The subsistence technology of forager communities has varied greatly over space and time. This paper (i) reviews briefly the main causal factors the literature identifies as responsible for this variation; (ii) analyzes in some detail the most prominent idea in the literature on spatial variation:Complex technology is an adaptive response to elevated risks of subsistence failure; (iii) it argues that the alleged empirical support for this hypothesis depends on dubious proxies of risk; (iv) it argues that it fails to explain (...) the subsistence technologies of desert foragers, who generally live with simple technologies in high‐risk environments; (v) it offers an alternative analysis, based on the reduced opportunity costs of complex technologies in highly seasonal environments, on the high value of typical forager targets in those environments and their relatively predictable location in space and time; and (v) the paper concludes with a conjecture about the role of environmental variation in toolkit change over deep time. (shrink)

Foraging‐ and feeding‐related behaviors across eumetazoans share similar molecular mechanisms, suggesting the early evolution of an optimal foraging behavior called area‐restricted search (ARS), involving mechanisms of dopamine and glutamate in the modulation of behavioral focus. Similar mechanisms in the vertebrate basal ganglia control motor behavior and cognition and reveal an evolutionary progression toward increasing internal connections between prefrontal cortex and striatum in moving from amphibian to primate. The basal ganglia in higher vertebrates show the ability to transfer dopaminergic activity from (...) unconditioned stimuli to conditioned stimuli. The evolutionary role of dopamine in the modulation of goal‐directed behavior and cognition is further supported by pathologies of human goal‐directed cognition, which have motor and cognitive dysfunction and organize themselves, with respect to dopaminergic activity, along the gradient described by ARS, from perseverative to unfocused. The evidence strongly supports the evolution of goal‐directed cognition out of mechanisms initially in control of spatial foraging but, through increasing cortical connections, eventually used to forage for information. (shrink)

When searching for concepts in memory—as in the verbal fluency task of naming all the animals one can think of—people appear to explore internal mental representations in much the same way that animals forage in physical space: searching locally within patches of information before transitioning globally between patches. However, the definition of the patches being searched in mental space is not well specified. Do we search by activating explicit predefined categories and recall items from within that category, or do we (...) activate and recall a connected sequence of individual items without using categorical information, with each item recalled leading to the retrieval of an associated item in a stream, or both? Using semantic representations in a search of associative memory framework and data from the animal fluency task, we tested competing hypotheses based on associative and categorical search models. Associative, but not categorical, patch transitions took longer to make than position-matched productions, suggesting that categorical transitions were not true transitions. There was also clear evidence of associative search even within categorical patch boundaries. Furthermore, most individuals' behavior was best explained by an associative search model without the addition of categorical information. Thus, our results support a search process that does not use categorical information, but for which patch boundaries shift with each recall and local search is well described by a random walk in semantic space, with switches to new regions of the semantic space when the current region is depleted. (shrink)

In this study, we used a word search puzzle paradigm to investigate age differences in the rate of information gain and the cues used to make patch-departure decisions in information foraging. The likelihood of patch departure increased as the profitability of the patch decreased generally. Both younger and older adults persisted past the point of optimality as defined by the marginal value theorem, which assumes perfect knowledge of the foraging ecology. Nevertheless, there was evidence that adults were rational in terms (...) of being sensitive to the change in RG for making the patch-departure decisions. However, given the limitations in cognitive resources and knowledge about the ecology, the estimation of RG may not be accurate. Younger adults were more likely to leave the puzzle as the long-term RG incrementally decreased, whereas older adults were more likely to leave the puzzle as the local RG decreased. However, older adults with better executive control were more likely to adjust their likelihood of patch-departure decisions to the long-term change in RG. Thus, age-dependent reliance on the long-term or local change in RG to make patch-departure decisions might be due to individual differences in executive control. (shrink)

Foraging for coherence is a pragmatist philosophy of the brain. It is a philosophy anchored to objects and instrumental in understanding the brain. Our age is dominated by neuroscience. A critical common sense underlies inquiry including that of neuroscience. Thus a pragmatist orientation to neuroscience is about foraging for coherence; not overselling neuroscience. Foraging for coherence is the search for adaptation – diverse epistemic orientation tied ideally to learning about oneself, one’s nature, and one’s history in the context of learning (...) about the brain. Neuroscience is about us: Our desires, habits, styles of reason, human vulnerability, and abuse. The language of the neuron, or the gene, or the systems does not replace the discussion about us as the person, in the social and historical context. (shrink)

