Inequality in nature and society

Examining inequality in aquatic ecosystem services: Evidence from large-scale monitoring programs

We hypothesize that aquatic ecosystem services are likely to be inequitably accessible and addressing this hypothesis requires systematic assessment at regional and national scales. We used existing data from large-scale aquatic monitoring programs (National Coastal Condition Assessment, National Lakes Assessment) to examine relationships between ecosystem condition, approximating a subset of cultural and provisioning services, and inequality (population below poverty level, minority population). We also assessed whether monitoring sites equitably represented the gradient of socioeconomic backgrounds. Several water quality indicators were associated with significantly different minority and low-income percentages; however, the effect size was generally small, with the exception of nitrogen condition status. Minority communities were somewhat under-represented when comparing the distribution of all census blocks to those in proximity to monitoring sites. Analyses were sensitive to the skewed distribution of monitoring sites with a low frequency of observations at the more socially vulnerable part of the gradient. We discuss implications of these findings for improving the representation of vulnerable communities in large-scale monitoring programs.

Effects of education on adult mortality: a global systematic review and meta-analysis

BACKGROUND

The positive effect of education on reducing all-cause adult mortality is known; however, the relative magnitude of this effect has not been systematically quantified. The aim of our study was to estimate the reduction in all-cause adult mortality associated with each year of schooling at a global level.

METHODS

In this systematic review and meta-analysis, we assessed the effect of education on all-cause adult mortality. We searched PubMed, Web of Science, Scopus, Embase, Global Health (CAB), EconLit, and Sociology Source Ultimate databases from Jan 1, 1980, to May 31, 2023. Reviewers (LD, TM, HDV, CW, IG, AG, CD, DS, KB, KE, and AA) assessed each record for individual-level data on educational attainment and mortality. Data were extracted by a single reviewer into a standard template from the Global Burden of Diseases, Injuries, and Risk Factors Study. We excluded studies that relied on case-crossover or ecological study designs to reduce the risk of bias from unlinked data and studies that did not report key measures of interest (all-cause adult mortality). Mixed-effects meta-regression models were implemented to address heterogeneity in referent and exposure measures among studies and to adjust for study-level covariates. This study was registered with PROSPERO (CRD42020183923).

FINDINGS

17 094 unique records were identified, 603 of which were eligible for analysis and included data from 70 locations in 59 countries, producing a final dataset of 10 355 observations. Education showed a dose-response relationship with all-cause adult mortality, with an average reduction in mortality risk of 1·9% (95% uncertainty interval 1·8-2·0) per additional year of education. The effect was greater in younger age groups than in older age groups, with an average reduction in mortality risk of 2·9% (2·8-3·0) associated with each additional year of education for adults aged 18-49 years, compared with a 0·8% (0·6-1·0) reduction for adults older than 70 years. We found no differential effect of education on all-cause mortality by sex or Socio-demographic Index level. We identified publication bias (p<0·0001) and identified and reported estimates of between-study heterogeneity.

INTERPRETATION

To our knowledge, this is the first systematic review and meta-analysis to quantify the importance of years of schooling in reducing adult mortality, the benefits of which extend into older age and are substantial across sexes and economic contexts. This work provides compelling evidence of the importance of education in improving life expectancy and supports calls for increased investment in education as a crucial pathway for reducing global inequities in mortality.

FUNDING

Research Council of Norway and the Bill & Melinda Gates Foundation.

