approach is useful for conservation planning as it updates knowledge of animal use in Indigenous remedies and can accurately identify species of high conservation priority. Furthermore, this study highlights the possibility of collaborative conservation planning with traditional health practitioners.

Multi-Omics Analysis in Mouse Primary Cortical Neurons Reveals Complex Positive and Negative Biological Interactions Between Constituent Compounds of Centella asiatica

Background: A water extract of the Ayurvedic plant Centella asiatica (L.) Urban, family Apiaceae (CAW), improves cognitive function in mouse models of aging and Alzheimer's disease and affects dendritic arborization, mitochondrial activity, and oxidative stress in mouse primary neurons. Triterpenes (TT) and caffeoylquinic acids (CQA) are constituents associated with these bioactivities of CAW, although little is known about how interactions between these compounds contribute to the plant's therapeutic benefit. Methods: Mouse primary cortical neurons were treated with CAW or equivalent concentrations of four TT combined, eight CQA combined, or these twelve compounds combined (TTCQA). Treatment effects on the cell transcriptome (18,491 genes) and metabolome (192 metabolites) relative to vehicle control were evaluated using RNAseq and metabolomic analyses, respectively. Results: Extensive differentially expressed genes (DEGs) were seen with all treatments, as well as evidence of interactions between compounds. Notably, many DEGs seen with TT treatment were not observed in the TTCQA condition, possibly suggesting CQA reduced the effects of TT. Moreover, additional gene activity seen with CAW as compared to TTCQA indicates the presence of additional compounds in CAW that further modulate TTCQA interactions. Weighted Gene Correlation Network Analysis (WGCNA) identified 4 gene co-expression modules altered by treatments that were associated with extracellular matrix organization, fatty acid metabolism, cellular response to stress and stimuli, and immune function. Compound interaction patterns were seen at the eigengene level in these modules. Interestingly, in metabolomics analysis, the TTCQA treatment saw the highest number of changes in individual metabolites (20), followed by CQA (15), then TT (8), and finally CAW (3). WGCNA analysis found two metabolomics modules with significant eigenmetabolite differences for TT and CQA and possible compound interactions at this level. Conclusions: Four gene expression modules and two metabolite modules were altered by the four treatment types applied. This methodology demonstrated the existence of both negative and positive interactions between TT, CQA, and additional compounds found in CAW on the transcriptome and metabolome of mouse primary cortical neurons.

Multi-omics analysis in mouse primary cortical neurons reveals complex positive and negative biological interactions between constituent compounds in Centella asiatica

Background

A water extract of the Ayurvedic plant Centella asiatica (CAW) improves cognitive function in mouse models of aging and Alzheimer's disease, and affects dendritic arborization, mitochondrial activity and oxidative stress in mouse primary neurons. Triterpenes (TT) and caffeoylquinic acids (CQA) are constituents associated with these bioactivities of CAW although little is known about how interactions between these compounds contribute to the plant's therapeutic benefit.

Methods

Mouse primary cortical neurons were treated with CAW, or equivalent concentrations of four TT combined, eight CQA combined, or these twelve compounds combined (TTCQA). Treatment effects on the cell transcriptome (18,491 genes) and metabolome (192 metabolites) relative to vehicle control were evaluated using RNAseq and metabolomic analyses respectively.

Results

Extensive differentially expressed genes (DEGs) were seen with all treatments, as well as evidence of interactions between compounds. Notably many DEGs seen with TT treatment were not observed in the TTCQA condition, possibly suggesting CQA reduced the effects of TT. Moreover, additional gene activity seen with CAW as compared to TTCQA indicate the presence of additional compounds in CAW that further modulate TTCQA interactions. Weighted Gene Correlation Network Analysis (WGCNA) identified 4 gene co-expression modules altered by treatments that were associated with extracellular matrix organization, fatty acid metabolism, cellular response to stress and stimuli, and immune function. Compound interaction patterns were seen at the eigengene level in these modules. Interestingly, in metabolomics analysis, the TTCQA treatment saw the highest number of changes in individual metabolites (20), followed by CQA (15), then TT (8) and finally CAW (3). WGCNA analysis found two metabolomics modules with significant eigenmetabolite differences for TT and CQA, and possible compound interactions at this level.

Conclusions

Four gene expression modules and two metabolite modules were altered by the four types of treatments applied. This methodology demonstrated the existence of both negative and positive interactions between TT, CQA and additional compounds found in CAW on the transcriptome and metabolome of mouse primary cortical neurons.

