To understand the meaning of evolutionary equilibria, it is necessary to comprehend the ramifications of the evolutionary model. For instance, a full appreciation of Axelrod's The Evolution of Cooperation requires that we identify assumptions under which conditionally cooperative strategies, like Tit For Tat, are and are not evolutionarily stable. And more generally, when does stability fail? To resolve these questions we re-examine the very foundations of the evolutionary model. The results of this paper can be analytically (...) separated into three parts. The first part is conceptual: it identifies the evolutionary model's assumptions and shows how different assumptions imply different types of evolutionary stability. The second part is deductive: it establishes necessary and sufficient conditions for the types of evolutionary stability identified in the first part, and demonstrates in which games these kinds of stability can (and cannot) be attained. The third and final part is applied: it relates the general findings (which are independent of the specific payoffs of any particular evolutionary game) to the issue of the evolutionary stability of cooperation. Results on cooperation appear throughout the paper as they both exemplify and motivate the general results. These results essentially explain when cooperation is and is not stable, and why, thus shedding new light on the meaning and applicability of Axelrod's widely known claims. (shrink)

Mealey's interesting interpretation of sociopathy is based on an inappropriate two-person game model. A multiperson, compound game version of Chicken would be more suitable, because a population engaging in random pairwise interactions with that structure would evolve to an equilibrium in which a fixed proportion of strategic choices was exploitative, antisocial, and risky, as required by Mealey's interpretation.

They are correct that punctuated equilibria apply to sexually reproducing organisms and that morphological evolutionary change is regarded as largely (if not exclusively) correlated with speciation events. However, they err in suggesting that we attribute stasis strictly to "developmental constraints," which represent only one of a set of possible mechanisms that we have suggested for the causes of stasis. Others include habitat tracking and the internal structure of species themselves [for example, (2)].

The allegedly alternative theories of Phyletic Gradualism and Punctuated Equilibria are examined as regards the nature of their differences. The explanatory value of both models is determined by establishing their actual connection with reality. It is concluded that they are to be considered complementary rather than mutually exclusive at all levels of infraspecific, specific, and supraspecific evolution. So, in order to be described comprehensively, the pathways of evolution require at least two distinct models, each based on a discrete range (...) of real phenomena. [Phyletic Gradualism; Punctuated Equilibria; evolutionary theories; divergence models; additive speciation; microevolution; macroevolution; anagenesis.]. (shrink)

This commentary suggests that an equilibrium framework may be retained, in an evolutionary model such as Gintis's and with more satisfactory results, if rationality is relaxed in a slightly different way than he proposes: that is, if decisions are assumed to be related to rewards probabilistically, rather than with certainty. This relaxed concept of rationality gives rise to probabilistic equilibria. (Published Online April 27 2007).

The allegedly alternative theories of Phyletic Gradualism and Punctuated Equilibria are examined as regards the nature of their differences. The explanatory value of both models is determined by establishing their actual connection with reality. It is concluded that they are to be considered complementary rather than mutually exclusive at all levels of infraspecific, specific, and supraspecific evolution. So, in order to be described comprehensively, the pathways of evolution require at least two distinct models, each based on a discrete range (...) of real phenomena. [Phyletic Gradualism; Punctuated Equilibria; evolutionary theories; divergence models; additive speciation; microevolution; macroevolution; anagenesis.]. (shrink)

Evolution is frequently concentrated in bursts of rapid morphological change and speciation followed by long‐term stasis. We propose that this pattern of punctuated equilibria results from an evolutionary tug‐of‐war between host genomes and transposable elements (TEs) mediated through the epigenome. According to this hypothesis, epigenetic regulatory mechanisms (RNA interference, DNA methylation and histone modifications) maintain stasis by suppressing TE mobilization. However, physiological stress, induced by climate change or invasion of new habitats, disrupts epigenetic regulation and unleashes TEs. With (...) their capacity to drive non‐adaptive host evolution, mobilized TEs can restructure the genome and displace populations from adaptive peaks, thus providing an escape from stasis and generating genetic innovations required for rapid diversification. This “epi‐transposon hypothesis” can not only explain macroevolutionary tempo and mode, but may also resolve other long‐standing controversies, such as Wright's shifting balance theory, Mayr's peripheral isolates model, and McClintock's view of genome restructuring as an adaptive response to challenge. (shrink)

Many attempts have been made at supporting either one of the allegedly complementary divergence models Phyletic Gradualism and Punctuated Equilibria by patterns found in specific fossil sequences. However, assessing each model's connection with reality via such “individual case histories” appears not to constitute a relevant approach. Instead, in order to correctly establish the possible merits of both concepts, the claims of each have to be verified against general evolutionary theory. This is being pointed out herein by analyzing cladogenesis (...) at the specific level as an example. [Phyletic Gradualism; Punctuated Equilibria; evolutionary theory; divergence models; case histories; additive speciation.]. (shrink)

Many attempts have been made at supporting either one of the allegedly complementary divergence models Phyletic Gradualism and Punctuated Equilibria by patterns found in specific fossil sequences. However, assessing each model's connection with reality via such “individual case histories” appears not to constitute a relevant approach. Instead, in order to correctly establish the possible merits of both concepts, the claims of each have to be verified against general evolutionary theory. This is being pointed out herein by analyzing cladogenesis (...) at the specific level as an example. [Phyletic Gradualism; Punctuated Equilibria; evolutionary theory; divergence models; case histories; additive speciation.]. (shrink)

