The evolution of early hominin food production and sharing.

How did humans evolve from individualistic to collective foraging with sex differences in production and widespread sharing of plant and animal foods? While current evolutionary scenarios focus on meat, cooking, or grandparental subsidies, considerations of the economics of foraging for extracted plant foods (e.g., roots, tubers), inferred to be important for early hominins (∼6 to 2.5 mya), suggest that early hominins shared such foods with offspring and others. Here, we present a conceptual and mathematical model of early hominin food production and sharing, prior to the emergence of frequent hunting, cooking, and increased lifespan. We hypothesize that extracted plant foods were vulnerable to theft, and that male mate guarding protected females from food theft. We identify conditions favoring extractive foraging and food sharing across mating systems (i.e., monogamy, polygyny, promiscuity), and we assess which system maximizes female fitness with changes in the profitability of extractive foraging. Females extract foods and share them with males only when: i) extracting rather than collecting plant foods pays off energetically; and ii) males guard females. Males extract foods when they are sufficiently high in value, but share with females only under promiscuous mating and/or no mate guarding. These results suggest that if early hominins had mating systems with pair-bonds (monogamous or polygynous), then food sharing by adult females with unrelated adult males occurred before hunting, cooking, and extensive grandparenting. Such cooperation may have enabled early hominins to expand into more open, seasonal habitats, and provided a foundation for the subsequent evolution of human life histories.

Typical diet and type of economy do not predict food-sharing behaviors in three Tanzanian societies.

Food sharing behavior is a widely observed phenomenon, and it draws attention of scholars interested in finding both proximate and ultimate explanations of such practices. In the current study, we focused on possible socio-economic and environmental food-sharing predictors: type of economy (i.e., immediate-return vs. delayed-return) and typical diet composition (i.e., proportion of proteins and carbohydrates in typical daily caloric intake). We investigated whether members of three societies from Tanzania (N = 177), namely hunter-gatherers (Hadza), pastoralists (Datoga), and agriculturalists (Iraqw) differ with regard to food-sharing patterns in the Dictator Game and reactions to violations of the food-sharing norms in the Ultimatum Game. We found that neither the type of economy nor the typical diet influenced our outcomes. The results indicated, however, that food sharing behavior was positively predicted by certain individual-level characteristics: people of higher strength and lower body fat shared more food, and women were more willing to share food than men.

Understanding food waste-reducing platforms: A mini-review.

Food waste is one of the main obstacles to transitioning to sustainable and circular food systems. Food waste-reducing platforms (FWRPs) have emerged as low-cost alternatives by donating or commercializing surpluses and non-commercial food. However, as a recent phenomenon, little is known about their actual contribution to the fight against food waste. This study aims to employ a systematic review of the literature to understand the main issues of FWRPs. Our results indicate that technology plays multiple roles in FWRPs: enabling the sharing of surpluses by connecting supply and demand, monitoring and generating data on waste, among others. However, technology is insufficient for food recovery. FWRPs' business models must be aligned with the sustainability concept, encompassing environmental, economic and social benefits. Innovators must design and prototype solutions to address these various intended functions. This study points out many barriers to implementing these digital platforms, such as delivering multiple benefits for heterogeneous actors. Other barriers involve building trust and changing the behaviour of actors concerning their food habits. The scarcity of empirical studies has limited a better understanding of FWRPs and their actual ability to tackle food waste on a large scale. Despite the limitations found in the literature, digital platforms are an interesting solution to food waste management by promoting food waste prevention and reduction strategies at the source.

A cross-cultural study of beliefs about the influence of food sharing on interpersonal relationships and food choices.

