Levels and Units of Selection

Endurance or Density (Huynh 2026) names its own single highest-value next step: the three-case ERI design selects entirely on the dependent variable, and no claim that the six structural attributes discriminate survival from mere age can be sustained without institutions that faced comparable disruption and did not survive it. This paper supplies twenty such cases — Chinese capitals and major cities physically destroyed between 278 BCE and 1937 CE — coded against the same variables the base index uses, and argues (...) four claims. First, the catalog requires a distinction the corpus's existing vocabulary can support but has not yet made explicit: interactor death, in which a regime or ruling house is removed but the underlying population, infrastructure, and administrative substrate survive, versus replicator death, in which the transmissible template itself is extinguished at that site. Most of this catalog's twenty cases are interactor deaths. Only a handful test replicator death, and they are the cases that matter. Second, the paper's central comparison — Ye Cheng (destroyed 580 CE, never rebuilt) against Jiankang (destroyed 589 CE, rebuilt repeatedly across the next thirteen centuries) — starts from a premise this paper's own sourcing overturns: both cities were, in the immediate act, comparably razed by forces under the same conqueror's authority, nine years apart. The real divergence is not in the destruction. It is in what happened afterward, and it isolates a variable Jiangnan Genotype's replicator/interactor framework needs but does not yet have: whether the template outlives the site's physical destruction. Third, Daliang/Kaifeng — flooded by the same tactic on the same ground twice, 225 BCE and 1642 CE, 1,867 years apart — supplies a second, geographically independent instance of dormancy-and-environmental-reactivation outside the Jiangnan cluster, which is the specific evidence Endurance or Density's F-ERI4 confound (that the six attributes might describe one recurring region rather than portable institutional design) requires and did not yet have. Fourth, the Disaster of Yongjia (311 CE) — already present in this corpus as background to Eastern Jin's move south, but never itself examined as a destruction event — is shown to be the literal recolonization trigger the Jiangnan Genotype's metapopulation argument invokes: the same catastrophe that ends Western Jin at Luoyang is the proximate cause of the elite migration that activates Jiankang as an interactor six years later. Destruction and regeneration are not two separate phenomena this corpus has been studying in different papers. In at least one well-documented case, they are the same event observed from two ends. A fifth, more exploratory section computes local disruption-density spikes — the Qin unification's final decade, the Yongjia collapse, the Ming-Qing transition — and finds that unlike any single institution's long-run average, these civilizational-scale clustering windows approach, and in one case briefly exceed, the corpus's own λ_bz ≈ 50/century benchmark, which reframes what the density gap in Endurance or Density's Section X.C is actually a gap between. (shrink)

Geoffrey Hodgson and Thorbjørn Knudsen’s Generalized Darwinism (Darwin’s Conjecture, 2010) argues that variation, inheritance, and selection are domain-independent necessary and sufficient conditions for evolutionary explanation — applicable literally, not by analogy, wherever a population of entities varies, some mechanism transmits traits between generations with reasonable fidelity, and that variation causes differential persistence. This paper applies that claim to the Longevity Asymmetry Corpus’s Entropy-Resistant Institution Index (Huynh 2026, “Endurance or Density”), using David Hull’s (1988) replicator/interactor distinction — the unit that passes (...) on structure with reasonable fidelity (replicator) versus the unit that interacts with the environment as a cohesive whole and whose fate makes replication differential (interactor) — to reanalyze the Jiangnan Regeneration Problem that paper’s Section VIII identifies. The paper argues four claims. First, Jiangnan is a literal replicator-interactor system, not a metaphor: a template of river-line defense doctrine, rice-paddy fiscal administration, and elite-absorption protocol persisted dormant for the entire 318-year span of unified Tang rule (589–907, during which no southern refuge regime existed at all) and re-expressed in three separate, non-continuous interactors — Eastern Jin–Southern Dynasties, Southern Tang, Southern Song — each time northern collapse recreated the triggering environmental condition. Second, this distinguishes homology from convergence with a precision the ERI paper’s own N = 3 circularity problem needed and did not yet have: Jiankang, Southern Tang, and Southern Song share common descent from one replicator, so their attribute agreement is not independent evidence. Japan’s Imperial House and the Holy See share no common ancestry with each other or with Jiangnan, yet independently evolved similar attribute profiles — decoupled legitimating authority, non-biological succession, universalist claims transcending territory — textbook convergent evolution, which in evolutionary biology is stronger evidence for adaptive significance than homology, precisely because independent origin rules out shared history as the explanation. Third, Formula A and Formula B from the ERI index are not two arbitrary weightings of one construct. They measure K-selected and r-selected fitness respectively (MacArthur and Wilson 1967) — two genuinely distinct, sometimes competing strategies in real ecological theory, not unique to institutions. Japan and the Holy See are K-strategists: one long-lived, heavily invested interactor, optimized for individual endurance. Jiangnan is an r-strategist at the regional level: rapid interactor turnover via extinction and recolonization (Levins 1969), persisting at the population level — the refuge function itself — even as every individual interactor eventually goes extinct. This explains, rather than merely redescribes, why the ERI paper’s ranking flip occurs: K-fitness and r-fitness are different quantities in nature, not an artifact of index construction. Fourth, applying Levins’s metapopulation persistence condition — persistence requires recolonization rate to exceed local extinction rate — to the density gap the ERI paper’s Section X.C already establishes (λ_bz ≈ 50 disruption-class events per century, against a historical -/- maximum δ of 1.36) shows that neither historically realized strategy is obviously sufficient for F2-era disruption density. Jiangnan’s own recolonization rate — three episodes across 1,059 years, ≈ 0.28 per century — is itself roughly 180 times below what would be required to match a local-extinction rate at BZM scale. This paper does not propose that a solution exists. It states precisely what order of magnitude of engineered, historically unprecedented recolonization capacity F2-era governance design would require if an r-selected strategy is the correct one to pursue. (shrink)