Notions of uniform and gradual evolution have been replaced in some circles by biological and paleontological models that postulate that periods of rapid change punctuate long periods of evolutionary stasis. This new theory, called punctuated equilibria (or PE for short), may have implications for paradigms in scholarly disciplines other than the sciences. Whereas old evolutionary models exerted great influence upon historians, sociologists, anthropologists, and students of religion for more than a century, the new model may provide heuristic (...) paradigms for research that correlate more adequately with the current observations of scholars. We therefore provide suggestions for deployment of this new scientific paradigm in history and anthropology. In particular, this model can explain the rise of the Israelite state and the religious ethos in the Hebrew Bible, two major concerns of today's socioscientific study of biblical materials. Thus the possibility of an overarching paradigm for the social sciences is entertained. (shrink)

This chapter surveys the philosophical problems raised by the two Darwinian claims of the existence of a Tree of a life, and the explanatory power of natural selection. It explores the specificity of explanations by natural selection, emphasizing the high context-dependency of any process of selection. Some consequences are drawn about the difficulty of those explanations to fit a nomological model of explanation, and the irreducibility of their historic-narrative dimension. The paper introduces to the debates about units of selection, stating (...) the compelling force of genic selectionnism but highlighting some critiques. Then it addresses the limits of selectionist explanations : the compared status of selection, drift and phylogenetic inertia are investigated, and the debates over adaptationism are presented, with the aim of defining the varieties of adaptationisms as research programs. In order to assess the scope of natural selection, the chapter addresses weak and strong challenges to the Synthetic theory of evolution, both from paleontology (punctuated equilibria, Gould’s contingency thesis) and evolutionary theory of development. We finally sketch some consequences of evolutionary theory concerning philosophical questions about human nature, on the basis of the hypothesis of the universality of selectionist explanations: this part deals mostly with epistemology and psychology. (shrink)

First, a brief history is provided of Popper's views on the status of evolutionary biology as a science. The views of some prominent biologists are then canvassed on the matter of falsifiability and its relation to evolutionary biology. Following that, I argue that Popper's programme of falsifiability does indeed exclude evolutionary biology from within the circumference of genuine science, that Popper's programme is fundamentally incoherent, and that the correction of this incoherence results in a greatly expanded and (...) much more realistic concept of what is empirical, resulting in the inclusion of evolutionary biology. Finally, this expanded concept of empirical is applied to two particular problems in evolutionary biology — viz., the species problem and the debate over the theory of punctuated equilibria — and it is argued that both of them are still mainly metaphysical. (shrink)

Several paleontologists have recently challenged the explanatory adequacy of the modern synthetic theory of evolution. Their position is that, contrary to the prevailing view that evolutionary change is gradual, the fossil record manifests long periods of species stasis (equilibrium) punctuated by periods of rapid species formation. And, they argue, this punctuated equilibria pattern challenges the gradualist, adaptationist and extrapolationist assumptions of the modern synthetic theory of evolution and supports a hierarchical, non-extrapolationist (non-reductionist) view of evolution. In this paper (...) I argue that the challenge rests on an inadequate characterization of the modern synthetic theory and that, even accepting punctuated equilibria and an irreducible evolutionary hierarchy, the modern synthetic theory is adequate to explain evolutionary change at all levels of the hierarchy. (shrink)

Several paleontologists have recently challenged the explanatory adequacy of the modern synthetic theory of evolution. Their position is that, contrary to the prevailing view that evolutionary change is gradual, the fossil record manifests long periods of species stasis punctuated by periods of rapid species formation. And, they argue, this punctuated equilibria pattern challenges the gradualist, adaptationist and extrapolationist assumptions of the modern synthetic theory of evolution and supports a hierarchical, non-extrapolationist view of evolution. In this paper I argue (...) that the challenge rests on an inadequate characterization of the modern synthetic theory and that, even accepting punctuated equilibria and an irreducible evolutionary hierarchy, the modern synthetic theory is adequate to explain evolutionary change at all levels of the hierarchy. (shrink)

The theory of Punctuated Equilibria challenges the neo‐Darwinian tenet that evolution is a uniform process. Recently, an article by Hunt1 has found that directional change during the evolution of a lineage is relatively small (occurring only in 5% of 250 analyzed traits). Of those traits that were shown to follow a trend, size was more likely to show gradual changes, whereas shape changes were more random. Here, we provide a short view of the nature of evolutionary trends, showing (...) that directional change within lineages and among clades provides valuable evolutionary information about the processes involved in their generation. BioEssays 30:521–525, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Mixed-strategy equilibria are typically rather unstable in evolutionary game theory. “Monocyclic” games, such as Rock–Paper–Scissors, have only mixed equilibria, some of which are “stable” in the sense that sequential best replies lead to them; yet, even these games are prone to stable cycles under discrete-time simultaneous best replies, giving an unusual equilibrium-selection problem. This article analyzes such games in a random-utility setting where changing strategies is costly, and the speed of the dynamic is, thus, endogenous. The stochastically (...) stable outcome is determined by the cost of switching strategies; when switching costs are high, mixed equilibria are selected, whereas when switching costs are low, cycles are selected. (shrink)