Centella asiatica and its caffeoylquinic acid and triterpene constituents increase dendritic arborization of mouse primary hippocampal neurons and improve age-related locomotion deficits in Drosophila

Introduction

Centella asiatica (CA) is known in Ayurvedic medicine as a rejuvenating herb with particular benefits in the nervous system. Two groups of specialized metabolites found in CA and purported to contribute to its beneficial effects are triterpenes (TTs) and caffeoylquinic acids (CQAs). In order to evaluate the role and interactions of TTs and CQAs in the effects of CA, we examined the neurotrophic effects of a water extract of CA (CAW) and combinations of its TT and CQA components in mouse primary hippocampal neurons in vitro and in Drosophila melanogaster flies in vivo.

Methods

Primary hippocampal neurons were isolated from mouse embryos and exposed in vitro for 5 days to CAW (50 μg/mL), mixtures of TTs, CQAs or TT + CQA components or to 4 TTs or 8 individual CQA compounds of CAW. Dendritic arborization was evaluated using Sholl analysis. Drosophila flies were aged to 28 days and treated for 2 weeks with CAW (10 mg/mL) in the food, mixtures of TTs, CQAs or TT + CQA and individual TT and CQA compounds. TTs and CQAs were tested at concentrations matching their levels in the CAW treatment used. After 2 weeks of treatment, Drosophila aged 42 days were evaluated for phototaxis responses.

Results

In mouse primary hippocampal neurons, CAW (50 μg/mL), the TT mix, CQA mix, all individual TTs and most CQAs significantly increased dendritic arborization to greater than control levels. However, the TT + CQA combination significantly decreased dendritic arborization. In Drosophila, a marked age-related decline in fast phototaxis response was observed in both males and females over a 60 days period. However, resilience to this decline was afforded in both male and female flies by treatment from 28 days onwards with CAW (10 mg/mL), or equivalent concentrations of mixed TTs, mixed CQAs and a TT + CQA mix. Of all the individual compounds, only 1,5-diCQA slowed age-related decline in phototaxis in male and female flies.

Discussion

This study confirmed the ability of CAW to increase mouse neuronal dendritic arborization, and to provide resilience to age-related neurological decline in Drosophila. The TT and CQA components both contribute to these effects but do not have a synergistic effect. While individual TTs and most individual CQAs increased dendritic arborization at CAW equivalent concentrations, in the Drosophila model, only 1,5-diCQA was able to slow down the age-related decline in phototaxis. This suggests that combinations (or potentially higher concentrations) of the other compounds are needed to provide resilience in this model.

Amelioration of age-related cognitive decline and anxiety in mice by Centella asiatica extract varies by sex, dose and mode of administration

Background: A water extract (CAW) of the Ayurvedic plant Centella asiatica administered in drinking water has been shown to improve cognitive deficits in mouse models of aging and neurodegenerative diseases. Here the effects of CAW administered in drinking water or the diet on cognition, measures of anxiety and depression-like behavior in healthy aged mice are compared. Methods: Three- and eighteen-month-old male and female C57BL6 mice were administered rodent AIN-93M diet containing CAW (0, 0.2, 0.5 or 1% w/w) to provide 0, 200 mg/kg/d, 500 mg/kg/d or 1,000 mg/kg/d CAW for a total of 5 weeks. An additional group of eighteen-month-old mice were treated with CAW (10 mg/mL) in their drinking water CAW for a total of 5 weeks to deliver the same exposure of CAW as the highest dietary dose (1,000 mg/kg/d). CAW doses delivered were calculated based on food and water consumption measured in previous experiments. In the fourth and fifth weeks, mice underwent behavioral testing of cognition, anxiety and depression (n = 12 of each sex per treatment group in each test). Results: Aged mice of both sexes showed cognitive deficits relative to young mice while only female aged mice showed increased anxiety compared to the young female mice and no differences in depression were observed between the different ages. CAW (1,000 mg/kg/d) in the drinking water improved deficits in aged mice in learning, executive function and recognition memory in both sexes and attenuated the increased measures of anxiety observed in the aged female mice. However, CAW in the diet only improved executive function in aged mice at the highest dose (1,000 mg/kg/d) in both sexes and did so less robustly than when given in the water. There were no effects of CAW on depression-like behavior in aged animals regardless of whether it was administered in the diet or the water. Conclusions: These results suggest that CAW can ameliorate age-related changes in measures of anxiety and cognition and that the mode of administration is important for the effects of CAW on resilience to these age-related changes.