The Extended Evolutionary Synthesis (EES) has been presented as an expansion of the Modern Synthesis (MS). A common and parsimonious view maintains that MS's quantitative evolutionary biology remains both valid and central within the EES, insofar as the EES primarily introduces a more elaborate qualitative research agenda. This article examines the relationship between qualitative and quantitative approaches in the EES debate and argues for a more complex view of how the EES relates to the MS. Its guiding question is whether (...) quantitative evolutionary biology itself might call for an EES. Although no specific answer is supported, the article analyzes the significance of this question and surveys the principal positions in the current literature. Two aims structure the discussion. First, by providing a detailed literature review, I show that, over the past two decades, quantitative research programs have increasingly contributed to modeling the phenomena at the core of the EES. The rationale for the EES is not confined to qualitative considerations; a growing body of work now (re)interprets population-level dynamics through the EES lens. Second, I present the problem of models: Is the mathematical framework of the MS sufficient to account for the phenomena emphasized by the EES, or must these models be extended? I identify and discuss four main positions: (1) strong accretionism-standard quantitative 1 evolutionary biology is enough; (2) mild accretionism-the continuous historical expansion implies that current extensions do not constitute a substantive theoretical shift; (3) mild radicalism-population models require EES assumptions and novel applications; and (4) strong radicalism-some biological phenomena demand genuine modifications to the existing modeling framework. -/- . (shrink)

The original Gaia hypothesis purports to explain the long-term maintenance of the Earth’s habitability by proposing that the biosphere has evolved homeostatic control of environmental parameters crucial to its survival. This idea was criticized for being incompatible with core Darwinian requirements for evolution by natural selection, since the biosphere is not part of a population of entities with variation, reproduction and heredity. Recently, however, some authors have defended a ‘Darwinized’ version of the Gaia hypothesis. Proponents of Darwinized Gaia argue that (...) there can be natural selection for persistence alone, with no need for reproduction or competition, and that a single lineage can undergo a process of sequential selection over time. This article examines these ideas in the light of two important distinctions in evolutionary biology: adaptation versus by-product, and transformational versus variational explanation. Despite these new interesting ideas, however, the Darwinized Gaia hypothesis still cannot overcome the main objections from evolutionary biology. (shrink)

The levels of selection debate is generally taken to be a debate about how natural selection can occur at the various levels of biological organization. In this paper, we argue that questions about levels of selection should be analyzed separately from questions about levels of organization. In the deflationary proposal we defend, all that is necessary for multilevel selection is that there are cases in which particles are nested in collectives, and that both the collectives and the particles that compose (...) them each separately undergo natural selection. We argue that adopting this deflationary account helps to disentangle the levels of selection and the levels of organization, and thereby contributes to advancing the levels of selection debate. (shrink)

