Since, it has become clear that individuality is not to be considered as a given, but rather as something which needs to be explained. How has individuality emerged through evolution, and how has it subsequently been maintained? In particular, why is it that multicellular organisms appeared and persisted, despite the obvious interest of each cell of favoring its own replication? Several biologists see the immune system as one of the key components for explaining the maintenance of multicellular organisms’ individuality. Indeed, (...) the immune system exerts a constant surveillance on all the constituents of the organism, including “cheaters” like tumor cells, which favor their own replication at the expense of the whole organism. In most cases, the immune system eliminates those cheaters. This is the “immune surveillance” hypothesis, first suggested by Burnet and Thomas. In this paper, I account for recent findings on immune surveillance in order to determine the precise role of the immune system in the emergence and maintenance of individuality. This investigation gives rise to a critical question for the domain of biological individuality: should immunity be considered as something unique to multicellular organisms? If it is indeed unique, should the multicellular organism be considered as an individual to a higher degree than any other living entity? If it is not unique, what precisely are the equivalents of the immune system in other living individuals? (shrink)

A crucial question for a process view of life is how to identify a process and how to follow it through time. The genidentity view can contribute decisively to this project. It says that the identity through time of an entity X is given by a well-identified series of continuous states of affairs. Genidentity helps address the problem of diachronic identity in the living world. This chapter describes the centrality of the concept of genidentity for David Hull and proposes an (...) extension of Hull’s view to the ubiquitous phenomenon of symbiosis. Finally, using immunology as a key example, it shows that the genidentity view suggests that the main interest of a process approach is epistemological rather than ontological and that its principal claim is one of priority, namely that processes precede and define things, and not vice versa. (shrink)

In this paper, I address the question of what the Developmental Systems Theory (DST) aims at explaining. I distinguish two lines of thought in DST, one which deals specifically with development, and tries to explain the development of the individual organism, and the other which presents itself as a reconceptualization of evolution, and tries to explain the evolution of populations of developmental systems (organism-environment units). I emphasize that, despite the claiming of the contrary by DST proponents, there are two very (...) different definitions of the ‘developmental system’, and therefore DST is not a unified theory of evolution and development. I show that the DST loses the most interesting aspects of its reconceptualization of development when it tries to reconceptualize evolutionary theory. I suggest that DST is about development per se, and that it fails at offering a new view on evolution. (shrink)

In this article, I address the question of what Developmental Systems Theory aims at explaining. I distinguish two lines of thought in DST, one that deals specifically with development and tries to explain the development of the individual organism, and the other that presents itself as a reconceptualization of evolution and tries to explain the evolution of populations of developmental systems. I emphasize that, despite the claim of the contrary by DST proponents, there are two very different definitions of the (...) “developmental system,” and therefore DST is not a unified theory of evolution and development. I show that DST loses the most interesting aspects of its reconceptualization of development when it tries to reconceptualize evolutionary theory. I suggest that DST is about development per se, and that it fails at offering a new view on evolution. (shrink)

In this paper, I introduce the notion of ‘philosophy moves’: prominent tropes featured in contemporary academic philosophy. Moves are more than patterns – they are tools for advancing and enriching philosophical debates. By recognizing these patterns in the philosophical literature, we collect an ensemble of moves for deployment in novel contexts, each with the potential to forge new paths of philosophical investigation through a given topic. The moves featured in this paper are constructive and progressive, with the potential to push (...) past stalemates and open up a wider conceptual landscape. Following a presentation of five exemplars taken from the philosophy of biology literature, I show how different moves could be made within a current interdisciplinary debate. Overall, I aim to demonstrate that recognizing these patterns is insightful pedagogically and potentially useful when put to use as part of one’s philosophical methodology. (shrink)

This paper focuses on physiological integration in multicellular systems, a notion often associated with biological individuality, but which has not received enough attention and needs a thorough theoretical treatment. Broadly speaking, physiological integration consists in how different components come together into a cohesive unit in which they are dependent on one another for their existence and activity. This paper argues that physiological integration can be understood by considering how the components of a biological multicellular system are controlled and coordinated in (...) such a way that their activities can contribute to the maintenance of the system. The main implication of this perspective is that different ways of controlling their parts may give rise to multicellular organizations with different degrees of integration. After defining control, this paper analyses how control is realized in two examples of multicellular systems located at different ends of the spectrum of multicellularity: biofilms and animals. It focuses on differences in control ranges, and it argues that a high degree of integration implies control exerted at both medium and long ranges, and that insofar as biofilms lack long-range control (relative to their size) they can be considered as less integrated than other multicellular systems. It then discusses the implication of this account for the debate on physiological individuality and the idea that degrees of physiological integration imply degrees of individuality. (shrink)

