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Phenotypic plasticity enables animals to adjust their behavior flexibly to their social environment—sometimes through the expression of adaptive traits that have not been exhibited for several generations. We investigated how long social adaptations can usefully persist when they are not routinely expressed, by using experimental evolution to document the loss of social traits associated with the supply and demand of parental care. We allowed populations of burying beetles Nicrophorus vespilloides to evolve in two different social environments for 48 generations in the lab. In “Full Care” populations, traits associated with the supply and demand of parental care were expressed at every generation, whereas in “No Care” populations we prevented expression of these traits experimentally. We then revived trait expression in the No Care populations at generations 24, 43, and 48 by allowing parents to supply post-hatching care and compared these social traits with those expressed by the Full Care populations. We found that offspring demands for care and male provision of care in the No Care populations were lost sooner than female provision of care. We suggest that this reflects differences in the strength of selection for the expression of alternative traits in offspring, males and females, which can enhance fitness when post-hatching care is disrupted.

Across the animal kingdom, social behaviour has been shown to be both a driver of and a response to selection. The question of how social interactions within the family contribute to evolutionary change has received much attention from behavioural ecologists and evolutionary biologists alike, with the former largely focussing on how these interactions are adaptive, and how they impose selection on each member of the partnership, and the latter focussing more on the specific mechanisms of inheritance and how social behaviours of one partner induce the evolution of traits in others. The aim of this thesis is to unite these approaches by asking how adaptive social behaviour (i.e. parental care) can potentially influence evolution: by providing a mechanism for non-genetic inheritance, by constructing the environment in which further social interactions play out, and by influencing trait loss and trait evolvability. The burying beetle *Nicrophorus vespilloides* represents an excellent system for investigating these consequences of parental care. This species exhibits elaborate but variable biparental care, whereby both parents prepare an edible nest for their young from a small vertebrate carcass. They then defend the larvae from predators and competitors and feed them trophallactically with oral fluids. Larvae can survive without any post-hatching care – in the lab at least. I begin in Chapter 2, by examining how burying beetles inherit their gut microbiome, in collaboration with Dr Rahia Mashoodh and Dr Helen Leggett at the University of Cambridge. Previous work suggests this is achieved by two routes: directly from the parents via oral trophallaxis and indirectly via the carcass, through the deposition by parents of oral and anal exudates, which larvae then consume. I eliminated the former mechanism of inheritance, by breeding beetles with and without post-hatching care for two generations, and analysed the resulting gut bacteria of grand-offspring using 16S sequencing. I found that different bacteria are inherited by each route but that gut bacterial communities are just as diverse when vertical transmission happens via the carcass alone. In future work it would be interesting to determine whether beetles have reduced fitness when vertical transmission of the gut bacterial community during post-hatching is prevented. In Chapters 3-6, I extended this approach of comparing populations that had and had not experienced post-hatching care. I analysed replicate experimental burying beetle populations that had evolved for 40 or more generations in the Kilner lab either with or without post-hatching care, respectively the ‘Full Care’ and ‘No Care’ populations. In Chapters 3 and 4, I focused on traits linked to the preparation of the carrion nest. In Chapter 3, I conducted breeding experiments that investigated whether nest construction had evolved divergently between the Full Care and No Care populations. I found that faster nest building in the No Care populations did not compensate for poorer post-hatching care. There was evidence of within-family co-adaptation for nest construction, but the extent of co-adaptation did not diverge between ‘Full Care’ and ‘No Care’ populations. In Chapter 4, in collaboration with Prof. Adria LeBoeuf at the University of Fribourg, Switzerland, I analysed the proteins in oral fluids produced by parents and offspring, which are deposited on the carrion nest. We found that No Care parents had evolved to deposit proteins that could assist their larvae in their absence, but found no evidence of equivalent change in the No Care larvae. Finally, to look at the longer-term evolutionary consequences of parental care, in Chapter 5 I investigated whether traits for supplying and receiving care can persist when they are no longer expressed (as experienced by the No Care populations). I found that No Care fathers and larvae had lower expression of post-hatching care-related traits than their Full Care counterparts, but similar trait loss was not found in mothers. In Chapter 6, I investigated whether evolving with or without care conferred greater resilience when beetles were exposed to increased temperatures during sexual maturation. I found that founder effects were a far better predictor of a population’s resilience than social evolutionary history. I conclude that long-term consequences of social evolution are unpredictable and that the resilience of a population will largely be predicted by the standing genetic variation of its founders.

Sociality has been suggested as a source of differences in evolvability between species, but predictions are lacking concerning the effects of different social dimensions. Using computer simulations, we provide a grain of salt in this direction. We varied four parameters along four social dimensions: Organization - 1) which sex disperses and 2) the number of males and females; Structure and Mating systems - 3) the levels of reproductive skew among males and females; and Care systems - 4) the presence or absence of cooperative care. This social variation was simulated according to the genetic transmission of some of the major taxa studied, haplodiploidy and diplodiploidy to emulate mammals, birds and Hymenoptera. To measure the impact on anagenesis, we assessed the spread of a hyper-successful variant in an alpha individual after three generations. We hypothesized that the higher this capacity for spread, the faster the speed of change in a species. To investigate cladogenetic effects, we measured the number of genetic lines that reproduced and the equitability of their contribution as a measure of how much mixing induced different social systems. We hypothesized that the more diversity the less chances of speciation to ensue. Variant spread and genetic diversity were strongly negatively correlated but showed their highest variation at different sites. Spread varied most at high group sizes while diversity changed most at the low end of the spectrum. Anagenesis and cladogenesis were the result of complex interactions between our social variables, endorsing recent claims for the need to measure social systems along multiple dimensions. We found that the number of breeding females in a unit and the level of reproductive skew determined variant spread through the number of dispersing offspring produced. Moreover, group augmentation increased potential spread because under constant population size fewer units existed. Hyper-successful variants in emigrants could flood the breeding positions of a smaller effective breeding population size and thus contribute disproportionately to the next generation. The social systems with highest variant spread were characterized by male biased dispersal and monopolization on big multi-male-multi-female groups and female- or male-biased dispersal with cooperative breeding where the alpha female could access the units’ full reproductive potential through cooperative care. Genetic diversity was mostly affected by the number of immigrants in units and the total number of units. The more group sizes increased through philopatry, the fewer number of distinct philopatric lines in different units there were, decreasing diversity. The more groups increased through immigration, the higher the inequality. Because philopatric lines always gathered at least 50% of genetic contributions, immigrants shared the rest. If there were more immigrants, each of them gathered less. The social system inducing the highest genetic diversity was characterized by a population of monogamous pairs while the lowest had highest multi-male-multifemale groups with only a monogamous pair reproducing. Overall, our model supports previous frameworks and empirical studies linking stronger sexual and social selection with faster adaptive and neutral anagenesis but is less suited to test for cladogenesis. We propose some evolutionary speed scenarios according to previously reconstructed social transitions in different taxa.&nbsp

