48,293 research outputs found

    Are You Trying to Recruit Suicide Bombers or Something?

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    Suicide terrorism has been extensively studied, although few researchers have been able to arrive at definitive conclusions. Often overlooked is the explanatory potential of evolutionary psychology. This study presents an evolutionary model of suicide terrorism using the principles of kin selection theory and inclusive fitness and offers several predictions about suicide terrorists. To test these predictions, an experimental design was constructed in which participants randomly received one of nine separate scenarios in which they were told that they were a member of a marginalized ethnic group and asked if they would be willing to commit a suicide bombing against their oppressors. The findings provide partial support for an evolutionary model of suicide terrorism and indicate future investigation is required to fully understand how evolutionary psychology can be used by practitioners and policy makers to combat suicide terrorism

    Evolutionary Suicide and Evolution of Dispersal in Structured Metapopulations

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    In this article we study the evolution of dispersal in a structured metapopulation model. The metapopulation consists of a large (infinite)number of local populations living in patches of habitable environment. Dispersal between patches is modeled by a disperser pool and individuals in transit between patches are exposed to a risk of mortality. Occasionally, local catastrophes eradicate a local population: all individuals in the affected patch die, yet the patch remains habitable. The rate at which such disasters occur can depend on the local population size of a patch. We prove that, in the absence of catastrophes, the strategy not to migrate is evolutionarily stable. It is also convergence stable unless there is no mortality during dispersal. Under a given set of environmental conditions, a metapopulation may be viable and yet selection may favor dispersal rates that drive the metapopulation to extinction. This phenomenon is known as evolutionary suicide. We show that in our model evolutionary suicide can occur for certain types of size-dependent catastrophes. Evolutionary suicide can also happen for constant catastrophe rates, if local growth within patches shows an Allee effect. We study the evolutionary bifurcation towards evolutionary suicide and show that a discontinuous transition to extinction is a necessary condition for evolutionary suicide to occur. In other words, if population size smoothly approaches zero at a boundary of viability in parameter space, this boundary is evolutionarily repelling and no suicide can occur

    Animal suicide: An account worth giving? Commentary on Peña-Guzmán on Animal Suicide

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    Peña-Guzmán (2017) argues that empirical evidence and evolutionary theory compel us to treat the phenomenon of suicide as continuous in the animal kingdom. He defends a “continuist” account in which suicide is a multiply-realizable phenomenon characterized by self-injurious and self-annihilative behaviors. This view is problematic for several reasons. First, it appears to mischaracterize the Darwinian view that mind is continuous in nature. Second, by focusing only on surface-level features of behavior, it groups causally and etiologically disparate phenomena under a single conceptual umbrella, thereby reducing the account’s explanatory power. Third, it obscures existing analyses of suicide in biomedical ethics and animal welfare literatures. A more promising naturalistic approach might seek a theoretical understanding of the social/ecological circumstances that drive humans and perhaps other animals to self-destruction

    Evolutionary suicide through a non-catastrophic bifurcation : adaptive dynamics of pathogens with frequency-dependent transmission

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    Evolutionary suicide is a riveting phenomenon in which adaptive evolution drives a viable population to extinction. Gyllenberg and Parvinen (Bull Math Biol 63(5):981-993, 2001) showed that, in a wide class of deterministic population models, a discontinuous transition to extinction is a necessary condition for evolutionary suicide. An implicit assumption of their proof is that the invasion fitness of a rare strategy is well-defined also in the extinction state of the population. Epidemic models with frequency-dependent incidence, which are often used to model the spread of sexually transmitted infections or the dynamics of infectious diseases within herds, violate this assumption. In these models, evolutionary suicide can occur through a non-catastrophic bifurcation whereby pathogen adaptation leads to a continuous decline of host (and consequently pathogen) population size to zero. Evolutionary suicide of pathogens with frequency-dependent transmission can occur in two ways, with pathogen strains evolving either higher or lower virulence.Peer reviewe

    Evolutionary Suicide of Prey : Matsuda and Abrams' Model Revisited

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    Under the threat of predation, a species of prey can evolve to its own extinction. Matsuda and Abrams (Theor Popul Biol 45:76-91, 1994a) found the earliest example of evolutionary suicide by demonstrating that the foraging effort of prey can evolve until its population dynamics cross a fold bifurcation, whereupon the prey crashes to extinction. We extend this model in three directions. First, we use critical function analysis to show that extinction cannot happen via increasing foraging effort. Second, we extend the model to non-equilibrium systems and demonstrate evolutionary suicide at a fold bifurcation of limit cycles. Third, we relax a crucial assumption of the original model. To find evolutionary suicide, Matsuda and Abrams assumed a generalist predator, whose population size is fixed independently of the focal prey. We embed the original model into a three-species community of the focal prey, the predator and an alternative prey that can support the predator also alone, and investigate the effect of increasingly strong coupling between the focal prey and the predator's population dynamics. Our three-species model exhibits (1) evolutionary suicide via a subcritical Hopf bifurcation and (2) indirect evolutionary suicide, where the evolution of the focal prey first makes the community open to the invasion of the alternative prey, which in turn makes evolutionary suicide of the focal prey possible. These new phenomena highlight the importance of studying evolution in a broader community context.Peer reviewe

    If nonhuman animals can suicide, why don’t they?