Given the central place organisms occupy in Kant’s account of living nature, it might seem unlikely that his claims about biological wholes could be relevant to current debates over the problem of biological individuality. These debates acknowledge the multiple realizability of biological individuality in vastly different forms, including parts of organisms and complex groups of organisms at various levels of the biological hierarchy, sparking much controversy in attempts to characterize a biological individual. I argue that, far from being irrelevant to (...) this controversy, Kant’s account provides a key insight for addressing the multiple realizability problem. I show how the reciprocal causality between a self-organizing whole and its parts, which Kant thinks characterizes a natural end, is not limited to organisms but is exhibited by numerous types of beings in living nature. Self-organizing wholes of various kinds, and at various biological levels, may count as biological individuals, depending on the degree to which their functionally integrated parts are represented by reflective judgement as a natural end. (shrink)

En este trabajo ofrezco una interpretación de la concepción heideggeriana del organismo biológico presente en sus cursos de 1929. Para ello, primero enmarcaré la discusión dentro de la interpretación heideggeriana del naturalismo y su manera de entender la relación entre filosofía y ciencia. Luego, analizaré su interpretación de la embriología y la ecología mediante la cual Heidegger esboza aportes originales a la filosofía de la biología, especialmente en torno al problema de la identidad del organismo biológico. Finalmente, mostraré cómo esta (...) interpretación supone una profunda crítica a las concepciones sustancialistas del organismo a favor de una concepción relacional y procesual. (shrink)

Recent attention to complex group-level behavior amongst bacteria has led some to conceive of multicellular clusters of bacteria as individuals. In this article, I assess these recent claims by first drawing a distinction between two concepts of individuality: physiological and evolutionary. I then survey cases that are representative of three different modes of growth: myxobacteria (surface-attached agglomerative growth), Bacillus subtilis (agglomerative growth not attached to a surface), and cyanobacteria (filamentous growth). A closer look at these cases indicates that multicellular individuality (...) among bacteria is remarkably complex. Physiologically, the three cases of multicellular clusters do not form physiological individuals. But matters are different when it comes to evolutionary individuality; although multicellular clusters that grow by agglomeration are not highly individuated, filament-forming groups achieve a relatively high degree of individuality. I also suggest that debates about bacterial multicellular individuality may have been obscured by a failure to see that selection on highly individuated groups is by no means the only mechanism to bring about the complex group-level behaviors that have led some to view bacteria as multicellular individuals. (shrink)

In this paper I develop a concept of behavioural ecological individuality. Using findings from a case study which employed qualitative methods, I argue that individuality in behavioural ecology should be defined as phenotypic and ecological uniqueness, a concept that is operationalised in terms of individual differences such as animal personality and individual specialisation. This account make sense of how the term “individuality” is used in relation to intrapopulation variation in behavioural ecology. The concept of behavioural ecological individuality can sometimes be (...) used to identify individuals. It also shapes research agendas and methodological choices in behavioural ecology, leading researchers to account for individuals as sources of variation. Overall, this paper draws attention to a field that has been largely overlooked in philosophical discussions of biological individuality and highlights the importance of individual differences and uniqueness for individuality in behavioural ecology. (shrink)

Contemporary biological research has suggested that some host–microbiome multispecies systems (referred to as “holobionts”) can in certain circumstances evolve as unique biological individual, thus being a unit of selection in evolution. If this is so, then it is arguably the case that some biological adaptations have evolved at the level of the multispecies system, what we call hologenomic adaptations. However, no research has yet been devoted to investigating their nature, or how these adaptations can be distinguished from adaptations at the (...) species-level (genomic adaptations). In this paper, we cover this gap by investigating the nature of hologenomic adaptations. By drawing on the case of the evolution of sanguivory diet in vampire bats, we argue that a trait constitutes a hologenomic adaptation when its evolution can only be explained if the holobiont is considered the biological individual that manifests this adaptation, while the bacterial taxa that bear the trait are only opportunistic beneficiaries of it. We then use the philosophical notions of emergence and inter-identity to explain the nature of this form of individuality and argue why it is special of holobionts. Overall, our paper illustrates how the use of philosophical concepts can illuminate scientific discussions, in the trend of what has recently been called metaphysics of biology. (shrink)

