569 research outputs found
Coevolution of teaching activity promotes cooperation
Evolutionary games are studied where the teaching activity of players can
evolve in time. Initially all players following either the cooperative or
defecting strategy are distributed on a square lattice. The rate of strategy
adoption is determined by the payoff difference and a teaching activity
characterizing the donor's capability to enforce its strategy on the opponent.
Each successful strategy adoption process is accompanied with an increase in
the donor's teaching activity. By applying an optimum value of the increment
this simple mechanism spontaneously creates relevant inhomogeneities in the
teaching activities that support the maintenance of cooperation for both the
prisoner's dilemma and the snowdrift game.Comment: 10 pages, 4 figures; accepted for publication in New Journal of
Physic
Evolution via imitation among like-minded individuals
In social situations with which evolutionary game is concerned, individuals
are considered to be heterogeneous in various aspects. In particular, they may
differently perceive the same outcome of the game owing to heterogeneity in
idiosyncratic preferences, fighting abilities, and positions in a social
network. In such a population, an individual may imitate successful and similar
others, where similarity refers to that in the idiosyncratic fitness function.
I propose an evolutionary game model with two subpopulations on the basis of
multipopulation replicator dynamics to describe such a situation. In the
proposed model, pairs of players are involved in a two-person game as a
well-mixed population, and imitation occurs within subpopulations in each of
which players have the same payoff matrix. It is shown that the model does not
allow any internal equilibrium such that the dynamics differs from that of
other related models such as the bimatrix game. In particular, even a slight
difference in the payoff matrix in the two subpopulations can make the opposite
strategies to be stably selected in the two subpopulations in the snowdrift and
coordination games.Comment: 3 figure
Participation costs dismiss the advantage of heterogeneous networks in evolution of cooperation
Real social interactions occur on networks in which each individual is
connected to some, but not all, of others. In social dilemma games with a fixed
population size, heterogeneity in the number of contacts per player is known to
promote evolution of cooperation. Under a common assumption of positively
biased payoff structure, well-connected players earn much by playing
frequently, and cooperation once adopted by well-connected players is
unbeatable and spreads to others. However, maintaining a social contact can be
costly, which would prevent local payoffs from being positively biased. In
replicator-type evolutionary dynamics, it is shown that even a relatively small
participation cost extinguishes the merit of heterogeneous networks in terms of
cooperation. In this situation, more connected players earn less so that they
are no longer spreaders of cooperation. Instead, those with fewer contacts win
and guide the evolution. The participation cost, or the baseline payoff, is
irrelevant in homogeneous populations but is essential for evolutionary games
on heterogeneous networks.Comment: 4 figures + 3 supplementary figure
Cheating is evolutionarily assimilated with cooperation in the continuous snowdrift game
It is well known that in contrast to the Prisoner's Dilemma, the snowdrift
game can lead to a stable coexistence of cooperators and cheaters. Recent
theoretical evidence on the snowdrift game suggests that gradual evolution for
individuals choosing to contribute in continuous degrees can result in the
social diversification to a 100% contribution and 0% contribution through
so-called evolutionary branching. Until now, however, game-theoretical studies
have shed little light on the evolutionary dynamics and consequences of the
loss of diversity in strategy. Here we analyze continuous snowdrift games with
quadratic payoff functions in dimorphic populations. Subsequently, conditions
are clarified under which gradual evolution can lead a population consisting of
those with 100% contribution and those with 0% contribution to merge into one
species with an intermediate contribution level. The key finding is that the
continuous snowdrift game is more likely to lead to assimilation of different
cooperation levels rather than maintenance of diversity. Importantly, this
implies that allowing the gradual evolution of cooperative behavior can
facilitate social inequity aversion in joint ventures that otherwise could
cause conflicts that are based on commonly accepted notions of fairness.Comment: 30 pages, 3 tables, 5 figure
Evolution of emotions on networks leads to the evolution of cooperation in social dilemmas
We show that the resolution of social dilemmas in random graphs and scale-free networks is facilitated by
imitating not the strategy of better-performing players but, rather, their emotions. We assume sympathy and
envy to be the two emotions that determine the strategy of each player in any given interaction, and we define
them as the probabilities of cooperating with players having a lower and a higher payoff, respectively. Starting
with a population where all possible combinations of the two emotions are available, the evolutionary process
leads to a spontaneous fixation to a single emotional profile that is eventually adopted by all players. However,
this emotional profile depends not only on the payoffs but also on the heterogeneity of the interaction network.
Homogeneous networks, such as lattices and regular random graphs, lead to fixations that are characterized by
high sympathy and high envy, while heterogeneous networks lead to low or modest sympathy but also low envy.