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    An evolutionary analysis suggests that selection is unlikely to have tolerated the capacity for intentional self-killing in nonhuman animals. The potential to escape pain by suicide would have presented a recurrent and severe adaptive problem for an animal with a reproductive future to protect. If the potential for suicide arose in the evolutionary past, anti-suicide mechanisms may have co-evolved, as we believe they have in adult humans. Peña-Guzmán’s (2017) argument that some nonhuman animals can suicide is incomplete without an account of the defences that result in the vast majority opting not to

    Self-extinction through optimizing selection

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    Evolutionary suicide is a process in which selection drives a viable population to extinction. So far such selection-driven self-extinction has been demonstrated in models with frequency-dependent selection. This is not surprising, since frequency-dependent selection can disconnect individual-level and population-level interests through environmental feedback. Hence it can lead to situations akin to the tragedy of the commons, with adaptations that serve the selfish interests of individuals ultimately ruining a population. For frequency-dependent selection to play such a role, it must not be optimizing. Together, all published studies of evolutionary suicide have created the impression that evolutionary suicide is not possible with optimizing selection. Here we disprove this misconception by presenting and analyzing an example in which optimizing selection causes self-extinction. We then take this line of argument one step further by showing, in a further example, that selection-driven self-extinction can occur even under frequency-independent selection

    Suicidal altruism under random assortment

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    Questions: Can there be a selective explanation for suicide? Or are all suicides evolutionary mistakes, ever pruned by natural selection to the extent that the tendency to perform them is heritable? Model: A simple variant of trait group selection (where a population is divided into mutually exclusive groups, with the direct effects of behaviour limited to group-mates), employing predators as the mechanism underlying group selection. Predators evaluate groups to avoid potentially suicidal defenders (which, when present, limit a predator’s net return), thus acting as a group selection mechanism favouring groups with potentially suicidal altruists. Conclusion: The model supports contingent strong altruism (depressing one’s direct reproduction – absolute fitness – to aid others) without kin assortment. Even an extreme contingent suicidal type (destroying self for the sake of others) may either saturate a population or be polymorphic with a type avoiding such altruism. The model does not, however, support a sterile worker caste, where sterility occurs before life-history events associated with effective altruism; under random assortment, reproductive suicide must remain contingent or facultative.Publicad

    Joint evolution of altruistic cooperation and dispersal in a metapopulation of small local populations

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    We investigate the joint evolution of public goods cooperation and dispersal in a metapopulation model with small local populations. Altruistic cooperation can evolve due to assortment and kin selection, and dispersal can evolve because of demographic stochasticity, catastrophes and kin selection. Metapopulation structures resulting in assortment have been shown to make selection for cooperation possible. But how does dispersal affect cooperation and vice versa, when both are allowed to evolve as continuous traits? We found four qualitatively different evolutionary outcomes. (1) Monomorphic evolution to full defection with positive dispersal. (2) Monomorphic evolution to an evolutionarily stable state with positive cooperation and dispersal. In this case, parameter changes selecting for increased cooperation typically also select for increased dispersal. (3) Evolutionary branching can result in the evolutionarily stable coexistence of defectors and cooperators. Although defectors could be expected to disperse more than cooperators, here we show that also the opposite case is possible: Defectors tend to disperse less than cooperators when the total amount of cooperation in the dimorphic population is low enough. (4) Selection for too low cooperation can cause the extinction of the evolving population. For moderate catastrophe rates dispersal needs to be initially very frequent for evolutionary suicide to occur. Although selection for less dispersal in principle could prevent such evolutionary suicide, in most cases this rescuing effect is not sufficient, because selection in the cooperation trait is typically much stronger. If the catastrophe rate is large enough, a part of the boundary of viability can be evolutionarily attracting with respect to both strategy components, in which case evolutionary suicide is expected from all initial conditions

    Extinction, Persistence, and Evolution

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    Extinction can occur for many reasons. We have a closer look at the most basic form, extinction of populations with stable but insufficient reproduction. Then we move on to competing populations and evolutionary suicide
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