Bacteria are highly social organisms that frequently engage in cooperative and competitive interactions to successfully survive and reproduce. Examples include cell-to-cell communication, nutrient scavenging, and chemical warfare. However, the vast majority of our understanding of bacterial sociality has come from the laboratory strains of a small number of gram-negative social evolution model organisms, such as Pseudomonas spp. and Escherichia coli. In my thesis, I aim to expand our understanding of bacterial sociality in natural populations and further across the bacterial tree of life. I do this using two different approaches. Firstly, I use laboratory experiments and sequence analysis to study the evolution and ecology of bacteriocin-mediated competition in natural S. aureus populations, sampled as part of a carriage study on human nasal passages. Theory and laboratory experiments to date have provided extensive evidence that bacteriocin production plays a key role in determining the competitive dynamics of bacterial strains, however evidence from natural populations to support this hypothesis is lacking. I find that inhibitory strains were associated with the propensity to displace competing strains from the nasal cavity, which occurs despite inhibitory activity not being displayed by the majority of strains and targeting interspecific over intraspecific competitors. I also provide evidence for the genetic underpinnings of bacteriocin activity, by identifying five bacteriocin gene clusters associated with inhibition. Secondly, I use a comparative approach to study the role of horizontal gene transfer in stabilising cooperation across bacteria. Bacterial cooperation is typically mediated by the secretion of extracellular public goods, which are costly molecules that provide a fitness benefit to neighbouring cells. Cooperation can be destabilised by the invasion of selfish ‘cheats’ that reap the benefit of public good production without paying a cost. It is widely accepted that horizontal gene transfer, especially via plasmids, can allow cooperators to ‘re-infect’ cheats with the gene for a cooperative trait, thus stabilising cooperation. Although theoretical and experimental studies have provided evidence to support this hypothesis, a comprehensive genomic study that controls for phylogenetic non-independence across species remains to be conducted. The results from our analysis of plasmid genes from 51 diverse bacterial species do not support the cooperation hypothesis across bacteria and are instead supportive of environmental variability as a determining factor in the relationship between horizontal gene transfer and extracellular proteins. Taken together, this thesis provides a body of work that emphasises the importance of testing predictions from theoretical and laboratory experiments in natural populations, and across diverse species.

Objective: to conduct a thorough analysis of the evolution of human rights at different stages of development of society, to study the main aspects of the formation of socio-legal status of man in the field of labor. Research methods: general scientific and special methods are used in the work. Results: the peculiarities of the formation and development of labor legislation are analyzed, specificity of the factory legislation in the period of activization of labor movement for labor rights is defined, it is established that «formation of the social status of the person in labor sphere» is formation and development of labor rights, duties. The stages of formation of the social status of a person in the sphere of labor are singled out, namely: 1)collective-dependent (primitive-communal); 2)individually dependent (slave, feudal); 3)factory-industrial (capitalist); 4)collective-totalitarian (Soviet period); 5)integration-European (modern development of Ukraine). It is established that the specificity of primitive society is the collective organization of labor at the initial stage of human life, namely the need for collective efforts to organize life, because man himself was unable to earn a living. Discussion: the question of the social and legal position of man in the field of labor shows that it is work that most fully reflects the level of socialization of man, his motivation, as well as needs. Trends in social evolution indicate the patterns of formation of human social status at different stages of formation of society and the development of labor legislation. Features of historical and legal aspects of formation of the labor legislation in the XX-XXI centuries are considered. Мета: провести ґрунтовний аналіз еволюції прав людини на різних етапах розвитку суспільства, дослідити основні аспекти формування соціально-правового статусу людини у сфері праці. Методи дослідження: у роботі використовуються загальнонаукові та спеціальні методи. Результати: проаналізовано особливості становлення та розвитку трудового законодавства, визначено специфіку заводського законодавства в період активізації трудового руху за трудові права, встановлено, що «формування соціального статусу людини у сфері праці» − це формування і розвиток трудових прав, обов'язків. Виокремлено етапи формування соціально-правового становища людини у сфері праці, а саме: 1)колективно-залежний (первіснообщинний); 2)індивідуально-залежний (рабовласницький, феодальний); 3)законодавчо-промисловий (капіталістичний); 4)колективно-тоталітарний (радянський період); 5)інтеграційно-європейський. Встановлено, що специфікою первісного суспільства є колективна організація праці на початковому етапі життя людини, а саме необхідність колективних зусиль, оскільки людина сама була не в змозі заробляти собі на життя. Обговорення: питання про соціально-правове становище людини у сфері праці показує, що саме праця найбільш повно відображає рівень соціалізації людини, її мотивацію, а також потреби. Тенденції соціальної еволюції вказують на закономірності формування соціального статусу людини на різних етапах становлення суспільства та розвитку законодавства про працю. Розглянуто особливості історико-правових аспектів становлення законодавства про працю у ХХ-ХХІст. Тенденції суспільної еволюції вказують на відповідність законам становлення соціального становища людини на різних етапах становлення суспільства.

Benevolent social behaviours, such as parental care, are thought to enable mildly deleterious mutations to persist. We tested this prediction experimentally using the burying beetle Nicrophorus vespilloides , an insect with biparental care. For 20 generations, we allowed replicate experimental burying beetle populations to evolve either with post-hatching care (‘Full Care’ populations) or without it (‘No Care’ populations). We then established new lineages, seeded from these experimental populations, which we inbred to assess their mutation load. Outbred lineages served as controls. We also tested whether the deleterious effects of a greater mutation load could be concealed by parental care by allowing half the lineages to receive post-hatching care, while half did not. We found that inbred lineages from the Full Care populations went extinct more quickly than inbred lineages from the No Care populations—but only when offspring received no post-hatching care. We infer that Full Care lineages carried a greater mutation load, but that the associated deleterious effects on fitness could be overcome if larvae received parental care. We suggest that the increased mutation load caused by parental care increases a population's dependence upon care. This could explain why care is seldom lost once it has evolved.

Historical archives provide invaluable insights into societies of the past, including social networks. However, the required amount of traditional archival work makes historical network studies usually small-scaled. We consider the problem of processing a large corpus of unstructured textual information to extract network data. The corpus consists of almost 170,000 documents of administrative correspondence of the Portuguese Empire, from 1610 to 1833, catalogued in the Portuguese Overseas Archives of Lisbon. Our contribution is twofold: the method and the result. Firstly, grounded in the review of manual, semi-manual and automatic methods of network data extraction from natural language corpora, we propose and demonstrate an approach using modern natural language processing algorithms. This approach tries to mimic traditional archivist’s coding practices and is applicable to large corpora of texts, for which manual coding is infeasible because of scale. We believe our approach is generic and adaptable to other substantive contexts, languages, and types of historical archives. Secondly, the dataset created is rich in additional information such as occupation, administrative affiliation, and geographical location of senders and recipients. We provide a preliminary network analysis suggesting that the dataset is an attractive material for historians and social network researchers for addressing research questions about the political and social evolution of the early modern Portuguese Empire, spanning the reign of seven Portuguese monarchs.

