Proponents of the standard evolutionary biology paradigm explain human “altruism” in terms of either nepotism or strict reciprocity. On that basis our underlying nature is reduced to a function of inclusive fitness: human nature has to be totally selfish or nepotistic. Proposed here are three possible paths to giving costly aid to nonrelatives, paths that are controversial because they involve assumed pleiotropic effects or group selection. One path is pleiotropic subsidies that help to extend nepotistic helping behavior (...) from close family to nonrelatives. Another is “warfare”—if and only if warfare recurred in the Paleolithic. The third and most plausible hypothesis is based on the morally based egalitarian syndrome of prehistoric hunter-gatherers, which reduced phenotypic variation at the within-group level, increased it at the between-group level, and drastically curtailed the advantages of free riders. In an analysis consistent with the fundamental tenets of evolutionary biology, these three paths are evaluated as explanations for the evolutionary development of a rather complicated human social nature. (shrink)

Reciprocal altruism was originally formulated in terms of individual selection and most theorists continue to view it in this way. However, this interpretation of reciprocal altruism has been challenged by Sober and Wilson (1998). They argue that reciprocal altruism (as well as all other forms of altruism) evolves by the process of group selection. In this paper, we argue that the original interpretation of reciprocal altruism is the correct one. We (...) accomplish this by arguing that if fitness attaches to (at minimum) entire life cycles, then the kind of fitness exchanges needed to form the group-level in such situations is not available. Reciprocal altruism is thus a result of individual selection and when it evolves, it does so because it is individually advantageous. (shrink)

Altruism is a central concept in evolutionary biology. Evolutionary biologists still disagree about its meaning (E.O. Wilson 2005; Fletcher et al. 2006; D.S. Wilson 2008; Foster et al. 2006a, b; West et al. 2007a, 2008). Semantic disagreement appears to be quite robust and not easily overcome by attempts at clarification, suggesting that substantive conceptual issues lurk in the background. Briefly, group selection theorists define altruism as any trait that makes altruists losers to selfish traits within groups, and (...) makes groups of altruists fitter than groups of non-altruists. Inclusive fitness theorists reject a definition based on within- and between-group fitness. Traits are altruistic only if they cause a direct and absolute fitness loss to the donor. The latter definition is more restrictive and rejects as cases of altruism behaviors that are accepted by the former. Fletcher and Doebeli (2009) recently proposed a simple, direct and individually based fitness approach, which they claim returns to first principles: carriers of the genotype of interest “must, on average, end up with more net direct fitness benefits than average population members.” This seductively simple proposal uses the concept of assortment to explain how diverse kinds of altruists end up on average with more net fitness than their non-altruistic rivals. In this paper I shall argue that their approach implies a new concept of altruism that contrasts with and improves on the concept of the inclusive fitness approach. (shrink)

Inclusive fitness theory provides conditions for the evolutionary success of a gene. These conditions ensure that the gene is selfish in the sense of Dawkins (The selfish gene, Oxford University Press, Oxford, 1976): genes do not and cannot sacrifice their own fitness on behalf of the reproductive population. Therefore, while natural selection explains the appearance of design in the living world (Dawkins in The blind watchmaker: why the evidence of evolution reveals a universe without design, W. W. Norton, (...) New York, 1996), inclusive fitness theory does not explain how. Indeed, Hamilton’s rule is equally compatible with the evolutionary success of prosocial altruistic genes and antisocial predatory genes, whereas only the former, which account for the appearance of design, predominate in successful organisms. Inclusive fitness theory, however, permits a formulation of the central problem of sociobiology in a particularly poignant form: how do interactions among loci induce utterly selfish genes to collaborate, or to predispose their carriers to collaborate, in promoting the fitness of their carriers? Inclusive fitness theory, because it abstracts from synergistic interactions among loci, does not answer this question. Fitness-enhancing collaboration among loci in the genome of a reproductive population requires suppressing alleles that decrease, and promoting alleles that increase the fitness of its carriers. Suppression and promotion are effected by regulatory networks of genes, each of which is itself utterly selfish. This implies that genes, and a fortiori individuals in a social species, do not maximize inclusive fitness but rather interact strategically in complex ways. It is the task of sociobiology to model these complex interactions. (shrink)

In both biology and the human sciences, social groups are sometimes treated as adaptive units whose organization cannot be reduced to individual interactions. This group-level view is opposed by a more individualistic one that treats social organization as a byproduct of self-interest. According to biologists, group-level adaptations can evolve only by a process of natural selection at the group level. Most biologists rejected group selection as an important evolutionary force during the 1960s and 1970s but (...) a positive literature began to grow during the 1970s and is rapidly expanding today. We review this recent literature and its implications for human evolutionary biology. We show that the rejection of group selection was based on a misplaced emphasis on genes as “replicators” which is in fact irrelevant to the question of whether groups can be like individuals in their functional organization. The fundamental question is whether social groups and other higher-level entities can be “vehicles” of selection. When this elementary fact is recognized, group selection emerges as an important force in nature and what seem to be competing theories, such as kin selection and reciprocity, reappear as special cases of group selection. The result is a unified theory of natural selection that operates on a nested hierarchy of units.The vehicle-based theory makes it clear that group selection is an important force to consider in human evolution. Humans can facultatively span the full range from self-interested individuals to “organs” of group-level “organisms.” Human behavior not only reflects the balance between levels of selection but it can also alter the balance through the construction of social structures that have the effect of reducing fitness differences within groups, concentrating natural selection (and functional organization) at the group level. These social structures and the cognitive abilities that produce them allow group selection to be important even among large groups of unrelated individuals. (shrink)

