883,359 research outputs found
Creationism and evolution
In Tower of Babel, Robert Pennock wrote that
“defenders of evolution would help their case
immeasurably if they would reassure their
audience that morality, purpose, and meaning are
not lost by accepting the truth of evolution.” We
first consider the thesis that the creationists’
movement exploits moral concerns to spread its
ideas against the theory of evolution. We analyze
their arguments and possible reasons why they are
easily accepted. Creationists usually employ two
contradictive strategies to expose the purported
moral degradation that comes with accepting the
theory of evolution. On the one hand they claim
that evolutionary theory is immoral. On the other
hand creationists think of evolutionary theory as
amoral. Both objections come naturally in a
monotheistic view. But we can find similar
conclusions about the supposed moral aspects of
evolution in non-religiously inspired discussions.
Meanwhile, the creationism-evolution debate
mainly focuses — understandably — on what
constitutes good science. We consider the need for
moral reassurance and analyze reassuring
arguments from philosophers. Philosophers may
stress that science does not prescribe and is
therefore not immoral, but this reaction opens the
door for the objection of amorality that evolution
— as a naturalistic world view at least —
supposedly endorses. We consider that the topic of
morality and its relation to the acceptance of
evolution may need more empirical research
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
The collapse of cooperation in evolving games
Game theory provides a quantitative framework for analyzing the behavior of
rational agents. The Iterated Prisoner's Dilemma in particular has become a
standard model for studying cooperation and cheating, with cooperation often
emerging as a robust outcome in evolving populations. Here we extend
evolutionary game theory by allowing players' strategies as well as their
payoffs to evolve in response to selection on heritable mutations. In nature,
many organisms engage in mutually beneficial interactions, and individuals may
seek to change the ratio of risk to reward for cooperation by altering the
resources they commit to cooperative interactions. To study this, we construct
a general framework for the co-evolution of strategies and payoffs in arbitrary
iterated games. We show that, as payoffs evolve, a trade-off between the
benefits and costs of cooperation precipitates a dramatic loss of cooperation
under the Iterated Prisoner's Dilemma; and eventually to evolution away from
the Prisoner's Dilemma altogether. The collapse of cooperation is so extreme
that the average payoff in a population may decline, even as the potential
payoff for mutual cooperation increases. Our work offers a new perspective on
the Prisoner's Dilemma and its predictions for cooperation in natural
populations; and it provides a general framework to understand the co-evolution
of strategies and payoffs in iterated interactions.Comment: 33 pages, 13 figure
The Evolution of Extortion in Iterated Prisoner's Dilemma Games
Iterated games are a fundamental component of economic and evolutionary game
theory. They describe situations where two players interact repeatedly and have
the possibility to use conditional strategies that depend on the outcome of
previous interactions. In the context of evolution of cooperation, repeated
games represent the mechanism of reciprocation. Recently a new class of
strategies has been proposed, so called 'zero determinant strategies'. These
strategies enforce a fixed linear relationship between one's own payoff and
that of the other player. A subset of those strategies are 'extortioners' which
ensure that any increase in the own payoff exceeds that of the other player by
a fixed percentage. Here we analyze the evolutionary performance of this new
class of strategies. We show that in reasonably large populations they can act
as catalysts for the evolution of cooperation, similar to tit-for-tat, but they
are not the stable outcome of natural selection. In very small populations,
however, relative payoff differences between two players in a contest matter,
and extortioners hold their ground. Extortion strategies do particularly well
in co-evolutionary arms races between two distinct populations: significantly,
they benefit the population which evolves at the slower rate - an instance of
the so-called Red King effect. This may affect the evolution of interactions
between host species and their endosymbionts.Comment: contains 4 figure
Evolution of virulence in opportunistic pathogens: generalism, plasticity, and control
Standard virulence evolution theory assumes that virulence factors are maintained because they aid parasitic exploitation, increasing growth within and/or transmission between hosts. An increasing number of studies now demonstrate that many opportunistic pathogens (OPs) do not conform to these assumptions, with virulence factors maintained instead because of advantages in non-parasitic contexts. Here we review virulence evolution theory in the context of OPs and highlight the importance of incorporating environments outside a focal virulence site. We illustrate that virulence selection is constrained by correlations between these external and focal settings and pinpoint drivers of key environmental correlations, with a focus on generalist strategies and phenotypic plasticity. We end with a summary of key theoretical and empirical challenges to be met for a fuller understanding of OPs
Cyclic dominance and biodiversity in well-mixed populations
Coevolutionary dynamics is investigated in chemical catalysis, biological
evolution, social and economic systems. The dynamics of these systems can be
analyzed within the unifying framework of evolutionary game theory. In this
Letter, we show that even in well-mixed finite populations, where the dynamics
is inherently stochastic, biodiversity is possible with three cyclic dominant
strategies. We show how the interplay of evolutionary dynamics, discreteness of
the population, and the nature of the interactions influences the coexistence
of strategies. We calculate a critical population size above which coexistence
is likely.Comment: Physical Review Letters, in print (2008
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