An understanding of the factors behind the evolution of multicellularity is one of today’s frontiers in evolutionary biology. This is because multicellular organisms are made of one subset of cells with the capacity to transmit genes to the next generation and another subset responsible for maintaining the functionality of the organism, but incapable of transmitting genes to the next generation. The question arises: why do somatic cells sacrifice their lives for the sake of germline cells? How is germ/soma separation maintained? (...) One conventional answer refers to inclusive fitness theory, according to which somatic cells sacrifice themselves altruistically, because in so doing they enhance the transmission of their genes by virtue of their genetic relatedness to germline cells. In the present article we will argue that this explanation ignores the key role of policing mechanisms in maintaining the germ/soma divide. Based on the pervasiveness of the latter, we argue that the role of altruistic mechanisms in the evolution of multicellularity is limited and that our understanding of this evolution must be enriched through the consideration of coercion mechanisms. (shrink)

It is now widely accepted that microorganisms play many important roles in the lives of plants and animals. Every macroorganism has been shaped in some way by microorganisms. The recognition of the ubiquity and importance of microorganisms has led some to argue for a revolution in how we understand biological individuality and the primary units of natural selection. The term “holobiont” was introduced as a name for the biological unit made up by a host and all of its associated microorganisms, (...) and much of this new debate about biological individuality has focused on whether holobionts are integrated individuals or communities. In this paper, I show how parts of the holobiont can span both characterizations. I argue that most holobionts share more affinities with communities than they do with organisms, and that, except for maybe in rare cases, holobionts do not meet the criteria for being organisms, evolutionary individuals, or units of selection. (shrink)

Organisms receded from view in much of twentieth-century biology, only to undergo a sort of renaissance at the start of the twenty-first. The story of why this should be so is complicated and fascinating, but belongs primarily to the history of biology. On the other hand, to the extent that it is so, a question naturally arises: what, after all, are organisms? This question has a long and complicated history of its own, both within and without of biology; an investigation (...) of this history yields some guidance as to how organisms might yet be conceived today. One suggestion borne of these investigations is this: organisms are, for better or worse, normatively delineated unities. (shrink)

Some philosophers of biology state that the metaphysical status of biological species is context determined by the use different branches of biology make of their corresponding proper names, so that one and the same biological species can be both an individual and a natural kind. In this paper, I aim to undermine the idea, often associated with the present thesis, according to which the debate about the metaphysical status of biological species should be deflated, since it would be possible to (...) translate every sentence from natural-kind talk to individual-talk and vice versa. I offer a charitable interpretation of the principle grounding such an idea and show how it is in tension with independent theoretical biological notions. (shrink)

Both concepts of the holobiont and the immune system are at the heart of an ongoing scientific and philosophical examination concerning questions of the organism’s individuality and identity as well as the relations between organisms and their environment. Examining the holobiont, the question of boundaries and individuality is challenging because it is both an assemblage of organisms with physiological cohesive aspects. I discuss the concept of immunity and the immune system function from the holobiont perspective. Because of the host-microbial close (...) relations of codependence and interdependence, the holobiont is more often than not confused with the host, as the host is the domain in which this entity exists. I discuss the holobiont unique ecological characteristics of microbial assemblages connected to a host in a network of interactions in which the host is one of the organisms in the community but also its landscape. Therefore, I suggest viewing the holobiont as a host-ecosystem and discuss the implication of such a view on the concept of immunity and the meaning of protection. Furthermore, I show that viewing the holobiont as a host ecosystem opens the possibility of using the same ecological definition of boundaries and immunity dealing with an ecological system. Thus, the holobiont’s boundaries and immunity are defined by the persistence of its complex system of interactions integrating existing and new interactions. This way of thinking presents a notion of immunity that materializes as the result of the complex interdependence relations between the different organisms composing the holobiont similar to that of an ecosystem. Taking this view further, I discuss the notion of immunogenicity that is ontologically heterogeneous with various causal explanations of the processes of tolerance and targeted immune response. Finally, I discuss the possible conceptualization of already existing and new biomedical practices. (shrink)

Marquis’ future-like-ours argument against the morality of abortion assumes animalism—a family of theories according to which we are animals. Such an assumption is theoretically useful for various reasons, e.g., because it provides the theoretical underpinning for a reply to the contraception-abstinence objection. However, the connection between the future-like-ours argument and one popular version of animalism can prove lethal to the former, or so I argue in this paper.