In social evolution theory, biological individuals are often represented on the model of rational agents, that is, as if they were ‘seeking’ to maximize their own (expected) reproductive success. In the 1990s, important criticisms of this mode of thinking were made by Brian Skyrms ([1994], [1996]) and Elliott Sober ([1998]), who both argued that ‘rational agent’ models can lead to incorrect predictions when there are positive correlations between individuals’ phenotypes. In this article, I argue that one model of rational choice—namely, (...) Savage’s model ([1954])—can actually be vindicated in evolutionary biology, provided that the pay-offs are computed in inclusive fitness terms. I also show that the use of this model is better avoided when pay-offs are non-additive, or when certain causal influences (due to manipulative behaviours) affect the outcome of natural selection. The result is a partial rehabilitation of this mode of thinking, conditional on both the additivity of the pay-off structure and the absence of any form of manipulation or coercion. 1 Introduction2 When Natural Selection and Rational Deliberation Part Ways3 A Simple Solution: Redefining the Pay-offs in Inclusive Fitness Terms4 Sober on Inclusive Fitness Maximization5 Inclusive Fitness with Non-additive Pay-offs6 Causal Influences and the Savage– Hamilton Model6.1 Reciprocity and partner choice6.2 Coercion and manipulation7 ConclusionAppendix. (shrink)

Various results show the ‘formal equivalence’ of kin and group selectionist methodologies, but this does not preclude there being a real and useful distinction between kin and group selection processes. I distinguish individual- and population-centred approaches to drawing such a distinction, and I proceed to develop the latter. On the account I advance, the differences between kin and group selection are differences of degree in the structural properties of populations. A spatial metaphor provides a useful framework for (...) thinking about these differences: kin and group selection may be conceptualized as large, overlapping regions of K - G space. I then consider some implications of the account, defend it from possible objections, and further argue that the structural features characteristic of both kin and group selection may recur at multiple levels of biological organization. (shrink)

ABSTRACT In social evolution theory, biological individuals are often represented on the model of rational agents, that is, as if they were ‘seeking’ to maximize their own reproductive success. In the 1990s, important criticisms of this mode of thinking were made by Brian Skyrms and Elliott Sober, who both argued that ‘rational agent’ models can lead to incorrect predictions when there are positive correlations between individuals’ phenotypes. In this article, I argue that one model of rational choice—namely, Savage’s model —can (...) actually be vindicated in evolutionary biology, provided that the pay-offs are computed in inclusive fitness terms. I also show that the use of this model is better avoided when pay-offs are non-additive, or when certain causal influences affect the outcome of natural selection. The result is a partial rehabilitation of this mode of thinking, conditional on both the additivity of the pay-off structure and the absence of any form of manipulation or coercion. _1_ Introduction _2_ When Natural Selection and Rational Deliberation Part Ways _3_ A Simple Solution: Redefining the Pay-offs in Inclusive Fitness Terms _4_ Sober on Inclusive Fitness Maximization _5_ Inclusive Fitness with Non-additive Pay-offs _6_ Causal Influences and the Savage– Hamilton Model _6.1_ Reciprocity and partner choice _6.2_ Coercion and manipulation _7_ Conclusion Appendix. (shrink)

In both biology and the human sciences, social groups are sometimes treated as adaptive units whose organization cannot be reduced to individual interactions. This group-level view is opposed by a more individualistic one that treats social organization as a byproduct of self-interest. According to biologists, group-level adaptations can evolve only by a process of natural selection at the group level. Most biologists rejected group selection as an important evolutionary force during the 1960s and 1970s but (...) a positive literature began to grow during the 1970s and is rapidly expanding today. We review this recent literature and its implications for human evolutionary biology. We show that the rejection of group selection was based on a misplaced emphasis on genes as "replicators" which is in fact irrelevant to the question of whether groups can be like individuals in their functional organization. The fundamental question is whether social groups and other higher-level entities can be "vehicles" of selection. When this elementary fact is recognized, group selection emerges as an important force in nature and what seem to be competing theories, such as kin selection and reciprocity, reappear as special cases of group selection. The result is a unified theory of natural selection that operates on a nested hierarchy of units. The vehicle-based theory makes it clear that group selection is an important force to consider in human evolution. Humans can facultatively span the full range from self-interested individuals to "organs" of group-level "organisms." Human behavior not only reflects the balance between levels of selection but it can also alter the balance through the construction of social structures that have the effect of reducing fitness differences within groups, concentrating natural selection (and functional organization) at the group level. These social structures and the cognitive abilities that produce them allow group selection to be important even among large groups of unrelated individuals. (shrink)