We conducted two studies on participants from China and the USA to investigate their beliefs about food sharing. In Study 1, the participants were asked to rate the influence of different types of sharing on the interpersonal relationships between two individuals. Compared to sharing non-food material, both groups expected sharing food to exert a more positive influence on the intimacy and mutual trust between the sharer and the recipient. In Study 2A, the participants were asked to rate to which extent it is appropriate to share a certain food with another person. The results revealed that the solid or liquid state and the type of foods influenced both groups of participants' beliefs about whether a food is appropriate for sharing. In Study 2B, the participants were asked to rate the likelihood of ordering certain foods when they were eating alone, eating together, or sharing food with another person in a restaurant scenario. When sharing food with other people, both groups of participants were less likely to order foods that were inappropriate for sharing and more likely to order foods that were appropriate for sharing, thus suggesting the influence of beliefs about food sharing on food choices. Despite some cross-cultural differences in both studies, the results revealed some cross-cultural shared beliefs about food sharing. These findings suggest that people's beliefs regarding the positive influence of food sharing on interpersonal relationships influence food choices and may help explain why foods are shared while eating with others even there is no social obligation to do so.

Rats play tit-for-tat instead of integrating social experience over multiple interactions.

Theoretical models of cooperation typically assume that agents use simple rules based on last encounters, such as 'tit-for-tat', to reciprocate help. By contrast, empiricists generally suppose that animals integrate multiple experiences over longer timespans. Here, we compared these two alternative hypotheses by exposing Norway rats to partners that cooperated on three consecutive days but failed to cooperate on the fourth day, and to partners that did the exact opposite. In additional controls, focal rats experienced cooperating and defecting partners only once. In a bar-pulling setup, focal rats based their decision to provide partners with food on last encounters instead of overall cooperation levels. To check whether this might be owing to a lack of memory capacity, we tested whether rats remember the outcome of encounters that had happened three days before. Cooperation was not diminished by the intermediate time interval. We conclude that rats reciprocate help mainly based on most recent encounters instead of integrating social experience over longer timespans.

Premasticated food transfer by wild chimpanzee mothers with their infants: Effects of maternal parity, infant age and sex, and food properties.

Premasticated food transfer, when an individual partially breaks down food through chewing and feeds it to another individual, usually mouth-to-mouth, is described widely across human cultures. This behavior plays an important role in modern humans' strategy of complementary feeding, which involves supplementing maternal milk in infant diets with processed, easily digestible versions of adult foods. The extent to which other primates engage in premasticated food transfer with infants is unclear, as premasticated food transfers have been only occasionally reported in other ape species. We investigated premasticated food transfers in 62 mother-infant pairs of wild chimpanzees at Ngogo, Uganda, as well as unresisted food taking, when mothers passively allow infants to seize food. We evaluated the presence or absence and rates of premasticated food transfer and unresisted food taking relative to maternal parity and infant age and sex and assessed the food species and part used. We found that chimpanzee mothers regularly shared premasticated food with their infants aged between 6 months and 4 years, but they were more likely to share, and more frequently shared, with younger infants. The frequency with which females shared premasticated food may relate to maternal experience, as multiparous females shared premasticated food more often than did first-time mothers, which we did not find with unresisted food taking. Both easy-to-chew, commonly eaten foods and tougher, rarely eaten foods were shared. Premasticated food transfer and unresisted food taking may be infant-rearing strategies to facilitate the transition from a diet of exclusive maternal milk to solid food during early infancy. Premasticated food transfer in particular may provide energetic, immune, or growth benefits to infants through reduced chewing effort and maternal saliva. Given our findings in chimpanzees and earlier reports in other ape species, we suggest that the foundation of complementary feeding, a uniquely hominin strategy, might have been present in a common ancestor shared with the other great apes in the form of premasticated, mouth-to-mouth food transfer by mothers with their offspring.

Why understanding multiplex social network structuring processes will help us better understand the evolution of human behavior.