The organism is one of the fundamental concepts of biology and has been at the center of many discussions about biological individuality, yet what exactly it is can be confusing. The definition that we find generally useful is that an organism is a unit in which all the subunits have evolved to be highly cooperative, with very little conflict. We focus on how often organisms evolve from two or more formerly independent organisms. Two canonical transitions of this type—replicators clustered in (...) cells and endosymbiotic organelles within host cells—demonstrate the reality of this kind of evolutionary transition and suggest conditions that can favor it. These conditions include co-transmission of the partners across generations and rules that strongly regulate and limit conflict, such as a fair meiosis. Recently, much attention has been given to associations of animals with microbes involved in their nutrition. These range from tight endosymbiotic associations like those between aphids and Buchnera bacteria, to the complex communities in animal intestines. Here, starting with a reflection about identity through time, we consider the distinctions between these kinds of animal–bacteria interactions and describe the criteria by which a few can be considered jointly organismal but most cannot. (shrink)

Viruses have been virtually absent from philosophy of biology. In this editorial introduction, we explain why we think viruses are philosophically important. We focus on six issues, and we show how they relate to classic questions of philosophy of biology and even general philosophy.

Biological individuality is a major topic of discussion in biology and philosophy of biology. Recently, several objections have been raised against traditional accounts of biological individuality, including the objections of monism, theory-centrism, ahistoricity, disciplinary isolationism, and the multiplication of conceptual uncertainties. In this introduction, I will examine the current philosophical landscape about biological individuality, and show how the contributions gathered in this special issue address these five objections. Overall, the aim of this issue is to offer a more diverse, unifying, (...) and scientifically informed conception of what a biological individual is. (shrink)

The definition of biological individuality is one of the most discussed topics in philosophy of biology, but current debate has focused almost exclusively on evolution-based accounts. Moreover, several participants in this debate consider the notions of a biological individual and an organism as equivalent. In this paper, I show that the debates would be considerably enriched and clarified if philosophers took into account two elements. First, physiological fields are crucial for the understanding of biological individuality. Second, the category of biological (...) individuals should be divided into two subcategories: physiological individuals and evolutionary individuals, which suggests that the notions of organism and biological individual should not be used interchangeably. I suggest that the combination of an evolutionary and a physiological perspective will enable biologists and philosophers to supply an account of biological individuality that will be both more comprehensive and more in accordance with scientific practices. (shrink)

Though viruses have generally been characterized by their pathogenic and more generally harmful effects, many examples of mutualistic viruses exist. Here I explain how the idea of mutualistic viruses has been defended in recent virology, and I explore four important conceptual and practical consequences of this idea. I ask to what extent this research modifies the way scientists might search for new viruses, our notion of how the host immune system interacts with microbes, the development of new therapeutic approaches, and, (...) finally, the role played by the criterion of autonomy in our understanding of living things. Overall, I suggest that the recognition of mutualistic viruses plays a major role in a wider ongoing revision of our conception of viruses. (shrink)

Since the 1950s, the common view of development has been internalist: development is seen as the result of the unfolding of potentialities already present in the egg cell. In this article, I show that this view is incorrect because of the crucial influence of the environment on development. I focus on a fascinating example, that of the role played by symbioses in development, especially bacterial symbioses, a phenomenon found in virtually all organisms (plants, invertebrates, and vertebrates). I claim that we (...) must consequently modify our conception of the boundaries of the developing entity, and I show how immunology can help us in accomplishing this task. I conclude that the developing entity encompasses many elements traditionally seen as “foreign,” while I reject the idea that there is no possible distinction between the organism and its environment. (shrink)

Criticisms of the “container” model of pregnancy picturing female and embryo as separate entities multiply in various philosophical and scientific contexts during the last decades. In this paper, we examine how this model underlies received views of pregnancy in evolutionary biology, in the characterization of the transition from oviparity to viviparity in mammals and in the selectionist explanations of pregnancy as an evolutionary strategy. In contrast, recent evo-devo studies on eutherian reproduction, including the role of inflammation and new maternal cell (...) types, gather evidence in favor of considering pregnancy as an evolved relational novelty. Our thesis is that from this perspective we can identify the emergence of a newhistoricalindividual in evolution. In evo-devo, historical units are conceptualized as evolved entities which fulfill two main criteria, their continuous persistence and their non-exchangeability. As pregnancy can be individuated in this way, we contend that pregnant females are historical individuals. We argue that historical individuality differs from, and coexists with, other views of biological individuality as applied to pregnancy (the physiological, the evolutionary and the ecological one), but brings forward an important new insight which might help dissolve misguided conceptions. (shrink)