Food uncertainty has the effect of invigorating food-related responses. Psychologists have noted that mammals and birds respond more to a conditioned stimulus that unreliably predicts food delivery, and ecologists have shown that animals consume and/or hoard more food and can get fatter when access to that resource is unpredictable. Are these phenomena related? We think they are. Psychologists have proposed several mechanistic interpretations, while ecologists have suggested a functional interpretation: The effect of unpredictability on fat reserves and hoarding behavior is (...) an evolutionary strategy acting against the risk of starvation when food is in short supply. Both perspectives are complementary, and we argue that the psychology of incentive motivational processes can shed some light on the causal mechanisms leading animals to seek and consume more food under uncertainty in the wild. Our theoretical approach is in agreement with neuroscientific data relating to the role of dopamine, a neurotransmitter strongly involved in incentive motivation, and its plausibility has received some explanatory and predictive value with respect to Pavlovian phenomena. Overall, we argue that the occasional and unavoidable absence of food rewards has motivational effects that facilitate foraging effort. We show that this hypothesis is computationally tenable, leading foragers in an unpredictable environment to consume more food items and to have higher long-term energy storage than foragers in a predictable environment. (shrink)

Research in evolutionary ecology on random foraging seems to ignore the possibility that some random foraging is an adaptation not to environmental randomness, but to what Wimsatt called “perceived randomness”. This occurs when environmental features are unpredictable, whether physically random or not. Mere perceived randomness may occur, for example, due to effects of climate change or certain kinds of static landscape variation. I argue that an important mathematical model concerning random foraging doesn’t depend on environmental randomness, despite contrary remarks by (...) researchers. I use computer simulations to illustrate the idea that random foraging is an adaptation to mere perceived randomness. (shrink)

This paper presents quantitative data on altruistic cooperation during food acquisition by Ache foragers. Cooperative activities are defined as those that entail a cost of time and energy to the donor but primarily lead to an increase in the foraging success of the recipient. Data show that Ache men and women spend about 10% of all foraging time engaged in altruistic cooperation on average, and that on some days they may spend more than 50% of their foraging time in (...) such activities. The most time-consuming cooperative activity for both sexes is helping during the pursuit of game animals, a pattern that is probably linked to the widespread sharing of game by Ache foragers. Cooperative food acquisition and subsequent food redistribution in hunter-gatherer societies are critical behaviors that probably helped shape universal, evolved, cooperative tendencies that are well illustrated in modern experimental economics. (shrink)

Foraging is a central competence of all mobile organisms. Models and concepts from foraging theory have been applied widely throughout biology to the search for many kinds of external resources, including food, sexual encounters, minerals, water, and the like. In cognitive science and neuroscience, the tools of foraging theory are increasingly applied to a wide range of other types of search, including for abstract resources like information or for internal resources like memories, concepts, and strategies for problem solving. Despite its (...) importance in ecology and increasing relevance for the study of cognition, the concept of foraging is rarely analyzed. Here, I aim to rectify this situation. I outline three desiderata: first, an analysis should differentiate foraging from search and decision making more generally; second, an analysis should unify different types of foraging; and third, an analysis should help ground predictions. I present an analysis of foraging as the serial search for general resources in accept-or-reject, exclusive, persistent decision contexts. Not all search is serial and not all decision making is exclusive, differentiating foraging from search and decision making generally. With the aid of Markov decision processes and directed cyclical models, I show how the analysis implies a cyclical graph. This cyclical graph is embedded in the description of many types of foraging, unifying the different instances. Finally, I argue that the cyclical graph is also embedded in representations of novel task contexts that have not previously been viewed as foraging. I illustrate this novel application of the concept of foraging by arguing that reasoning is a type of foraging. (shrink)