What role does non-genetic inheritance play in evolution? In recent work we have independently and collectively argued that the existence and scope of non-genetic inheritance systems, including epigenetic inheritance, niche construction/ecological inheritance, and cultural inheritance—alongside certain other theory revisions—necessitates an extension to the neo-Darwinian Modern Synthesis (MS) in the form of an Extended Evolutionary Synthesis (EES). However, this argument has been challenged on the grounds that non-genetic inheritance systems are exclusively proximate mechanisms that serve the ultimate function of calibrating (...) organisms to stochastic environments. In this paper we defend our claims, pointing out that critics of the EES (1) conflate non-genetic inheritance with early 20th-century notions of soft inheritance; (2) misunderstand the nature of the EES in relation to the MS; (3) confuse individual phenotypic plasticity with trans-generational non-genetic inheritance; (4) fail to address the extensive theoretical and empirical literature which shows that non-genetic inheritance can generate novel targets for selection, create new genetic equilibria that would not exist in the absence of non-genetic inheritance, and generate phenotypic variation that is independent of genetic variation; (5) artificially limit ultimate explanations for traits to gene-based selection, which is unsatisfactory for phenotypic traits that originate and spread via non-genetic inheritance systems; and (6) fail to provide an explanation for biological organization. We conclude by noting ways in which we feel that an overly gene-centric theory of evolution is hindering progress in biology and other sciences. (shrink)

How significant is social evolution theory for the maintenance of virulence in natural populations? We assume that secreted, distantly acting virulence factors are highly likely to be cooperative public goods. Using this assumption, we discuss and critically assess the potential importance of social interactions for understanding the evolution, diversity and distribution of virulence in the Bacillus cereus group, a novel study system for microbial social biology. We conclude that dynamic equilibria in Cry toxin production, as well as strong spatial (...) structure and population bottlenecks in hosts are the main ecological factors maintaining the cooperative secretion of virulence factors and argue that collective action has contributed to the evolution of narrow host range. Non‐linearities in the benefits associated with public goods, as well as the lack of private secretion systems in the Firmicutes may also explain the prevalence and importance of distantly acting virulence factors in B. cereus and its relatives. (shrink)

An insider's provocative account of one of the most contentious debates in science today When Niles Eldredge and Stephen Jay Gould, two of the world's leading evolutionary theorists, proposed a bold new theory of evolution—the theory of "punctuated equilibria"—they stood the standard interpretation of Darwin on its head. They also ignited a furious debate about the true nature of evolution. On the one side are the geneticists. They contend that evolution proceeds slowly but surely, driven by competition among (...) organisms to transmit their genes from generation to generation. On the other are the paleontologists, like Eldredge and Gould, who show in the fossil record that in fact evolution proceeds only sporadically. Long periods of no change—equilibria—are "punctuated" by episodes of rapid evolutionary activity. According to the paleontologists, this pattern shows that evolution is driven far more by environmental forces than by genetic competition. How can the prevailing views on evolution be so different? In Reinventing Darwin, Niles Eldredge offers a spirited account of the dispute and an impressive case for the paleontologists' side of the story. With the mastery that only a leading contributor to the debate can provide, he charts the course of theory from Darwin's day to the present and explores the fundamental mysteries and crucial questions that underlie the current quarrels. Is evolution fired by a gentle and persistent motor and fueled by the survival instincts of "selfish genes"? Or does it proceed in fits and starts, as the fossil record seems to show? What is the role of environmental changes such as habitat destruction and of cataclysmic events like meteor impacts? Are most species inherently stable, changing only very little until they succumb to extinction? Or are species highly adaptable, changing all the time? Eldredge sorts through the major findings and interpretations and presents a lively introduction to the leading edge of evolutionary theory today. Reinventing Darwin offers a rare insider's view of the sometimes contentious, but always stimulating work of scientific inquiry. PRAISE FOR NILES ELDREDGE'S PREVIOUS BOOKS The Miner's Canary: Unraveling the Mysteries of Extinction "The Miner's Canary rings with integrity. The author takes care to present opposing views. Some readers, indeed, might view Mr. Eldredge as a little too self-effacing; he is, after all, one of the world's leading experts in his field."—The New York Times Book Review Fossils: The Evolution and Extinction of Species "... an important and informative book. It is also delightfully idiosyncratic. This is no scholarly treatise defending academic argument. It is an essay for everyone interested in the story of earthly life."—The Christian Science Monitor Life Pulse: Episodes from the Story of the Fossil Record "This is Earth history on a grand scale; those who enjoy the works of Stephen Jay Gould will appreciate Life Pulse."—Publishers Weekly. (shrink)

As our understanding of biological evolution continues to deepen, tension still surrounds the relationship between competition and cooperation in the evolution of the biosphere, with rival viewpoints often associated with the Red Queen and Black Queen hypotheses respectively. This essay seeks to reconcile these viewpoints by integrating observations of some general trends in biosphere evolution with concepts from game theory. It is here argued that biodiversity and ecological cooperation are intimately related, and that both tend to cyclically increase over biological (...) history; this is likely due to the greater relative stability of cooperation over competition as a means of long-term conflict resolution within ecosystems. By integrating this view of the biosphere with existing models such as Niche Game Theory, it may be argued that competition and cooperation in ecosystems coexist at equilibria which shift preferentially towards increasing cooperation over biological history. This potentially points to a state of “cooperative equilibrium” as a limit or endpoint in long-term biosphere evolution, such that Black Queen and Red Queen behavior dominate different phases in an evolutionary movement towards optimal cooperative stability in ecological networks. This concept, if accepted, may also bear implications for developing future mathematical models in evolutionary biology, as well as for resolving the perennial debate regarding the relative roles of conflict and harmony in nature. (shrink)