Social scientists have long appreciated that relationships between individuals cannot be described from observing a single domain, and that the structure across domains of interaction can have important effects on outcomes of interest (e.g., cooperation; Durkheim, 1893). One debate explicitly about this surrounds food sharing. Some argue that failing to find reciprocal food sharing means that some process other than reciprocity must be occurring, whereas others argue for models that allow reciprocity to span domains in the form of trade (Kaplan and Hill, 1985.). Multilayer networks, high-dimensional networks that allow us to consider multiple sets of relationships at the same time, are ubiquitous and have consequences, so processes giving rise to them are important social phenomena. The analysis of multi-dimensional social networks has recently garnered the attention of the network science community (Kivelä et al., 2014). Recent models of these processes show how ignoring layer interdependencies can lead one to miss why a layer formed the way it did, and/or draw erroneous conclusions (Górski et al., 2018). Understanding the structuring processes that underlie multiplex networks will help understand increasingly rich data sets, giving more accurate and complete pictures of social interactions.

To the hunter go the spoils? No evidence of nutritional benefit to being or marrying a well-reputed Hadza hunter.

OBJECTIVES: The incentives underlying men's hunting acquisition patterns among foragers are much debated. Some argue that hunters preferentially channel foods to their households, others maintain that foods are widely redistributed. Debates have focused on the redistribution of foods brought to camp, though the proper interpretation of results is contested. Here we instead address this question using two nutritional variables, employed as proxies for longer-term food access. We also report on broader patterns in nutritional status. MATERIALS AND METHODS: We measured male hunting success, hemoglobin concentration and body fatness among bush-living Hadza. Hunting success was measured using an aggregated reputation score. Hemoglobin concentration, a proxy for dietary red meat, was measured from fingerprick capillary blood. Body fatness, a proxy for energy balance, was measured using BMI and bioelectrical impedance. RESULTS: We find no statistically significant relationship between a hunter's success and any measure of his nutritional status or that of his spouse. We further find that: women are, as elsewhere, at greater risk of iron-deficiency anemia than men; men had slightly lower BMIs than women; men but not women had significantly lower hemoglobin levels than in the 1960s. DISCUSSION: The absence of an association between hunting reputation and nutritional status is consistent with generalized food sharing. Null results are difficult to interpret and findings could potentially be a consequence of insufficient signal in the study measures or some confounding effect. In any event, our results add to a substantial corpus of existing research that identifies few nutritional advantages to being or marrying a well-reputed Hadza hunter.

The effect of individual and food characteristics on food retrieval and food sharing in captive Guinea baboons (Papio papio).

Access to food is of major importance to the fitness and survival of every individual, particularly in group-living animals, in which individual characteristics and food distribution can affect food intake. Additionally, several species of primates are known to share food under certain conditions. Such unresisted transfer of food from one individual to another appears to be adaptive, for instance as a tool to maintain and reinforce social bonds. In this study, we aimed to test how food retrieval and food sharing varies depending on the social relationship between individuals, and on the characteristics of the food. In six different test conditions, we provided a captive group of Guinea baboons (Papio papio, N = 23) with multiple food items, differing in quality, quantity, density, monopolizability, and effort required to obtain it. We further used behavioral observations to assess individual relationships and possible variations in grooming exchanges linked to food sharing events. Out of 424 events in which food items were retrieved by the subjects, we detected no instances of active food sharing and only 17 of passive food sharing. The way food was retrieved was affected by individual and food characteristics (i.e., quantity, quality, and monopolizability of food): Males and central individuals (i.e., those connected to many partners, and/or having partners with many connections in the social network) were more likely to retrieve food during test conditions. In particular, events of passive food sharing mostly happened when the quality of food was low, and between individuals belonging to the same community (i.e., having close relationships). No other food characteristics affected the probability to share food, and the occurrence of food sharing had no immediate effect on grooming exchanges. Overall, our findings suggest that food sharing is relatively rare in Guinea baboons unless the food has a low quality and individuals form close social bonds.

Variable infant care contributions in cooperatively breeding groups of wild saddleback tamarins.