The necessity of incorporating societal and environmental concerns into publicly funded agricultural initiatives in research, extension, and practice is increasingly evident. Agriculturalists are urged to acknowledge and respond to societal concerns before an insensitive and largely ill-informed urban majority assumes a dominant posture in agricultural policy. In recent history, the availability of unrealistically cheap energy encouraged the evolution of a form of commercial agriculture unfettered by sound ecological principles. At present, external, resource-intensive intervention of increasing magnitude is needed to compensate (...) for the apparent ecological instability generated by practices such as intensive cereal management or conservation tillage practices. Polarization of the enterprises of plant and animal agriculture to enable centralized, concentrate-intensive, confinement feeding has disrupted the natural cycling of nutrients and carbon in the soil, encouraged the withdrawal of perennial forages from crop rotations, and invoked a widely ramifying network of agricultural and societal problems. Solutions to these problems must evolve from a holistic and far-reaching appraisal of causes, rather than from a piecemeal approach to individual symptoms. (shrink)

Identifying the determinants of reproductive success in small-scale societies is critical for understanding how natural selection has shaped human evolution and behavior. The available evidence suggests that status-accruing behaviors such as hunting and prosociality are pathways to reproductive success, but social egalitarianism may diminish this pathway. Here we introduce a mixed longitudinal/cross-sectional dataset based on 45 years of research with the Batek, a population of egalitarian rain forest hunter-gatherers in Peninsular Malaysia, and use it to test the effects of four (...) predictors of lifetime reproductive success: foraging return rate, sharing proclivity, cooperative foraging tendency, and kin presence. We found that none of these factors can explain variation in lifetime reproduction among males or females. We suggest that social egalitarianism, combined with strikingly low infant and juvenile mortality rates, can mediate the pathway between foraging, status-accruing behavior, and reproductive success. Our approach advocates for greater theoretical and empirical attention to quantitative social network measures, female foraging, and fitness outcomes. (shrink)

Rendell and Whitehead argue persuasively that individual foraging specializations, if socially learned, are examples of cetacean culture. However, they discount ecological variation experienced by individuals within a population as a factor in such behavior. I suggest that ecological variation may play an important role in individual foraging specializations and describe several ecological parameters that may help us understand the high frequency of this interesting behavior in the marine habitat.

This study sheds a light on economic roots of optimal foraging/mating theory. Two examples show graphical optimisation models of behavioural ecology that are identical to much older ones of economics. The knowledge transfer has been conscious and explicit in some cases, but also less visible in others. This does no imply plagiarism or misconduct but merely shows how knowledge can diffuse along obscure, sometimes unconscious, routes of non-public and private communication.

We are economists with a long-standing interest in evolutionary psychology, who recently came to appreciate the rich collections of relevant data cultural anthropologists have spent decades collecting on the social environments of a wide range of human societies. While we found some systematic collections of these observations, we could not find a systematic summary of the social environment of the subsample of societies that most resemble the social environment where most human psychology seems to have evolved: small bands of nomadic (...) foragers. This short paper therefore represents our attempt to create such a summary. Using an existing dataset aggregated from diverse ethnographies, we collect statistics on the social environment of the studied cultures which most closely resemble our hunter-gatherer ancestors. Compared with relatively modern societies, nomadic foragers had similar levels of food and disease, and less murder and suicide. They did not fight over land or resources, and they enforced justice directly and personally. They avoided class divisions like rich vs. poor, shared food more, and their leaders had no formal powers. Polygamy, premarital sex, and extramarital sex were all widespread, divorce was easy, and men and women were generally considered equal. Kids were taught to be more generous, trusting, and honest, and were never punished physically. (shrink)

This article describes rational analyses and cognitive models of Web users developed within information foraging theory. This is done by following the rational analysis methodology of (a) characterizing the problems posed by the environment, (b) developing rational analyses of behavioral solutions to those problems, and (c) developing cognitive models that approach the realization of those solutions. Navigation choice is modeled as a random utility model that uses spreading activation mechanisms that link proximal cues (information scent) that occur in Web browsers (...) to internal user goals. Web‐site leaving is modeled as an ongoing assessment by the Web user of the expected benefits of continuing at a Web site as opposed to going elsewhere. These cost–benefit assessments are also based on spreading activation models of information scent. Evaluations include a computational model of Web user behavior called Scent‐Based Navigation and Information Foraging in the ACT Architecture, and the Law of Surfing, which characterizes the empirical distribution of the length of paths of visitors at a Web site. (shrink)