The Nature of Selection is a straightforward, self-contained introduction to philosophical and biological problems in evolutionary theory. It presents a powerful analysis of the evolutionary concepts of natural selection, fitness, and adaptation and clarifies controversial issues concerning altruism, group selection, and the idea that organisms are survival machines built for the good of the genes that inhabit them. "Sober's is the answering philosophical voice, the voice of a first-rate philosopher and a knowledgeable student of contemporary evolutionary theory. (...) His book merits broad attention among both communities. It should also inspire others to continue the conversation."-Philip Kitcher, Nature "Elliott Sober has made extraordinarily important contributions to our understanding of biological problems in evolutionary biology and causality. The Nature of Selection is a major contribution to understanding epistemological problems in evolutionary theory. I predict that it will have a long lasting place in the literature."-Richard C. Lewontin. (shrink)

The question on how the diverse forms of cooperative behavior in humans and nonhuman animals could have evolved under the pressure of natural selection has been a challenge for evolutionary biology ever since Darwin himself. In this chapter, we briefly review and summarize results from the last 50 years of research on human and nonhuman cooperativeness from a theoretical (biology) and an experimental perspective (experimental economics). The first section presents six concepts from theoretical biology able to explain a variety (...) of forms of cooperativeness which evolved in many different species. These are kin selection, mutualism, reciprocity, green-beard altruism, costly signaling, and cultural group selection. These considerations are complemented by two short examples of evolved cooperative behavior, one from microbiology and one from ethology. The second main section focuses on recent experimental research on human cooperativeness. We present a brief review of factors known to impact individual human decision-making in social dilemmas, most prominently communication, punishment, reputation, and assortment. Our conclusion then draws attention to tasks for further research in this area. (shrink)

From mitochondria to meerkats, the natural world is full of spectacular examples of social behaviour. In the early 1960s W. D. Hamilton changed the way we think about how such behaviour evolves. He introduced three key innovations - now known as Hamilton's rule, kin selection, and inclusive fitness - and his pioneering work kick-started a research program now known as social evolution theory. This is a book about the philosophical foundations and future prospects of that program. [Note: only (...) the Introduction is available to download.]. (shrink)

Phenomena like meat sharing in hunter-gatherers, altruistic self-sacrifice in intergroup conflicts, and contribution to the production of public goods in laboratory experiments have led to the development of numerous theories trying to explain human prosocial preferences and behavior. Many of these focus on direct and indirect reciprocity, assortment, or (cultural) group selection. Here, I investigate analytically how genetic relatedness changes the incentive structure of that paradigmatic game which is conventionally used to model and experimentally investigate collective action problems: the (...) public goods game. Using data on contemporary hunter-gatherer societies I then estimate a threshold value determining when biological altruism turns into maximizing inclusive fitness in this game. I find that, on average, contributing no less than about 40% of individual fitness to public goods production still is an optimal strategy from an inclusive fitness perspective under plausible socio-ecological conditions. (shrink)

Sober and Wilson's enthusiasm for a multi-level perspective in evolutionary biology leads to conceptualizations which appropriate all sources of bio-altruistic traits as products of ‘group’ selection. The key biological issue is whether genes enhancing one sub-population's viability in competition with others can thrive, despite inducing some members to lose fitness in intra-group terms. The case for such selection amongst primates remains unproven. Flexible social loyalties required prior evolution of subjective self-definition and self-identification with others. But normative readiness for (...) truly group-serving sacrifices of ego-interests presupposes entitative conceptions of in-groups as collective social units -- only made possible with the emergence of human symbolic language. (shrink)

Through a series of essays, the author discusses the conflict between cultural and biological evolution, covering intelligent design, gender differences, and the meaning of life while offering insight into the ethical aspects of civilization.

I distinguish two roles for a fitness concept in the context of explaining cumulative adaptive evolution: fitness as a predictor of gene frequency change, and fitness as a criterion for phenotypic improvement. Critics of inclusive fitness argue, correctly, that it is not an ideal fitness concept for the purpose of predicting gene-frequency change, since it relies on assumptions about the causal structure of social interaction that are unlikely to be exactly true in real populations, and that hold as approximations (...) only given a specific type of weak selection. However, Hamilton took this type of weak selection, on independent grounds, to be responsible for cumulative assembly of complex adaptations. In this special context, I argue that inclusive fitness is distinctively valuable as a criterion for improvement and a standard for optimality. Yet to call inclusive fitness a criterion for improvement and a standard for optimality is not to make any claim about the frequency with which inclusive fitness optimization actually occurs in nature. This is an empirical question that cannot be settled by theory alone. I close with some reflections on the place of inclusive fitness in the long running clash between ‘causalist’ and ‘statisticalist’ conceptions of fitness. (shrink)

It’s recently been argued that biological fitness can’t change over the course of an organism’s life as a result of organisms’ behaviors. However, some characterizations of biological function and biological altruism tacitly or explicitly assume that an effect of a trait can change an organism’s fitness. In the first part of the paper, I explain that the core idea of changing fitness can be understood in terms of conditional probabilities defined over sequences of events in an organism’s life. The (...) result is a notion of “conditional fitness” which is static but which captures intuitions about apparent behavioral effects on fitness. The second part of the paper investigates the possibility of providing a systematic foundation for conditional fitness in terms of spaces of sequences of states of an organism and its environment. I argue that the resulting “organism–environment history conception” helps unify diverse biological perspectives, and may provide part of a metaphysics of natural selection. (shrink)