Among non-human primates, alloparental infant care is most extensive in callitrichines, and is thought to be particularly costly for tamarins whose helpers may suffer increased energy expenditure, weight loss, and reduced feeding time and mobility. The costs and benefits of infant care likely vary among group members yet very few wild studies have investigated variable infant care contributions. We studied infant care over an 8-month period in four wild groups of saddleback tamarins in Bolivia to evaluate: (a) what forms of infant care are provided, by whom, and when, (b) how individuals adjust their behavior (activity, vigilance, height) while caring for infants, and (c) whether individuals differ in their infant care contributions. We found that infant carrying, food sharing, and grooming varied among groups, and immigrant males-those who joined the group after infants were conceived-participated less in infant care compared to resident males. Adult tamarins fed less, rested more, and increased vigilance while carrying infants. Although we did not detect changes in overall activity budgets between prepartum and postpartum periods, tamarins spent more time scanning their environments postpartum, potentially reflecting increased predation risk to both carriers and infants during this period. Our study provides the first quantitative data on the timing and amount of infant carrying, grooming, and food transfer contributed by all individuals within and among multiple wild groups, filling a critical knowledge gap about the factors affecting infant care, and highlighting evolutionary hypotheses for cooperative breeding in tamarins.

How food brings us together: The ties between attachment and food behaviors.

Interpersonal food behaviors, such as food sharing and food offering, are associated with closeness between people and thought to facilitate the formation and strengthening of social bonds. Despite the importance of food and food-related behavior in general and for social bonding specifically, there is relatively little research about the psychological underpinnings of food-related behavior within relationship science. To fill this gap, we conducted three studies focusing on food behaviors and attachment style. In Study 1, we found attachment avoidance to be negatively associated with engagement in food sharing behaviors, and with a lower likelihood of dating a potential partner due to the partner's food preferences. In Study 2, we found that enhancing attachment security increased the tendency to offer one's food to a fellow participant. In Study 3, we found that the tendency to accept food from a fellow participant was positively associated with attachment anxiety, but security priming did not affect this tendency. Implications for attachment, close relationships, and food sciences are discussed.

Costly signaling and the handicap principle in hunter-gatherer research: A critical review.

It has been argued that men's hunting in many forager groups is not, primarily, a means of family provisioning but is a costly way of signaling otherwise cryptic qualities related to hunting ability. Much literature concerning the signaling value of hunting draws links to Zahavi's handicap principle and the costly signaling literature in zoology. However, although nominally grounded in the same theoretical paradigm, these literatures have evolved separately. Here I review honest signaling theory in both hunter-gatherer studies and zoology and highlight three issues with the costly signaling literature in hunter-gather studies: (a) an overemphasis on the demonstration of realized costs, which are neither necessary nor sufficient to diagnose costly signaling; (b) a lack of clear predictions about what specific qualities hunting actually signals; and (c) an insufficient focus on the broadcast effectiveness of hunting and its value as a heuristics for signal recipients. Rather than signaling hunting prowess, hunting might instead facilitate reputation-building.

Multiplex social ecological network analysis reveals how social changes affect community robustness more than resource depletion.

Network analysis provides a powerful tool to analyze complex influences of social and ecological structures on community and household dynamics. Most network studies of social-ecological systems use simple, undirected, unweighted networks. We analyze multiplex, directed, and weighted networks of subsistence food flows collected in three small indigenous communities in Arctic Alaska potentially facing substantial economic and ecological changes. Our analysis of plausible future scenarios suggests that changes to social relations and key households have greater effects on community robustness than changes to specific wild food resources.

New Observations of Meat Eating and Sharing in Wild Bonobos (Pan paniscus) at Iyema, Lomako Forest Reserve, Democratic Republic of the Congo.