Special Contribution

The widely spread evolutionary strategy of parental care is considered an important driver of social evolution. Although offspring were long thought to primarily interact competitively, recent studies revealed the potential importance of sibling cooperation. Theories suggest that the degree of cooperation in offspring interactions depends on the degree of offspring dependence on parental care: offspring unable to forage on their own should compete more, whereas more independent juveniles may increase the degree of cooperation. In this study, we tested the occurrence of sibling cooperation in the absence of posthatching care in several burying beetle species exhibiting varying degrees of offspring dependence. To this end, we measured larval growth rate and survival in the presence and absence of prehatching care using different brood sizes. We found that sibling cooperation cannot be exclusively explained by offspring dependence on parental care. Although only species with more independent larvae cooperated when receiving prehatching care, larval cooperation occurred across species in the absence of care. The latter result suggests that sibling cooperation was already present in an early ancestor of the genus Nicrophorus. Overall, these findings give important insights into the transition from facultative to obligate family life.

There is a lack of studies assessing how hearing impairment relates to reproductive outcomes. We examined whether childhood hearing impairment (HI) affects reproductive patterns based on longitudinal Norwegian population level data for birth cohorts 1940–1980. We used Poisson regression to estimate the association between the number of children ever born and HI. The association with childlessness is estimated by a logit model. As a robustness check, we also estimated family fixed effects Poisson and logit models. Hearing was assessed at ages 7, 10 and 13, and reproduction was observed at adult ages until 2014. Air conduction hearing threshold levels were obtained by pure-tone audiometry at eight frequencies from 0.25 to 8 kHz. Fertility data were collected from Norwegian administrative registers. The combined dataset size was N = 50,022. Our analyses reveal that HI in childhood is associated with lower fertility in adulthood, especially for men. The proportion of childless individuals among those with childhood HI was almost twice as large as that of individuals with normal childhood hearing (20.8% vs. 10.7%). The negative association is robust to the inclusion of family fixed effects in the model that allow to control for the unobserved heterogeneity that are shared between siblings, including factors related to the upbringing and parent characteristics. Less family support in later life could add to the health challenges faced by those with HI. More attention should be given to how fertility relates to HI.

Indirect reciprocity is a key mechanism that promotes cooperation in social dilemmas by means of reputation. Although it has been a common practice to represent reputations by binary values, either `good' or `bad', such a dichotomy is a crude approximation considering the complexity of reality. In this work, we studied norms with three different reputations, i.e., `good', `neutral', and `bad'. Through massive supercomputing for handling more than thirty billion possibilities, we fully identified which norms achieve cooperation and possess evolutionary stability against behavioural mutants. By systematically categorizing all these norms according to their behaviours, we found similarities and dissimilarities to their binary-reputation counterpart, the leading eight. We obtained four rules that should be satisfied by the successful norms, and the behaviour of the leading eight can be understood as a special case of these rules. A couple of norms that show counter-intuitive behaviours are also presented. We believe the findings are also useful for designing successful norms with more general reputation systems., 18 pages, 6 figures

The rapid advancements in artificial intelligence (AI) have raised concerns about whether AI will surpass and eventually replace humans, leading to a future dominated by digitally sentient entities. This paper challenges this notion by examining the impact of AI evolution on humanity from an evolutionary theorist's perspective. Instead of viewing AI as an existential threat, this paper argues that a better understanding of evolution, kinship, and cooperation allows for a more informed and balanced view of the future relationship between humans and AI. The principles of evolution do not necessitate the replacement of humans by AI systems, and the potential for cooperation and symbiosis can lead to a mutually beneficial relationship between both entities. By reassessing the impact of AI evolution on humanity through the lens of evolutionary theory, this paper offers a more balanced and informed understanding of the future relationship between humans and AI, ultimately paving the way for a collaborative and thriving coexistence.

Given the absence of written records, the main source of information available to analyze gender inequalities in early complex societies is the human body itself. And yet, for decades, archaeologists have struggled with the sex estimation of poorly preserved human remains. Here we present an exceptional case study that shows how ground-breaking new scientific methods may address this problem. Through the analysis of sexually dimorphic amelogenin peptides in tooth enamel, we establish that the most socially prominent person of the Iberian Copper Age (c. 3200–2200 BC) was not male, as previously thought, but female. The analysis of this woman, discovered in 2008 at Valencina, Spain, reveals that she was a leading social figure at a time where no male attained a remotely comparable social position. Only other women buried a short time after in the Montelirio tholos, part of the same burial area, appear to have enjoyed a similarly high social position. Our results invite to reconsider established interpretations about the political role of women at the onset of early social complexity, and question traditionally held views of the past. Furthermore, this study anticipates the changes that newly developed scientific methods may bring to prehistoric archaeology and the study of human social evolution.

Le repérage des inégalités économiques émergentes à la Préhistoire soulève trois ensembles de problèmes qui doivent être traités séparément. Le premier, qu’on n’abordera pas ici, concerne la tâche archéologique proprement dite de la reconstitution des traces matérielles laissées par les sociétés étudiées à partir d’éléments parfois très ténus. Le second touche au phénomène social lui-même, d’autant plus difficile à cerner de près qu’il a pu être progressif, localisé, et susceptible de s’inscrire dans une évolution non nécessairement cumulative. Si, globalement, la marche aux inégalités de richesse a représenté une tendance lourde et évidente des derniers millénaires, elle a pu s’effectuer localement sur un rythme relativement lent et connaître interruptions et retours en arrière. Enfin, le repérage archéologique de ces transformations sociales suppose également de déterminer quels éléments matériels peuvent en être considérés comme des marqueurs fiables, qu’ils soient liés soit à ses causes, soit à ses conséquences. On procède donc à un rapide inventaire des principales possibilités (stockage, sédentarité, biens dits « de prestige », dépôts funéraires, etc.), avec une attention particulière portée à l’art paléolithique, qui recouvre à la fois la dimension de la spécialisation technique et celle du naturalisme. Si, à titre général, la plupart de ces éléments indique avec une certaine probabilité la présence d’inégalités de richesse, ils autorisent très rarement des conclusions tranchées. En tout état de cause, ces incertitudes sont dues au moins en partie aux insuffisances de notre compréhension de ces processus sociaux, qui doivent impérativement être améliorées. The identification of emerging economic inequalities in Prehistory raises three sets of problems that must be addressed separately. The first, which will not be addressed here, concerns the archaeological task proper of reconstructing the material traces left by the studied societies on the basis of sometimes very tenuous elements. The second concerns the social phenomenon itself, which is all the more difficult to pin down as it may have been progressive, localized and likely to be part of a not necessarily cumulative evolution. If, globally, the march towards wealth inequality has been a heavy and obvious trend over the last millennia, it may have been carried out locally at a relatively slow pace, with interruptions and setbacks. Finally, the archaeological identification of these social transformations also implies determining which material elements can be considered as reliable markers, whether they are linked to their causes or to their consequences. We therefore proceed to a rapid inventory of the main possibilities (storage, sedentary life, so-called “prestige” goods, funerary deposits, etc.), with particular attention paid to Palaeolithic art, which covers both the dimension of technical specialization and that of naturalism. Although, in general, most of these elements indicate with a certain probability the presence of inequalities of wealth, they very rarely allow for clear-cut conclusions. In any case, these uncertainties are due at least in part to shortcomings in our understanding of these social processes, which must be improved.