Abstract. Scientists have long puzzled over how homosexual orientation has evolved, given the assumed low relative fitness of homosexual individuals compared to heterosexual individuals. A number of theoretical models for the evolution of homosexuality have been postulated including balance polymorphism, "Fertile females", hypervariability of DNA sequences, kin selection, and "parental manipulation". In this paper, I propose a new group-selection model for the evolution of homosexuality which offers two advantages over existing models: (1) its non-assumption of genetic determinism, and (2) (...) its lack of dependency on an inefficient altruism relation and family dynamics theory. (shrink)

Humans often behave altruistically towards strangers with no chance of reciprocation. From an evolutionary perspective, this is puzzling. The evolution of altruistic cooperative behavior—in which an organism’s action reduces its fitness and increases the fitness of another organism —only makes sense when it is directed at genetically related organisms or when one can expect the favor to be returned. Therefore, evolutionary theorists such as Sober and Wilson have argued that we should revise Neo-Darwininian evolutionary theory. They argue that human (...) class='Hi'>altruism evolved through group selection in which groups of altruists were naturally selected because they had a comparative advantage over other groups. Wilson and Sober’s hypothesis attracted followers but is rejected by most of their peers. The heated debate between advocates and critics of group selection often suffers from a lack of conceptual clarity. In response, I set out to clearly distinguish ‘genetic’ from ‘cultural’ group selection and argue that the latter does not face the potentially debilitating problems plaguing the former. I defend the claim that human altruistic dispositions evolved through cultural group selection and gene-culture coevolution and offer empirical evidence in support. I also argue that actual altruistic behavior often goes beyond the kind of behavior humans have evolved to display. Conscious and voluntary reasoning processes, I show, have an important role in altruistic behavior. This is often overlooked in the scientific literature on human altruism. (shrink)

We argue that a fashionable interpretation of the theory of natural selection as a claim exclusively about populations is mistaken. The interpretation rests on adopting an analysis of fitness as a probabilistic propensity which cannot be substantiated, draws parallels with thermodynamics which are without foundations, and fails to do justice to the fundamental distinction between drift and selection. This distinction requires a notion of fitness as a pairwise comparison between individuals taken two at a time, and so vitiates the (...) interpretation of the theory as one about populations exclusively. (shrink)

I examine the relationship between evolutionary definitions of altruism that are based on fitness effects and psychological definitions that are based on the motives of the actor. I show that evolutionary altruism can be motivated by proximate mechanisms that are psychologically either altruistic or selfish. I also show that evolutionary definitions do rely upon motives as a metaphor in which the outcome of natural selection is compared to the decisions of a psychologically selfish (or altruistic) individual. Ignoring (...) the precise nature of both psychological and evolutionary definitions has obscured many important issues, including the biological roots of psychological altruism. (shrink)

The group selection controversy is about whether natural selection ever operates at the level of groups, rather than at the level of individual organisms. Traditionally, group selection has been invoked to explain the existence of altruistic behaviour in nature. However, most contemporary evolutionary biologists are highly sceptical of the hypothesis of group selection, which they regard as biologically implausible and not needed to explain the evolution of altruism anyway. But in their recent book, Elliot Sober (...) and David Sloan Wilson [1998] argue that the widespread opposition to group selection is founded on conceptual confusion. The theories that have been propounded as alternatives to group selection are actually group selection in disguise, they maintain. I examine their arguments for this claim, and John Maynard Smith's arguments against it. I argue that Sober and Wilson arrive at a correct position by faulty reasoning. In the final section, I examine the issue of how to apply the principle of natural selection at different levels of the biological hierarchy, which underlies the dispute between Sober and Wilson and Maynard Smith. (shrink)

Group selection is one acknowledged mechanism for the evolution of altruism. It is well known that for altruism to spread by natural selection, interactions must be correlated; that is, altruists must tend to associate with one another. But does group selection itself require correlated interactions? Two possible arguments for answering this question affirmatively are explored. The first is a bad argument, for it rests on a product/process confusion. The second is a more subtle argument, whose (...) validity (or otherwise) turns on issues concerning the meaning of multi-level selection and how it should be modelled. A cautious defence of the second argument is offered. Introduction Multi-level selection and the evolution of altruism Price's equation and multi-level selection Contextual analysis and multi-level selection The neighbour approach Recapitulation and conclusion. (shrink)

We show how Richard Jeffrey’s The Logic of Decision provides the proper formalism for calculating expected fitness for correlated encounters in general. As an illustration, some puzzles about kin selection are resolved.

We show how Richard Jeffrey's The Logic of Decision provides the proper formalism for calculating expected fitness for correlated encounters in general. As an illustration, some puzzles about kin selection are resolved.