Moral foundations theory (MFT) proposes the existence of innate psychological systems, which would have been subjected to selective forces over the course of evolution. One approach for evaluating MFT, therefore, is to consider the proposed psychological foundations in relation to the reconstructed Environment of Evolutionary Adaptedness. This study draws upon ethnographic data on nomadic forager societies to evaluate MFT. Moral foundations theory receives support only regarding the Caring/harm and Fairness/cheating foundations but not regarding the proposed Loyalty/betrayal and Authority/subversion foundations. These (...) latter two proposed foundations would seem to reflect the historical classic assumptions of modernity, involving self-interest, competition, individualism, hierarchy, authority and so forth. Studying the ethical dimensions of nomadic forager societies can highlight our biases about the foundations of morality, some of which may be steeped in particularist Western political and social traditions. Some recent developments from cosmopolitanism are discussed as an alternative evolving worldview that parallels nomadic forager ethos. (shrink)

Using simple stochastic models, we discuss how cooperative breeders, especially wasps and bees, can improve their productivity by reducing foraging work. In a harsh environment, where foraging is the main cause of mortality, such breeders achieve greater productivity by reducing their foraging effort below full capacity, and they may thrive by adopting cooperative breeding. This could prevent the population extinction of cooperative breeders under conditions where a population of lone breeders cannot be maintained.

Fodor (1990) argues that the theory of evolution by natural selection will not help to save naturalistic accounts of representation from the disjunction problem. This is because, he claims, the context 'was selected for representing things as F' is transparent to the substitution of predicates coextensive with F. But, I respond, from an evolutionary perspective representational contexts cannot be transparent: only under particular descriptions will a representational state appear as a "solution" to a selection "problem" and so be adaptive. Only (...) when we construe representational states as opaque in this manner are the generalizations of branches of evolutionary theory, like foraging theory, possible. (shrink)

The Hadza foragers of Tanzania are currently experiencing a nutritional shift that includes the intensification of domesticated cultigens in the diet. Despite these changes, no study, to date, has examined the possible effects of this transition on the food collection behavior of young foragers. Here we present a cross-sectional study on foraging behavior taken from two time points, 2005 and 2017. We compare the number of days foraged and the type and amount of food collected for young (...) class='Hi'>foragers, aged 5–14 years, in age- and season-matched samples. Compared with 2005, in 2017 fewer subadults left camp to forage, and overall, they targeted a smaller variety of wild foods, with the noticeable absence of wild honey, figs, and tubers. In addition, participants in 2017 were significantly more likely to have attended school. Despite the increased presence of domesticated plant foods in the diet and increased attendance at school, some young foragers continue to be highly productive in collecting wild, undomesticated foods. Despite the preliminary nature of our results, our findings suggest that the range of wild foods targeted by subadults is decreasing as the amount of domesticated cultigens in the diet increases. These data underscore the importance of studying diet composition and foraging decisions across temporal, nutritional, and ecological landscapes. (shrink)

Even though female food acquisition is an area of considerable interest in hunter-gatherer research, the ecological determinants of women’s economic decisions in these populations are still poorly understood. The literature on female foraging behavior indicates that there is considerable variation within and across foraging societies in the amount of time that women spend foraging and in the amount and types of food that they acquire. It is possible that this heterogeneity reflects variation in the trade-offs between time spent in food (...) acquisition and child care activities that women face in different groups of hunter-gatherers. In this paper we discuss the fitness trade-offs between food acquisition and child care that Hiwi and Ache women foragers might face. Multiple regression analyses show that in both populations the daily food acquisition of a woman’s spouse is negatively related to female foraging effort. In addition, nursing mothers spend less time foraging and acquire less food than do nonnursing women. As the number of dependents that a woman has increases, however, women also increase foraging time and the amount of food they acquire. Some interesting exceptions to these general trends are as follows: (a) differences in foraging effort between nursing and nonnursing women are less pronounced when fruits and roots are in season than in other seasons of the year; (b) foraging return rates decrease for Ache women as their numbers of dependents increase; and (c) among Ache women, the positive effect of number of dependents on foraging behavior is less pronounced when fruits are in season than at other times of the year. Lastly, in the Hiwi sample we found that postreproductive women work considerably harder than women of reproductive age in the root season but not in other seasons of the year. We discuss how ecological variation in constraints, the number of health insults to children that Hiwi and Ache mothers can avoid, and the fitness benefits they can gain from spending time in food acquisition and child care might account for differences and similarities in the foraging behaviors of subgroups of Hiwi and Ache mothers across different seasons of the year. Valid tests of the explanations we propose will require considerable effort to measure the relationship between maternal food acquisition, child care, and adverse health outcomes in offspring. (shrink)