Cooperation among unequal players with aspiration-driven learning

Direct reciprocity promotes the evolution of cooperation when players are sufficiently equal, such that they have similar influence on each other. In the light of ubiquitous inequality, this raises the question of how reciprocity evolves among unequal players. Existing studies on inequality mainly focus on payoff-driven learning rules, which rely on the knowledge of others' strategies. However, inferring one's strategy is a difficult task even if the whole interaction history is known. Here, we consider aspiration-driven learning rules, where players seek strategies that satisfy their aspirations based on their own information. Under aspiration-driven learning rules, we explore the evolutionary dynamics among players with inequality in endowments and productivity. We model the interactions among unequal players with asymmetric games and characterize the condition where cooperation is feasible. Remarkably, we find that aspiration-driven learning rules lead to a higher level of cooperation than payoff-driven ones over a wide range of inequality. Moreover, our results show that high aspiration levels are conducive to the evolution of cooperation when more productive players are equipped with higher endowments. Our work highlights the advantages of aspiration-driven learning for promoting cooperation among unequal players and suggests that aspiration-based decision-making may be more beneficial for the collective.

The vulnerability of aging states: A survival analysis across premodern societies

How states and great powers rise and fall is an intriguing enigma of human history. Are there any patterns? Do polities become more vulnerable over time as they age? We analyze longevity in hundreds of premodern states using survival analysis to help provide initial insights into these questions. This approach is commonly used to study the risk of death in biological organisms or failure in mechanical systems. The results reveal that the risk of state termination increased steeply over approximately the first two centuries after formation and stabilized thereafter. This provides the first quantitative support for the hypothesis that the resilience of political states decreases over time. Potential mechanisms that could drive such declining resilience include environmental degradation, increasing complexity, growing inequality, and extractive institutions. While the cases are from premodern times, such dynamics and drivers of vulnerability may remain relevant today.

Toward an evolutionary ecology of (in)equality

Inequality is increasingly recognized as a major problem in contemporary society. The causes and consequences of inequality in wealth and power have long been central concerns in the social sciences, whereas comparable research in biology has focused on dominance and reproductive skew. This theme issue builds on these existing research traditions, exploring ways they might enrich each other, with evolutionary ecology as a possibly unifying framework. Contributors investigate ways in which inequality is resisted or avoided and developed or imposed in societies of past and contemporary humans, as well as a variety of social mammals. Particular attention is paid to systematic, socially driven inequality in wealth (defined broadly) and the effects this has on differential power, health, survival and reproduction. Analyses include field studies, simulations, archaeological and ethnographic case studies, and analytical models. The results reveal similarities and divergences between human and non-human patterns in wealth, power and social dynamics. We draw on these insights to present a unifying conceptual framework for analysing the evolutionary ecology of (in)equality, with the hope of both understanding the past and improving our collective future. This article is part of the theme issue 'Evolutionary ecology of inequality'.

Cooperation and coordination in heterogeneous populations

One landmark application of evolutionary game theory is the study of social dilemmas. This literature explores why people cooperate even when there are strong incentives to defect. Much of this literature, however, assumes that interactions are symmetric. Individuals are assumed to have the same strategic options and the same potential pay-offs. Yet many interesting questions arise once individuals are allowed to differ. Here, we study asymmetry in simple coordination games. In our set-up, human participants need to decide how much of their endowment to contribute to a public good. If a group's collective contribution reaches a pre-defined threshold, all group members receive a reward. To account for possible asymmetries, individuals either differ in their endowments or their productivities. According to a theoretical equilibrium analysis, such games tend to have many possible solutions. In equilibrium, group members may contribute the same amount, different amounts or nothing at all. According to our behavioural experiment, however, humans favour the equilibrium in which everyone contributes the same proportion of their endowment. We use these experimental results to highlight the non-trivial effects of inequality on cooperation, and we discuss to which extent models of evolutionary game theory can account for these effects. This article is part of the theme issue 'Half a century of evolutionary games: a synthesis of theory, application and future directions'.