We extend recent information-theoretic phase transition approaches to evolutionary and cognitive process via the Rate Distortion and Joint Asymptotic Equipartition Theorems, in the circumstance of interaction with a highly structured environment. This suggests that learning plateaus in cognitive systems and punctuated equilibria in evolutionary process are formally analogous, even though evolution is not cognitive. Extending arguments by Adami et al. (2000), we argue that 'adaptation' is the process by which a distorted genetic image of a coherently structured (...) environment is imposed upon a species. (shrink)

In the second half of the twentieth century, a surprising change in the notion of scientific truth gained ground when an evolutionary cosmology made the Newtonian world machine into no more than a passing phase of the cosmos, subject to exceptions in the neighborhood of Black Holes and other unusual objects. Physical and chemical laws ceased to be eternal and universal and became local and changeable, that is, fundamentally historical instead, and faced an uncertain, changeable future just as they (...) had in the initial phases of the cosmos.The earth sciences along with biology had become historical in the nineteenth century; and the Big Bang cosmology in effect brought physics and chemistry into line, allowing venturesome intellects to concoct a new all-embracing worldview that recognizes the catalytic role of the observer in defining what is observed, and how different levels of local complexity provoke new and surprising phenomena--including terrestrial life forms, and most notably for us, humanly-constructed symbolic meanings--of which science is only one example.The article then argues that it is time for historians to take note of the imperial role thus thrust upon their discipline by making a sustained effort to enlarge their views and explore the career of humankind on earth as a whole, thus making human history an integral part of the emerging scientific and evolutionary worldview.Tentative suggestions of how this might be addressed, focusing on changes in patterns of communication that expanded the scale of human cooperation, and thus conduced to survival, follow. Dance, then speech, were early breakthroughs expanding the practicable size of wandering human bands; then caravans and shipping allowed civilizations to arise; writing expanded the scale of coordination; warfare and trade harshly imposed best practice across wide areas of Eurasia and Africa and kept the skills of that part of the world ahead of what the peoples of other continents and islands had at their command. Then with the crossing of the oceans after 1492 our One World began to emerge and swiftly assumed its contemporary shape with further improvements in the range and capacity of communication--for example, printing, mechanically-powered transport, instantaneous data transmission--with consequences for human society and earth's ecosystem yet to be experienced.Much remains to be investigated and, in particular, interactions between the history of human symbolic meanings and the history of other equilibria--ecological, chemical, physical--within which we exist needs further study. But with suitable effort, history can perhaps become scientific and the emerging scientific evolutionary worldview begin to achieve logical completeness by bringing humankind within its scope. (shrink)

Since formulating the theory of punctuated equilibria in 1972, a group of prominent evolutionary biologists, geneticists, and paleontologists have contributed towards a significant reinterpretation of the neo-Darwinian image of evolution that had consolidated during the second half of the twentieth century. We believe a research program, which we might define as "evolutionary pluralism" or "post-Darwinism," has been outlined, one that is centered on the discovery of the complexity and multiplicity of elements that work together to produce changes (...) in our evolutionary systems. We are talking about a three-dimensional multiplicity: a multiplicity of rhythms in evolution (i.e., the theory of punctuated equilibria); a multiplicity of evolutionary units and levels (i.e., the hierarchical theory of evolution); and a multiplicity of factors and causes in evolution (i.e., the concept of exaptation). Although the reductionistic and deterministic view of natural history interprets the intelligence of evolution as a panoptic and executory rationality, evolutionary pluralism, going back to the original flexibility of the Darwinian opus, sees in the intelligence of evolution an ingenious m tis, an imperfect but very creative, craftsmanlike cleverness. The new metaphors of change introduced by evolutionary pluralism and the consequent criticism of the adaptational paradigm offer some very interesting spin-offs for the study of evolutionary systems in widely differing fields, from theoretical economics to the cognitive sciences. I propose a particular hypothesis concerning the possibility and usefulness of expanding the concept of exaptation into a general theory of developmental processes, both in biology as well as in the cognitive sciences. (shrink)

Weak links, in the form of inadequacies in both reasoning and supporting evidence, exist at several critical steps in the derivation of an hierarchical concept of evolution from punctuated equilibria. Punctuation itself is predicated on a distorted reading of phyletic change as phyletic gradualism, and of allopatric speciation as the instantaneous formation of unchanging typological taxa. The concept of punctuation is further confounded by the indescriminate employment of the same term to denote both a causal explanation for evolutionary (...) change and an outcome of substantiated evolutionary processes. Even when the intended usage for the term is specified, each denotation of punctuation entails respective drawbacks. As a causal explanation, punctuation clearly belongs to the class of quantum theories with all their attendant impedimenta, including special salsatory non-adaptive mechanisms of evolutionary change. Redefinition of punctuation as a pattern of morphologic change reduces it to one possible outcome of known microevolutioanry processes, thus obviating any need for an hierarchical explanation of macroevolution. While vacillation between usages has preserved the term in the literature, the end result of this obfuscation has been a circle of faulty reasoning in which the pattern of punctuation is invoked as its own proof. Widespread confusion concerning what constitutes an adequate test of punctuation is directly attributable to imprecision in both the original and revised formulations of the concept.The argument for species-level selection is based on the typological and philosphically flawed premise of species as individuals, and further requires the hypothesis of heritable emergent properties, for which empirical evidence is lacking. (shrink)