Our results thus suggest that public emotions and the propensity to cooperate at large depend, and are in fact
determined by, the properties of the interaction network
Evolutionary game theory: Temporal and spatial effects beyond replicator dynamics
Evolutionary game dynamics is one of the most fruitful frameworks for
studying evolution in different disciplines, from Biology to Economics. Within
this context, the approach of choice for many researchers is the so-called
replicator equation, that describes mathematically the idea that those
individuals performing better have more offspring and thus their frequency in
the population grows. While very many interesting results have been obtained
with this equation in the three decades elapsed since it was first proposed, it
is important to realize the limits of its applicability. One particularly
relevant issue in this respect is that of non-mean-field effects, that may
arise from temporal fluctuations or from spatial correlations, both neglected
in the replicator equation. This review discusses these temporal and spatial
effects focusing on the non-trivial modifications they induce when compared to
the outcome of replicator dynamics. Alongside this question, the hypothesis of
linearity and its relation to the choice of the rule for strategy update is
also analyzed. The discussion is presented in terms of the emergence of
cooperation, as one of the current key problems in Biology and in other
disciplines.Comment: Review, 48 pages, 26 figure
Coevolutionary games - a mini review
Prevalence of cooperation within groups of selfish individuals is puzzling in
that it contradicts with the basic premise of natural selection. Favoring
players with higher fitness, the latter is key for understanding the challenges
faced by cooperators when competing with defectors. Evolutionary game theory
provides a competent theoretical framework for addressing the subtleties of
cooperation in such situations, which are known as social dilemmas. Recent
advances point towards the fact that the evolution of strategies alone may be
insufficient to fully exploit the benefits offered by cooperative behavior.
Indeed, while spatial structure and heterogeneity, for example, have been
recognized as potent promoters of cooperation, coevolutionary rules can extend
the potentials of such entities further, and even more importantly, lead to the
understanding of their emergence. The introduction of coevolutionary rules to
evolutionary games implies, that besides the evolution of strategies, another
property may simultaneously be subject to evolution as well. Coevolutionary
rules may affect the interaction network, the reproduction capability of
players, their reputation, mobility or age. Here we review recent works on
evolutionary games incorporating coevolutionary rules, as well as give a
didactic description of potential pitfalls and misconceptions associated with
the subject. In addition, we briefly outline directions for future research
that we feel are promising, thereby particularly focusing on dynamical effects
of coevolutionary rules on the evolution of cooperation, which are still widely
open to research and thus hold promise of exciting new discoveries.Comment: 24 two-column pages, 10 figures; accepted for publication in
BioSystem
Asymmetric evolutionary games
Evolutionary game theory is a powerful framework for studying evolution in
populations of interacting individuals. A common assumption in evolutionary
game theory is that interactions are symmetric, which means that the players
are distinguished by only their strategies. In nature, however, the microscopic
interactions between players are nearly always asymmetric due to environmental
effects, differing baseline characteristics, and other possible sources of
heterogeneity. To model these phenomena, we introduce into evolutionary game
theory two broad classes of asymmetric interactions: ecological and genotypic.
Ecological asymmetry results from variation in the environments of the players,
while genotypic asymmetry is a consequence of the players having differing
baseline genotypes. We develop a theory of these forms of asymmetry for games
in structured populations and use the classical social dilemmas, the Prisoner's
Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric
games reveal essential differences between models of genetic evolution based on
reproduction and models of cultural evolution based on imitation that are not
apparent in symmetric games.Comment: accepted for publication in PLOS Comp. Bio
Social Dilemmas and Cooperation in Complex Networks
In this paper we extend the investigation of cooperation in some classical
evolutionary games on populations were the network of interactions among
individuals is of the scale-free type. We show that the update rule, the payoff
computation and, to some extent the timing of the operations, have a marked
influence on the transient dynamics and on the amount of cooperation that can
be established at equilibrium. We also study the dynamical behavior of the
populations and their evolutionary stability.Comment: 12 pages, 7 figures. to appea
Coveting thy neighbors fitness as a means to resolve social dilemmas
In spatial evolutionary games the fitness of each individual is traditionally
determined by the payoffs it obtains upon playing the game with its neighbors.
Since defection yields the highest individual benefits, the outlook for
cooperators is gloomy. While network reciprocity promotes collaborative
efforts, chances of averting the impending social decline are slim if the
temptation to defect is strong. It is therefore of interest to identify viable
mechanisms that provide additional support for the evolution of cooperation.
Inspired by the fact that the environment may be just as important as
inheritance for individual development, we introduce a simple switch that
allows a player to either keep its original payoff or use the average payoff of
all its neighbors. Depending on which payoff is higher, the influence of either
option can be tuned by means of a single parameter. We show that, in general,
taking into account the environment promotes cooperation. Yet coveting the
fitness of one's neighbors too strongly is not optimal. In fact, cooperation
thrives best only if the influence of payoffs obtained in the traditional way
is equal to that of the average payoff of the neighborhood. We present results
for the prisoner's dilemma and the snowdrift game, for different levels of
uncertainty governing the strategy adoption process, and for different
neighborhood sizes. Our approach outlines a viable route to increased levels of
cooperative behavior in structured populations, but one that requires a
thoughtful implementation.Comment: 10 two-column pages, 5 figures; accepted for publication in Journal
of Theoretical Biolog
- …