Market integration, income inequality, and kinship system among the Mosuo of China

Increased access to defensible material wealth is hypothesised to escalate inequality. Market integration, which creates novel opportunities in cash economies, provides a means of testing this hypothesis. Using demographic data collected from 505 households among the matrilineal and patrilineal Mosuo in 2017, we test whether market integration is associated with increased material wealth, whether increased material wealth is associated with wealth inequality, and whether being in a matrilineal vs. patrilineal kinship system alters the relationship between wealth and inequality. We find evidence that market integration, measured as distance to the nearest source of tourism and primary source of household income, is associated with increased household income and 'modern' asset value. Both village-level market integration and mean asset value were associated negatively, rather than positively, with inequality, contrary to predictions. Finally, income, modern wealth and inequality were higher in matrilineal communities that were located closer to the centre of tourism and where tourism has long provided a relatively stable source of income. However, we also observed exacerbated inequality with increasing farm animal value in patriliny. We conclude that the forces affecting wealth and inequality depend on local context and that the importance of local institutions is obscured by aggregate statistics drawn from modern nation states.

A Proposal for Integrating Theories of Complexity for Better Understanding Global Systemic Risks

The global financial crisis of 2008 has shown that the present financial system involves global systemic risks. The dimension of these risks is hard to grasp with the conceptual tools that have been developed to tackle conventional risks like fire or car accidents. While modern societies know quite well how to deal with conventional risks, we have not yet been equally successful at dealing with global systemic risks. For managing this kind of risks, one needs to understand critical features of specific global systems where many human agents interact in ever changing complex networks. Here we apply two specific dimensions of complexity theory for dealing with global systemic risk in an integrated fashion: normal accidents and extended evolution. Both of them have successfully been applied to the analysis of systemic risks. As a paradigmatic example of global systemic risks, we focus on the global financial crisis that began in 2008, and suggest that the future evolution of the financial system could either see a further increase in complexity, or a reversal to a less complex system. We explore and contrast the implications of normal accident theory and extended evolution perspectives and suggest a four-point research strategy informed by complexity theory for better understanding global systemic risks in financial systems.

Ten facts about land systems for sustainability

Land use is central to addressing sustainability issues, including biodiversity conservation, climate change, food security, poverty alleviation, and sustainable energy. In this paper, we synthesize knowledge accumulated in land system science, the integrated study of terrestrial social-ecological systems, into 10 hard truths that have strong, general, empirical support. These facts help to explain the challenges of achieving sustainability in land use and thus also point toward solutions. The 10 facts are as follows: 1) Meanings and values of land are socially constructed and contested; 2) land systems exhibit complex behaviors with abrupt, hard-to-predict changes; 3) irreversible changes and path dependence are common features of land systems; 4) some land uses have a small footprint but very large impacts; 5) drivers and impacts of land-use change are globally interconnected and spill over to distant locations; 6) humanity lives on a used planet where all land provides benefits to societies; 7) land-use change usually entails trade-offs between different benefits-"win-wins" are thus rare; 8) land tenure and land-use claims are often unclear, overlapping, and contested; 9) the benefits and burdens from land are unequally distributed; and 10) land users have multiple, sometimes conflicting, ideas of what social and environmental justice entails. The facts have implications for governance, but do not provide fixed answers. Instead they constitute a set of core principles which can guide scientists, policy makers, and practitioners toward meeting sustainability challenges in land use.

Prosociality from the perspective of environmental psychology

Pro-environmental behavior, a form of prosocial behavior that ultimately benefits all humanity, is essential for addressing climate change. This review presents pro-environmental behavior in a social dilemma framework describing how non-aligned interests in nested groups (e.g. smaller groups with interests opposing the interests of a superordinate group entailing the smaller groups) and unequal opportunities (e.g. differential access to resources) constitute barriers to pro-environmental behavior. We then summarize recent literature on three ways in which these barriers could be addressed. Specifically, we review how individual and conflicting interests might be overcome and benefits for the collective can be achieved by (1) collective action and global identities, (2) applying insights from another global crisis, the COVID-19 pandemic, and (3) a shift to research methods that consider the nested structure of and unequal opportunities within global crises as well as high-impact actions. Taken together, these approaches might foster one form of prosociality, pro-environmental behavior, that is desperately needed in the pursuit of sustainability.