Abnormal or drastic changes in the natural environment may lead to unexpected events, such as tsunamis and earthquakes, which are becoming a major threat to national economy. Currently, no effective assessment approach can deduce a situation and determine the optimal response strategy when a natural disaster occurs. In this study, we propose a social evolution modeling approach and construct a deduction model for self-playing, self-learning, and self-upgrading on the basis of the idea of parallel data and reinforcement learning. The proposed approach can evaluate the impact of an event, deduce the situation, and provide optimal strategies for decision-making. Taking the breakage of a submarine cable caused by earthquake as an example, we find that the proposed modeling approach can obtain a higher reward compared with other existing methods.

Biofilm formation is an important and ubiquitous mode of growth among bacteria. Central to the evolutionary advantage of biofilm formation is cell–cell and cell–surface adhesion achieved by a variety of factors, some of which are diffusible compounds that may operate as classical public goods—factors that are costly to produce but may benefit other cells. An outstanding question is how diffusible matrix production, in general, can be stable over evolutionary timescales. In this work, using Vibrio cholerae as a model, we show that shared diffusible biofilm matrix proteins are indeed susceptible to cheater exploitation and that the evolutionary stability of producing these matrix components fundamentally depends on biofilm spatial structure, intrinsic sharing mechanisms of these components, and flow conditions in the environment. We further show that exploitation of diffusible adhesion proteins is localized within a well-defined spatial range around cell clusters that produce them. Based on this exploitation range and the spatial distribution of cell clusters, we constructed a model of costly diffusible matrix production and related these length scales to the relatedness coefficient in social evolution theory. Our results show that production of diffusible biofilm matrix components is evolutionarily stable under conditions consistent with natural biofilm habitats and host environments. We expect the mechanisms revealed in this study to be relevant to other secreted factors that operate as cooperative public goods in bacterial communities and the concept of exploitation range and the associated analysis tools to be generally applicable.

BACKGROUND: Social defectors may meet diverse cooperators. Genotype-by-genotype interactions may constrain the ranges of cooperators upon which particular defectors can cheat, limiting cheater spread. Upon starvation, the soil bacterium Myxococcus xanthus cooperatively develops into spore-bearing fruiting bodies, using a complex regulatory network and several intercellular signals. Some strains (cheaters) are unable to sporulate effectively in pure culture due to mutations that reduce signal production but can exploit and outcompete cooperators within mixed groups. RESULTS: In this study, interactions between a cheater disrupted at the signaling gene csgA and allopatrically diversified cooperators reveal a very small cheating range. Expectedly, the cheater failed to cheat on all natural-isolate cooperators owing to non-cheater-specific antagonisms. Surprisingly, some lab-evolved cooperators had already exited the csgA mutant's cheating range after accumulating fewer than 20 mutations and without experiencing cheating during evolution. Cooperators might also diversify in the potential for a mutation to reduce expression of a cooperative trait or generate a cheating phenotype. A new csgA mutation constructed in several highly diverged cooperators generated diverse sporulation phenotypes, ranging from a complete defect to no defect, indicating that genetic backgrounds can limit the set of genomes in which a mutation creates a defector. CONCLUSIONS: Our results demonstrate that natural populations may feature geographic mosaics of cooperators that have diversified in their susceptibility to particular cheaters, limiting defectors' cheating ranges and preventing them from spreading. This diversification may also lead to variation in the phenotypes generated by any given cooperation-gene mutation, further decreasing the chance of a cheater emerging which threatens the persistence of cooperation in the system.

An efficient immune system is essential to the survival of many animals. Sociality increases risk of pathogen transmission, which should select for enhanced immune function. However, two hypotheses instead predict a weakened immune function: relaxed selection caused by social immunity/protection, and reduced efficacy of selection due to inbreeding, reproductive skew and female bias in social species that reduce effective population size and accelerate genetic drift. We assessed the effect of social evolution on immune function in a comparative study of two social spider species and their closely related subsocial sister species (genus Stegodyphus ). The haemolymph of social species was less efficient in inhibiting bacterial growth of the potentially pathogenic bacteria Bacillus subtilis than that of subsocial species. Reduced efficacy of selection in social species was supported by comparative genomic analysis showing substantially elevated non-synonymous substitutions in immune genes in one of the social species. We propose that impaired immune function results from reduced efficacy of selection because the evolution of sociality in spiders is accompanied by demographic processes that elevate genetic drift. Positive feedback between pathogen-induced local extinctions and the resulting elevation of genetic drift may further weaken responses to selection by pathogens, and threaten species persistence.

Standard specifications that realize mutual availability in data distribution are indispensable for cooperation between different fields. On the other hand, the forming standardization processes that allow many different things such as physical objects and services to be connected through the Internet, generate costs and require time to form consensus due to stakeholder diversification. To adapt to social evolution and use of big data generated by a massive amount of distributed data, establishing a method to develop a standard of data specification that involves a large number of diverse industries and stakeholders is necessary. The paper analyzes the evolution of the Standard Developing Organizations (SDOs) management policy for data-related technologies and discusses strategies for encouraging data transactions with rapid standardization processes and early diffusion.