The influence of exotic and native plants on illnesses with physical and spiritual causes in the semiarid region of Piauí, Northeast of Brazil

BACKGROUND

Local medical systems (LMS) include native and exotic plants used for the treatment of diseases of physical and spiritual nature. The incorporation of exotic plants into these systems has been the subject of many studies. In this context, an analysis was conducted on the influence of the origin of plants on diseases of physical and spiritual nature in order to evaluate the therapeutic versatility of native and exotic species in these therapeutic targets, to investigate whether exotic plants mainly fill gaps not met by native plants (diversification hypothesis), and identify which species are prioritized in the redundant targets in these two therapeutic groups in the rural community of Morrinhos, Monsenhor Hipólito, Piauí.

METHODS

Data collection took place in 2 stages. First, free lists and semi-structured interviews with local residents (n = 134) were conducted to survey plants used for therapeutic purposes and the associated illnesses. Then, another phase of interviews was carried out to evaluate the prioritization between native and exotic plants in redundant therapeutic targets. To test the diversification hypothesis (DH) in each group of illnesses, data were analyzed using generalized linear models (Poisson and Binomial GLMs); versatility was measured by the number of therapeutic indications and compared between resources using the Mann-Whitney test, and prioritization in each group was verified by comparing the proportions of native and exotic plants with the χ2 test.

RESULTS

One hundred and thirty-two species of plants were surveyed, being 71 exotic and 61 native, with indications for physical and spiritual illnesses. The results revealed that the diversification hypothesis did not explain the inclusion of exotic plants in the local medical system to treat physical or spiritual illnesses and that the therapeutic versatility of exotic and native resources in the two groups was also similar (p > 0.05). However, exotic plants were prioritized in illnesses with physical causes and native plants in illnesses with spiritual causes.

CONCLUSIONS

The local medical system presents similar and distinct patterns in the therapeutic targets, depending on the perspective evaluated. Therefore, it is necessary to investigate the patterns of use of medicinal plants in different sociocultural contexts in order to broaden the debate about the role of plant origin in the selection of treatments for illnesses with different causes.

Amelioration of age-related cognitive decline and anxiety in mice by Centella asiatica extract varies by sex, dose and mode of administration

We have previously reported that a water extract (CAW) of the Ayurvedic plant Centella asiatica administered in drinking water can improve cognitive deficits in mouse models of aging and neurodegenerative diseases. Here we compared the effects of CAW administered in drinking water or the diet on cognition, measures of anxiety and depression-like behavior in healthy aged mice. Three- and eighteen-month-old male and female C57BL6 mice were administered rodent AIN-93M diet containing CAW (0, 0.2, 0.5 or 1% w/w) to provide 0, 200 mg/kg/d, 500 mg/kg/d or 1000 mg/kg/d for a total of 5 weeks. An additional group of eighteen-month-old mice were treated with CAW (10 mg/mL) in their drinking water for a total of five weeks to deliver the same exposure of CAW as the highest dietary dose (1000 mg/kg/d). CAW doses delivered were calculated based on food and water consumption measured in previous experiments. In the fourth and fifth weeks, mice underwent behavioral testing of cognition, anxiety and depression (n=12 of each sex per treatment group in each test). Aged mice of both sexes showed cognitive deficits relative to young mice while only female aged mice showed increased anxiety compared to the young female mice and no differences in depression were observed between the different ages. CAW (1000 mg/kg/d) in the drinking water improved deficits in aged mice in learning, executive function and recognition memory in both sexes and attenuated the increased measures of anxiety observed in the aged female mice. However, CAW in the diet only improved executive function in aged mice at the highest dose (1000 mg/kg/d) in both sexes and did so less robustly than when given in the water. There were no effects of CAW on depression-like behavior in aged animals regardless of whether it was administered in the diet or the water. These results suggest that CAW can ameliorate age-related changes in measures of anxiety and cognition and that the mode of administration is important for the effects of CAW on resilience to these age-related changes.

Interactions between local medical systems and the biomedical system: a conceptual and methodological review in light of hybridization subprocesses

Local medical systems (LMSs) are complex and dynamic, encompassing local perceptions of diseases, prevention and treatment strategies, and evaluations of therapeutic responses. These systems are not isolated and interact with other medical systems, such as the biomedical system. The interaction between these systems creates a "contact zone", which some authors refer to as intermedicality, involving both competitive and complementary interactions. However, there is limited discussion in the literature regarding the complexity of these interactions. Some studies seek to understand this interaction through the lens of hybridization, a concept introduced to ethnobiology by Ana Ladio and Ulysses Albuquerque. The authors conceptualize hybridization as "discrete structures and practices coming together to form a new practice not necessarily implying homogenization." They discuss hybridization in the context of medicinal plants used in urban settings and propose seven hybridization subprocesses to gain a deeper understanding of this phenomenon. In this study, we update these hybridization subprocesses, expanding the concepts to comprehend the specific interaction of resources from LMS and biomedical systems known and used by different human groups. In this context, we propose a new subprocess and have made adjustments to the existing subprocesses to encompass the diversity of possible interactions between medicinal plants and pharmaceuticals, providing evidence from the literature demonstrating interactions that can be classified within the proposed subprocesses. Furthermore, we discuss, from a theoretical standpoint, how these subprocesses may have implications for the resilience of medical systems. Moreover, we propose a flowchart that can be utilized to identify these hybridization subprocesses in intermedicality contexts in future studies. These classifications are crucial because they enable us to comprehend the complexity of interactions between medicinal plants and pharmaceuticals, as well as the impacts that these different interactions can have on the resilience of LMSs.