It is usually assumed that, when applied to cases with regularly reshuffled, non-overlapping groups whose characters are defined as the average character of their individual members (such as David Sloan Wilson’s well-known trait-group model for the evolution of altruism), Price’s hierarchical equation tracks changes in the average value of individual-level traits and uses a notion of group fitness defined in terms of the number of individuals that groups produce. I argue that this is not necessarily so, and that Price’s equation (...) can be used for estimating the magnitude of the influence of certain factors on the change in the average value of group-level traits and that the notion of group fitness used therein can be defined in terms of groups making more groups. (shrink)

This paper reconsiders the Darwinian assumption regarding the fundamental driver of biological evolution and proposes a new framework through the lens of Judgemental Philosophy (JP). Contrary to traditional evolutionary theory, which posits the primary drive of living organisms as the replication of genetic information, we argue that the deeper human imperative is the transmission of 'Meaning' beyond the preservation of genes. The act of reproduction is reinterpreted not merely as a biological instinct but as a profound judgemental act, contingent upon (...) the structural integrity of the Judgemental Triad (Constructivity, Coherence, and Resonance). This judgement affirms the world as a meaningful place worthy of being passed down to future generations. From this perspective, the rapid decline in birthrates observed across technologically advanced societies is understood not just as a reflection of economic or social instability, but as a signal of 'existential restraint'—a collective refusal to bring new life into a world where the conditions for such meaningful judgement have structurally collapsed. By analyzing historical cases from societies like Japan, South Korea, and post-unification East Germany, the paper demonstrates a strong coherence between meaning collapse and declining birthrates. This inquiry expands the concept of evolution from a genetic dimension to a structural dimension of judgement and meaning, raising new questions about the fundamental purpose and future of humanity. (shrink)

(This is the preprint version) This book is about disease, but disease from a very specific perspective, namely that of evolutionary medicine. However, in doing so, it explains evolutionary medicine in its current form now, criticizes it, and tries to apply it not directly on disease instances or tokens of disease, but rather the concept of disease. Doing so, the aim of this book is to ask the question; how to build a better concept of disease? The parts of the (...) answer to this question are answered in different chapters piece by piece, trying to give an account of a better concept first and giving an account of how to see the concept of disease grounded differently. This book is not about giving every possible account of disease, or even the major ones including the established or traditional concept. This book is not about providing a singular perspective on diseases in general, however it assumes a general orthodoxy of medicalized disease understanding. In this book, I will defend the thesis that, when the concept of disease is seen from perspectives provided by evolutionary biology, the ontology of disease and the surrounding perspectives shall change, leading our understandings in medicine related to concept of disease and social, action guiding concepts to shift towards a more individualized and care based understanding of medicine to overcome the epistemic injustices that are done by the orthodox understanding of disease that prevails in medicine. (shrink)

Theoretical frameworks concerning cell fate typically center on proximate causes to explain how cells know what type they are meant to become. While major advances in cell fate theory have been achieved by these mechanism-focused frameworks, there are some aspects of cell decision-making that require an evolutionary interpretation. While mechanistic biologists sometimes turn to evolutionary theory to gain insights about cell fate (cancer is a good example), it is not entirely clear in cell fate theory what insights evolutionary theory can (...) add, and why in some cases it is required for understanding cell fate. In this perspective we draw on our work on cellular mortality to illustrate how evolutionary theory provides an explanation for death being selected as one of the potential cell fates. Using our hypothesis for why some microbes in a community choose death as their fate, we suggest that some insights in cell fate theory are inaccessible to a theoretical framework that focuses solely on proximate causes. (shrink)

Review of Javier Suárez and Elisabeth A. Lloyd, _Units of Selection_. Cambridge: Cambridge University Press, 2023, 75 pp, £49.99 HB.

Cancer is often seen as a case of multilevel selection, in which selfish cancer cells pursue short-term proliferation to the detriment of the collective. Thus cancer cells are described as ‘cheats’, and an analogy is often drawn between the mechanisms by which organisms fight cancer and the mechanisms by which social groups enforce cooperation. Recently, Andy Gardner and Max Shpak and Jie Lu have argued that cancer is not a true case of multilevel selection, that cancer cells should be not (...) regarded as cheats, and that the analogy between anti-cancer adaptations and suppression mechanisms in social groups is misleading. Their arguments are powerful. However, by drawing on the (presumed) link between cancer and the evolution of multicellularity, the notion that cancer represents a form of selective conflict between cells and organisms can be salvaged. (shrink)

'Unit of selection' is a polysemic expression, meaning interactor, replicator/reproducer or manifestor of adaptation/type-1 agent in today's biological research. This Element presents each of these concepts and demonstrates the necessity of their isolation.