According to the species-as-individuals thesis(hereafter S-A-I), species are cohesive entities. Barker and Wilson recently pointed out that the type of cohesion exhibited by species is fundamentally different from that of organisms (paradigmatic individuals), suggesting that species are homeostatic property cluster kinds. In this article, I propose a shift in how to approach cohesion in the context of S-A-I: instead of analyzing the different types of cohesion and questioning whether species have them, I focus on the role played by cohesion in (...) the identity of individuals. This shift allows us to recognize why cohesion matters to S-A-I, as well as to reconceive the analogy between species and organisms (paradigmatic individuals), and also allows us to highlight the context sensitivity of both ‘‘cohesion’’ and ‘‘individuals.’’ From this perspective, I identify two problems in Barker and Wilson’s argumentation. Firstly, the authors fail to recognize that species are individuals even if they do not have the same type of cohesion that organisms have. Secondly, their argument relies on a misinterpretation of S-A-I. I conclude that species cohesion is still best framed as a feature of species individuality rather than a feature of species as homeostatic property cluster kinds. The arguments presented here contribute to the re-articulation and reevaluation of S-A-I in the face of contemporary discussions. (shrink)

The Problem of Biological Individuality is the problem of how to count organisms. Whilst counting organisms may seem easy, the biological world is full of difficult cases such as colonial siphonophores and aspen tree groves. One of the main solutions to the Problem of Biological Individuality is the Physiological Approach. Drawing on an argument made by Eric Olson in the personal identity debate, I argue that the Physiological Approach faces a metaphysical problem - the ‘Foetus Problem’. This paper illustrates how (...) metaphysics can contribute to debates about organisms in the philosophy of biology. (shrink)

The Problem of Biological Individuality is the problem of how to count organisms. Whilst counting organisms may seem easy, the biological world is full of difficult cases such as colonial siphonophores and aspen tree groves. One of the main solutions to the Problem of Biological Individuality is the Physiological Approach. Drawing on an argument made by Eric Olson in the personal identity debate, I argue that the Physiological Approach faces a metaphysical problem - the ‘Foetus Problem’. This paper illustrates how (...) metaphysics can contribute to debates about organisms in the philosophy of biology. (shrink)

In this paper, I argue that attempts in the philosophy of biology to show that organisms are processes rather than substances fail. Despite what process ontologists have said, I argue that substance ontology is perfectly able to accommodate the dynamic nature of organisms, their ecological dependence, and their vague boundaries, and that their criticisms are not directed at substance ontology simpliciter, but only at specific (perhaps untenable) characterisations of substances. The paper ends by considering what a processual philosophy of biology (...) that is radically in conflict with an ontology of substances might look like. (shrink)

No comprehensive theory of development is available yet. Traditionally, we regard the development of animals as a sequence of changes through which an adult multicellular animal is produced, starting from a single cell which is usually a fertilized egg, through increasingly complex stages. However, many phenomena that would not qualify as developmental according to these criteria would nevertheless qualify as developmental in that they imply nontrivial (e.g., non degenerative) changes of form, and/or substantial changes in gene expression. A broad, comparative (...) approach is badly needed. In the Cnidaria, for example, even the boundary between generations is problematic. Describing their life cycle in terms of metagenesis (alternation between polyp generation and medusa generation) or in terms of metamorphosis (polyp as larva or juvenile) are matters of semantics more than biology. The life cycle of other metazoans, described in textbooks in terms of larva-to-adult metamorphosis, is hardly different from a typical metagenetic life cycle of cnidarians. This applies to holometabolous insects and to marine invertebrates like sea urchins, where most of the larval cells are discarded at metamorphosis. The uncertain temporal and spatial boundaries of individual development are also shown by the widespread lack of a strict correspondence between adult and mature. A comprehensive theory of development should start with a zero principle of “developmental inertia,” corresponding to an indeterminate local self-perpetuation of cell-level dynamics. Indeterminate growth, scale-invariance, segmentation, and regeneration provide examples of developmental dynamics close to that. (shrink)