The effects of taxes on wealth inequality in Artificial Chemistry models of economic activity

We consider a number of Artificial Chemistry models for economic activity and what consequences they have for the formation of economic inequality. We are particularly interested in what tax measures are effective in dampening economic inequality. By starting from well-known kinetic exchange models, we examine different scenarios for reducing the tendency of economic activity models to form unequal wealth distribution in equilibrium.

Loss of resilience preceded transformations of pre-Hispanic Pueblo societies

Collapse of civilizations remains one of the most enigmatic phenomena in human history. In this paper we provide quantitative evidence that loss of resilience systematically preceded collapses. We take advantage of unique time series documenting both construction activity and climate conditions for pre-Columbian societies of the southwestern United States on an annual basis over a period of eight centuries. These data cover five transformations encompassing shifts to novel constellations of beliefs, social practices, and styles of art and architecture. The remarkable high-resolution time series allowed us to quantify the dynamics of social fragility using numerical techniques for probing resilience. Our results demonstrate that all but one of these transformations happened after decades of rising social instability.

Climate extremes are thought to have triggered large-scale transformations of various ancient societies, but they rarely seem to be the sole cause. It has been hypothesized that slow internal developments often made societies less resilient over time, setting them up for collapse. Here, we provide quantitative evidence for this idea. We use annual-resolution time series of building activity to demonstrate that repeated dramatic transformations of Pueblo cultures in the pre-Hispanic US Southwest were preceded by signals of critical slowing down, a dynamic hallmark of fragility. Declining stability of the status quo is consistent with archaeological evidence for increasing violence and in some cases, increasing wealth inequality toward the end of these periods. Our work thus supports the view that the cumulative impact of gradual processes may make societies more vulnerable through time, elevating the likelihood that a perturbation will trigger a large-scale transformation that includes radically rejecting the status quo and seeking alternative pathways.

Evolution of diversity and dominance of companies in online activity

Ever since the web began, the number of websites has been growing exponentially. These websites cover an ever-increasing range of online services that fill a variety of social and economic functions across a growing range of industries. Yet the networked nature of the web, combined with the economics of preferential attachment, increasing returns and global trade, suggest that over the long run a small number of competitive giants are likely to dominate each functional market segment, such as search, retail and social media. Here we perform a large scale longitudinal study to quantify the distribution of attention given in the online environment to competing organisations. In two large online social media datasets, containing more than 10 billion posts and spanning more than a decade, we tally the volume of external links posted towards the organisations' main domain name as a proxy for the online attention they receive. We also use the Common Crawl dataset-which contains the linkage patterns between more than a billion different websites-to study the patterns of link concentration over the past three years across the entire web. Lastly, we showcase the linking between economic, financial and market data by exploring the relationships between online attention on social media and the growth in enterprise value in the electric carmaker Tesla. Our analysis shows that despite the fact that we observe consistent growth in all the macro indicators-the total amount of online attention, in the number of organisations with an online presence, and in the functions they perform-we also observe that a smaller number of organisations account for an ever-increasing proportion of total user attention, usually with one large player dominating each function. These results highlight how evolution of the online economy involves innovation, diversity, and then competitive dominance.

Unequal access to resources undermines global sustainability

Within a global society there exist various land use patterns, inequality, and the movement of people and goods. The various practices and behaviours associated with our current society raise questions about the future sustainability of the human population and the natural environment. We derive a simplified model of the global socio-ecological system in an effort to explore the connections between human well-being and land resources, specifically looking at resource accessibility, conservation initiatives and human migration between two economically diverse regions. We find that the spatial aspect of a global system with two distinct regions allows for faster development of technology, higher peaks in population size, greater natural land degradation, and generally speaking lower population well-being in the long-term. The unequal access to resources and differences in technological progress, alter the outcome of land management (i.e., conservation) and social behaviours (i.e., migration). We conclude that any socio-ecological management practices should be conscientious of the diversity in land access, population size, population well-being and development within the global society, as the potential for unintended consequences is high.