Short-term temporal analysis and children's knowledge of the composition of important medicinal plants: the structural core hypothesis

BACKGROUND

Measures of the importance of medicinal plants have long been used in ethnobotany and ethnobiology to understand the influence of social-ecological system factors in the formation of individuals' differential knowledge and use. However, there is still a gap in empirical studies that seek to understand the temporal aspects of this process.

METHODS

To overcome this issue, we used the concept of the structural core of medicinal plants, a theoretical-evolutionary model, which argues that the importance of medicinal plant resources is related to the increase in individual and population fitness. It represents the set of the most effective and available resources that would treat the most common diseases in an environment. This composition of knowledge would be conservative over space and time. To test these questions, we hypothesized that the composition of the structural core remains constant during temporal changes in a social-ecological context, and that the composition of the infantile structural core (new generation) is similar to that of the adults (older generation). For 2 years, we tracked the structure of important medicinal plants among the same 49 residents of a community located in Vale do Catimbau in Pernambuco, Brazil. We also compared the importance of the medicinal plants among two different generations, children/adolescents and adults, in the same space/time context.

RESULTS AND CONCLUSION

Our results refuted both hypotheses. Regarding the composition of important medicinal plants through temporal variations and for children's learning, our results were not predicted by the model. This suggests that the structural core should not be regarded as a conservative phenomenon, but rather a congenital, dynamic, and plastic occurrence that has adapted to configure itself as a short-term population response to the treatment of local diseases.

Utilitarian redundancy in local medical systems - theoretical and methodological contributions

The utilitarian redundancy model (URM) is one of the recent contributions to ethnobiology. We argue that URM can be applied to access use-pressure on plant species, the resilience of socioecological systems (e.g., local medical systems), cultural keystone species, and the role of exotic species in social-ecological systems. Based on previous URM studies, we also emphasize the need to differ practical (considering plants and uses that are currently employed) and theoretical (considering both currently employed and potentially employed plants and uses) redundancy. Based on the main applications of the URM, we propose a new index to access redundancy of a therapeutic indication: the Uredit, so that Uredit = NSp + CR, were Uredit is the Utilitarian Redundancy Index for the therapeutic indication; NSp is the total number of species mentioned for the indication, and CR is the species' contribution to redundancy (in terms of knowledge sharing). The maximum value that the Uredit could reach is twice the number of species employed for the therapeutic indication. We believe that this theoretical and methodological improvement in the model can improve comparisons of redundancy in different social-ecological systems. We also highlight some limitations of the URM (and our Uredit), and we believe that conscious reasons behind people's decisions should be incorporated into future studies on the subject.

Gender and Its Role in the Resilience of Local Medical Systems of the Fulni-ô People in NE Brazil: Effects on Structure and Functionality

Ethnobotanical studies focused on understanding how local medical systems are functionally maintained suggest that utilitarian redundancy and knowledge transmission are factors that influence the resilience of the system. However, to date, there have not been any studies that analyze these factors in relation to the variables that influence the variation of knowledge. Given the above, this study aims to analyze the influence of gender in the resilience of the system, using utilitarian redundancy and knowledge transmission as factors. Information from 198 married couples (396 people) was collected from the indigenous community of Fulni-ô (NE Brazil). Knowledge between men and women was analyzed based on the total number of known plants, therapeutic targets, information units, utilitarian redundancy, models of transmission, and sharing for each gender. Fulni-ô men know a greater number of plants, therapeutic targets treated with plants, and information units than women. They also had greater utilitarian redundancy. However, regarding knowledge transmission, sharing among women was greater, transmission is related to gender, and there is no difference between the numbers of models of knowledge information. In the system of local medical knowledge, gender exerts an important role in the resilience of the system. This study shows that men have a greater contribution to the structure and function of the system; however, both genders contribute to the flow of information in the system, which makes both genders important in the feedback of information.