Published comments by American scientists on Darwin’s evolutionary theory are rather rare in the latter half of the 19th century. Clarence King, the founding director of the U.S. Geological Survey in 1879, and an experienced field geologist, focused on the relation between Darwin’s evolutionary concepts and the larger context of Hutton/Lyell’s uniformitarianism versus Cuvier’s catastrophism in his 1877 paper, “Catastrophism and Evolution.” King knew that the fossil record contains little or no data supporting Darwin’s vision of gradual (...) class='Hi'>evolutionary change. Instead, using horse evolution seen in the rocks of the American West, the very example that by the 1920s had become the shining exemplar of gradual evolutionary change, King argued for catastrophic extinction and evolutionary replacement by “plastic” species that were able to survive in modified form as components of the succeeding biota. Though he could not see such change as involving natural selection, in this novel use of the term “plasticity,” there may well be adumbrations of modern evolutionary biology. King’s themes became muted as Americans began to embrace more fully Darwin’s work. But his version of catastrophism never entirely disappeared, especially in paleobiological circles. And it came back in more fully modern form with force beginning with the work of Norman D. Newell on mass extinctions in the mid-20th century—and with that of two of his students: Eldredge and Gould’s “Punctuated Equilibria.” This essay introduces King’s “Catastrophism and Evolution” for the journal’s “Classics in Biological Theory” collection; King’s article is available as supplementary material in the online version of this introduction. (shrink)

Species are thought by many to be important units of evolution. In this paper, I argue against that view. My argument is based on an examination of the role of species in the synthetic theory of evolution. I argue that if one adopts a gradualist view of evolution, one cannot make sense of the claim that species are units in the minimal sense needed to claim that they are units of evolution, namely, that they exist as discrete entities over time. (...) My second argument is directed against an appeal to Eldredge and Gould's theory of punctuated equilibria to support the claim that species are units of evolution. If one adopts their view, it may be possible to identify discrete temporal entities that can plausibly be termed species, but there is no reason to claim that those entities are units of evolution. Thus, on two plausible interpretations of the role of natural selection in the process of evolution, species are of no special importance. I then consider some of the reasons why species have been thought to be important evolutionary units by many contemporary evolutionary biologists. Finally, I discuss briefly the implications of this conclusion for evolutionary biology. (shrink)

offers an evolutionary approach to morality, in which moral rules form a cultural system that is robust and evolutionarily stable. The folk theorem is the analytical basis for his theory of justice. I argue that this is a mistake, as the equilibria described by the folk theorem lack dynamic stability in games with several players. While the dependence of Binmore's argument on the folk theorem is more tactical than strategic, this choice does have policy implications. I do not (...) believe that moral rules are solutions to the Nash bargaining problem. Rather, I believe that human beings are emotionally constituted, by virtue of their evolutionary history, to embrace prosocial and altruistic notions of in-group–out-group identification and reciprocity. These aspects of human nature are incompatible with Binmore's notion that humans are self-regarding creatures. I present empirical evidence supporting a specific form of human, other-regarding preferences known as strong reciprocity. Key Words: justice • ethics • folk theorem • evolutionary game theory. (shrink)

We present a dynamical model of a multi-site fishery. The fish stock is located on a discrete set of fish habitats where it is catched by the fishing fleet. We assume that fishes remain on fishing habitats while the fishing vessels can move at a fast time scale to visit the different fishing sites. We use the existence of two time scales to reduce the dimension of the model : we build an aggregated model considering the habitat fish densities and (...) the total fishing effort. We explore a regulation procedure, which imposes an average residence time in patches. Several equilibria exist, a Fishery Free Equilibria as well as a Sustainable Fishery Equilibria . We show that the dynamics depends on a threshold which is similar to a basic reproduction ratio for the fishery. When the basic reproduction ratio is less or equal to 1, one of the FFEs is globally asymptotically stable , otherwise one of the SFEs is GAS. (shrink)

The use of evolutionary game theory to explain the evolution of human norms and the behavior of humans who act according to those norms is widespread. Both the aims and motivation for its use are clearly articulated by Harms and Skyrms (2008) in the following passage: "A good theory of evolution of norms might start by explaining the evolution of altruism in Prisoner’s Dilemma, of Stag Hunting, and of the equal split in the symmetric bargaining game. These are not (...) well-explained by classical game theory based on rational choice. From a technical point of view, they present different theoretical challenges. In the bargaining game, there are an infinite number of equilibria with no principled (rational choice) way to select the cooperative one. In Stag Hunt there are only two, but the non-cooperative one is selected by risk-dominance. In Prisoner’s Dilemma the state of mutual cooperation is not a Nash equilibrium at all, and cooperation flies in the face of the rational-choice principle that one does not choose less rather than more. In contrast to rational choice theory, the most common tool of evolutionary game theory is the replicator dynamics, in which the propagation rate of each strategy is determined by its current payoffs. These dynamics have a rationale in both biological and cultural evolutionary modeling, and sometimes tell us things that rational choice theory does not." We agree with the first sentence in this quotation: a good theory about the behavior under norms ought to explain altruism in the Prisoner’s Dilemma (PD), playing Stag in Stag Hunt (SH), and offering equal splits in the symmetric Nash bargaining game (NB). We also agree with Harms and Skyrms about the difference in technical challenges each of these games poses. Finding a single mechanism, even one as broadly understood as evolution, that could solve these challenges en masse is no doubt a tall order. Nonetheless, in this paper, we present a single, simple, modification to SH, NB, and a general n-player PD that does just that: we introduce deontological autonomy into the models. (shrink)