The effects of natural selection as a process in natural populations differs from ''survival of the fittest'' as it was formulated by Darwin in his ''Origin of Species''. The environment of a population exists of continuous changing conditions, which are heterogeneous in space. During its life each individual successively meets with differing conditions. During these confrontations the individual may appear to be ''unfit'' or ''unlucky'' and may die. If it survives it will meet the following conditions to which (...) it is ''tested'' anew, a.s.o. Hence, many individuals being less fit under certain conditions will survive and reproduce, because they did not meet a deadly moment. Therefore, being ''fit'' only refers to special prevalent conditions. In each generation the individuals thus being ''unfit'' will be eliminated together with the ''unlucky'' ones. All other individuals will survive and reproduce, notwithstanding their properties.Hence, natural selection results in the ''non-survival of the non-fit'' rather than in ''survival of the fittest'', because being ''fit'' simply means ''having survived and reproduced'', whereas being ''unfit'' can be connected with many kinds of properties and environmental conditions, e.g. being killed by a predator. Only after many generations (hundreds or even thousands) the effect of eventually dominating properties of the survivors may result in a set of properties suggesting an overall ''survival of the fittest''. This was what Darwin wanted to explain as he was mainly interested in evolutionary processes. (shrink)

In models of multi-level selection, the property of Darwinian fitness is attributed to entities at more than one level of the biological hierarchy, e.g. individuals and groups. However, the relation between individual and group fitness is a controversial matter. Theorists disagree about whether group fitness should always, or ever, be defined as total (or average) individual fitness. This paper tries to shed light on the issue by drawing on work in social choice theory, and pursuing an analogy between (...) fitness and utility. Social choice theorists have long been interested in the relation between individual and social utility, and have identified conditions under which social utility equals total (or average) individual utility. These ideas are used to shed light on the biological problem. (shrink)

Matthen (Philos Sci 76(4):464–487, 2009) argues that explanations of evolutionary change that appeal to natural selection are statistically abstractive explanations, explanations that ignore some possible explanatory partitions that in fact impact the outcome. This recognition highlights a difficulty with making selective analyses fully rigorous. Natural selection is not about the details of what happens to any particular organism, nor, by extension, to the details of what happens in any particular population. Since selective accounts focus on tendencies, those factors (...) that impact the actual outcomes but do not impact the tendencies must be excluded. So, in order to properly exclude the factors irrelevant to selection, the relevant factors must be identified, and physical processes, environments, and populations individuated on the basis of being relevantly similar for the purposes of selective accounts. Natural selection, on this view, becomes in part a measure of the robustness of particular kinds of outcomes given variations over some kinds of inputs. (shrink)

We characterize a type of functional explanation that addresses why a homologous trait originating deep in the evolutionary history of a group remains widespread and largely unchanged across the group’s lineages. We argue that biologists regularly provide this type of explanation when they attribute conserved functions to phenotypic and genetic traits. The concept of conserved function applies broadly to many biological domains, and we illustrate its importance using examples of molecular sequence alignments at the intersection of evolution and (...) cell biology. We use these examples to show how the study of conserved functions can integrate knowledge of a trait’s causal effects on fitness and its history of natural selection without invoking adaptation. We also show how conserved function provides a novel basis for addressing objections against evolutionary functions raised by Robert Cummins. (shrink)

The group selection controversy largely focuses on altruism (e.g., Wilson 1983; Lloyd 2001; Shavit 2004; Okasha 2006, 173ff; Borrello 2010; Leigh 2010; Rosas 2010; Hamilton and Dimond in press). Multilevel selection theory is a resolution of this controversy. Whereas kin selection partitions inclusive fitness into direct and indirect components (via influencing the replication of copies of genes in other individuals), multilevel selection considers within-group and between-group components of fitness (Gardner et al. 2011; Lion et al. (...) 2011). Two scenarios of multilevel selection are often distinguished (Damuth and Heisler 1988; Okasha 2006; Pigliucci 2010): (1) group structure only divides individual fitnesses into within- and between-group components (MLS1); and, (2) groups get their own component of fitness and also, in most definitions, a group-level adaptation (MLS2). (shrink)

Human cooperation is held to be an evolutionary puzzle because people voluntarily engage in costly cooperation, and costly punishment of non-cooperators, even among anonymous strangers they will never meet again. The costs of such cooperation cannot be recovered through kin-selection, reciprocal altruism, indirect reciprocity, or costly signaling. A number of recent authors label this behavior ‘strong reciprocity’, and argue that it is: (a) a newly documented aspect of human nature, (b) adaptive, and (c) evolved by group selection. (...) We argue exactly the opposite; that the phenomenon is: (a) not new, (b) maladaptive, and (c) evolved by individual selection. In our perspective, the apparent puzzle disappears to reveal a biological and evolutionary logic to human cooperation. Group selection may play a role in theory, but it is neither necessary nor sufficient to explain human cooperation. Our alternative solution is simpler, makes fewer assumptions, and is more parsimonious with the empirical data. (shrink)