Bonobos (Pan paniscus) consume a variety of vertebrates, although direct observations remain relatively rare compared to chimpanzees (Pan troglodytes). We report the first direct observations of meat eating and sharing among bonobos at Iyema, Lomako Forest, Democratic Republic of Congo. We collected meat consumption data ad libitum from June to November 2017 over 176.5 observation hours and conducted monthly censuses to measure the abundance of potential prey species. We observed 3 occasions of duiker consumption and found indirect evidence of meat consumption twice (n = 5). We identified the prey species as Weyn's duiker (Cephalophus weynsi) in all 4 cases that we saw the carcass. This species was the most abundant duiker species at Iyema, but other potential prey species were also available. Meat sharing was observed or inferred during all 3 observations. However, the individual controlling the carcass frequently resisted sharing, and aggressive attempts to take the carcass were observed. This report contributes to a growing body of data suggesting that wild bonobos consume meat at higher rates than previously thought, female control of carcasses is frequent but not exclusive, and meat sharing in bonobos is primarily passive but not without aggression.

Reverse audience effects on helping in cooperatively breeding marmoset monkeys.

Cooperatively breeding common marmosets show substantial variation in the amount of help they provide. Pay-to-stay and social prestige models of helping attribute this variation to audience effects, i.e. that individuals help more if group members can witness their interactions with immatures, whereas models of kin selection, group augmentation or those stressing the need to gain parenting experience do not predict any audience effects. We quantified the readiness of adult marmosets to share food in the presence or absence of other group members. Contrary to both predictions, we found a reverse audience effect on food-sharing behaviour: marmosets would systematically share more food with immatures when no audience was present. Thus, helping in common marmosets, at least in related family groups, does not support the pay-to-stay or the social prestige model, and helpers do not take advantage of the opportunity to engage in reputation management. Rather, the results appear to reflect a genuine concern for the immatures' well-being, which seems particularly strong when solely responsible for the immatures.

Stable and fluctuating social preferences and implications for cooperation among female bonobos at LuiKotale, Salonga National Park, DRC.

OBJECTIVES: Female bonobos (Pan paniscus) are characterized as highly affiliative and cooperative, but few studies have quantified the strength and stability of female intra-sexual relationships or explored how variation in social relationships influences cooperation. We measure female social preferences, identify causes of variation in preferences, and test whether variation in social preferences predicts food sharing or coalitionary support. METHODS: Data were collected over 3 years from females in the Bompusa community at LuiKotale, DRC. We measured genetic relatedness and constructed social preference indices for party association, proximity, grooming, GG-rubbing and aggression. We identified preferred social partners based on permutation tests and measured stability using Mantel tests. We used factor analysis to identify inter-relationships between preference indices and used LMMs to test whether variation in social preferences was explained by relatedness, rank differences, having dependent young or co-residency time. We used GLMMs to test whether variation in social preferences predicted food sharing or coalitionary support. RESULTS: All females had preferred non-kin partners for proximity, grooming or GG-rubbing, but only grooming preferences were stable across years. Association indices were higher among lactating females, and aggression was lower among females with longer co-residency times. The factor analysis identified one factor, representing proximity and GG-rubbing preferences, labeled behavioral coordination. Dyads with higher levels of behavioral coordination were more likely to share food. CONCLUSIONS: Female bonobos exhibit stable, differentiated grooming relationships outside of kinship and philopatry. Females also exhibit flexible proximity and GG-rubbing preferences that may facilitate cooperation with a wider range of social partners.

Creative construction: crafting, negotiating and performing urban food sharing landscapes.

Activities utilising online tools are an increasingly visible part of our everyday lives, providing new subjects, objects and relationships - essentially new landscapes - for research, as well as new conceptual and methodological challenges for researchers. In parallel, calls for collaborative interdisciplinary, even transdisciplinary, research are increasing. Yet practical guidance and critical reflection on the challenges and opportunities of conducting collaborative research online, particularly in emergent areas, is limited. In response, this paper details what we term the 'creative construction' involved in a collaborative project building an exploratory database of more than 4000 food sharing activities in 100 cities that utilise internet and digital technologies in some way (ICT mediated for brevity) to pursue their goals. The research was undertaken by an international team of researchers, including geographers, which utilised a combination of reflexive coding and online collaboration to develop a system for exploring the practice and performance of ICT-mediated food sharing in cities. This paper will unpack the black box of using the internet as a source of data about emergent practices and provide critical reflection on that highly negotiated and essentially handcrafted process. While the substance of the paper focuses on the under-determined realm of food sharing, a site where it is claimed that ICT is transforming practices, the issues raised have resonance far beyond the specificities of this particular endeavour. While challenging, we argue that handcrafting systems for navigating emergent online data is vital, not least to render visible the complexities and contestations around definition, categorisation and translation.