This book is a rebuttal of the common charge that the moral doctrine of utilitarianism permits horrible acts, justifies unfair distribution of wealth and other social goods, and demands too much of moral agents. Bailey defends utilitarianism by applying central insights of game theory regarding feasible equilibria and evolutionary stability of norms to elaborate an account of institutions that real-world utilitarians would want to foster. With such an account he shows that utilitarianism, while still a useful doctrine for (...) criticizing existing institutions, is far more congruent with ordinary moral common sense than has been generally recognized. A controversial attempt to support the practical use of utilitarian ethics in a world of conflicting interests and competing moral agents, Bailey's work uniquely bridges the abstract debate of philosophers and the practical, consequence-based debates of political scientists. (shrink)

We make the case that scientifically accurate and politically feasible responses to the climate crisis require a complex understanding of human cultural practices of niche construction that moves beyond the adaptive significance of culture. We develop this thesis in two related ways. First, we argue that cumulative cultural practices of niche construction can generate stable equilibria and runaway selection processes that result in long-term existential risks within and across cultural groups. We dub this the back of the invisible hand. (...) Second, we argue that the ability of cultural groups to innovate technological solutions to environmental problems is highly constrained in ways that are exacerbated by sustained intergroup conflict, inequality and by inherently unpredictable cascades in climate change and human migration patterns. After developing these theoretical points about human cultural practices of niche construction in detail, we conclude our discussion with some tentative practical suggestions about the way that cultural evolutionary history can more fruitfully be used in efforts to remit the climate crisis and contribute to sustainable practices of human climate change adaptation. (shrink)

Agents in a large population are randomly matched to play a certain game, payoffs in which represent fitness. Agents may have preferences that are different from fitness. They learn strategies according to their preferences, and evolution changes the preference distribution in the population according to fitness. When agents know the preferences of the opponent in a match, only efficient symmetric strategy profiles of the fitness game can be stable. When agents do not know the preferences of the opponent, only Nash (...) equilibria of the fitness game can be stable. For 2 × 2 symmetric games I characterize preferences that are stable. (shrink)

Ecologists are challenged by the need to bridge and synthesize different approaches and theories to obtain a coherent understanding of ecosystems in a changing world. Both food web theory and regime shift theory shine light on mechanisms that confer stability to ecosystems, but from different angles. Empirical food web models are developed to analyze how equilibria in real multi-trophic ecosystems are shaped by species interactions, and often include linear functional response terms for simple estimation of interaction strengths from observations. (...) Models of regime shifts focus on qualitative changes of equilibrium points in a slowly changing environment, and typically include non-linear functional response terms. Currently, it is unclear how the stability of an empirical food web model, expressed as the rate of system recovery after a small perturbation, relates to the vulnerability of the ecosystem to collapse. Here, we conduct structural sensitivity analyses of classical consumer-resource models in equilibrium along an environmental gradient. Specifically, we change non-proportional interaction terms into proportional ones, while maintaining the equilibrium biomass densities and material flux rates, to analyze how alternative model formulations shape the stability properties of the equilibria. The results reveal no consistent relationship between the stability of the original models and the proportionalized versions, even though they describe the same biomass values and material flows. We use these findings to critically discuss whether stability analysis of observed equilibria by empirical food web models can provide insight into regime shift dynamics, and highlight the challenge of bridging alternative modelling approaches in ecology and beyond. (shrink)

In the wake of the paleobiological revolution of the 1970s and 1980s, paleontologists continue to investigate far-reaching questions about how evolution works. Many of those questions have a philosophical dimension. How is macroevolution related to evolutionary changes within populations? Is evolutionary history contingent? How much can we know about the causes of evolutionary trends? How do paleontologists read the patterns in the fossil record to learn about the underlying evolutionary processes? Derek Turner explores these and other (...) questions, introducing the reader to exciting recent work in the philosophy of paleontology and to theoretical issues including punctuated equilibria and species selection. He also critically examines some of the major accomplishments and arguments of paleontologists of the last 40 years. (shrink)

Radopholus Similis or burrowing nematode, is one of the most damaging and widespread nematodes attacking bananas, causing toppling or blackhead disease. A mathematical model for the population dynamics of R. Similis is considered, with the aim of investigating the impact of climatic factors on the growth of R. Similis. In this paper, based on the life cycle of R. Similis, we first propose a mathematical model to study and control the population dynamics of this banana pest. We show also how (...) control terms based on biological and chemical controls can be integrated to reduce the population of R. Similis within banana-plantain roots. Sensitivity analysis was performed to show the most important parameters of the model. We present the theoretical analysis of the model. More precisely, we derive a threshold parameter N0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal{N}}_0$$\end{document}, called the basic offspring number and show that the trivial equilibrium is globally asymptotically stable whenever N0≤1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal{N}}_0\le 1$$\end{document}, while when N0>1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal{N}}_0> 1$$\end{document}, the non trivial equilibrium is globally asymptotically stable. After, we extend the proposed model by taking account climatic factors that influence the growth of this pest. Biological and chemical controls are now introduced through impulsive equations. Threshold and equilibria are obtained and global stabilities have been studied. The theoretical results are supported by numerical simulations. Numerical results of model with biological and chemical controls reveal that biological methods are more effective than chemical methods. We also found that the month February is the best time to apply these controls. (shrink)

