Evolution Of Cooperative Behavior Research Articles

Coevolution of game strategy and link weight promotes cooperation in structured population

Evolutionary prisoner's dilemma game in structured populations on a weighted square lattice, on which the edge weight represents the relationship between agents and adaptively changes in time, has been proved to be an efficient way that can promote cooperation. In fact, such an adaptive link weight introduces a new time scale τa, not necessarily equal to the time scale of game strategy τɛ. Inspired from aforementioned above, we investigate the effect of w=τɛτa on the evolution of cooperative behavior. Through numerical simulation, we find cooperation can be promoted effectively with a larger value of w, which is related to the increase of average link weight in the structured population.

Consistent cooperation in a cichlid fish is caused by maternal and developmental effects rather than heritable genetic variation.

Studies on the evolution of cooperative behaviour are typically confined to understanding its adaptive value. It is equally essential, however, to understand its potential to evolve, requiring knowledge about the phenotypic consistency and genetic basis of cooperative behaviour. While previous observational studies reported considerably high heritabilities of helping behaviour in cooperatively breeding vertebrates, experimental studies disentangling the relevant genetic and non-genetic components of cooperative behaviour are lacking. In a half-sibling breeding experiment, we investigated the repeatability and heritability of three major helping behaviours performed by subordinates of the cooperatively breeding fish Neolamprologus pulcher To experimentally manipulate the amount of help needed in a territory, we raised the fish in two environments differing in egg predation risk. All three helping behaviours were significantly repeatable, but had very low heritabilities. The high within-individual consistencies were predominantly due to maternal and permanent environment effects. The perceived egg predation risk had no effect on helping, but social interactions significantly influenced helping propensities. Our results reveal that developmentally plastic adjustments of provided help to social context shape cooperative phenotypes, whereas heritable genetic variation plays a minor role.

The promotion of cooperation by the poor in dynamic chicken games

The evolution of cooperative behavior is one of the most important issues in game theory. Previous studies have shown that cooperation can evolve only under highly limited conditions, and various modifications have been introduced to games to explain the evolution of cooperation. Recently, a utility function basic to game theory was shown to be dependent on current wealth as a conditional (state) variable in a dynamic version of utility theory. Here, we introduce this dynamic utility function to several games. Under certain conditions, poor players exhibit cooperative behavior in two types of chicken games (the hawk-dove game and the snowdrift game) but not in the prisoner’s dilemma game and the stag hunt game. This result indicates that cooperation can be exhibited by the poor in some chicken games. Thus, the evolution of cooperation may not be as limited as has been suggested in previous studies.

Evolution of cooperation under social pressure in multiplex networks.

In this work, we aim to contribute to the understanding of human prosocial behavior by studying the influence that a particular form of social pressure, "being watched," has on the evolution of cooperative behavior. We study how cooperation emerges in multiplex complex topologies by analyzing a particular bidirectionally coupled dynamics on top of a two-layer multiplex network (duplex). The coupled dynamics appears between the prisoner's dilemma game in a network and a threshold cascade model in the other. The threshold model is intended to abstract the behavior of a network of vigilant nodes that impose the pressure of being observed altering hence the temptation to defect of the dilemma. Cooperation or defection in the game also affects the state of a node of being vigilant. We analyze these processes on different duplex networks structures and assess the influence of the topology, average degree and correlated multiplexity, on the outcome of cooperation. Interestingly, we find that the social pressure of vigilance may impact cooperation positively or negatively, depending on the duplex structure, specifically the degree correlations between layers is determinant. Our results give further quantitative insights in the promotion of cooperation under social pressure.

Evolutionary transitions during RNA virus experimental evolution.