Cooperative behaviour often co-occurs with the defence of key resources, typically in the form of a breeding site or territory communally exploited by a group of cooperating individuals. Nevertheless, not all animals that defend resources evolve advanced forms of cooperation and sociality—many non-cooperative species occupy resources that do not differ in obvious ways from those inhabited by cooperative species. A key question is thus whether cooperation confers more subtle benefits, for example by allowing access to higher quality resources through competitive exclusion of less social rivals. In other words, it is not clear whether defendable resources are a necessary precondition for sociality or whether they also contribute to the maintenance and enhancement of cooperative societies. Here, we highlight how advances in imaging technology, machine-learning, and environmental reconstruction enable the collection of behavioural and ecological data in unparalleled quantity and quality to address this question. These new techniques are especially suited to compare small-scale differences in resource use between cooperative and non-cooperative species that share a general habitat and have similar ecologies. The lamprologine cichlids of Lake Tanganyika are a prominent example of such a system and Michael Taborsky's pioneering work on this group has done much to promote these fishes as models of social evolution. We show that habitat features indicative of increased resource quality, namely increased stone cover, are indeed associated with the distribution of cooperative cichlids—at least where these resources are relatively scarce. We thus support a point Michael Taborsky made in 1981: the evolution of cooperative behaviour among cichlids is tied to their close association with a crucial resource, the substrate in which they hide and breed. In the future, the techniques we introduce here will allow to also investigate whether this substrate is indeed more than just the necessary precondition for cooperation among fishes; in addition, they will likely find application in a wide range of research fields interested in the interplay between biotic and abiotic environmental factors. published

Theory posits that situations of existential threat will enhance prosociality in general and particularly toward others perceived as belonging to the same group as the individual (parochial altruism). Yet, the global character of the COVID-19 pandemic may blur boundaries between ingroups and outgroups and engage altruism at a broader level. In an online experiment, participants from the U.S. and Italy chose whether to allocate a monetary bonus to a charity active in COVID-19 relief efforts at the local, national, or international level. The purpose was to address two important questions about charitable giving in this context: first, what influences the propensity to give, and second, how is charitable giving distributed across different levels of collective welfare? We found that personal exposure to COVID-19 increased donations relative to those not exposed, even as levels of environmental exposure (numbers of cases locally) had no effect. With respect to targets of giving, we found that donors predominantly benefitted the local level; donations toward country and world levels were half as large. Social identity was found to influence charity choice in both countries, although an experimental manipulation of identity salience did not have any direct effect.

Theories on the evolutionary origins of altruistic behavior have a long history and have become a canonical part of the theory of evolution. Nevertheless, the mechanisms that allow altruism to appear and persist are still incompletely understood. It is well known, however, that the spatial structure of populations is an important determinant. In both theoretical and experimental studies, much attention has been devoted to populations that are subdivided into discrete groups. Such studies typically imposed the structure and dynamics of the groups by hand. Here, we instead present a simple individual-based model in which altruistic organisms spontaneously self-organize into spatially separated colonies that themselves reproduce by binary fission and hence behave as Darwinian entities in their own right. Using software to automatically track the rise and fall of colonies, we are able to apply formal theory on multilevel selection and thus quantify the within- and among-group dynamics. This reveals that individual colonies inevitably succumb to defectors in a within-colony “tragedy of the commons”. Even so, altruism persists in the population because more altruistic colonies reproduce more frequently and drive less altruistic ones to extinction. Evidently, the colonies promote the selection of altruism but in turn depend on altruism for their existence; the selection of altruism hence involves a kind of evolutionary bootstrapping. The emergence of the colonies also depends crucially on the length scales of motility, altruism, and competition. This reconfirms the general relevance of these scales for social evolution, but also stresses that their impact can only be understood fully in the light of the emergent eco-evolutionary spatial patterns. The results also suggest that emergent spatial population patterns can function as a starting point for transitions of individuality.

The territory of the Starodub regiment is unique in historical terms. Being the center of the region of the Grand Duchy of Lithuania, it was one of its lands able to gain a foothold in the Getman Ukraine. At the same time, Starodubshchina is now the only part of the Hetman region that is part of the Russian Federation. Thus, the region has incorporated traditions, culture and legal customs of all three states, on the border of which it is now located. Despite the considerable interest in the history of the Starodub regiment as a whole, the social history of ordinary rural and urban residents remains poorly understood. The aim of this work is an attempt to illuminate the social situation of the pospolits: townspeople and peasants of the Starodubsky regiment from the moment the Cossack administration was established in the region in 1654 until the population of the region was subordinated to general imperial Russian standards. And also to reveal the characteristic differences of this region. The article was created on the basis of the analysis of various, including little-studied documents stored in the archives of Belarus, Ukraine and Russia, as well as the works of Russian and Ukrainian scientists. The process of establishing city self-government in Starodub and the formation in its midst of a unique elite – noble bourgeois is shown. Many representatives of this social group went through the process of evolution from urban dwellers to Cossack foreman and the subsequent Russian nobility over the indicated period. In addition, the social status of rural residents of the Starodub regiment is described. Which with the establishment of the Cossack administration received personal freedom, but by the end of the 18th century completely lost her. The examples of residents of specific settlements show the methods that the peasants resorted to trying to avoid dependence on large landowners, as well as the process of distinguishing between the pospolits and the Cossack class. At the same time, emphasis was placed on the characteristic differences in the social status of urban and rural residents of the Starodub regiment from other lands that were part of the Russian Empire. The totality of the facts revealed in this way reinforces the main thesis about the complexity and versatility of this Belarusian-Russian-Ukrainian region.

Animal sociality can vary in response to both biotic and abiotic factors, and variation in the rate and types of interactions that occur between individuals of a group can result in greatly differentiated social structure and ultimately social evolution. However, social structures are often generalized to the species or population level and do not consider potential shifts in structure over time. We used social network analysis to investigate the social structure of black-tailed prairie dogs (hereafter ‘prairie dogs’) and determine the demographic features that may underpin the observed social structures in a population that experiences increased seasonal shifts of environmental conditions compared to populations in the centre of the geographical range. Prairie dogs live in highly social colonies, display an elaborate range of social behaviours and experience very dynamic changes in body condition due to variable environmental conditions. We used exponential random graph models (ERGMs) to examine the effects of body condition, age, sex and spatial arrangement on static and temporal social networks. We expected that spatial arrangement would most strongly influence social structure given the delineated burrow systems of a prairie dog colony. We hypothesized that body condition influences social structure over time, where those in better body condition maintain the social structure. Prairie dogs associated preferentially with individuals near themselves and of the same age. Furthermore, we also determined that body condition correlated positively with maintaining social structure over time, where those in poorer body condition experienced an increase in the loss and gain of relationships compared to those in better body condition that maintained connections. Our study confirms previous conclusions of association based on age and also highlights the importance of considering dynamic individual traits such as body condition in the importance of long-term social structure. These results also show the promise of both static and temporal ERGMs in a biological system and demonstrate the potential for increased temporally driven hypothesis testing using this technique.