Our future in the Anthropocene biosphere

The COVID-19 pandemic has exposed an interconnected and tightly coupled globalized world in rapid change. This article sets the scientific stage for understanding and responding to such change for global sustainability and resilient societies. We provide a systemic overview of the current situation where people and nature are dynamically intertwined and embedded in the biosphere, placing shocks and extreme events as part of this dynamic; humanity has become the major force in shaping the future of the Earth system as a whole; and the scale and pace of the human dimension have caused climate change, rapid loss of biodiversity, growing inequalities, and loss of resilience to deal with uncertainty and surprise. Taken together, human actions are challenging the biosphere foundation for a prosperous development of civilizations. The Anthropocene reality-of rising system-wide turbulence-calls for transformative change towards sustainable futures. Emerging technologies, social innovations, broader shifts in cultural repertoires, as well as a diverse portfolio of active stewardship of human actions in support of a resilient biosphere are highlighted as essential parts of such transformations.

Unequal access to resources undermines global sustainability

Within a global society there exist various land use patterns, inequality, and the movement of people and goods. The various practices and behaviours associated with our current society raise questions about the future sustainability of the human population and the natural environment. We derive a simplified model of the global socio-ecological system in an effort to explore the connections between human well-being and land resources, specifically looking at resource accessibility, conservation initiatives and human migration between two economically diverse regions. We find that the spatial aspect of a global system with two distinct regions allows for faster development of technology, higher peaks in population size, greater natural land degradation, and generally speaking lower population well-being in the long-term. The unequal access to resources and differences in technological progress, alter the outcome of land management (i.e., conservation) and social behaviours (i.e., migration). We conclude that any socio-ecological management practices should be conscientious of the diversity in land access, population size, population well-being and development within the global society, as the potential for unintended consequences is high.

Voluntary restrictions on self-reliance increase cooperation and mitigate wealth inequality

Humans are considered a highly cooperative species. Through cooperation, we can tackle shared problems like climate change or pandemics and cater for shared needs like shelter, mobility, or healthcare. However, cooperation invites free-riding and can easily break down. Maybe because of this reason, societies also enable individuals to solve shared problems individually, like in the case of private healthcare plans or private retirement planning. Such "self-reliance" allows individuals to avoid problems related to public goods provision, like free-riding or underprovision, and decreases social interdependence. However, not everyone can equally afford to be self-reliant, and amid shared problems, self-reliance may lead to conflicts within groups on how to solve shared problems. In two preregistered studies, we investigate how the ability of self-reliance influences collective action and cooperation. We show that self-reliance crowds out cooperation and exacerbates inequality, especially when some heavily depend on collective action while others do not. However, we also show that groups are willing to curtail their ability of self-reliance. When given the opportunity, groups overwhelmingly vote in favor of abolishing individual solutions to shared problems, which, in turn, increases cooperation and decreases inequality, particularly between group members that differ in their ability to be self-reliant. The support for such endogenously imposed interdependence, however, reduces when individual solutions become more affordable, resonating with findings of increased individualism in wealthier societies and suggesting a link between wealth inequality and favoring individual independence and freedom over communalism and interdependence.