In their search to understand the evolution of biological complexity, John Maynard Smith and Eörs Szathmáry put forward the notion of major evolutionary transitions as those in which elementary units get together to generate something new, larger and more complex. The origins of chromosomes, eukaryotic cells, multicellular organisms, colonies and, more recently, language and technological societies are examples that clearly illustrate this notion. However, a transition may be considered as anecdotal or as major depending on the specific level of biological organization under study. In this contribution, I will argue that transitions may also be occurring at a much smaller scale of biological organization: the viral world. Not only that, but also that we can observe in real time how these major transitions take place during experimental evolution. I will review the outcome of recent evolution experiments with viruses that illustrate four major evolutionary transitions: (i) the origin of a new virus that infects an otherwise inaccessible host and completely changes the way it interacts with the host regulatory and metabolic networks, (ii) the incorporation and loss of genes, (iii) the origin of segmented genomes from a non-segmented one, and (iv) the evolution of cooperative behaviour and cheating between different viruses or strains during co-infection of the same host.This article is part of the themed issue 'The major synthetic evolutionary transitions'.

Climate Dilemma: Link between Uncertainty and Success

Climate change has been described as one of the greatest challenges to international cooperation that the world has faced. Thus the climate problem is a classic problem of dealing with global goods. Game theory is one of the tools that can be used to identify key criteria for designing frameworks for international collective action on climate change. Such collective action will be used to present the evolution of cooperative behaviour. The world has realized that tackling the climate change will be costly and therefore the temptation to pollute will be always present. Can the stochastic element in our climate game, which means some level of uncertainty, increase the probability of adopting the cleaner strategy? Historic climate deal in Paris sets out a global actions plan to put the world on track to avoid dangerous climate change by limiting global warming to well below 2°C. To reach such ambitious target cooperation by all countries is required. All countries need to act urgently and collectively.

Variability in group size and the evolution of collective action

Models of the evolution of collective action typically assume that interactions occur in groups of identical size. In contrast, social interactions between animals occur in groups of widely dispersed size. This paper models collective action problems as two-strategy multiplayer games and studies the effect of variability in group size on the evolution of cooperative behavior under the replicator dynamics. The analysis identifies elementary conditions on the payoff structure of the game implying that the evolution of cooperative behavior is promoted or inhibited when the group size experienced by a focal player is more or less variable. Similar but more stringent conditions are applicable when the confounding effect of size-biased sampling, which causes the group-size distribution experienced by a focal player to differ from the statistical distribution of group sizes, is taken into account.

Fine-scale genetic structure reflects sex-specific dispersal strategies in a population of sociable weavers (Philetairus socius).

Dispersal is a critical driver of gene flow, with important consequences for population genetic structure, social interactions and other biological processes. Limited dispersal may result in kin-structured populations in which kin selection may operate, but it may also increase the risk of kin competition and inbreeding. Here, we use a combination of long-term field data and molecular genetics to examine dispersal patterns and their consequences for the population genetics of a highly social bird, the sociable weaver (Philetairus socius), which exhibits cooperation at various levels of sociality from nuclear family groups to its unique communal nests. Using 20 years of data, involving capture of 6508 birds and 3151 recaptures at 48 colonies, we found that both sexes exhibit philopatry and that any dispersal occurs over relatively short distances. Dispersal is female-biased, with females dispersing earlier, further, and to less closely related destination colonies than males. Genotyping data from 30 colonies showed that this pattern of dispersal is reflected by fine-scale genetic structure for both sexes, revealed by isolation by distance in terms of genetic relatedness and significant genetic variance among colonies. Both relationships were stronger among males than females. Crucially, significant relatedness extended beyond the level of the colony for both sexes. Such fine-scale population genetic structure may have played an important role in the evolution of cooperative behaviour in this species, but it may also result in a significant inbreeding risk, against which female-biased dispersal alone is unlikely to be an effective strategy.