Biologists study life in its various physical forms, while philosophers of biology seek answers to questions about the nature, purpose, and impact of this research. What permits us to distinguish between living and nonliving things even though both are made of the same minerals? Is the complex structure of organisms proof that a creative force is working its will in the physical universe, or are existing life-forms the random result of an evolutionary process working itself out over eons of time? (...) What moral and social questions arise regarding modern advances in biotechnology? What is more relevant to human nature: genetics or sociocultural influences? Is Darwinism the death-knell of God? These are just some of the vital questions addressed by a distinguished group of philosophers and scientists which includes: Aristotle, Francisco J. Ayala, , Michael Benton, Tom Bethell, Joe Cain, David Castle, Charles Darwin, Richard Dawkins, Michael Denton, A.G.N. Flew, Stephen Jay Gould, J.B.S. Haldane, John F. Haught, D. W. E. Hone, James W. Kirchner, James Lovelock, Jane Maienschein, Ernst Mayr, Gregory M. Mikkelson, Leslie Orgal, William Paley, the Prince of Wales, Christopher Pynes, Richard A. Richards, Mark Ridley, Holmes Rolston III, Michael Ruse, Lee Silver, Elliott Sober, Kim Sterelny, Derek Turner, and Edward O. Wilson. This second edition contains material on design without selection, testing macroevolutionary claims, recent biotechnological issues, key ecological concerns, the Gaia hypothesis, genetically modified foods, and the so-called intelligent design movement. (shrink)

This paper defends global realism about the units of selection, the view that there is always (or nearly always) an objective fact of the matter concerning the level at which natural selection acts. The argument proceeds in two stages. First, it is argued that global conventionalist-pluralism is false. This is established by identifying plausible sufficient conditions for irreducible selection at a particular level, and showing that these conditions are sometimes satisfied in nature. Second, it is argued that local pluralism (...) – the view that while realism is true of some selection regimes, pluralist conventionalism holds for others – should also be rejected. I show that the main arguments for local pluralism are consistent with global realism. I also suggest that local pluralism offers an unacceptably disunified view of the metaphysics of selection. It follows that we should accept global realism. But this leaves open the question of how to classify so called ‘multi-level selection type 1’ (MLS1) processes, such as Wilson’s classic trait-group model for the evolution of altruism: should they be interpreted as particle selection or collective selection? On the assumption of global realism, at most one of these is correct. I argue, against global realists such as Sober, that MLS1 processes should be understood as particle, not collective, selection, due to three features of MLS1: the reducibility of collective fitness, the absence of collective reproduction, and the dispensable role of collectives. (shrink)

Philosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. ‘Macrobe’ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes – the dominant life form on the planet, both now and throughout evolutionary history – will transform some of the (...) class='Hi'>philosophy of biology’s standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology – including biofilm formation, chemotaxis, quorum sensing and gene transfer – that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations. (shrink)

Runaway social selection resulting from partner choice may have shaped aspects of human cooperation and complex sociality that are otherwise hard to account for. Social selection is the subtype of natural selection that results from the social behaviors of other individuals. Competition to be chosen as a social partner can, like competition to be chosen as a mate, result in runaway selection that shapes extreme traits. People prefer partners who display valuable resources and bestow them selectively on close partners. (...) The resulting phenotypic covariance between displays and preferences gives fitness advantages to both, creating runaway selection that could shape a whole suite of prosocial traits including altruism, moral capacities, empathy, and theory of mind. Even though they give a net fitness benefit, traits at the endpoint of runaway social selection can have substantial deleterious effects on other traits such as viability, ability to accumulate resources, or vulnerability to mental disorders. Social selection forces arising from self-interested partner choices may be an invisible hand that shaped capacities for commitment, altruism, and other prosocial capacities of the human social brain. (shrink)

This paper is a commentary on the focal article by Grafen and on earlier papers of his on which many of the results of this focal paper depend. Thus it is in effect a commentary on the “formal Darwinian project”, the focus of this sequence of papers. Several problems with this sequence are raised and discussed. The first of these concerns fitness maximization. It is often claimed in these papers that natural selection leads to a maximization of fitness and (...) that this view is claimed in Fisher’s “fundamental theorem of natural selection”. These claims are refuted, and various incorrect statements about the meaning and interpretation of the fundamental theorem of natural selection, in this sequence and in other papers by other authors, are discussed. Next, much of the work in this sequence rests on the first Price equation. In the deterministic (infinite population) case this equation is no more than the standard classical equation relating to changes in gene frequencies. In the stochastic case the equation gives the change in gene frequencies as the sum of two terms (the second of which vanishes in the deterministic case). These two terms are of essentially equal importance in the situation considered in the focal article, yet one of Grafen’s results ignores the second term in the stochastic analysis. This is associated with a wavering between deterministic and stochastic analyses and the use of the Price fitness concept and the classical fitness concept. These comments cast doubts on Grafen’s optimization theory. (shrink)

This paper explores two philosophical issues related to Darwin’s treatment of the sterile castes of insects in the Origin of Species. The first aim is to review the scholarly articles on the subjects of Darwin’s acceptance or rejection of natural selection acting at levels above that of the individuals. The second aim is to see whether Darwin’s position on group selection informs in any way contemporary debates on group selection and multilevel selection. The paper arrives at the (...) conclusion that, there is significant evidence in the Origin that Darwin did see natural selection acting at the level of the community, but it is hard to say anything more than evolutionary biology is compatible with multilevel selection if we take this point into account. Many present-day individualistic and pluralistic accounts of natural selection that seek legitimacy from Darwin’s views on the subject open up to charges of anachronism. (shrink)