Genic selectionists (Williams 1966; Dawkins 1976) defend the view that genes are the (unique) units of selection and that all evolutionary events can be adequately represented at the genic level. Pluralistic genic selectionists (Sterelny and Kitcher 1988; Waters 1991; Dawkins 1982) defend the weaker view that in many cases there are multiple equally adequate accounts of evolutionary events, but that always among the set of equally adequate representations will be one at the genic level. We describe a range (...) of cases all involving stable equilibria actively maintained by selection. In these cases genotypic models correctly show that selection is active at the equilibrium point. In contrast, the genic models have selection disappearing at equilibrium. For deterministic models this difference makes no difference. However, once drift is added in, the two sets of models diverge in their predicted evolutionary trajectories. Thus, contrary to received wisdom on this matter, the two sets of models are not empirically equivalent. Moreover, the genic models get the facts wrong. (shrink)

In this paper I will discuss why (un) marked expressionstypically get an (un)marked interpretation: Horn''sdivision of pragmatic labor. It is argued that it is aconventional fact that we use language this way.This convention will be explained in terms ofthe equilibria of signalling games introduced byLewis (1969), but now in an evolutionary setting. Iwill also relate this signalling game analysis withParikh''s (1991, 2000, 2001) game-theoretical analysis ofsuccessful communication, which in turn is compared withBlutner''s: 2000) bi-directional optimality theory.

A two strain HIV/AIDS model with treatment which allows AIDS patients with sensitive HIV-strain to undergo amelioration is presented as a system of non-linear ordinary differential equations. The disease-free equilibrium is shown to be globally asymptotically stable when the associated epidemic threshold known as the basic reproduction number for the model is less than unity. The centre manifold theory is used to show that the sensitive HIV-strain only and resistant HIV-strain only endemic equilibria are locally asymptotically stable when the (...) associated reproduction numbers are greater than unity. Qualitative analysis of the model including positivity, boundedness and persistence of solutions are presented. The model is numerically analysed to assess the effects of treatment with amelioration on the dynamics of a two strain HIV/AIDS model. Numerical simulations of the model show that the two strains co-exist whenever the reproduction numbers exceed unity. Further, treatment with amelioration may result in an increase in the total number of infective individuals (asymptomatic) but results in a decrease in the number of AIDS patients. Further, analysis of the reproduction numbers show that antiretroviral resistance increases with increase in antiretroviral use. (shrink)

This article is extracted from a forthcoming book, ‘Natural Justice’. It is a nontechnical introduction to the part of game theory immediately relevant to social contract theory. The latter part of the article reviews how concepts such as trust, responsibility, and authority can be seen as emergent phenomena in models that take formal account only of equilibria in indefinitely repeated games. Key Words: game theory • equilibrium • evolutionary stability • reciprocity • folk theorem • trust • altruism (...) • responsibility • authority. (shrink)

Science, and with it our understanding of evolutionary processes, is itself undergoing evolution. The evolutionary framework still most frequently used by the general public to describe and guide processes of societal development is erroneously grounded in Darwinian perspectives or, at the very least, draws facile analogies from biological evolution. The present inquiry incorporates fresh insights on the general systemic nature of developmental dynamics from the most recent advances in the transdisciplinary realm of the sciences of complexity (e.g., general (...) evolution theory, cybernetics, information and communication theory, chaos theory, dynamical systems theory, and nonequilibrium thermodynamics). The description of the evolutionary trajectory of complex dynamical systems as irreversible, periodically chaotic, and strongly nonlinear agrees with certain features of the historical processes of societal development. But there are additional features of the evolutionary dynamic of natural systems that are seldom portrayed as part of human developmental deportment. These features include elements such as the convergence of existing systems at progressively higher levels of organization, the increasingly efficient utilization of environmental energy, and the complexification of system structures in states that are progressively further removed from chemical and thermodynamic equilibria. The sciences of complexity offer insight into the laws and dynamics that govern the evolution of complex systems across a variety of disciplinary areas of investigation. Through a study of the isomorphisms across disciplinary constructs in the theoretical analyses of the principles governing the evolution of human societies, it is possible to enrich the account of developmental dynamics at the socio-civilizational level. Such an account would further our understanding of the phenomenon of societal development and provide the means for the purposeful guidance of this phenomenon in accordance with general evolutionary principles. This article sets forth the type of considerations, and outlines a general research agenda, for inquiry toward an operational model of the evolutionary development of social systems. (shrink)

This paper summarizes a theory of fairness that replaces the metaphysical foundations of the egalitarian theory of John Rawls and the utilitarian theory of John Harsanyi with evolutionary arguments. As such, it represents an attempt to realize John Mackie’s call for a theory based on the data provided by anthroplogists and the propositions proved by game theorists. The basic claim is that fairness norms evolved as a device for selecting one of the infinity of efficient equilibria of the (...) repeated game of life played by our prehuman ancestors. (shrink)

Pre‐play signals that cost nothing are sometimes thought to be of no significance in interactions which are not games of pure common interest. We investigate the effect of pre‐play signals in an evolutionary setting for Assurance, or Stag Hunt, games and for a Bargaining game. The evolutionary game with signals is found to have dramatically different dynamics from the same game without signals. Signals change stability properties of equilibria in the base game, create new polymorphic equilibria, (...) and change the basins of attraction of equilibria in the base game. Signals carry information at equilibrium in the case of the new polymorphic equilibria, but transient information is the basis for large changes in the magnitude of basins of attraction of equilibria in the base game. These phenomena exemplify new and important differences between evolutionary game theory and game theory based on rational choice. (shrink)