The multinomial index: a robust measure of reproductive skew

Inequality or skew in reproductive success (RS) is common across many animal species and is of long-standing interest to the study of social evolution. However, the measurement of inequality in RS in natural populations has been challenging because existing quantitative measures are highly sensitive to variation in group/sample size, mean RS, and age-structure. This makes comparisons across multiple groups and/or species vulnerable to statistical artefacts and hinders empirical and theoretical progress. Here, we present a new measure of reproductive skew, the multinomial index, M, that is unaffected by many of the structural biases affecting existing indices. M is analytically related to Nonacs’ binomial index, B, and comparably accounts for heterogeneity in age across individuals; in addition, M allows for the possibility of diminishing or even highly nonlinear RS returns to age. Unlike B, however, M is not biased by differences in sample/group size. To demonstrate the value of our index for cross-population comparisons, we conduct a reanalysis of male reproductive skew in 31 primate species. We show that a previously reported negative effect of group size on mating skew was an artefact of structural biases in existing skew measures, which inevitably decline with group size; this bias disappears when using M. Applying phylogenetically controlled, mixed-effects models to the same dataset, we identify key similarities and differences in the inferred within- and between-species predictors of reproductive skew across metrics. Finally, we provide an R package, SkewCalc, to estimate M from empirical data.

Heterogeneous groups cooperate in public good problems despite normative disagreements about individual contribution levels

Norms can promote human cooperation to provide public goods. Yet, the potential of norms to promote cooperation may be limited to homogeneous groups in which all members benefit equally from the public good. Individual heterogeneity in the benefits of public good provision is commonly conjectured to bring about normative disagreements that harm cooperation. However, the role of these normative disagreements remains unclear because they are rarely directly measured or manipulated. In a laboratory experiment, we first measure participants' views on the appropriate way to contribute to a public good with heterogeneous returns. We then use this information to sort people into groups that either agree or disagree on these views, thereby manipulating group-level disagreement on normative views. Participants subsequently make several incentivized contribution decisions in a public goods game with peer punishment. We find that although there are considerable disagreements about individual contribution levels in heterogeneous groups, these disagreements do not impede cooperation. While cooperation is maintained because low contributors are punished, participants do not use punishment to impose their normative views on others. The contribution levels at which groups cooperate strongly relate to the average normative views of these groups.

Collective choice fosters sustainable resource management in the presence of asymmetric opportunities

Asymmetric distribution of opportunities among actors can reinforce the conflict between individual and collective interests in social dilemma situations. The present study investigates the interplay of asymmetric distribution of opportunities to consume resources and three choice systems: individual choice, median choice, and majority voting. Participants (N = 248) took part in a common resource game in groups of four under each of the three choice systems. We examined the average percentage taken of the resource as well as satisfaction and fairness ratings depending on the choice system in interaction with (a) whether the distribution of opportunities among group members was symmetric versus asymmetric, and (b) the status of an actor (advantaged versus disadvantaged) within asymmetric groups. Both implemented collective choice systems (median choice and majority voting) increased sustainable resource management, especially in asymmetric groups, by restricting overconsumption of advantaged individuals, as well as satisfaction and fairness ratings. Collective choice increased collective welfare by increasing profits of disadvantaged individuals and members of symmetric groups. The results indicate that in the presence of asymmetric distribution of opportunities, collective choice is a means to reconcile the conflict between individual and collective interests in social dilemmas and to foster sustainable resource management.

Social dilemmas among unequals

Direct reciprocity is a powerful mechanism for the evolution of cooperation on the basis of repeated interactions^1-4. It requires that interacting individuals are sufficiently equal, such that everyone faces similar consequences when they cooperate or defect. Yet inequality is ubiquitous among humans^5,6 and is generally considered to undermine cooperation and welfare^7-10. Most previous models of reciprocity do not include inequality^11-15. These models assume that individuals are the same in all relevant aspects. Here we introduce a general framework to study direct reciprocity among unequal individuals. Our model allows for multiple sources of inequality. Subjects can differ in their endowments, their productivities and in how much they benefit from public goods. We find that extreme inequality prevents cooperation. But if subjects differ in productivity, some endowment inequality can be necessary for cooperation to prevail. Our mathematical predictions are supported by a behavioural experiment in which we vary the endowments and productivities of the subjects. We observe that overall welfare is maximized when the two sources of heterogeneity are aligned, such that more productive individuals receive higher endowments. By contrast, when endowments and productivities are misaligned, cooperation quickly breaks down. Our findings have implications for policy-makers concerned with equity, efficiency and the provisioning of public goods.