The evolution of complex life forms, such as multicellular organisms, is the result of a number of evolutionary transitions in individuality (ETIs). Several attempts have been made to explain their origins, many of which have been internalist (i.e., based largely on internal properties of these life form's ancestors). Here, we show how an externalist perspective, via the ecological scaffolding model in which properties of complex life forms arise from an external scaffold, can shed new light on the question of ETIs. (...) Ultimately, we anticipate progress in the field will occur by recognizing the importance of both the internalist and externalist modes of explanation for ETIs. We illustrate this by considering an extension of the ecological scaffolding model by niche construction in which particles modify the environment which later becomes the scaffold giving rise to collective-level individuality. (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)

Selection operates at many levels. Some of the most obvious cases are organismic, such as changes in coloration under the influence of predation (cf. Kettlewell 1973; also Endler 1986). It also operates at other levels. Meiotic drive involves selection for a gene, independently of its effect on the organism. At a higher level, there may also be selection for patterns of colony growth in social insects, again under the influence of predation (cf. Wilson 1971). The appropriate level of selection is (...) a matter of the causal patterns exhibited, or the target of selection. It can also be understood as a question of the appropriate level at which to seek explanatory laws.Robert Brandon (1982, 1990) first clearly distinguished the question of the level of selection from debates over the units of selection. In doing so, he argued that the phenotype is commonly the target of selection, whatever the unit of selection might be. (shrink)

The units of selection problem is an issue within evolutionary theory (or the philosophy thereof) and concerns the question of what units or objects are acted upon by natural selection -- for example, whether these are genes, organisms or groups of organisms. One of the central theses of Elliot Sober’s recent book,The Nature of Selection, is that the philosophical problem of what it means for something to be a unit of selection is to be understood by applying the correct account (...) of what it isin generalfor a factor to be a cause in a population.The account of population-causation that Sober utilizes for this purpose comes from the recent literature on probabilistic causality. This account requires that for C to cause E in a population, aunanimitycondition must be satisfied: C must raise the probability of E in each causal context. (shrink)

The different sciences furnish us with a wide variety of explanations: some work at macroscopic scales, some work at microscopic scales, and some operate across different levels. How do these different explanatory levels relate to one another, and what is an explanatory level in the first place? Over the last 50 years, more and more philosophers—both reductionists and anti-reductionists—no longer subscribe to the idea that the best explanation resides at the fundamental physical level. New challenges arise from the success of (...) scientific explanations employing multi-level models which mix levels of explanation, from distinctive differences between levels structures in biology, cognitive science, and social science, from the apparently radical reimagining of the explanatory role of spacetime in our current best theories of fundamental physics, and from the enduring mystery of how higher-level explanations are possible in the first place. These questions naturally connect to classic philosophical ways of thinking about the relationships between levels: reduction, emergence, and fundamentality. This volume presents a snapshot of cutting-edge research on explanatory levels, from their conceptual foundations to the details of how they are used in scientific practice. (shrink)

Natural selection is an important force that shapes the evolution of all living things by determining which individuals contribute the most descendents to future generations. The biological unit upon which selection acts has been the subject of serious debate, with reasonable arguments made on behalf of populations, individuals, individual phenotypic characters and, finally, individual genes themselves. In this essay, I argue that the usual unit of selection is the gene. There are powerful logical arguments in favor of this conclusion, as (...) well as many real-world examples. I also explore the possibility that epigenetic differences between individuals may be heritable between generations. Although few such examples exist, epigenetic differences provide an exciting source of potentially heritable variation that may allow rapid evolutionary change to occur, perhaps in response to environmental influences. (shrink)

Life on Earth descends from a common ancestor. However, it is likely that there are other instances of life in the universe. If so, each abiogenesis event will have given rise to an independently originated life clade, of which Earth-life is an example. In this paper, I argue that the set of all IOLCs in the universe forms a Darwinian population subject to natural selection, with more widely dispersed IOLCs being less likely to face extinction. As a result, we should (...) expect that, over time, more planets will become inhabited by fewer, more successful IOLCs. (shrink)

The task of Philosophy in Science (PinS) is to use philosophical tools to help solve scientific problems. This article describes how I stumbled into this line of work and then addressed several topics in philosophy of biology—units of selection, cladistic parsimony, robustness and trade-offs in model building, adaptationism, and evidence for common ancestry—often in collaboration with scientists. I conclude by offering advice for would-be PinS practitioners.