ExtractBrian Skyrms's Signals has the virtues familiar from his Evolution of the Social Contract and The Stag Hunt. He begins with a very simple model of agents in interaction, and in a series of brief and beautifully clear chapters, this model and its successors are explored, elaborated, connected and illustrated through biological theory and the social sciences. Signals borrows its core model from David Lewis: it is Lewis's signalling game. In this game, two agents interact. One agent can observe which (...) of two equi-probable states the world is in, but that agent cannot act directly and profitably on that information. However, the informed agent can act in a way that will be perceptually salient to a second agent: say, by raising a red or a green flag. The second agent does have the capacity to respond appropriately to each state of the world. If that second agent chooses the right option, given the state of the world, both are rewarded. If the second agent fails to choose the right action, neither are. Obviously, the two agents are best off if they have a practice in which the informed agent regularly chooses a distinct, salient cue in response to each of the two world states, and in which the powerful agent uses that cue to select the rewarding act. Less obviously, agents with simple trial and error learning capacities can learn to signal and respond: neither explicit negotiation nor cognitive sophistication are required. Likewise, if individual agents do not have the capacity to learn, but if they breed true but with some variation, the evolutionary version of trial and error learning can take a population to one of the signalling system equilibria. View HTML Send article to KindleTo send this article to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle. Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply. Find out more about the Kindle Personal Document Service.A GLASS HALF-FULL: BRIAN SKYRMS'S SIGNALSVolume 28, Issue 1Kim Sterelny DOI: https://doi.org/10.1017/S0266267112000120Your Kindle email address Please provide your Kindle [email protected]@kindle.com Available formats PDF Please select a format to send. By using this service, you agree that you will only keep articles for personal use, and will not openly distribute them via Dropbox, Google Drive or other file sharing services. Please confirm that you accept the terms of use. Cancel Send ×Send article to Dropbox To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Dropbox. A GLASS HALF-FULL: BRIAN SKYRMS'S SIGNALSVolume 28, Issue 1Kim Sterelny DOI: https://doi.org/10.1017/S0266267112000120Available formats PDF Please select a format to send. By using this service, you agree that you will only keep articles for personal use, and will not openly distribute them via Dropbox, Google Drive or other file sharing services. Please confirm that you accept the terms of use. Cancel Send ×Send article to Google Drive To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Google Drive. A GLASS HALF-FULL: BRIAN SKYRMS'S SIGNALSVolume 28, Issue 1Kim Sterelny DOI: https://doi.org/10.1017/S0266267112000120Available formats PDF Please select a format to send. By using this service, you agree that you will only keep articles for personal use, and will not openly distribute them via Dropbox, Google Drive or other file sharing services. Please confirm that you accept the terms of use. Cancel Send ×Export citation Request permission. (shrink)

Government subsidies have a direct impact on firms' innovation strategies. The game relationship between the government, the subsidized firm and its competitors under different subsidy strategies affects firms' innovation behavior and thus innovation performance. This paper uses a dynamic evolutionary game theory approach based on cost-benefit differences to analyse the mechanisms by which government subsidy strategies affect firms' innovation strategies. It is found that the marginal benefits of a firm's innovation strategy will directly affect the game outcome, indicating that (...) the choice of innovation strategy depends on the maximization of individual firm's interests. At the same time, a firm's innovation strategy is influenced by the firm's own innovation ability and competitors' innovation strategy, and there are two game equilibria. Government subsidies have a positive contribution to the innovation strategy choice of subsidized firms, but have a crowding-out effect on non-subsidized competing firms. The strength of the penalty, the marginal revenue of the subsidized firms' rational use of government subsidies and the competitors' strategic choices will directly affect the game outcome. (shrink)

This collection of essays, written over the past fifteen years by one of the more intrepid defenders of current Darwinian theory, contains material that will be of interest both to historians and philosophers of science and, since Ruse writes well and in an accessible manner, to an even wider audience. A preliminary glance at the contents primes one to expect to be both engaged and provoked; one is not disappointed. The essays include historical speculation on some of the views of (...) Charles Darwin, a defence of human sociobiology and discussion of its feminist critique, punctuated equilibria theory, teleology in biology, extraterrestrial biology and moral theory, the plate tectonic revolution in geology, and the relationship between evolutionary theory and Christian ethics. (shrink)

We study the dynamics and stability of the economics of crime and punishment game from an evolutionary perspective. Specifically, we model the interaction between agents and controllers as an asymmetric game exploring the dynamics of the classic static model using a replicator dynamics equation, given exogenous levels of monitoring and criminal sanctions. The dynamics show five possible equilibria, from which three are stable. Our results show that a culture of honest agents is never stable; however when the penalty (...) is high enough, the system will neutrally tend to an equilibrium of honest agents and a monitoring firm. By contrast, when the probability of detecting wrongdoing is small, the system, in some cases, will remain in a transient state, in which it is impossible to predict the proportion of honest agents. (shrink)

On many occasions, individuals are able to coordinate their actions. The first empirical evidence to this effect has been described by Schelling (1960) in an informal experiment. His results were corroborated many years later by Mehta et al. (1994a,b) and Bacharach and Bernasconi (1997). From the point of view of mainstream game theory, the success of individuals in coordinating their actions is something of a mystery. If there are two or more strict Nash equilibria, mainstream game theory has no (...) means of explaining why people tend to choose their part of one and the same equilibrium. Textbooks (see, e.g., Rasmusen, 1989 and Kreps, 1990) refer to the fact that players may use focal points (see Schelling (1960)) or social conventions (see Lewis (1969)). Both notions cannot easily be incorporated into mainstream game theory, however. The notion of social conventions has recently been extensively studied in the context of evolutionary game theory where a population of agents interacts with each other. The central focus of this paper, however, is on situations where a few players play a game only once and I study how they may coordinate their actions. (shrink)