Background The reproductive division of labor of eusocial insects, whereby one or several queens monopolize reproduction, evolved in a context of high genetic relatedness. However, many extant eusocial species have developed strategies that decrease genetic relatedness in their colonies, suggesting some benefits of the increased diversity. Multiple studies support this hypothesis by showing positive correlations between genetic diversity and colony fitness, as well as finding effects of experimental manipulations of diversity on colony performance. However, alternative explanations could account for most of these reports, and the benefits of diversity on performance in eusocial insects still await validation. In this study, we experimentally increased worker diversity in small colonies of the ant Lasius niger while controlling for typical confounding factors. Results We found that experimental colonies composed of workers coming from three different source colonies produced more larvae and showed more variation in size compared to groups of workers coming from a single colony. Conclusions We propose that the benefits of increased diversity stemmed from an improved division of labor. Our study confirms that worker diversity enhances colony performance, thus providing a possible explanation for the evolution of multiply mated queens and multiple-queen colonies in many species of eusocial insects. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01890-x.

A well-documented phenomenon among social insects is that brain changes occur prior to or at the onset of certain experiences, potentially serving to prime the brain for specific tasks. This insight comes almost exclusively from studies considering developmental maturation in females. As a result, it is unclear whether age-related brain plasticity is consistent across sexes, and to what extent developmental patterns differ. Using confocal microscopy and volumetric analyses, we investigated age-related brain changes coinciding with sexual maturation in the males of the facultatively eusocial sweat bee, Megalopta genalis, and the obligately eusocial bumble bee, Bombus impatiens. We compared volumetric measurements between newly eclosed and reproductively mature males kept isolated in the lab. We found expansion of the mushroom bodies—brain regions associated with learning and memory—with maturation, which were consistent across both species. This age-related plasticity may, therefore, play a functionally-relevant role in preparing male bees for mating, and suggests that developmentally-driven neural restructuring can occur in males, even in species where it is absent in females.

Social dilemmas are mixed-motive games. Although the players have a common interest in maintaining cooperation, each may try to obtain a larger payoff by cooperating less than the other. This phenomenon received increased attention after Press and Dyson discovered a class of strategies for the repeated prisoner’s dilemma (extortionate strategies) that secure for themselves a payoff that is never smaller, but can be larger, than the opponent’s payoff. We conducted an experiment to test whether humans adopt extortionate strategies when playing a social dilemma. Our results reveal that human subjects do try to extort a larger payoff from their opponents. However, they are only successful when extortionate strategies are part of a Nash equilibrium. In settings where extortionate strategies do not appear in any Nash equilibrium, attempts at extortion only result in a breakdown of cooperation. Our subjects recognized the different incentives implied by the two settings, and they were ready to “extort” the opponent when allowed to do so. This suggests that deviations from mutually cooperative equilibria, which are usually attributed to players’ impatience, coordination problems, or lack of information, can instead be driven by subjects trying to reach more favorable outcomes.

Humans are capable of solving cooperation problems following social norms. Social norms dictate appropriate behaviour and judgement on others in response to their previous actions and reputation. Recently, the so-called leading eight norms have been identified from many potential social norms that can sustain cooperation through a reputation-based indirect reciprocity mechanism. Despite indirect reciprocity being claimed to extend direct reciprocity in larger populations where direct experiences cannot be accumulated, the success of social norms have been analysed in models with global information and evolution. This study is the first to analyse the leading eight norms with local information and evolution. We find that the leading eight are robust against selfish players within most scenarios and can maintain a high level of cooperation also with local information and evolution. In fact, local evolution sustains cooperation under a wider set of conditions than global evolution, while local reputation does not hinder cooperation compared to global reputation. Four of the leading eight norms that do not reward justified defection offer better chances for cooperation with quick evolution, reputation with noise, larger networks, and when unconditional defectors enter the population.

Animal sociality plays a crucial organisational role in evolution. As a result, understanding the factors that promote the emergence, maintenance, and diversification of animal societies is of great interest to biologists. Climate is among the foremost ecological factors implicated in evolutionary transitions in social organisation, but we are only beginning to unravel the possible mechanisms and specific climatic variables that underlie these associations. Ambient temperature is a key abiotic factor shaping the spatio-temporal distribution of individuals and has a particularly strong influence on behaviour. Whether such effects play a broader role in social evolution remains to be seen. In this review, we develop a conceptual framework for understanding how thermal effects integrate into pathways that mediate the opportunities, nature, and context of social interactions. We then implement this framework to discuss the capacity for temperature to initiate organisational changes across three broad categories of social evolution: group formation, group maintenance, and group elaboration. For each category, we focus on pivotal traits likely to have underpinned key social transitions and explore the potential for temperature to affect changes in these traits by leveraging empirical examples from the literature on thermal and behavioural ecology. Finally, we discuss research directions that should be prioritised to understand the potentially constructive and/or destructive effects of future warming on the origins, maintenance, and diversification of animal societies.

Parasitism-generated negative effects on ant societies are multifaceted, implying individual and colony-level responses. Though laboratory based evidence shows that the sublethal fungus Rickia wasmannii is responsible for physiological and behavioral responses that may negatively affect individual workers’ resilience and life expectancy in Myrmica ant workers, colony-level stress response to this parasite is largely unknown. Here, we focus on understanding of a long-term, colony-level effect of Rickia infection on Myrmica scabrinodis ant populations by tracking trait size-based changes. We collected worker specimens from infected and uninfected colonies from the same population in order to: (1) compare body size in response to parasitism, (2) assess the extent to which possible changes in size are associated with the severity of infection, and (3) investigate shifts in body size in response to infection over time by testing correlation of workers’ ages and sizes. We found that workers from infected colonies were significantly smaller than their healthy congeners, but neither infection level nor the age of the workers showed significant correlation with the size in infected colonies. Decreasing body sizes in infected colonies can be ascribed to workers’ mediated effect toward developing larvae, which are unable to attain the average body size before they pupate.

People are often generous even when it is not in their apparent self-interest to do so as demonstrated by numerous experiments using the dictator game (DG). More recent research using DGs has varied the number of dictators and recipients and used these games to investigate the bystander effect and congestible altruism. These studies have found that people are less generous when there are others who could be generous (the bystander effect) and also less generous when there are multiple recipients (congestible altruism) though the sum of their generosity to all recipients increases. A working hypothesis is proposed that the context-sensitive generosity observed in n-person DGs can be explained as equitable behavior. From an evolutionary perspective, explaining the evolution of equitable behavior is challenging at best. To provide an evolutionary explanation, a second working hypothesis is proposed: equitable offers evolve because they reduce resource deficits produced by variability in the accumulation of resources and thereby minimize the length of interbirth intervals (IBIs) and increase fitness. Based on this working hypothesis, an evolutionary model was developed for n-person DGs to investigate the evolution of equitable offers as a resource allocation problem when reproduction is constrained by IBIs. Simulations demonstrated that equitable offers could evolve in group-structured populations when there is a cost (i.e., longer IBIs) to running resource deficits. Mean evolved offers also varied as a function of the number of dictators and recipients in patterns consistent with the bystander effect and congestible altruism. Equitable offers evolved because they reduced resource variability among group members and thereby reduced resource deficits, which insured higher average rates of reproduction for more equitable groups of agents. Implications of these results are discussed.