A few Ascomycota taxa dominate soil fungal communities worldwide

Despite having key functions in terrestrial ecosystems, information on the dominant soil fungi and their ecological preferences at the global scale is lacking. To fill this knowledge gap, we surveyed 235 soils from across the globe. Our findings indicate that 83 phylotypes (<0.1% of the retrieved fungi), mostly belonging to wind dispersed, generalist Ascomycota, dominate soils globally. We identify patterns and ecological drivers of dominant soil fungal taxa occurrence, and present a map of their distribution in soils worldwide. Whole-genome comparisons with less dominant, generalist fungi point at a significantly higher number of genes related to stress-tolerance and resource uptake in the dominant fungi, suggesting that they might be better in colonising a wide range of environments. Our findings constitute a major advance in our understanding of the ecology of fungi, and have implications for the development of strategies to preserve them and the ecosystem functions they provide.

Soil fungi play essential roles in ecosystems worldwide. Here, the authors sequence and analyze 235 soil samples collected from across the globe, and identify dominant fungal taxa and their associated environmental attributes.

Superior Dispersal Ability Can Lead to Persistent Ecological Dominance throughout Succession

Microbial communities are ubiquitous and occupy nearly every imaginable habitat and resource, including human-influenced habitats (e.g., fermenting food and hospital surfaces) and habitats with little human influence (e.g., aquatic communities living in carnivorous plant pitchers). We studied yeast communities living in pitchers of the carnivorous purple pitcher plant to understand how and why microbial communities change over time. We found that dispersal ability is not only important for fungal communities early in their existence, it can also determine which species is dominant (here, the yeast Candida pseudoglaebosa) long after the species and its competitors have arrived. These results contrast with observations from many human-influenced habitats, in which a good competitor eventually outcompetes good dispersers, since humans often design these habitats to favor a specific competitor. This study will help microbiologists understand the qualities of microbial species that enable takeover of new habitats in both natural and human-influenced environments.

A large number of descriptive surveys have shown that microbial communities experience successional changes over time and that ecological dominance is common in the microbial world. However, direct evidence for the ecological processes mediating succession or causing ecological dominance remains rare. Different dispersal abilities among species may be a key mechanism. We surveyed fungal diversity within a metacommunity of pitchers of the model carnivorous plant Sarracenia purpurea and discovered that the yeast Candida pseudoglaebosa was ecologically dominant. Its frequency in the metacommunity increased during the growing season, and it was not replaced by other taxa. We next measured its competitive ability in a manipulative laboratory experiment and tracked its dispersal over time in nature. Despite its dominance, C. pseudoglaebosa is not a superior competitor. Instead, it is a superior disperser: it arrives in pitchers earlier, and disperses into more pitchers, than other fungi. Differential dispersal across the spatially structured metacommunity of individual pitchers emerges as a key driver of the continuous dominance of C. pseudoglaebosa during succession.

IMPORTANCE Microbial communities are ubiquitous and occupy nearly every imaginable habitat and resource, including human-influenced habitats (e.g., fermenting food and hospital surfaces) and habitats with little human influence (e.g., aquatic communities living in carnivorous plant pitchers). We studied yeast communities living in pitchers of the carnivorous purple pitcher plant to understand how and why microbial communities change over time. We found that dispersal ability is not only important for fungal communities early in their existence, it can also determine which species is dominant (here, the yeast Candida pseudoglaebosa) long after the species and its competitors have arrived. These results contrast with observations from many human-influenced habitats, in which a good competitor eventually outcompetes good dispersers, since humans often design these habitats to favor a specific competitor. This study will help microbiologists understand the qualities of microbial species that enable takeover of new habitats in both natural and human-influenced environments.