This paper examines the social, ethical, and governance implications of introducing AI- and drone-based automation into wild berry foraging in Finland. Drawing on expert interviews and Science and Technology Studies (STS), particularly sociotechnical imaginaries and co-production, it focuses on an efficiency-driven imaginary embedded in the FEROX project, where automation and data-driven optimisation are positioned as solutions to labour shortages and underutilised forest resources. Rather than analysing this imaginary in isolation, the paper shows how it becomes disrupted when confronted with shifting (...) labour conditions, cultural practices, and environmental values. Interview findings from foragers, engineers, ethicists, and forest scientists reveal how AI-enabled technologies intersect with existing socioecological dynamics in ways that generate tension and contestation. In particular, recent restrictions on seasonal migrant labour expose the fragility of assumptions underpinning the system, while local traditions, ecological ethics, and concerns about surveillance and data governance challenge efficiency-oriented approaches to automation. The paper argues that AI-enabled foraging technologies are not neutral tools but are shaped by, and reshape, the social and ecological contexts in which they are deployed. By foregrounding these tensions, it calls for participatory, culturally informed, and ecologically sensitive approaches to AI design and governance in natural resource settings. (shrink)

A widespread perception is that carnivores are limited by the amount of prey that can be captured rather than their nutritional quality, and thus have no need to regulate macronutrient balance. Contrary to this view, recent laboratory studies show macronutrient‐specific food selection by both invertebrate and vertebrate predators, and in some cases also associated performance benefits. The question thus arises of whether wild predators might likewise feed selectively according to the macronutrient content of prey. Here we review laboratory studies demonstrating (...) the regulation of macronutrient intake by invertebrate and vertebrate predators, and address the question of whether this is likely to also occur in the wild. We conclude that it is highly likely that wild predators select prey or selectively feed on body parts according to their macronutrient composition, a possibility that could have significant implications for ecological and foraging theory, as well as applied wildlife conservation and management. (shrink)

We come prepared to track events and objects, building our knowledge base while foraging for coherence. Classical pragmatism recognizes that the acquisition of knowledge is in part a contact sport (e.g. Peirce, Dewey). One of the aims of neuroscience is to capture human experience. One route to perhaps achieve this may be through the study of the visual system and its expansion in our evolutionary history. Embodied cephalic systems, as Dewey knew well, are tied to self-corrective inquiry. A philosophy of (...) neuroscience needs to capture how such events are tracked, tested through experience, and subsequently modified in the brain to comprise a knowledge base. (shrink)

Animals depleting one patch of resources must decide when to leave and switch to a fresh patch. Foraging theory has predicted various decision mechanisms; which is best depends on environmental variation in patch quality. Previously we tested whether these mechanisms underlie human decision making when foraging for external resources; here we test whether humans behave similarly in a cognitive task seeking internally generated solutions. Subjects searched for meaningful words made from random letter sequences, and as their success rate declined, they (...) could opt to switch to a fresh sequence. As in the external foraging context, time since the previous success and the interval preceding it had a major influence on when subjects switched. Subjects also used the commonness of sequence letters as a proximal cue to patch quality that influenced when to switch. Contrary to optimality predictions, switching decisions were independent of whether sequences differed little or widely in quality. (shrink)