In socially living mammals, females often form highly differentiated and stable social relationships, commonly with genetically related individuals, which leads to social clusters within groups (i.e. matrilines). However, in primates, research on female social relationships commonly focuses on species and populations with female philopatry and the frequent occurrence of affiliative and agonistic behaviours. Therefore, our aim was to investigate the long-term patterns of female social relationships in a primate with female-biased dispersal, where affiliative and agonistic behaviours among females are rare. We analysed 9 years of continuous data from female Ugandan red colobus monkeys, Piliocolobus tephrosceles, in Kibale National Park, Uganda, and used spatial proximity to establish social networks for 3- and 6-month periods. Then, we investigated the differentiation, stability and clustering of social relationships for each of these periods using several approaches. As expected for a primate with female-biased dispersal, our results largely confirmed the absence of temporally stable social relationships and social clusters within the group. However, in about half of the analysed time periods, females formed differentiated social relationships. This indicates that factors other than dispersal patterns and within-group contest competition contribute to the formation of the ephemeral relationships, as measured by spatial proximity, among female red colobus. Therefore, our results on the patterns of female social relationships in a primate with female-biased dispersal provide important empirical insight for the refinements of theories that aim to explain social evolution in mammals.

Reputation is a powerful mechanism to enforce cooperation among unrelated individuals through indirect reciprocity, but it suffers from disagreement originating from private assessment, noise, and incomplete information. In this work, we investigate stability of cooperation in the donation game by regarding each player's reputation and behaviour as continuous variables. Through perturbative calculation, we derive a condition that a social norm should satisfy to give penalties to its close variants, provided that everyone initially cooperates with a good reputation, and this result is supported by numerical simulation. A crucial factor of the condition is whether a well-reputed player's donation to an ill-reputed co-player is appreciated by other members of the society, and the condition can be reduced to a threshold for the benefit-cost ratio of cooperation which depends on the reputational sensitivity to a donor's behaviour as well as on the behavioural sensitivity to a recipient's reputation. Our continuum formulation suggests how indirect reciprocity can work beyond the dichotomy between good and bad even in the presence of inhomogeneity, noise, and incomplete information., 13 pages, 3 figures

Se comenta un libro de reciente publicación producido por el Centro de Estudios de la Argentina Rural de la Universidad Nacional de Quilmes (UNQ), Argentina. Este texto, contiene un conjunto de estudios sociales de la Argentina rural encarados desde múltiples perspectivas disciplinares: las formaciones estatales y su impacto en el devenir social, el papel de las escuelas y la salud en espacios periurbanos, la vivienda y las industrias en las economías regionales, entre otras. La propuesta se torna enriquecedora para los espacios rurales latinoamericanos en tanto se ofrecen diferentes herramientas teóricas y metodológicas que pueden contribuir al desarrollo de este tipo de análisis en la región. La comprensión de los espacios y las problemáticas sociales se torna en una herramienta fundamental para pensar soluciones a largo plazo tras las transformaciones rurales desarrolladas en el último cuarto del siglo. Las ciencias sociales tienen un papel principal en este cometido.

El ensayo que se muestra a continuación trata de un tema muy general como lo es la didáctica en la Educación Superior. Su objetivo fundamental está dirigido a analizar sus principios didácticos y algunos elementos del proceso enseñanza aprendizaje de la universidad con los nuevos paradigmas que se están imponiendo a nivel global, los cuales a su vez descansan en varias fuentes de teóricos notables que han ido evolucionando según lo hace la sociedad. El método, descansó en la revisión y análisis de diferentes fuentes teóricas de carácter documental y su relación con el tema, que a la vez aparecen en las referencias. En el mismo no se han trazado esquemas rígidos ni se brindan fórmulas al tratar con elementos específicamente cualitativos, sin embargo, se ofrecen algunas sugerencias que de forma directa enlazan a la llamada Sociedad del Conocimiento con los cambios didácticos necesarios que requieren de vías activas para que el alumno se convierta en actor y creador de su propio conocimiento. En ese sentido se ha hecho hincapié en las nuevas herramientas tecnológicas que han surgido precisamente del desarrollo del propio conocimiento, analizando con brevedad los pros y los contras de esa utilización; dando por sentado que significan un paso de avance notable siempre y cuando se profundice en su esencia y se apliquen adecuadamente. Aunque el trabajo está dirigido a la realidad peruana, no es menos cierto que también compromete a otros países del área donde los cambios didácticos resultan un denominador común de acuerdo con la evolución social actual.

PurposeThe purpose of this paper is to explain the US society’s insignificant mitigation of climate change using Niklas Luhmann’s (1989) autopoietic social systems theory in ecological communication. Specifically, the author’s analysis falls within the context of Luhmann re-moralized while focusing on particular function systems’ binary codes and their repellence of substantive US climate change mitigation policy across systems.Design/methodology/approachThe author achieves this purpose by resituating Luhmann’s conception of evolution to forgo systems teleology and better contextualize the spatial-temporal scale of climate change; reinforcing complexity reduction and differentiation by integrating communication and media scholar John D. Peters’s (1999) “communication chasm” concept as one mechanism through which codes sustain over time; and applying these integrated concepts to prominent the US climate change mitigation attempts.FindingsThe author concludes that climate change mitigation efforts are the amalgamation of the systems’ moral communications. Mitigation efforts have relegated themselves to subsystems of the ten major systems given the polarizing nature of their predominant care/harm moral binary. Communication chasms persist because these moral communications cannot both adhere to the systems’ binary codes and communicate the climate crisis’s urgency. The more time that passes, the more codes force mitigation organizations, activist efforts and their moral communications to adapt and sacrifice their actions to align with the encircling systems’ code.Social implicationsIn addition to the conceptual contribution, the social implication is that by identifying how and why climate change mitigation efforts are subsumed by the larger systems and their codes, climate change activists and practitioners can better tool their tactics to change the codes at the heart of the systems if serious and substantive climate change mitigation is to prevail.Originality/valueTo the author’s knowledge, there has not been an integration of a historical communication concept into, and sociological application of, ecological communication in the context of climate change mitigation.