Both physiological and evolutionary criteria of biological individuality are underpinned by the idea that an individual is a functionally integrated whole. However, a precise account of functional integration has not been provided so far, and current notions are not developed in the details, especially in the case of composite systems. To address this issue, this paper focuses on the organisational dimension of two representative associations of prokaryotes: biofilms and the endosymbiosis between prokaryotes. Some critical voices have been raised against the (...) thesis that biofilms are biological individuals. Nevertheless, it has not been investigated which structural and functional obstacles may prevent them from being fully integrated physiological or evolutionary units. By contrast, the endosymbiotic association of different species of prokaryotes has the potential for achieving a different type of physiological integration based on a common boundary and interlocked functions. This type of association had made it possible, under specific conditions, to evolve endosymbionts into fully integrated organelles. This paper therefore has three aims: first, to analyse the organisational conditions and the physiological mechanisms that enable integration in prokaryotic associations; second, to discuss the organisational differences between biofilms and prokaryotic endosymbiosis and the types of integration they achieve; finally, to provide a more precise account of functional integration based on these case studies. (shrink)

Recently, philosophers have sought to determine the nature of individuals relevant to evolution by natural selection or evolutionary individuals. The Evolutionary Contingency Thesis is a claim about evolution that emphasizes the role of contingency or dependency relations and chance-based factors in how evolution unfolds. In this article, I argue that if we take evolutionary contingency seriously, then we should be pluralists about the types of individuals in selection.

Medical classification systems aim to provide a manageable taxonomy for sorting diagnoses into their proper classes. The question, this paper wants to critically examine, is how to correctly systematise diseases within classification systems that are applied in a variety of different settings. ICD and DSM , the two major classification systems in medicine and psychiatry, will be the main subjects of this paper; however, the arguments are not restricted to these classification systems but point out general methodological and epistemological challenges (...) of classifying diseases for differing purposes. Deciding what qualifies as a disease to be included into a classification system as well as choosing a specific validator for correctly systematising diseases is complicated because the broad applicability of medical classification systems simultaneously appears as aim and challenge. Drawing upon the case study of classifying Alzheimer’s disease, this paper will address three dilemmas in designing ‘good’ medical classification systems. They are due to general epistemological problems of medicine, such as the relationship between individual manifestations of diseases and the necessity of building groups in order to scientifically elucidate causes of diseases. Moreover, they involve pragmatic issues of designing usable classifications that allow for easily discriminating between classes of diseases, restricting, however, the completeness of disease representations. This paper wants to trace how the choice of certain validators is unavoidably value-laden and deeply intertwined with epistemological assumptions of how different uses relate to each other, resulting either in a prioritisation of (constrained) coherence or of (vague) pluralistic connectibility. (shrink)

Is the mammalian embryo/fetus a part of the organism that gestates it? According to the containment view, the fetus is not a part of, but merely contained within or surrounded by, the gestating organism. According to the parthood view, the fetus is a part of the gestating organism. This paper proceeds in two stages. First, I argue that the containment view is the received view; that it is generally assumed without good reason; and that it needs substantial support if it (...) is to be taken seriously. Second, I argue that the parthood view derives considerable support from a range of biological and physiological considerations. I tentatively conclude in favour of the parthood view, and end by identifying some of the interesting questions it raises. (shrink)

Mammals are usually considered unproblematic as biological individuals. This article contends the opposite. Once we consider pregnancy, criteria for biological individuality are not easily applicab...

Biological individuals are usually defined by evolutionists through a reference to natural selection. This article looks for a concept of individuality that would hold at the same time for organisms and for communities or ecosystems, the latter being unaffected by natural selection. In the wake of Simon’s notion of “quasi-independence,” I elaborate a concept of “weak individuality” defined by probabilistic connections between sub-entities, read off our knowledge of their interactions. This formal scheme of connections allows one to infer what are (...) the individuals in the domain addressed by the theory of the interactions. The article argues that if ecosystems do not have strong individuality, they still possess a weak individuality, ecological theories providing the values of the variables in the formula for individuality. (shrink)

Many aspects of biology, such as population genetics and senescence, are predicated on identifying individuals and generations. Conventional demarcations of individuals and generations, such as physiological autonomy, unicellular bottlenecks, and alternation of generation, are rife with problems. Do physically separated cuttings or plant ramets constitute separate individuals or generations? Are chimaeras one or more individuals? To resolve these problems, Clarke : 321–361, 2012) proposed that individuals are circumscribed by mechanisms that constrain heritable variance in fitness. Simultaneously, Gorelick and Heng : (...) 1088–1098 2011) showed that sex constrains heritable variance Therefore, for eukaryotes, meiosis and karyogamy provide a consistent way to demarcate individuals and generations. Epigenetic reset associated with meiosis and karyogamy rejuvenates the next generation, but not the parent that engaged in the sex act. Wholesale epigenetic resets that probably only occur with meiosis and karyogamy imply that monozygotic twins are two different individuals, but apomictic progeny are diffuse parts of one disaggregated individual. Mitotic heritability circumscribes an individual, whereas meiotic heritability demarcates new individuals and generations. (shrink)

