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Claims that our species is an “evolutionary success” typically do not feature prominently in academic articles. However, they do seem to be a recurring trope in science popularization. Why do we seem to be attracted to viewing human evolution through the lenses of “success”? In this chapter we discuss how evolutionary success has both causal-descriptive and ethical-normative components, and how its ethical status is ambiguous, with possible hints of anthropocentrism. We also place the concept of “success” in a wider context of biological thought, contrasting it with two other value-laden concepts: evolutionary progress and human uniqueness. Claiming the human species to be an evolutionary success is ostensibly grounded in metrics such as the dominance or the size of the human population, but the claim often goes beyond this, suggesting that humans are a unique species or the pinnacle of evolutionary progress.

Niche construction theory concerns how organisms can change selection pressures by altering the feature–factor relationship between themselves and their environment. These alterations are standardly understood to be brought about through two kinds of organism–environment interaction: perturbative and relocational niche construction. We argue that a reconceptualization is needed on the grounds that if a niche is understood as the feature–factor relationship, then there are three fundamental ways in which organisms can engage in niche construction: constitutive, relational, and external niche construction. We further motivate our reconceptualization by showing some examples of organismic activities that fall outside of the current categorization of niche construction, but nonetheless should be included. We end by discussing two objections to niche construction and show how our reconceptualization helps to undercut these objections. ispartof: British Journal for the Philosophy of Science vol:73 issue:2 pages:351-372 status: published

Fitness is a central concept in evolutionary theory. Just as it is central to biological evolution, so, it seems, it should be central to cultural evolutionary theory (CET). But importing the biological fitness concept to CET is no straightforward task—there are many features unique to cultural evolution that make this difficult. This has led some theorists to argue that there are fundamental problems with cultural fitness that render it hopelessly confused. In this essay, we defend the coherency of cultural fitness against those who call it into doubt.

In multicellular organisms, cells are frequently programmed to die. This makes good sense: cells that fail to, or are no longer playing important roles are eliminated. From the cell’s perspective, this also makes sense, since somatic cells in multicellular organisms require the cooperation of clonal relatives. In unicellular organisms, however, programmed cell death (PCD) poses a difficult and unresolved evolutionary problem. The empirical evidence for PCD in diverse microbial taxa has spurred debates about what precisely PCD means in the case of unicellular organisms (how it should be defined). In this article, we survey the concepts of PCD in the literature and the selective pressures associated with its evolution. We show that definitions of PCD have been almost entirely mechanistic and fail to separate questions concerning what PCD fundamentally is from questions about the kinds of mechanisms that realize PCD. We conclude that an evolutionary definition is best able to distinguish PCD from closely related phenomena. Specifically, we define “true” PCD as an adaptation for death triggered by abiotic or biotic environmental stresses. True PCD is thus not only an evolutionary product but must also have been a target of selection. Apparent PCD resulting from pleiotropy, genetic drift, or trade-offs is not true PCD. We call this “ersatz PCD.”

Recent evolutionary perspectives on guilt tend to focus on how guilt functions as a means for the individual to self-regulate behavior and as a mechanism for reinforcing cooperative tendencies. While these accounts highlight important dimensions of guilt and provide important insights into its evolutionary emergence, they pay scant attention to the large empirical literature on its maladaptive effects on individuals. This paper considers the nature of guilt, explores its biological function, and provides an evolutionary perspective on whether it is an individual-level or group selected trait. After surveying philosophical and psychological analyses of guilt, we consider which psychological mechanisms underlie the capacity to experience and act from guilt and whether they point to an emergence of guilt in early humans or to guilt having a longer phylogenetic history. Because guilt is a characteristically social emotion, we then examine its contemporary role in social and legal contexts, which may provide clues to its original biological function. Finally, we provide the outlines of two evolutionary explanations for guilt. We argue that group selection may have promoted the capacity to experience guilt, but that under certain conditions there may have been a positive individual selection force as well.

Fitness is a central theoretical concept in evolutionary theory. Despite its importance, much debate has occurred over how to conceptualize and formalize fitness. One point of debate concerns the roles of organismic and trait fitness. In a recent addition to this debate, Elliott Sober argues that trait fitness is the central fitness concept, and that organismic fitness is of little value. In this paper, by contrast, we argue that it is organismic fitness that lies at the bases of both the conceptual role of fitness and its role as a measure of evolutionary dynamics.