Self-organization and time-stability of social hierarchies

The formation and stability of social hierarchies is a question of general relevance. Here, we propose a simple generalized theoretical model for establishing social hierarchy via pair-wise interactions between individuals and investigate its stability. In each interaction or fight, the probability of "winning" depends solely on the relative societal status of the participants, and the winner has a gain of status whereas there is an equal loss to the loser. The interactions are characterized by two parameters. The first parameter represents how much can be lost, and the second parameter represents the degree to which even a small difference of status can guarantee a win for the higher-status individual. Depending on the parameters, the resulting status distributions reach either a continuous unimodal form or lead to a totalitarian end state with one high-status individual and all other individuals having status approaching zero. However, we find that in the latter case long-lived intermediary distributions often exist, which can give the illusion of a stable society. As we show, our model allows us to make predictions consistent with animal interaction data and their evolution over a number of years. Moreover, by implementing a simple, but realistic rule that restricts interactions to sufficiently similar-status individuals, the stable or long-lived distributions acquire high-status structure corresponding to a distinct high-status class. Using household income as a proxy for societal status in human societies, we find agreement over their entire range from the low-to-middle-status parts to the characteristic high-status "tail". We discuss how the model provides a conceptual framework for understanding the origin of social hierarchy and the factors which lead to the preservation or deterioration of the societal structure.

The emergence of inequality in social groups: Network structure and institutions affect the distribution of earnings in cooperation games

From small communities to entire nations and society at large, inequality in wealth, social status, and power is one of the most pervasive and tenacious features of the social world. What causes inequality to emerge and persist? In this study, we investigate how the structure and rules of our interactions can increase inequality in social groups. Specifically, we look into the effects of four structural conditions—network structure, network fluidity, reputation tracking, and punishment institutions—on the distribution of earnings in network cooperation games. We analyze 33 experiments comprising 96 experimental conditions altogether. We find that there is more inequality in clustered networks compared to random networks, in fixed networks compared to randomly rewired and strategically updated networks, and in groups with punishment institutions compared to groups without. Secondary analyses suggest that the reasons inequality emerges under these conditions may have to do with the fact that fixed networks allow exploitation of the poor by the wealthy and clustered networks foster segregation between the poor and the wealthy, while the burden of costly punishment falls onto the poor, leaving them poorer. Surprisingly, we do not find evidence that inequality is affected by reputation in a systematic way but this could be because reputation needs to play out in a particular network environment in order to have an effect. Overall, our findings suggest possible strategies and interventions to decrease inequality and mitigate its negative impact, particularly in the context of mid- and large-sized organizations and online communities.

Plans are useless, but planning is essential

Development over the next decade in northern Australia will proceed along the unpredictable intersection of two complex adaptive systems: the anthropic (social, economic) and the bio-physical/geophysical. These two domains are tightly linked and profoundly indeterminate. If we are to improve our capacity to nudge the future towards consensual outcomes, we will need tools suited for that purpose, and a culture pattern that embraces the baked-in complexity of our human and non-human environments. Planning is a process-focussed form of social ritual and narrative construction that is especially suited to the challenges and opportunities of the north. The prevalent narratives that define our relationship with the land are both insufficient for enduring prosperity and captive to narrow ideologies. Development will happen on, around, and through the small communities and sparse landscapes of the north. This region is highly sensitive to the presence or absence of cooperation networks and is exposed, for better and worse, to powerful external forces. This paper argues for a new posture, a re-freshed commitment to the processes of civil society in order to find the best ways forward in the north. A revival of planning culture promises to expand the capacity for resilience at the scale of community, local economy, and watershed. Australia’s Regional Natural Resource Management network is presented as an appropriate structure in which the specific processes of planning can be effectively realised. I will show that Regional Natural Resource Management Plans are evidence of a remarkable social process that opens new understandings of ourselves and the land we are part of. A collection of guiding queries, the Seven Signs of Planning, is proposed as a method for consistently evaluating the depth and quality of planning processes. Regional Natural Resource Management and its technology of planning can provide a foundation on which to build a culture of profitable and consensual development in north Australia.