318 research outputs found
Selfishness, fraternity, and other-regarding preference in spatial evolutionary games
Spatial evolutionary games are studied with myopic players whose payoff
interest, as a personal character, is tuned from selfishness to other-regarding
preference via fraternity. The players are located on a square lattice and
collect income from symmetric two-person two-strategy (called cooperation and
defection) games with their nearest neighbors. During the elementary steps of
evolution a randomly chosen player modifies her strategy in order to maximize
stochastically her utility function composed from her own and the co-players'
income with weight factors and Q. These models are studied within a wide
range of payoff parameters using Monte Carlo simulations for noisy strategy
updates and by spatial stability analysis in the low noise limit. For fraternal
players () the system evolves into ordered arrangements of strategies in
the low noise limit in a way providing optimum payoff for the whole society.
Dominance of defectors, representing the "tragedy of the commons", is found
within the regions of prisoner's dilemma and stag hunt game for selfish players
(Q=0). Due to the symmetry in the effective utility function the system
exhibits similar behavior even for Q=1 that can be interpreted as the "lovers'
dilemma".Comment: 7 two-column pages, 8 figures; accepted for publication in J. Theor.
Bio
How Natural Selection Can Create Both Self- and Other-Regarding Preferences, and Networked Minds
Biological competition is widely believed to result in the evolution of
selfish preferences. The related concept of the `homo economicus' is at the
core of mainstream economics. However, there is also experimental and empirical
evidence for other-regarding preferences. Here we present a theory that
explains both, self-regarding and other-regarding preferences. Assuming
conditions promoting non-cooperative behaviour, we demonstrate that
intergenerational migration determines whether evolutionary competition results
in a `homo economicus' (showing self-regarding preferences) or a `homo
socialis' (having other-regarding preferences). Our model assumes spatially
interacting agents playing prisoner's dilemmas, who inherit a trait determining
`friendliness', but mutations tend to undermine it. Reproduction is ruled by
fitness-based selection without a cultural modification of reproduction rates.
Our model calls for a complementary economic theory for `networked minds' (the
`homo socialis') and lays the foundations for an evolutionarily grounded theory
of other-regarding agents, explaining individually different utility functions
as well as conditional cooperation
Risk-Averse Evolutionary Game Model of Aviation Joint Emergency Response
We study effects of risk-averse attitude of both participators in aviation joint emergency response on the coevolution of cooperation mechanisms and individual preferences between airport and nonprofit organization. First, based on the current aviation joint emergency mechanism in China, we put forward two mechanisms to select the joint nonprofit organization, including reputation cooperation and bidding competition. Meanwhile, we consider two preferences including altruism and selfishness. Then we build replicator dynamics equations using the theory of conditional value-at-risk (CVaR) taking risk aversion attitude into account. Finally, we introduce the factor of government and give all participators some suggestions. We show that the risk-averse attitude of the other game participator affects the one participator's decision and the effects subject to some parameters
Restoring spatial cooperation with myopic agents in a three-strategy social dilemma
Introducing strategy complexity into the basic conflict of cooperation and
defection is a natural response to avoid the tragedy of the common state. As an
intermediate approach, quasi-cooperators were recently suggested to address the
original problem. In this study, we test its vitality in structured populations
where players have fixed partners. Naively, the latter condition should support
cooperation unambiguously via enhanced network reciprocity. However, the
opposite is true because the spatial structure may provide a humbler
cooperation level than a well-mixed population. This unexpected behavior can be
understood if we consider that at a certain parameter interval the original
prisoner's dilemma game is transformed into a snow-drift game. If we replace
the original imitating strategy protocol by assuming myopic players, the
spatial population becomes a friendly environment for cooperation. This
observation is valid in a huge region of parameter space. This study highlights
that spatial structure can reveal a new aspect of social dilemmas when strategy
complexity is introduced.Comment: 9 pages, 4 figures, accepted by Applied Mathematics and Computatio
How norms shape the evolution of prosocial behavior. Compassion, Universalizability, Reciprocity, Equity: A C.U.R.E for social dilemmas
How cooperation evolves and particularly maintains at a large scale remains
an open problem for improving humanity across domains ranging from climate
change to pandemic response. To shed light on how behavioral norms can resolve
the social dilemma of cooperation, here we present a formal mathematical model
of individuals' decision making under general social norms, encompassing a
variety of concerns and motivations an individual may have beyond simply
maximizing their own payoffs. Using the canonical game of the Prisoner's