Description of the biologicalhierarchy of the organism has been extendedhere to included the evolutionary andecological sub-hierarchies with theirrespective levels in order to give a completehierarchical description of life. These newdescriptions include direction of formation,types of constraints, and dual levels. Constraints are produced at the macromolecularlevel of genes/proteins, some of which (a) aredescendent restraints which hold a hierarchytogether and others (b) interact horizontallywith selective agents at corresponding levelsof the niche. The organism is a dual levelconstrained by both the ecologicalsub-hierarchy (survival) and (...) evolutionarysub-hierarchy (fitness) while serving as thehighest level of the specializationsub-hierarchy, therefore, it is unique inbelonging to three sub-hierarchies. Organismsexperience birth, sometimes death, andparticipate in evolution. Birth of an organismis realized when a cell is removed from theconstraints of the organism and assumes itsown organismal constraints. Death occurs withthe cessation of protein synthesis becauseproteins and their products constitutecomponents at high levels of the hierarchy. Selection is of two types, natural selection,involving adaptive traits interacting withfeatures in a niche, and hierarchicalselection, requiring traits to be compatiblewith existing hierarchical constraints. (shrink)

One version of pluralism was defended in a well-known paper by Sterelny and Kitcher. In this sense, pluralism is the view that any given selective process can be described at a variety of different levels in the biological hierarchy. On Sterelny and Kitcher’s view, one can explain giraffe necks in terms of competition among longer-necked and shorter-necked giraffes, and one can also explain them in terms of competition among the genes that lead to these differences in neck size. Although these (...) descriptions might have different heuristic virtues, neither description has a special explanatory status that the other lacks. (shrink)

The key problem in the controversy over group selection is that of defining a criterion of group selection that identifies a distinct causal process that is irreducible to the causal process of individual selection. We aim to clarify this problem and to formulate an adequate model of irreducible group selection. We distinguish two types of group selection models, labeling them type I and type II models. Type I models are invoked to explain differences among groups in (...) their respective rates of production of contained individuals. Type II models are invoked to explain differences among groups in their respective rates of production of distinct new groups. Taking Elliott Sober's model as an exemplar, we argue that although type I models have some biological importance--they force biologists to consider the role of group properties in influencing the fitness of organisms--they fail to identify a distinct group-level causal selection process. Type II models if properly framed, however, do identify a group-level causal selection process that is not reducible to individual selection. We propose such a type II model and apply it to some of the major candidates for group selection. (shrink)

In 1975, the English evolutionist William Donald Hamilton held in Brazil a series of lectures entitled “Population genetics and social behaviour”. The unpublished notes of these conferences—written by Hamilton and recently discovered at the British Library—offer an opportunity to reflect on some of the author’s ideas about evolution. The year of the conference is particularly significant, as it took place shortly after the applications of the Price equation with which Hamilton was able to build a model that included several levels (...) of selection. In this paper I mainly analyse the inaugural lecture in which Hamilton proposes a simple model to disprove the hypothesis supported by the British zoologist C. Vero Wynne-Edwards regarding mechanisms to prevent “over-exploitation of the food supply” in “the interests of the survival of the group”. The document presented here is of great historical interest. Not only because manuscript offers a model that—since it was intended for teaching purposes—had never before appeared in the published version, but also because of the general index of the lectures that accompanies it. The latter allows us to make some hypothetical considerations on the relationship and differences between kin-selection, group-selection and inclusive fitness that Hamilton wanted to present to the attentive, well-prepared audience of the foreign university that had invited him. (shrink)

How to measure fitness in the theory of natural selection? A fitness measure that has been proposed in both the biological and the philosophical literature is the expected relative reproductive success. The aim of this article is to examine the relationship between expected relative reproductive success and future actual evolutionary success. Doing so will not only clarify the use of expected relative reproductive success as a fitness measure but also shed light on the role of fitness in the theory (...) of natural selection. _1_ Introduction _2_ The Role of Fitness _3_ Geometric Mean versus Expected Relative Reproductive Success _4_ Reconciliation _5_ Reconciliation Continued _6_ Alternative Justifications _7_ Conclusion. (shrink)

I argue that images of the notion of group, in correspondence with their social and political values, shape the debate over the evolution of altruism by group selection. Important aspects of this debate are empirical, and criteria can decide among a variety of selection processes. However, leading researchers undermine or reinterpret such tests, explaining the evolution of altruism on the basis of a single extreme metaphor of ‘group’ and a single inclusive selection process. I (...) shall argue that the extreme images for the notion of group are associated with ideologies that these researchers support or fear. Hence, the history of social and political uses of ‘group’ and ‘group selection’ can explain, at least in part, some of the empirical deficiencies of the debate, and why it has continued without resolution or dissolution. (shrink)

The study of biological altruism is a cornerstone of modern evolutionary biology. Associated with foundational issues about natural selection, it is often supposed that explaining altruism is key to understanding social behavior more generally. Typically, biological altruism is defined in purely effects-based, behavioral terms – as an interaction in which one organism contributes fitness to another, at its own expense. Crucially, such a definition isn’t meant to rest on psychological or intentional assumptions. We show that, appearances (...) and official definitions notwithstanding, the notion biological altruism carries a vestige of the psychological, intentional concept familiar to us from the human domain. In particular, definitions of altruism from Hamilton onwards presuppose an actor\recipient distinction – a distinction, so we argue, that has questionable biological grounding. We arrive at this conclusion step-by-step, first looking at several simple, “austere” definitions and their problems, and then critiquing the actor\recipient distinction directly. If successful, our arguments suggest that the category of biological altruism requires a significant rethink. (shrink)