Reciprocal preening and food sharing in colour-polymorphic nestling barn owls.

Barn owl (Tyto alba) siblings preen and offer food items to one another, behaviours that can be considered prosocial because they benefit a conspecific by relieving distress or need. In experimental broods, we analysed whether such behaviours were reciprocated, preferentially exchanged between specific phenotypes, performed to avoid harassment and food theft or signals of hierarchy status. Three of the results are consistent with the hypothesis of direct reciprocity. First, food sharing was reciprocated in three-chick broods but not in pairs of siblings, that is when nestlings could choose a partner with whom to develop a reciprocating interaction. Second, a nestling was more likely to give a prey item to its sibling if the latter individual had preened the former. Third, siblings matched their investment in preening each other. Manipulation of age hierarchy showed that food stealing was directed towards older siblings but was not performed to compensate for a low level of cooperation received. Social behaviours were related to melanin-based coloration, suggesting that animals may signal their propensity to interact socially. The most prosocial phenotype (darker reddish) was also the phenotype that stole more food, and the effect of coloration on prosocial behaviour depended upon rank and sex, suggesting that colour-related prosociality is state dependent.

Oxytocin is associated with infant-care behavior and motivation in cooperatively breeding marmoset monkeys.

The neurohormone oxytocin (OT) is positively involved in the regulation of parenting and social bonding in mammals, and may thus also be important for the mediation of alloparental care. In cooperatively breeding marmosets, infants are raised in teamwork by parents and adult and sub-adult non-reproductive helpers (usually older siblings). Despite high intrinsic motivation, which may be mediated by hormonal priming, not all individuals are always equally able to contribute to infant-care due to competition among care-takers. Among the various care-taking behaviors, proactive food sharing may reflect motivational levels best, since it can be performed ad libitum by several individuals even if competition among surplus care-takers constrains access to infants. Our aim was to study the link between urinary OT levels and care-taking behaviors in group-living marmosets, while taking affiliation with other adults and infant age into account. Over eight reproductive cycles, 26 individuals were monitored for urinary baseline OT, care-taking behaviors (baby-licking, -grooming, -carrying, and proactive food sharing), and adult-directed affiliation. Mean OT levels were generally highest in female breeders and OT increased significantly in all individuals after birth. During early infancy, high urinary OT levels were associated with increased infant-licking but low levels of adult-affiliation, and during late infancy, with increased proactive food sharing. Our results show that, in marmoset parents and alloparents, OT is positively involved in the regulation of care-taking, thereby reflecting the changing needs during infant development. This particularly included behaviors that are more likely to reflect intrinsic care motivation, suggesting a positive link between OT and motivational regulation of infant-care.

Country food sharing networks, household structure, and implications for understanding food insecurity in Arctic Canada.

We examine the cultural context of food insecurity among Inuit in Ulukhaktok, Northwest Territories, Canada. An analysis of the social network of country food exchanges among 122 households in the settlement reveals that a household's betweenness centrality-a measure of brokerage-in the country food network is predicted by the age of the household. The households of married couples were better positioned within the sharing network than were the households of single females or single males. Households with an active hunter or elder were also better positioned in the network. The households of single men and women appear to experience limited access to country food, a considerable problem given the increasing number of single-adult households over time. We conclude that the differences between how single women and single men experience constrained access to country foods may partially account for previous findings that single women in arctic settlements appear to be at particular risk for food insecurity.