Conceptions of human nature fall under two broad categories, trait bin accounts and trait cluster accounts. Trait bin accounts take there to be a special bin of traits, one composed of all and only those traits constituting our nature. For those arguing for a trait bin account of human nature, the challenge is to articulate what it is that marks a trait as being in or outside of the bin. For some, the bin is filled by the traits essential to being human. Others, such as Machery in his contribution to this volume, offer a non-essentialist trait bin conception of human nature. In this chapter, I argue that trait bin approaches to human nature are misguided, that there is no good way of dividing human traits into those that are a part of our nature and those that are not. Instead, I argue for a trait cluster account, which sees human nature not as a special bin of traits, but as the relationship among traits. Under this account, human nature lies in the patterns of trait expression within and across human life histories. This account does a superior job characterizing what humans are like and aligning human nature with the human sciences.

In this paper, we distinguish two different approaches to cultural evolution. One approach is meme-centered, the other organism-centered. We argue that in situations in which the meme- and organism-centered approaches are competing alternatives, the organism-centered approach is in many ways superior. Furthermore, the organism-centered approach can go a long way toward understanding the evolution of institutions. Although the organism-centered approach is preferable for a broad class of situations, we do leave room for super-organismic (group based) or sub-organismic (meme-based) explanations of some cultural phenomena.

In this essay I examine a well-known articulation of human nature skepticism, a paper by Hull. I then review a recent reply to Hull by Machery, which argues for an account of human nature that he claims is both useful and scientifically robust. I challenge Machery’s account and introduce an alternative account—the “life-history trait cluster” conception of human nature—that I hold is scientifically sound and makes sense of (at least some of) our intuitions about—and desiderata for—human nature.

The propensity interpretation of fitness (PIF) is commonly taken to be subject to a set of simple counterexamples. We argue that three of the most important of these are not counterexamples to the PIF itself, but only to the traditional mathematical model of this propensity: fitness as expected number of offspring. They fail to demonstrate that a new mathematical model of the PIF could not succeed where this older model fails. We then propose a new formalization of the PIF that avoids these (and other) counterexamples. By producing a counterexample-free model of the PIF, we call into question one of the primary motivations for adopting the statisticalist interpretation of fitness. In addition, this new model has the benefit of being more closely allied with contemporary mathematical biology than the traditional model of the PIF.

A major debate in the philosophy of biology centers on the question of how we should understand the causal structure of natural selection. This debate is polarized into the causal and statistical positions. The main arguments from the statistical side are that a causal construal of the theory of natural selection’s central concept, fitness, either (i) leads to inaccurate predictions about population dynamics, or (ii) leads to an incoherent set of causal commitments. In this essay, I argue that neither the predictive inaccuracy nor the incoherency arguments successfully undermine the causal account of fitness.

In this paper, I argue (contra some recent philosophical work) that an objective distinction between natural selection and drift can be drawn. I draw this distinction by conceiving of drift, in the most fundamental sense, as an individual-level phenomenon. This goes against some other attempts to distinguish selection from drift, which have argued either that drift is a population-level process or that it is a population-level product. Instead of identifying drift with population-level features, the account introduced here can explain these population-level features based on a property that I label driftability. Additionally, this account shows that biology’s “first law”—the Principle of Drift (Brandon, J Phil 102(7):319–335 2006)—is not a foundational law, but is a consequence of driftability.

The study of animal culture is a flourishing field, with culture being recorded in a wide range of taxa, including non-human primates, birds, cetaceans, and rodents. In spite of this research, however, the concept of culture itself remains elusive. There is no universally assented to concept of culture, and there is debate over the connection between culture and related concepts like tradition and social learning. Furthermore, it is not clear whether culture in humans and culture in non-human animals is really the same thing, or merely loose analogues that go by the same name. The purpose of this paper is to explicate core desiderata for a concept of culture and then to construct a concept that meets these desiderata. The paper then applies this concept in both humans and non-human animals.

In this commentary on Lewens (2012), I argue that although his criticisms of Machery's (2008) conception of human nature are sound, I disagree with his conclusion that human nature cannot inform us regarding issues of human enhancement. I introduce a framework for understanding human nature, the “life history trait cluster account,” which aligns the concept of human nature with the human sciences and allows human nature to inform questions of human enhancement.

Homology is a biological sameness relation that is purported to hold in the face of changes in form, composition, and function. In spite of the centrality and importance of homology, there is no consensus on how we should understand this concept. The two leading views of homology, the genealogical and developmental accounts, have significant shortcomings. We propose a new account, the hierarchical-dependency account of homology, which avoids these shortcomings. Furthermore, our account provides for continuity between special, general, and serial homology.

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.