I consider two attempts to combine realism with pluralism about the units of selection: Sober and Wilson’s combination of “model” and “unit” pluralism, and Sterelny and Griffiths’ “local pluralism”. I argue that both of these attempts fail to show that realism and pluralism are compatible. Sober and Wilson’s pluralism turns out, on closer inspection, to be a kind of monism in disguise, while Sterelny and Griffiths’ local pluralism involves a combination of realism and anti-realism about interactors, and the units of (...) selection, that is fundamentally unstable. My conclusion is that one must choose whether to be a realist or a pluralist in this area: one cannot be both. The question of which we should choose is a further question that I do not take a stand on. (shrink)

The units or levels of selection debate concerns the question of what kind of biological systems are stable enough that part of their evolution is a result of the process of natural selection acting at their level. Traditionally, the debate has concerned at least two different, though related, questions: the question of the level at which interaction with the environment occurs, and the question of the level at which reproduction occurs. In recent years, biologists and philosophers have discussed a new (...) aspect of this debate, namely the possibility that certain multi-species consortia formed by a host and its microbiome may act as a unit of selection. This thesis, however, has not been without criticism, as it is doubtful that such consortia could meet the conditions required to achieve the degree of stability that would allow them to experience natural selection. The purpose of this paper is to systematically examine such criticisms and to defend the thesis that the holobiont/hologenome can act as a genuine level of selection both in the form of an interactor and in the form of a reproducer. To do so, it will be argued that the microbiome should be characterized in functional rather than taxonomic terms. (shrink)

In this short paper, I argue against what I call the “belonging to” interpretation of group selection in scenarios in which a group’s fitness is defined as the per capita reproductive output of the individuals of the group. According to this interpretation, group selection acts on “belonging to” properties of individuals, i.e. on relational or contextual properties that all the individuals of a group share simply by belonging to that group; thus, if differences in the individuals’ “belonging to” properties cause (...) differences in their fitness, group selection sensu the “belonging to” interpretation is said to be at work. I argue that the main problem with the “belonging to” interpretation is that it confuses evolutionary changes due to differences in environmental quality with evolutionary changes due to selection. In other words, I argue that, in the majority of cases, this interpretation actually takes the “selection” out of the “group selection” notion it aims to interpret: by adopting this perspective, one implicitly commits to explaining the evolutionary change under consideration not by a kind of selection, but by differences in the environmental quality experienced by individual types. (shrink)

Given one conception of biological individuality (evolutionary, physiological, etc.), can a holobiont – that is the host + its symbiotic (mutualistic, commensalist and parasitic) microbiome – be simultaneously a biological individual and an ecological community? Herein, we support this possibility by arguing that the notion of biological individuality is part‐dependent. In our account, the individuality of a biological ensemble should not only be determined by the conception of biological individuality in use, but also by the biological characteristics of the part (...) of the ensemble under investigation. In the specific case of holobionts, evaluations of their individuality should be made either host‐relative or microbe‐relative. We support the claim that biological individuality is part‐dependent by drawing upon recent empirical evidence regarding the physiology of hosts and microbes, and the recent characterization of the ‘demibiont’. Our account shows that contemporary disagreements about the individuality of the holobiont derive from an incorrect understanding of the ontology of biological individuality. We show that collaboration between philosophers and biologists can be very fruitful in attempts to solve some contemporary biological debates. (shrink)