Dilemma, we compare four different norms: compassion, universalizability,
reciprocity, and equity, to determine which social forces can facilitate the
evolution of cooperation, if any. We analyze our model through a variety of
limiting cases, including weak selection, low mutation, and large population
sizes. This is complemented by computer simulations of population dynamics via
a Fisher process, which confirm our theoretical results. We find that the first
two norms lead to the emergence of cooperation in a wide range of games, but
the latter two do not on their own. Due to its generality, our framework can be
used to investigate many more norms, as well as how norms themselves emerge and
evolve. Our work complements recent work on fair-minded learning dynamics and
provides a useful bottom-up perspective into understanding the impact of
top-down social norms on collective cooperative intelligence
Social dilemmas in off-lattice populations
Exploring the possible consequences of spatial reciprocity on the evolution
of cooperation is an intensively studied research avenue. Related works assumed
a certain interaction graph of competing players and studied how particular
topologies may influence the dynamical behavior. In this paper we apply a
numerically more demanding off-lattice population approach which could be
potentially relevant especially in microbiological environments. As expected,
results are conceptually similar to those which were obtained for lattice-type
interaction graphs, but some spectacular differences can also be revealed. On
one hand, in off-lattice populations spatial reciprocity may work more
efficiently than for a lattice-based system. On the other hand, competing
strategies may separate from each other in the continuous space concept, which
gives a chance for cooperators to survive even at relatively high temptation
values. Furthermore, the lack of strict neighborhood results in soft borders
between competing patches which jeopardizes the long term stability of
homogeneous domains. We survey the major social dilemma games based on pair
interactions of players and reveal all analogies and differences compared to
on-lattice simulations.Comment: 8 pages, 9 figure
Heterogeneity in background fitness acts as a suppressor of selection
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.We introduce the concept of heterogeneity in background fitness to evolutionary dynamics in finite populations. Background fitness is specific to an individual but not linked to its strategy. It can be thought of as a property that is related to the physical or societal position of an individual, but is not dependent on the strategy that is adopted in the evolutionary process under consideration. In our model, an individual's total fitness is the sum of its background fitness and the fitness derived from using a specific strategy. This approach has important implications for the imitation of behavioural strategies: if we imitate others for their success, but can only adopt their behaviour and not their social and economic ties, we may imitate in vain. We study the effect of heterogeneity in background fitness on the fixation of a mutant strategy with constant fitness. We find that heterogeneity suppresses selection, but also decreases the time until a novel strategy either takes over the population or is lost again. We derive analytical solutions of the fixation probability in small populations. In the case of large total background fitness in a population with maximum inequality, we find a particularly simple approximation of the fixation probability. Numerical simulations suggest that this simple approximation also holds for larger population sizes.
Previous article in issueO.P.H. is grateful for fellowship support from Harvard's Department of Organismic and Evolutionary Biology. O.P.H. and M.A.N. are thankful for support from the Templeton Foundation. A.T. thanks the Max-Planck-Gesellschaft for generous funding
Seasonal payoff variations and the evolution of cooperation in social dilemmas
Varying environmental conditions affect relations between interacting
individuals in social dilemmas, thus affecting also the evolution of
cooperation. Oftentimes these environmental variations are seasonal and can
therefore be mathematically described as periodic changes. Accordingly, we here
study how periodic shifts between different manifestations of social dilemmas
affect cooperation. We observe a non-trivial interplay between the inherent
spatiotemporal dynamics that characterizes the spreading of cooperation in a
particular social dilemma type and the frequency of payoff changes. In
particular, we show that periodic changes between two available games with
global ordering best be fast, while periodic changes between global and local
ordering games best be slow for cooperation to thrive. We also show that the
frequency of periodic changes between two local ordering social dilemmas is
irrelevant, because then the process is fast and simply the average cooperation
level of the two is returned. The structure of the interaction network plays an
important role too in that lattices promote local ordering, whilst random
graphs hinder the formation of compact cooperative clusters. Conversely, for
local ordering the regular structure of the interaction network is only
marginally relevant as role-separating checkerboard patterns do not rely on
long-range order.Comment: 9 two-column pages, 6 figures; accepted for publication in Scientific
Report
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