There is clearly a plurality of forms of altruism. Classically, biological altruism is distinguished from psychological altruism. Recent discussions of altruism have attempted to distinguish even more forms of altruism. I will focus on three altruism concepts, biological altruism, psychological altruism, and helping altruism. The questions I am concerned with here are, first, how should we understand these concepts? and second, what relationship do these concepts bear to one another? In particular, is there an essence to altruism that unifies these concepts? I suggest that while there is no essence to altruism, this does not mean that the array of altruism concepts is completely disunified. Instead, I propose we place all the concepts into a common framework—an altruism space—that could lead to new questions about how this space can be filled.

This paper argues that there is a general constraint on the evolution of culture. This constraint – what I am calling the Fundamental Constraint – must be satisfied in order for a cultural system to be adaptive. The Fundamental Constraint is this: for culture to be adaptive there must be a positive correlation between the fitness of cultural variants and their fitness impact on the organisms adopting those variants. Two ways of satisfying the Fundamental Constraint are introduced, structural solutions and evaluative solutions. Because of the limitations on these solutions, this constraint helps explain why there is not more culture in nature, why the culture that does exist has the form it has, and why complex, cumulative culture is restricted to the human species. ispartof: Biology & Philosophy vol:22 issue:3 pages:401-414 ispartof: location:CANADA, Guelph status: published

Hope Hollocher,* Charles H. Pence, Grant Ramsey, and Michelle M. Wirth Department of Biological Sciences, Galvin Life Sciences, University of Notre Dame, Notre Dame, IN 46556, USA Program in History and Philosophy of Science, John J. Reilly Center for Science, Technology and Values, University of Notre Dame, Geddes Hall, Notre Dame, IN 46556, USA Department of Philosophy, University of Notre Dame, Malloy Hall, Notre Dame, IN 46556, USA Department of Psychology, University of Notre Dame, Haggar Hall, Notre Dame, IN 46556, USA

The dynamics of epiphytic bryophyte communities following natural and human disturbance have rarely been quantified. We describe the response of bryophyte communities on bigleaf maple trees (Acer macrophyllum Pursh) in Olympia, Washington, following their experimental removal. Approximately 8% of the exposed area was recolonized by bryophytes 1 year after clearing, and 27% after 3 years. Lateral encroachment from bryophytes on the sides of the 20-cm-long plots accounted for 75% of this recolonization, with growth from residual plant parts or aerially dispersed diaspores accounting for the remaining 25%. Though it was not possible to distinguish between the latter two sources of cover, the number of clear de novo colonization events over the course of the year was low (0.18 dm-2). Disturbance appeared to reduce bryophyte diversity at this successional stage, as alpha and gamma diversity remained low after 1 year and had not recovered after 3 years. Reflecting the preponderance of lateral encroachment as the mechanism for recolonization, disturbance size may significantly affect the time needed to recolonize disturbed branch substrates. In addition to contributing to ecologists' understanding of processes of succession, these experiments may help to develop sustainable practices for moss-harvesting in the Pacific Northwest.Key words: succession, bryophytes, epiphytes, Acer macrophyllum, recolonization, canopy studies.

Fitness plays many roles throughout evolutionary theory, from a measure of populations in the wild to a central element in abstract theoretical presentations of natural selection. It has thus been the subject of an extensive philosophical literature, which has primarily centered on the way to understand the relationship between fitness values and reproductive outcomes. If fitness is a probabilistic or statistical quantity, how is it to be defined in general theoretical contexts? How can it be measured? Can a single conceptual model for fitness be offered that applies in all biological cases, or must fitness measures be case-specific? Philosophers have explored these questions over the last several decades, largely in the context of an influential definition of fitness proposed in the late 1970s: the propensity interpretation. This interpretation as first described undeniably suffers from significant difficulties, and debate regarding the tenability of amendments and alternatives to it remains unsettled.

The causal status of fitness and natural selection is increasingly called into doubt in the philosophical literature. For example, Elliott Sober argues that the fitness of individual organisms is holistic; i.e., it is dependent on causally independent factors like census size. Others have argued that fitness differences cannot properly be causes of evolutionary change. In this paper I directly challenge the holistic conclusion, and thereby shed light on the debates over the causal status of fitness. I show that the causalists and statisticalists are—to a large degree—arguing past each other. There is a plurality of fitness concepts; some are legitimately causal, while others seem to be based, at least in part, on purely statistical parameters. But such facts say nothing about whether fitness in general is causal or statistical. ispartof: Philosophy and Theory in Biology vol:5 pages:1-13 status: published