Recent studies of semantic memory have investigated two theories of optimal search adopted from the animal foraging literature: Lévy flights and marginal value theorem. Each theory makes different simplifying assumptions and addresses different findings in search behaviors. In this study, an experiment is conducted to test whether clustering in semantic memory may play a role in evidence for both theories. Labeled magnets and a whiteboard were used to elicit spatial representations of semantic knowledge about animals. Category recall sequences from a (...) separate experiment were used to trace search paths over the spatial representations of animal knowledge. Results showed that spatial distances between animal names arranged on the whiteboard were correlated with inter-response intervals during category recall, and distributions of both dependent measures approximated inverse power laws associated with Lévy flights. In addition, IRIs were relatively shorter when paths first entered animal clusters, and longer when they exited clusters, which is consistent with marginal value theorem. In conclusion, area-restricted searches over clustered semantic spaces may account for two different patterns of results interpreted as supporting two different theories of optimal memory foraging. (shrink)

Western scholarly literature suggests that (1) weaning is initiated by mothers; (2) weaning takes place within a few days once mothers decide to stop nursing; (3) mothers employ specific techniques to terminate nursing; (4) semi-solid foods (gruels and mashed foods) are essential when weaning; (5) weaning is traumatic for children (it leads to temper tantrums, aggression, etc.); (6) developmental stages in relationships with mothers and others can be demarcated by weaning; and (7) weaning is a process that involves mothers and (...) children exclusively, with weaned children moving from close relationships with their mothers to strengthened relationships with other children. In many respects, these presumptions are consistent with contemporary Euroamerican practices: nursing stops early (usually before six months) relative to other cultures and takes place over a few days or weeks with the help of bottles and baby foods. Because bottles are available, weaning seldom appears traumatic, but it is seen as an important step in the establishment of independence between mothers and infants. By contrast, weaning from the bottle is often perceived as traumatic. Despite considerable academic and popular interest, weaning has seldom been studied systematically, especially in small-scale cultures. Qualitative and quantitative data from a study of Bofi foragers in Central Africa are used here to evaluate the cross-cultural applicability of the assumptions summarized above. (shrink)

Given the complexity of human foraging strategies, especially hunting, recent attention has focused on the ways in which hunters acquire needed knowledge and skills, including via social learning. One potentially useful heuristic is a “conformist bias,” in which individuals identify and adopt the most common beliefs or strategies, but the usefulness of this heuristic depends on the accuracy of the information. In this study, 45 indigenous Mayangna and Miskito informants in Nicaragua were asked to rank 17 game species on the (...) extent to which harvests of these species are associated with the use of hunting dogs. Consensus analysis indicates that there is high agreement on the rankings, and the aggregated rankings closely reflect harvest data from a yearlong study that documented the use of dogs and other hunting accessories (e.g., firearms). There were noteworthy outliers in the analysis, however, and a possible explanation is that informants are inferring that dogs are useful for some species because they are valuable for hunting perceptually similar species, as revealed by pile sort data. In addition, the consensus analysis reveals sex-related subgroup agreement in the rankings, but the aggregated rankings of neither men nor women seem to more closely correspond to the harvest data. Overall, these results suggest that a conformist learning bias could allow novice hunters to acquire information that would promote optimizing hunting strategies. (shrink)

Mata and von Helversen's integrative review of adult age differences in search performance makes a good case that cognitive control may impact certain aspects of self-regulation of search. However, information foraging as a framework also offers an avenue to consider how adults of different ages adapt to age-related changes in cognition, such as in cognitive control.

This paper presents a stylized bioeconomic model of hunter-gatherer foraging effort designed to study the process of intensification on open-access resources. A critical insight derived from the model is that the very success of an adaptation at the level of an individual forager group can create system-level vulnerabilities that subsequently feed back to cause emergent social change. The model illustrates how the intensification of harvest time by individuals within a habitat creates a forager-resource system that becomes vulnerable to perturbations. When (...) the system is vulnerable, it is characterized by two resource harvest equilibria: a sustainable, low-effort equilibrium and a degraded, high-effort equilibrium. In this situation, the forager-resource system can be shocked back and forth between these different equilibria by perturbations, generating considerable risk for foragers. We use the model to isolate the ecological conditions under which the instability of the system generates the risk that foragers will experience a shortfall of resources, and we suggest a mechanism that might lead foragers to adopt social institutions that regulate who can access a habitat as an adaptive response. As an illustration of the potential utility of the insights drawn from the model, comparisons are made with a substantial ethnographic data set. (shrink)