Proximate mechanisms underlying cooperation in carnivores

While the evolution of cooperative behaviors has generated an intense debate among evolutionists and animal behaviorists, the proximate mechanisms underlying cooperative relationships have received much less attention. In recent years, it has become clear that an understanding of proximate causation of cooperation is needed in order to obtain a more balanced and complete picture of the phenomenon. The proximate cause of cooperation refers to the immediate situation that triggers behavior, and the role of learning, memory, physiology, and neural processes. Since from an evolutionary point of view cooperative relationships are maintained because of the subsequent benefits they bring, there has been the tendency to erroneously assume that they are also motivated by their future benefits. This assumption would imply that animals engage in social interactions in order to gain future benefits, or that they are able to remember the services given by another individual in order to offer a service in return at a later date. While this “rational” calculation offers a possible explanation, it is currently unclear whether or not some animal species have these cognitive capacities. Here I will argue that, while complex cognitive mechanisms may be present in some species, less cognitively demanding mechanisms, based on emotions, could be at the basis of the flexibility needed to form complex, enduring cooperative relationships in both human and non-human animals.

Lack of prosociality in great apes, capuchin monkeys and spider monkeys: convergent evidence from two different food distribution tasks.

Prosociality can be defined as any behaviour performed to alleviate the needs of others or to improve their welfare. Prosociality has probably played an essential role in the evolution of cooperative behaviour and several studies have already investigated it in primates to understand the evolutionary origins of human prosociality. Two main tasks have been used to test prosociality in a food context. In the Platforms task, subjects can prosocially provide food to a partner by selecting a prosocial platform over a selfish one. In the Tokens task, subjects can prosocially provide food to a partner by selecting a prosocial token over a selfish one. As these tasks have provided mixed results, we used both tasks to test prosociality in great apes, capuchin monkeys and spider monkeys. Our results provided no compelling evidence of prosociality in a food context in any of the species tested. Additionally, our study revealed serious limitations of the Tokens task as it has been previously used. These results highlight the importance of controlling for confounding variables and of using multiple tasks to address inconsistencies present in the literature.

Beyond Carrots and Sticks: How Cooperation and Its Rewards Evolve Together

This paper is based on the intuition of Dragonetti, an old Neapolitan economist, which argues that a society experiences economic and civic development if agents promote values and virtues, more than solely rely on punishments stated by law. We thus study the evolution of cooperative behaviors using a mechanism of endogenous social rewards for cooperation (SRC). These additional (material) rewards depend on the recognition that the society—each agent in the society—gives to cooperative strategies. We formalize it with a cultural evolution model in which the payoff matrix and the population shares coevolve. We find that this endogenous mechanism can produce a large variety of long-run situations (victory of cooperators, of non-cooperators or, finally, their coexistence) depending on the social features. Moreover, we analyze the differences between SRC and exogenous punishment, changes in cooperation costs or changes in repetition of interactions and we disentangle their respective contributions.

Using robots to understand social behaviour

A major challenge in studying social behaviour stems from the need to disentangle the behaviour of each individual from the resulting collective. One way to overcome this problem is to construct a model of the behaviour of an individual, and observe whether combining many such individuals leads to the predicted outcome. This can be achieved by using robots. In this review we discuss the strengths and weaknesses of such an approach for studies of social behaviour. We find that robots-whether studied in groups of simulated or physical robots, or used to infiltrate and manipulate groups of living organisms-have important advantages over conventional individual-based models and have contributed greatly to the study of social behaviour. In particular, robots have increased our understanding of self-organization and the evolution of cooperative behaviour and communication. However, the resulting findings have not had the desired impact on the biological community. We suggest reasons for why this may be the case, and how the benefits of using robots can be maximized in future research on social behaviour.