Bourrat and Griffiths :33, 2018) have recently argued that most of the evidence presented by holobiont defenders to support the thesis that holobionts are evolutionary individuals is not to the point and is not even adequate to discriminate multispecies evolutionary individuals from other multispecies assemblages that would not be considered evolutionary individuals by most holobiont defenders. They further argue that an adequate criterion to distinguish the two categories is fitness alignment, presenting the notion of fitness boundedness as a criterion that (...) allows divorcing true multispecies evolutionary individuals from other multispecies assemblages and provides an adequate criterion to single out genuine evolutionary multispecies assemblages. A consequence of their criterion is that holobionts, as conventionally defined by hologenome defenders, are not evolutionary individuals except in very rare cases, and for very specific host-symbiont associations. This paper is a critical response to Bourrat and Griffiths’ arguments and a defence of the arguments presented by holobiont defenders. Drawing upon the case of the hologenomic basis of the evolution of sanguivory in vampire bats, I argue that Bourrat and Griffiths overlook some aspects of the biological nature of the microbiome that justifies the thesis that holobionts are evolutionarily different to other multispecies assemblages. I argue that the hologenome theory of evolution should not define the hologenome as a collection of genomes, but as the sum of the host genome plus some traits of the microbiome which together constitute an evolutionary individual, a conception I refer to as the stability of traits conception of the hologenome. Based on that conception I argue that the evidence presented by holobiont defenders is to the point, and supports the thesis that holobionts are evolutionary individuals. In this sense, the paper offers an account of the holobiont that aims to foster a dialogue between hologenome advocates and hologenome critics. (shrink)

This volume of twelve specially commissioned essays about species draws on the perspectives of prominent researchers from anthropology , botany, developmental psychology , the philosophy of biology and science, protozoology, and zoology . The concept of species has played a focal role in both evolutionary biology and the philosophy of biology , and the last decade has seen something of a publication boom on the topic (e.g., Otte and Endler 1989; Ereshefsky 1992b; Paterson 1994; lambert and Spence 1995; Claridge, Dawah, (...) and Wilson 1997; Wheeler and Meier 1999; Howard and Berlocher 1998). (shrink)

The hologenome concept of evolution is a hypothesis about the evolution of animals and plants. It asserts that the evolution of animals and plants was partially triggered by their interactions with their symbiotic microbiomes. In that vein, the hologenome concept posits that the holobiont (animal host + symbionts of the microbiome) is a unit of selection. -/- The hologenome concept has been severely criticized on the basis that selection on holobionts would only be possible if there were a tight transgenerational (...) host-genotype-to-symbiont-genotype connection. As our current evidence suggests that this is not the case for most of the symbiont species that compose the microbiome of animals and plants, the opportunity for holobiont selection is very low in relation to the opportunity for selection on each of the species that compose the host microbiome. Therefore, holobiont selection will always be disrupted ‘from below’, by selection on each of the species that compose the microbiome. -/- This thesis constitutes a conceptual effort to defend philosophically the hologenome concept. I argue that the criticism according to which holobiont selection requires tight transgenerational host-genotype-to-symbiont-genotype connection is grounded on a metaphysical view of the world according to which the biological hierarchy needs to be nested, such that each new level of selection includes every entity from below. Applied to hologenomes, it entails that the hologenome is a collection of genomes, and selection of hologenomes is assumed to entail cospeciation of the host with the species that constitute its microbiome. -/- Against that interpretation, I propose the ‘stability of traits’ account, according to which hologenome evolution is the result of the action of natural selection in a non-nested hierarchical world. In that vein, hologenome evolution does not entail cospeciation, and thus it does not require tight transgenerational host-genotype-to-symbiont-genotype connection. By embracing a multilevel selection perspective, I argue that hologenome evolution results from the simultaneous action of natural selection on each of the lineages that compose the microbiome, and on the assemblage composed by the host genome plus the functional traits of its microbiome. Hologenome selection occurs when the evolution of the traits of the microbiome result from their effects on the fitness of the host, and it can take the form of multilevel selection 1, or multilevel selection 2. In both cases, hologenome selection entails the evolution of microbiome traits, as well as evolution of the host genome, rather than cospeciation of lineages. (shrink)

The impressive variation amongst biological individuals generates many complexities in addressing the simple-sounding question what is a biological individual? A distinction between evolutionary and physiological individuals is useful in thinking about biological individuals, as is attention to the kinds of groups, such as superorganisms and species, that have sometimes been thought of as biological individuals. More fully understanding the conceptual space that biological individuals occupy also involves considering a range of other concepts, such as life, reproduction, and agency. There has (...) been a focus in some recent discussions by both philosophers and biologists on how evolutionary individuals are created and regulated, as well as continuing work on the evolution of individuality. (shrink)

The Social Evolution of Human Nature: From Biology to Language. By Smit Harry.