Given immunity’s general role in the organism’s economy—both in terms of its internal environment as well as mediating its external relations—immune theory has expanded its traditional formulation of preserving individual autonomy to one that includes accounting for nutritional processes and symbiotic relationships that require immune tolerance. When such a full ecological alignment is adopted, the immune system becomes the mediator of both defensive and assimilative environmental intercourse, where a balance of immune rejection and tolerance governs the complex interactions of the (...) organism’s ecological relationships. Accordingly, immunology, which historically had affiliated with the biology of individuals, now becomes a science concerned with the biology of communities. With this translocation, the ontological basis of the organism is undergoing a profound change. Indeed, the recent recognition of the ubiquity of symbiosis has challenged the traditional notions of biological individuality and requires a shift in the metaphysics undergirding biology, in which a philosophy of the organism must be characterized by ecological dialectics “all-the-way-down.”. (shrink)

Elselijn Kingma argues that, in cases of mammalian placental pregnancy, the foster (roughly, the post-implantation embryo/foetus) is part of the gravida (the pregnant organism). But she does not consider the possibility of proper overlap. I show that this generates a number of serious problems for her argument and trace the oversight to a quite general issue within the literature on biological individuality. Doing so provides an opportunity to pull apart and clarify the relations between some importantly distinct questions concerning organismality (...) and organismic parthood, and to identify the implications that this has for those who want to draw on this literature when making metaphysical or mereological arguments. (shrink)

This paper addresses the question of what organisms are and therefore what kinds of biological entities qualify as organisms. For some time now, the concept of organismality has been eclipsed by the notion of individuality. Biological individuals are those systems that are units of selection. I develop a conception of organismality that does not rely on evolutionary considerations, but instead draws on development and ecology. On this account, organismality and individuality can come apart. Organisms, in my view, are as Godfrey-Smith (...) puts it “essentially persisters.” I argue that persistence is underpinned by differentiation, integration, development, and the constitutive embeddedness of organisms in their worlds. I examine two marginal cases, the Portuguese Man O’ War and the honey bee colony, and show that both count as organisms in light of my analysis. Next, I examine the case of holobionts, hosts plus their microsymbionts, and argue that they can be counted as organisms even though they may not be biological individuals. Finally, I consider the question of whether other, less tightly integrated biological systems might also be treated as organisms. (shrink)

One of Leibniz’s most original ideas is his conception of the living individual as a hierarchical network of living beings whose relationships are essential to the proper functioning of its organic body. This idea is also valid to explain any existing order in nature that depends on the set of relationships of living beings that inhabit it. Both ideas are present in the conception of the natural world that Leibniz presents in his Monadology through his idea of biological infinitism. According (...) to this idea, nature consists of infinite theatres where living beings unfold their vital functions. Through this idea Leibniz defines both the biological complexity of nature and the living individual, which is in turn a portion of nature that unfolds from an infinite set of inferior living beings. The thesis that I defend in this work is that this Leibnizian understanding of the living individual and the natural complexity that includes infinite hierarchical levels of individuality has a marked ecological sense, as we would say today. This Leibnizian metaphysics of individuality that we could call biological is also interesting in light of the recent studies in the philosophy of biology. (shrink)

Individuality is an important concept in biology, yet there are many non-equivalent criteria of individuality expressed in different kinds of biological individuals. This article evaluates these different kinds in terms of their capacity to support explanatory generalizations over the systems they individuate. Viewing the problem of individuality from this perspective promotes a splitting strategy in which different kinds make different epistemic trade-offs that suit them for different explanatory roles. I argue that evolutionary individuals, interpreted as forming a functional kind, face (...) difficulties of individuation and explanatory power that are mitigated by relying on more structurally based properties and non-evolutionary kinds. 1Introduction2Kinds of Biological Individuals3Evolutionary Individuals and Functional Kinds4Evolutionary versus Non-evolutionary Kinds of Individuals 4.1Physiological individuality4.2Ecological individuality4.3Developmental individuality5Conclusion. (shrink)

Darwin’s classic ‘Origin of Species’ (Darwin 1859) described forces of selection acting upon individuals, but there remains a great deal of controversy about what exactly the status and definition of a biological individual is. Recently some authors have argued that the individual is dispensable – that an inability to pin it down is not problematic because little rests on it anyway. The aim of this paper is to show that there is a real problem of biological individuality, and an urgent (...) need to arbitrate over the current plethora of solutions to it. (shrink)