Arginine Vasotocin Regulation of Interspecific Cooperative Behaviour in a Cleaner Fish

In an interspecific cooperative context, individuals must be prepared to tolerate close interactive proximity to other species but also need to be able to respond to relevant social stimuli in the most appropriate manner. The neuropeptides vasopressin and oxytocin and their non-mammalian homologues have been implicated in the evolution of sociality and in the regulation of social behaviour across vertebrates. However, little is known about the underlying physiological mechanisms of interspecific cooperative interactions. In interspecific cleaning mutualisms, interactions functionally resemble most intraspecific social interactions. Here we provide the first empirical evidence that arginine vasotocin (AVT), a non-mammalian homologue of arginine vasopressin (AVP), plays a critical role as moderator of interspecific behaviour in the best studied and ubiquitous marine cleaning mutualism involving the Indo-Pacific bluestreak cleaner wrasse Labroides dimidiatus. Exogenous administration of AVT caused a substantial decrease of most interspecific cleaning activities, without similarly affecting the expression of conspecific directed behaviour, which suggests a differential effect of AVT on cleaning behaviour and not a general effect on social behaviour. Furthermore, the AVP-V1a receptor antagonist (manning compound) induced a higher likelihood for cleaners to engage in cleaning interactions and also to increase their levels of dishonesty towards clients. The present findings extend the knowledge of neuropeptide effects on social interactions beyond the study of their influence on conspecific social behaviour. Our evidence demonstrates that AVT pathways might play a pivotal role in the regulation of interspecific cooperative behaviour and conspecific social behaviour among stabilized pairs of cleaner fish. Moreover, our results suggest that the role of AVT as a neurochemical regulator of social behaviour may have been co-opted in the evolution of cooperative behaviour in an interspecific context, a hypothesis that is amenable to further testing on the potential direct central mechanism involved.

YELLOW SADDLE GOATFISH ARE TEAM PLAYERS

![][1] Spectacular discoveries within coral reefs continue to be made and in recent years the Red Sea has proven to be a treasure trove for neuroethologists in particular. For those interested in animal cognition and the evolution of cooperative behavior, a rich and diverse list of

The Evolution of Cooperative Behaviours in Physically Heterogeneous Multi-Robot Systems

Evolutionary Robotics (ER) is a methodology that uses evolutionary computation to develop controllers for autonomous robots. The existing works focus on single robot systems or physically homogenous multi-robot teams, although physical heterogeneousness is more prevalent in the real world. It is therefore instructive to examine whether cooperative behaviours can be synthesized using artificial evolution for a team of physically heterogeneous robots. This paper makes an important contribution in answering the question of whether robots with distinct capabilities can synthesize their control strategies to accommodate their own capabilities without human intervention. We present an empirical analysis of the collaboration mechanisms and suggest guidelines about how to choose appropriate evolution methods. Simulated experiments with a team of e-puck robots show that evolution can lead to effective controllers for robots with distinct capabilities.

A Simple Mechanism for Complex Social Behavior

The evolution of cooperation is a paradox because natural selection should favor exploitative individuals that avoid paying their fair share of any costs. Such conflict between the self-interests of cooperating individuals often results in the evolution of complex, opponent-specific, social strategies and counterstrategies. However, the genetic and biological mechanisms underlying complex social strategies, and therefore the evolution of cooperative behavior, are largely unknown. To address this dearth of empirical data, we combine mathematical modeling, molecular genetic, and developmental approaches to test whether variation in the production of and response to social signals is sufficient to generate the complex partner-specific social success seen in the social amoeba Dictyostelium discoideum. Firstly, we find that the simple model of production of and response to social signals can generate the sort of apparent complex changes in social behavior seen in this system, without the need for partner recognition. Secondly, measurements of signal production and response in a mutant with a change in a single gene that leads to a shift in social behavior provide support for this model. Finally, these simple measurements of social signaling can also explain complex patterns of variation in social behavior generated by the natural genetic diversity found in isolates collected from the wild. Our studies therefore demonstrate a novel and elegantly simple underlying mechanistic basis for natural variation in complex social strategies in D. discoideum. More generally, they suggest that simple rules governing interactions between individuals can be sufficient to generate a diverse array of outcomes that appear complex and unpredictable when those rules are unknown.