Written by leading theorists and empirical researchers, this book presents new ways of addressing the old question: Why did religion first emerge and then continue to evolve in all human societies? The authors of the book--each with a different background across the social sciences and humanities -- assimilate conceptual leads and empirical findings from anthropology, evolutionary biology, evolutionary sociology, neurology, primate behavioral studies, explanations of human interaction and group dynamics, and a wide range of religious scholarship to construct a (...) deeper and more powerful explanation of the origins and subsequent evolutionary development of religions than can be currently found in what is now vast literature. While explaining religion has been a central question in many disciplines for a long time, this book draws upon a much wider array of literatures to develop a robust and cross-disciplinary analysis of religion. The book remains true to its subtitle by emphasizing an array of both biological and sociocultural forms of selection dynamics that are fundamental to explaining religion as a universal institution in human societies. In addition to Darwinian selection, which can explain the biology and neurology of religion, the book outlines a set of four additional types of sociocultural natural selection that can explain fill out the explanation of why religion first emerged as an institutional system in human societies, and why it has continued to evolve over the last 200,000 years of societal evolution. These sociocultural forms of natural selection are labeled by the names of the early sociologists who first emphasized them; and these can be seen as a necessary supplement to the type of natural selection theorized by Charles Darwin. Explanations of religion that remain in the shadow cast by Darwin's great insights will, it is argued, remain narrow and incomplete when explaining a robust sociocultural phenomena like religion. (shrink)

Evolutionary gradualism, the randomness of mutations, and the hypothesis that natural selection exerts a pervasive and substantial influence on evolutionary outcomes are pair-wise logically independent. Can the claims about selection and mutation be used to formulate an argument for gradualism? In his Genetical Theory of Natural Selection, R.A. Fisher made an important start at this project in his famous “geometric argument” by showing that a random mutation that has a smaller effect on two or more phenotypes will have (...) a higher average fitness than a random mutation that has a larger phenotypic effect. Motoo Kimura’s demonstration that a gene’s probability of fixation depends on both the selection coefficient and the effective population size shows that Fisher’s argument for gradualism was mistaken. Here we analyze Fisher’s argument and explain how Kimura’s theory leads to a conclusion that Fisher did not anticipate. We identify a fallacy that reasoning about fitness differences and their evolutionary consequences should avoid. We then distinguish forward-directed from backward-directed versions of gradualism. The backward-directed thesis about a single mutation may be correct, but the forward-directed thesis is not. After that we consider a sequence of random mutations that all affect the same cluster of phenotypes and Allen Orr’s idea that there is an optimal sequence of mutation sizes, moving from larger to smaller as the population approaches a fixed optimum. This provides a likelihood justification for a forward-directed version of gradualism when there is a fixed optimum, but it also provides an argument against forward-directed gradualism if the optimum shifts substantially as the population evolves. Finally, we consider whether genome-wide association studies (GWASs) can furnish empirical evidence that bears on the truth of gradualism. The version of gradualism that GWASs directly bear on concerns the phenotypic effect size of a gene after it arises by mutation and has reached an appreciable frequency, not the phenotypic size of the mutation event itself. (shrink)

I argue that images of the notion of group, in correspondence with their social and political values, shape the debate over the evolution of altruism by group selection. Important aspects of this debate are empirical, and criteria can decide among a variety of selection processes. However, leading researchers undermine or reinterpret such tests, explaining the evolution of altruism on the basis of a single extreme metaphor of ‘group’ and a single inclusive selection process. I (...) shall argue that the extreme images for the notion of group are associated with ideologies that these researchers support or fear. Hence, the history of social and political uses of ‘group’ and ‘group selection’ can explain, at least in part, some of the empirical deficiencies of the debate, and why it has continued without resolution or dissolution. (shrink)

Multi-level selection can be understood via the Price equation or contextual analysis, which offer incompatible statistical decompositions of evolutionary change into components of group and individual selection. Okasha argued that each approach suffers from problem cases. I introduce further problem cases for the Price approach, arguing that it is appropriate for MLS 2 group selection but not MLS 1. I also show that the problem cases Okasha raises for contextual analysis can be resolved. For some such cases, however, (...) it emerges that there is no determinate answer to the question of how much of the total selective effect was due to group selection compared to individual selection. This suggests that when there is interaction between the effect of group character and individual character, one cannot separate selection into distinct ‘levels’ at all. (shrink)

Kin selection, reciprocity and group selection are widely regarded as evolutionary mechanisms capable of sustaining altruism among humans andother cooperative species. Our research indicates, however, that these mechanisms are only particular examples of a broader set of evolutionary possibilities.In this paper we present the results of a series of simple replicator simulations, run on variations of the 2–player prisoner's dilemma, designed to illustrate the wide range of scenarios under which altruism proves to be robust under evolutionary pressures. (...) The set of mechanisms we explore is divided into four categories :correlation, group selection, imitation, and punishment. We argue that correlation is the core phenomenon at work in all four categories. (shrink)