Multicellularity has evolved numerous times across the tree of life. One of the most fundamental distinctions among multicellular organisms is their developmental mode: whether they stay together during growth and develop clonally, or form a group through the aggregation of free-living cells. The five eukaryotic lineages to independently evolve complex multicellularity (animals, plants, red algae, brown algae, and fungi) all develop clonally. This fact has largely been explained through social evolutionary theory's lens of cooperation and conflict, where cheating within non-clonal groups has the potential to undermine multicellular adaptation. Multicellular organisms that form groups via aggregation could mitigate the costs of cheating by evolving kin recognition systems that prevent the formation of chimeric groups. However, recent work suggests that selection for the ability to aggregate quickly may constrain the evolution of highly specific kin recognition, sowing the seeds for persistent evolutionary conflict. Importantly, other features of aggregative multicellular life cycles may independently act to constrain the evolution of complex multicellularity. All known aggregative multicellular organisms are facultatively multicellular (as opposed to obligately multicellular), allowing unicellular-level adaptation to environmental selection. Because they primarily exist in a unicellular state, it may be difficult for aggregative multicellular organisms to evolve multicellular traits that carry pleiotropic cell-level fitness costs. Thus, even in the absence of social conflict, aggregative multicellular organisms may have limited potential for the evolution of complex multicellularity.

To resolve the major controversy about why prosocial behaviors persist in large-scale human societies, we propose that two questions need to be answered. First, how do social interactions in small-scale and large-scale societies differ? By reviewing the exchange and collective-action dilemmas in both small-scale and large-scale societies, we show they are not different. Second, are individual decision-making mechanisms driven by self-interest? We extract from the literature three types of individual decision-making mechanism, which differ in their social influence and sensitivity to self-interest, to conclude that humans interacting with non-relatives are largely driven by self-interest. We then ask: what was the key mechanism that allowed prosocial behaviors to continue as societies grew? We show the key role played by new social interaction mechanisms-change in the rules of exchange and collective-action dilemmas-devised by the interacting individuals, which allow for self-interested individuals to remain prosocial as societies grow.

Identity fusion represents a strongly-held personal identity that significantly overlaps with that of a group, and is the current best explanation as to why individuals become empowered to act with extreme self-sacrifice for a group of non-kin. This is widely seen and documented, yet how identity fusion is promoted by evolution is not well-understood, being seemingly counter to the selfish pursuit of survival. In this paper we extend agent-based modelling to explore how and why identity fusion can establish itself in an unrelated population with no previous shared experiences. Using indirect reciprocity to provide a framework for agent interaction, we enable agents to express their identity fusion towards a group, and observe the effects of potential behaviours that are incentivised by a heightened fusion level. These build on the social psychology literature and involve heightened sensitivity of fused individuals to perceived hypocritical group support from others. We find that simple self-referential judgement and ignorance of perceived hypocrites is sufficient to promote identity fusion and this is easily triggered by a sub-group of the population. Interestingly the self-referential judgement that we impose is an individual-level behaviour with no direct collective benefit shared by the population. The study provides clues, beyond qualitative and observational studies, as to how hypocrisy may have established itself to reinforce the collective benefit of a fused group identity. It also provides an alternative perspective on the controversial proposition of group selection - showing how fluidity between an individual’s reputation and that of a group may function and influence selection as a consequence of identity fusion.

Robust evidence supports the importance of apologies for promoting forgiveness. Yet less is known about how apologies exert their effects. Here, we focus on their potential to promote forgiveness by way of increasing perceptions of relationship value. We used a method for directly testing these causal claims by manipulating both the independent variable and the proposed mediator. Namely, we use a 2 (Apology: yes vs. no) × 2 (Value: high vs. low) concurrent double-randomization design to test whether apologies cause forgiveness by affecting the same causal pathway as relationship value. In addition to supporting this causal claim, we also find that apologies had weaker effects on forgiveness when received from high-value transgressors, suggesting that the forgiveness-relevant information provided by apologies is redundant with relationship value. Taken together, these findings from a rigorous methodological paradigm help us parse out how apologies promote relationship repair.

This 2020 Presidential Address was given at the American Pediatric Surgical Association 2021 Virtual Annual Meeting, May 20–22, 2021.

Sociality is a fundamental organizing principle across taxa, thought to come with a suite of adaptive benefits. However, making causal inferences about these adaptive benefits requires experimental manipulation of the social environment, which is rarely feasible in the field. Here we manipulated the number of conspecifics in Trinidadian guppies (Poecilia reticulata) in the wild, and quantified how this affected a key benefit of sociality, social foraging, by investigating several components of foraging success. As adaptive benefits of social foraging may differ between sexes, we studied males and females separately, expecting females, the more social and risk-averse sex, to benefit more from conspecifics than males. Conducting over 1,600 foraging trials, we found that in both sexes, increasing the number of conspecifics led to faster detection of novel food patches and a higher probability of feeding following detection of the patch, resulting in greater individual resource consumption. The slope of the latter relationship differed between the sexes, with males unexpectedly exhibiting a stronger social benefit. Our study provides rare causal evidence for the adaptive benefits of social foraging in the wild, and highlights that sex differences in sociality do not necessarily imply an unequal ability to profit from the presence of others.

Barone proposes a theory of war influenced by marginalist theory and Prussian military thought which is critical of historical determinism and includes the belief that the main reason of social evolution is the search for power.

Microbial conflicts have a particularly aggressive nature. In addition to other chemical, mechanical, and biological weapons in their repertoire, bacteria have evolved bacteriocins, which are narrow-spectrum toxins that kill closely related strains. Bacterial cells are known to frequently use their arsenal while competing against each other for nutrients and space. This stands in contrast with the animal world, where conflicts over resources and mating opportunities are far less lethal, and get commonly resolved via ritualized fighting or "limited war" tactics. Prevalence of aggression in microbial communities is usually explained as due to their limited ability to resolve conflicts via signaling as well as their limited ability to pull out from conflicts due to the sessile nature of their life within biofilms. We use an approach that combines Evolutionary Game Theory (EGT) and Individual-based Modeling (IbM) to investigate the origins of aggression in microbial conflicts. In order to understand how the spatial mode of growth affects the cost of a fight, we compare the growth dynamics emerging from engaging in aggression in a well-mixed system to a spatially structured system. To this end, a mathematical model is constructed for the competition between two bacterial strains where each strain produces a diffusible toxin to which the other strain is sensitive. It is observed that in the biofilm growth mode, starting from a mixed layer of two strains, mutual aggression gives rise to an exceedingly high level of spatial segregation, which in turn reduces the cost of aggression on both strains compared to when the same competition occurs in a well-mixed culture. Another observation is that the transition from a mixed layer to segregated growth is characterized by a switch in the overall growth dynamics. An increased "lag time" is observed in the overall population growth curve that is associated with the earlier stages of growth, when each strain is still experiencing the inhibiting effect of the toxin produced by its competitor. Afterwards, an exponential phase of growth kicks in once the competing strains start segregating from each other. The emerging "lag time" arises from the spiteful interactions between the two strains rather than acclimation of cells' internal physiology. Our analysis highlights the territorial nature of microbial conflicts as the key driver to their elevated levels of aggression as it increases the benefit-to-cost ratio of participating in antagonistic interactions. ispartof: FRONTIERS IN MICROBIOLOGY vol:13 ispartof: location:Switzerland status: published