Factors in hybridization of local medical systems: Simultaneous use of medicinal plants and modern medicine in Northeast Brazil

The presence of mainstream medicine in local medical systems inserts a set of external treatments and concepts that generate adjustments in the local conceptions of health and disease. What points in the system are most receptive to change? Who are the residents most likely to adopt these external treatments to deal with diseases? To answer these questions, this work used a study model consisting of the simultaneous use of medicinal plants and modern medicine, testing whether diseases that require greater treatment efforts are the main targets of adherence to modern medicine and if socioeconomic characteristics of residents can cause intracultural variation in relation to simultaneous use. To obtain socioeconomic data on the knowledge of medicinal plants and simultaneous use of these resources with modern medicine, semistructured interviews were conducted in a rural community that has easy access to modern medicine. Participatory workshops were held to access the local perceptions about the frequency of occurrence and severity of illnesses. A multilevel logistic regression model was applied for data analysis. We found that chronic, severe and frequently occurring diseases in the community tended to show greater simultaneous use locally. Among the socioeconomic factors, we determined that high educational levels positively influenced the combined use of plants and modern medicine. The need to ensure the cure of frequent, severe and chronic diseases is a factor that leads residents to seek a greater number of possible treatments, stimulating the combined use of plants and modern medicine. Residents with higher educational levels were more likely to use a combination of treatments than those with lower educational levels, demonstrating that more participation in formal education may facilitate the combined use of medicinal plants and modern medicine.

Ethnomedicinal applications of animal species by the local communities of Punjab, Pakistan

BACKGROUND

Different species of animals are being utilized in traditional therapies by various cultures for a long time and such uses still exist in folk medicine. The present study aimed to document animal-based traditional therapies used by the local communities of Jhelum and Lahore districts of the Punjab province, Pakistan.

METHODS

Field surveys were conducted in 2015-2016 in six different sites of the study areas. Data were collected through semi-structured interviews and face to face conversation with local informants.

RESULTS

The ethnomedicinal uses of 57 species of animals including mammals, birds, fish, reptiles, amphibian, and invertebrates (30, 25, 25, 7, 3.5, and 3.5%, respectively) were documented. Meat, oil, brain, fats, milk, eggs, and skin were the most utilized body parts. Ovis orientalis punjabiensis, Francolinus francolinus, Sperata sarwari, Channa punctata, Oreochromis niloticus, Ctenopharyngodon idella, Cyprinus carpio, Labeo rohita, and Carassius auratus were reported for the first time to treat human diseases, i.e., allergy, epilepsy, fever, joint pain, and backache, to act as aphrodisiac, and to enhance memory. Streptopelia decaocto and S. tranquebarica were the most frequently utilized species with highest frequency of citation (32 for each). Columba livia depicted highest fidelity level and used value of 92.86% and 0.89, respectively.

CONCLUSIONS

Being agro-pastoralists, the inhabitants of Jhelum possess more traditional knowledge compared to Lahore. The present study could be important for conservation and sustainable use of animal biodiversity in this region. Additionally, detailed study on chemical profiling and bioactivities may lead to animal-based novel drug discovery.

[The use of animal-assisted therapy: a bioethical question]

This paper addresses ethical questions concerning animal-assisted therapy (zootherapy). While it has been documented for centuries in several cultures and is resistant to urban and technological developments, it combines multiple moral and vulnerable agents, constituting a dilemma whose fair and consensual solution calls for new perspectives, like environmental bioethics. Through analyses of scientific texts, the arguments and values intrinsic to decisions about how and when to use animals as medical resources are systematized. Using bioethics as a method, reflections are offered about the potential solutions dependent on the multidimensional communication between the players from the three pillars of sustainability - environment, society, and economy - involved in this global ethical question, focusing on conservation and sustainable production.

Evolutionary ethnobiology and cultural evolution: opportunities for research and dialog

The interest in theoretical frameworks that improve our understanding of social-ecological systems is growing within the field of ethnobiology. Several evolutionary questions may underlie the relationships between people and the natural resources that are investigated in this field. A new branch of research, known as evolutionary ethnobiology (EE), focuses on these questions and has recently been formally conceptualized. The field of cultural evolution (CE) has significantly contributed to the development of this new field, and it has introduced the Darwinian concepts of variation, competition, and heredity to studies that focus on the dynamics of local knowledge. In this article, we introduce CE as an important theoretical framework for evolutionary ethnobiological research. We present the basic concepts and assumptions of CE, along with the adjustments that are necessary for its application in EE. We discuss different ethnobiological studies in the context of this new framework and the new opportunities for research that exist in this area. We also propose a dialog that includes our findings in the context of cultural evolution.