The problem of plant individuality is something which has vexed botanists throughout the ages, with fashion swinging back and forth from treating plants as communities of individuals (Darwin 1800 ; Braun and Stone 1853 ; Münch 1938 ) to treating them as organisms in their own right, and although the latter view has dominated mainstream thought most recently (Harper 1977 ; Cook 1985 ; Ariew and Lewontin 2004 ), a lively debate conducted mostly in Scandinavian journals proves that the issues (...) are far from being resolved (Tuomi and Vuorisalo 1989b ; Fagerström 1992 ; Pan and Price 2001 ). In this paper I settle the matter once and for all, by showing which elements of each side are correct. (shrink)

What changes when an evolutionary transition in individuality takes place? Many different answers have been given, in respect of different cases of actual transition, but some have suggested a general answer: that a major transition is a change in the extent to which selection acts at one hierarchical level rather than another. The current paper evaluates some different ways to develop this general answer as a way to characterise the property ‘evolutionary individuality’; and offers a justification of the option taken (...) in Clarke :413–435, 2013)—to define evolutionary individuality in terms of an object’s capacity to undergo selection at its own level. In addition, I suggest a method by which the property can be measured and argue that a problem which is often considered to be fatal to that method—the problem of ‘cross-level by-products’—can be avoided. (shrink)

There is currently a great debate about whether the holobiont, i.e. a multicellular host and its residential microorganisms, constitutes a biological individual. We propose that resident microorganisms have a general and important role in the individuality of the host organism, not the holobiont. Drawing upon the Equilibrium Model of Immunity, we argue that microorganisms are scaffolds of immune capacities and processes that determine the constituency and persistence of the host organism. A scaffolding perspective accommodates the contingency and heterogeneity of resident (...) microorganisms while accounting for their necessity and unifying contributions to host individuality. In our symbiotic view of life, holobionts may not be organisms or units of selection, but macroorganisms cannot persist nor function as individuals without their scaffolding microorganisms. (shrink)

In dicephalus conjoined twinning, it appears that two heads share a body; in cephalopagus, it appears that two bodies share a head. How many human animals are present in these cases? One answer is that there are two in both cases—conjoined twins are precisely that, conjoined twins. Another is that the number of humans corresponds to the number of bodies—so there is one in dicephalus and two in cephalopagus. I show that both of these answers are incorrect. Prominent accounts of (...) biological individuation, which treat the organism as an integrated whole, reveal that in these and other cases of conjoined twinning the ‘twins’ share a single human animal. This has a number of consequences for the debate about what we are. First, if animalism is true, individuals of our kind can be—and are—profoundly psychologically divided. Second, cephalopagus twinning does not divide animalism from its rivals, as has been claimed. Finally, animalists can reply to a vicious species of the ‘too many thinkers’ problem to which they are allegedly uniquely vulnerable. (shrink)

A recent development in biology has been the growing acceptance that holobionts, entities comprised of symbiotic microbes and their host organisms, are widespread in nature. There is agreement that holobionts are evolved outcomes, but disagreement on how to characterize the operation of natural selection on them. The aim of this paper is to articulate the contours of the disagreement. I explain how two distinct foundational accounts of the process of natural selection give rise to competing views about evolutionary individuality.

Convincing disputes about explanatory reductionism in the philosophy of biology require a clear and precise understanding of what a reductive explanation in biology is. The central aim of this book is to provide such an account by revealing the features that determine the reductive character of a biological explanation. Chapters I-IV provide the ground, on which I can then, in Chapter V, develop my own account of explanatory reduction in biology: Chapter I reveals the meta-philosophical assumptions that underlie my analysis (...) of reduction, Chapter II introduces the previous debate about reduction in the philosophy of biology by pointing out the most crucial lessons one should learn from this debate, Chapter III critically discusses the two perspectives on explanatory reduction that have been proposed in the philosophy of biology so far, and Chapter IV clarifies in what ways the issue of reduction is entangled with the issue of explanation. In Chapter V I present my own account of explanatory reduction. My main claim is that reductive explanations in the biological sciences possess three main characteristics: they explain the behavior of a biological system S, first, exclusively in terms of factors that are located on a lower level of organization than S, second, by focusing on factors that are internal to S , and third, by describing the genuine parts of S only as “parts in isolation”. This account is ontic because it traces the reductivity of an explanation back to certain relations that exist in the world. (shrink)