Margulis’ evolutionary theory entails a revision of certain core concepts of traditional biology. One of these changes is related to the hot debate about units of selection. This paper considers Margulis’ proposal as a new research tradition (RT) and evaluates its consequences to the mentioned issue. Three ideas are suggested here: firstly, that her theory represents the revision of many classical biological concepts; secondly, that her position implies a reappraisal of many traditional issues in philosophy of biology; and thirdly, that (...) studying it from Lakatos and Laudan’s ideas about RT allows us to enlighten the richness of her theory. (shrink)

Holobionts are symbiotic assemblages composed by a host plus its microbiome. The status of holobionts as individuals has recently been a subject of continuous controversy, which has given rise to two main positions: on the one hand, holobiont advocates argue that holobionts are biological individuals; on the other, holobiont detractors argue that they are just mere chimeras or ecological communities, but not individuals. Both parties in the dispute develop their arguments from the framework of the philosophy of biology, in terms (...) of what it takes for a “conglomerate” to be considered an interesting individual from a biological point of view. However, the debates about holobiont individuality have important ontological implications that have remained vaguely explored from a metaphysical framework. The purpose of this paper is to cover that gap by presenting a metaphysical approach to holobionts individuality. Drawing upon a conception of natural selection that puts the focus on the transgenerational recurrence of the traits and that supports the thesis that holobionts are units of selection, we argue that holobionts bear emergent traits and exert downward powers over the entities that compose them. In this vein, we argue, a reasonable argument can be made for conceiving holobionts as emergent biological individuals. (shrink)

Many subscribe to an Ethic of Life, an ethical perspective on which all living things are deserving of some level of moral concern. Within philosophy, the Ethic of Life has been clarified, developed, and rigorously defended; it has also found its strongest critics. Currently, the debate is at a standstill. This book ends this stalemate by proving that the Ethic of Life must be abandoned.

The clonal evolution model and the cancer stem cell model are two independent models of cancers, yet recent data shows intersections between the two models. This article explores the impacts of the CSC model on the CE model. I show that CSC restriction, which depends on CSC frequency in cancer cell populations and on the probability of dedifferentiation of cancer non-stem cells into CSCs, can favor or impede some patterns of evolution and some processes of evolution. Taking CSC restriction into (...) account for the CE model thus has implications for the way in which we understand the patterns and processes of evolution, and can also provide new leads for therapeutic interventions. (shrink)

Darwin himself suggested the idea of generalizing the core Darwinian principles to cover the evolution of social entities. Also in the nineteenth century, influential social scientists proposed their extension to political society and economic institutions. Nevertheless, misunderstanding and misrepresentation have hindered the realization of the powerful potential in this longstanding idea. Some critics confuse generalization with analogy. Others mistakenly presume that generalizing Darwinism necessarily involves biological reductionism. This essay outlines the types of phenomena to which a generalized Darwinism applies, and (...) upholds that there is no reason to exclude social or economic entities. (shrink)

References in Darwin’s Origin of Species to competition between units of selection at and above the level of individual organisms are enumerated. In many cases these references clearly speak of natural selection and do not support the view that Darwin thought selection only occurred at the level of the individual organism. Darwin did see organismal selection as the main process by which varieties were created but he also espoused what is here termed community and varietal selection. He saw no essential (...) difference between varieties and species and the references show that he also believed that selection could operate at the species level. (shrink)

I argue for the usefulness of the evolutionary kind of biological individual.

That holobionts are units of selection squares poorly with the observation that microbes are often recruited from the environment, not passed down vertically from parent to offspring, as required for collective reproduction. The taxonomic makeup of a holobiont’s microbial community may vary over its lifetime and differ from that of conspecifics. In contrast, biochemical functions of the microbiota and contributions to host biology are more conserved, with taxonomically variable but functionally similar microbes recurring across generations and hosts. To save what (...) is of interest in holobiont thinking, we propose casting metabolic and developmental interaction patterns, rather than the taxa responsible for them, as units of selection. Such units need not directly reproduce or form parent-offspring lineages: their prior existence has created the conditions under which taxa with the genes necessary to carry out their steps have evolved in large numbers. These taxa or genes will reconstruct the original interaction patterns when favorable conditions occur. Interaction patterns will vary in ways that affect the likelihood of and circumstances under which such reconstruction occurs. Thus, they vary in fitness, and evolution by natural selection will occur at this level. It is on the persistence, reconstruction, and spread of such interaction patterns that students of holobiosis should concentrate, we suggest. This model also addresses other multi-species collectively beneficial interactions, such as biofilms or biogeochemical cycles maintaining all life. (shrink)