One of the major criticisms of optimal foraging theory (OFT) is that it is not testable. In discussions of this criticism opposing parties have confused methodological concepts and used meaningless biological concepts. In this paper we discuss such misunderstandings and show that OFr has an empirically testable, and even well-confirmed, general core theory. One of our main conclusions is that specific model testing should not be aimed at ‘proving’ optimality, but rather at identifying the context in which certain types of (...) behaviour are optimal. To do this, it is necessary to be aware of the assumptions made in testing a model. The assumptions that are explicitly stated in the literature up to now do not completely cover the actual assumptions made in testing OFT models in practice. We present a more comprehensive set of assumptions. Although all the assumptions play a role in testing models, they are not of equal status. Crucial assumptions concern constraints and the relation between fitness and currency. Therefore, it is essential to make such assumptions testable in practice. We show that a more explicit relationship between OFT modelling and evolutionary theory can help with this. Specifically, phylogeny reconstruction and population dynamic modelling can and should be used to formulate assumptions concerning constraints and currencies. (shrink)

A general framework for analysing the effects of variability and the effects of interruptions on foraging is presented. The animal is characterised by its level of energetic reserves, x. We consider behaviour over a period of time [0,T]. A terminal reward function R(x) determines the expected future reproductive success of an animal with reserves x at time T. For any state x at a time in the period, we give the animal a choice between various options and then constrain it (...) to follow a background strategy. The best option is the one that maximizes expected future reproductive success. Using this framework, we show that sensitivity to variability in amount of energy gained is logically distinct from sensitivity to variability in the time at which food is obtained. We also show that incorporating interruptions results in both a preference for variability in time and a preference for a reward followed by a delay as opposed to the same delay before the reward. (shrink)

The significance of teaching to the evolution of human culture is under debate. We contribute to the discussion by using a quantitative, cross-cultural comparative approach to investigate the role of teaching in the lives of children in two small-scale societies: Aka foragers and Ngandu farmers of the Central African Republic. Focal follows with behavior coding were used to record social learning experiences of children aged 4 to 16 during daily life. “Teaching” was coded based on a functional definition from (...) evolutionary biology. Frequencies, contexts, and subtypes of teaching as well as the identity of teachers were analyzed. Teaching was rare compared to observational learning, although both forms of social learning were negatively correlated with age. Children received teaching from a variety of individuals, and they also engaged in teaching. Several teaching types were observed, including instruction, negative feedback, and commands. Statistical differences in the distribution of teaching types and the identity of teachers corresponded with contrasting forager vs. farmer foundational cultural schema. For example, Aka children received less instruction, which empirically limits autonomous learning, and were as likely to receive instruction and negative feedback from other children as they were from adults. Commands, however, exhibited a different pattern suggesting a more complex role for this teaching type. Although consistent with claims that teaching is relatively rare in small-scale societies, this evidence supports the conclusion that teaching is a universal, early emerging cognitive ability in humans. However, culture structures the nature of teaching. (shrink)

A fundamental cognitive function found across a wide range of species and necessary for survival is the ability to navigate complex environments. It has been suggested that mobility may play an important role in the development of spatial skills. Despite evolutionary arguments offering logical explanations for why sex/gender differences in spatial abilities and mobility might exist, thus far there has been limited sampling from nonindustrialized and subsistence-based societies. This lack of sampling diversity has left many unanswered questions regarding the effects (...) that environmental variation and cultural norms may have in shaping mobility patterns during childhood and the development of spatial competencies that may be associated with it. Here we examine variation in mobility, performance on large-scale spatial skills, and performance on small-scale spatial skills among Twa forager/pastoralist children whose daily lives have been dramatically altered since settlement and the introduction of government-funded boarding schools. Unlike in previous findings among Twa adults, boys and girls show similar patterns of travel on all measures of mobility. We also find no significant differences in spatial task performance by gender for large- or small-scale spatial skills. Further, children performed as well as adults did on mental rotation, and they outperformed adults on the water-level task. We discuss how children’s early learning environments may influence the development of both large- and small-scale spatial skills. (shrink)