Promiscuity and the evolutionary transition to complex societies

Theory predicts that the evolution of cooperative behaviour is favoured by low levels of promiscuity leading to high within-group relatedness. However, in vertebrates, cooperation often occurs between non-relatives and promiscuity rates are among the highest recorded. Here we resolve this apparent inconsistency with a phylogenetic analysis of 267 bird species, demonstrating that cooperative breeding is associated with low promiscuity; that in cooperative species, helping is more common when promiscuity is low; and that intermediate levels of promiscuity favour kin discrimination. Overall, these results suggest that promiscuity is a unifying feature across taxa in explaining transitions to and from cooperative societies.

Cryptic Kin Selection: Kin Structure in Vertebrate Populations and Opportunities for Kin‐Directed Cooperation

AbstractAnimal societies of varying complexity have been the favoured testing ground for inclusive fitness theory, and there is now abundant evidence that kin selection has played a critical role in the evolution of cooperative behaviour. One of the key theoretical and empirical findings underlying this conclusion is that cooperative systems have a degree of kin structure, often the product of delayed dispersal, that facilitates interactions with relatives. However, recent population genetic studies have revealed that many non‐cooperative animals also have kin‐structured populations, providing more cryptic opportunities for kin selection to operate. In this article, I first review the evidence that kin structure is widespread among non‐cooperative vertebrates, and then consider the various contexts in which kin selection may occur in such taxa, including: leks, brood parasitism, crèches, breeding associations, territoriality and population dynamics, foraging and predator deterrence. I describe the evidence that kin‐selected benefits arise from interacting with kin in each of these contexts, notwithstanding the potential costs of kin competition and inbreeding. I conclude that as the tools required to determine population genetic structure are readily available, measurement of kin structure and the potential for kin selection on a routine basis is likely to reveal that this process has been an important driver of evolutionary adaptation in many non‐cooperative as well as cooperative species.

Cooperators Unite! Assortative linking promotes cooperation particularly for medium sized associations

BackgroundEvolution of cooperative behaviour is widely studied in different models where interaction is heterogeneous, although static among individuals. However, in nature individuals can often recognize each other and chose, besides to cooperate or not, to preferentially associate with or to avoid certain individuals.Here we consider a dynamical interaction graph, in contrast to a static one. We propose several rules of rejecting unwanted partners and seeking out new ones, and study the probability of emergence and maintenance of cooperation on these dynamic networks.ResultsOur simulations reveal that cooperation can evolve and be stable in the population if we introduce preferential linking, even if defectors can perform it too. The fixation of cooperation has higher probability than that of on static graphs, and this effect is more prevalent at high benefit to cost ratios. We also find an optimal number of partners, for which the fixation probability of cooperation shows a maximum.ConclusionsThe ability to recognize, seek out or avoid interaction partners based on the outcome of past interactions has an important effect on the emergence of cooperation. Observations about the number of partners in natural cooperating groups are in concordance with the result of our model.

Evolution of cooperative behavior among heterogeneous agents with different strategy representations in an iterated prisoner’s dilemma game

The iterated prisoner’s dilemma (IPD) game has frequently been used to examine the evolution of cooperative behavior among agents. When the effect of representation schemes of IPD game strategies was examined, the same representation scheme was usually assigned to all agents. That is, in the literature, a population of homogeneous agents was usually used in computational experiments. In this article, we focus on a slightly different situation where every agent does not necessarily use the same representation scheme. That is, a population can be a mixture of heterogeneous agents with different representation schemes. In computational experiments, we used binary strings of different lengths (i.e., three-bit and five-bit strings) to represent IPD game strategies. We examined the evolution of cooperative behavior among heterogeneous agents in comparison with the case of homogeneous ones for the standard IPD game with typical payoff values of 0, 1, 3, and 5. Experimental results showed that the evolution of cooperative behavior was slowed down by the use of heterogeneous agents. It was also demonstrated that a faster evolution of cooperative behavior is achieved among majority agents than among minority ones in a heterogeneous population.