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)

"Greed, for lack of a better word, is good. Greed is right. Greed works. Greed clarifies, cuts through, and captures the essence of the evolutionary spirit." "From the outset [in 1976] the reviews were gratifyingly favorable and it [The Selfish Gene] was not seen, initially, as a controversial book. Its reputation for contentiousness took years to grow until, by now, it is widely regarded as a work of radical extremism. But over the very same years as the book’s reputation for (...) extremism has escalated, its actual content has seemed less and less extreme, more and more the common currency." How could it be that Dawkins’ most famous book became controversial, but not as a result of what it .. (shrink)

According to a classical narrative, early geneticists, failing to see how Mendelism provides the missing pieces of Darwin’s theory, rejected gradual changes and advocated an implausible yet briefly popular view of evolution-by-mutation; after decades of delay (in which synthesis was prevented by personal conflicts, disciplinary rivalries, and anti-Darwinian animus), Darwinism emerged on a new Mendelian basis. Based on the works of four influential early geneticists – Bateson, de Vries, Morgan and Punnett –, and drawing on recent scholarship, we offer an (...) alternative that turns the classical view on its head. For early geneticists, embracing discrete inheritance and the mutation theory (for the origin of hereditary variation) did not entail rejection of selection, but rejection of Darwin’s non-Mendelian views of heredity and variation, his doctrine of natura non facit saltum, and his conception of “natural selection” as a creative force that shapes features out of masses of infinitesimal differences. We find no evidence of a delay in synthesizing mutation, rules of discrete inheritance, and selection in a Mendelian-Mutationist Synthesis. Instead, before 1918, early geneticists had conceptualized allelic selection, the Hardy–Weinberg equilibrium, the evolution of a quantitative trait under selection, the probability of fixation of a new mutation, and other key innovations. Contemporary evolutionary thinking seems closer to their more ecumenical view than to the restrictive mid-twentieth-century consensus known as the Modern Synthesis. (shrink)

The beginning of the twentieth century saw the emergence of the discipline of genetics. It is striking how many female scientists were contributing to this new field at the time. At least three female pioneers succeeded in becoming professors: Kristine Bonnevie (Norway), Elisabeth Schiemann (Germany) and the Tine Tammes (The Netherlands). The question is which factors contributed to the success of these women's careers? At the time women were gaining access to university education it had become quite the norm for (...) universities to be sites for teaching and research. They were still expanding: new laboratories were being built and new disciplines were being established. All three women benefited from the fact that genetics was considered a new field promising in terms of its utility to society; in the case of Tammes and Schiemann in agriculture and in the case of Bonnevie in eugenics. On the other hand, the field of genetics also benefited from the fact that these first female researchers were eager for the chance to work in science and wanted to make active contributions. They all worked and studied in environments which, although different from one another, were positive towards them, at least at the start. Having a patron was generally a prerequisite. Tammes profited from her teacher's contacts and status. Bonnevie made herself indispensable through her success as a teacher and eventually made her position so strong that she was no longer dependent on a single patron. The case of Schiemann adds something new; it shows the vulnerability of such dependency. Initially, Schiemann's teacher had to rely on the first generation of university women simply because he was unable to attract ambitious young men to his institute. In those early, uncertain years of the new discipline, male scientists tended to choose other, better established, and more prestigious disciplines. However, when genetics itself had become an established field, it also became more attractive to men. Our case studies also demonstrate that a new field at first relatively open to women closes its doors to them once it becomes established. (shrink)

Since the discovery of the double helical structure of DNA, the standard account of the inheritance of features has been in terms of DNA-copying and DNA-transmission. This theory is just a version of the old theory according to which the inheritance of features is explained by the transfer at conception of some developmentally privileged material from parents to offspring. This paper does the following things: (1) it explains what the inheritance of features is; (2) it explains how the DNA-centric theory (...) emerged; (3) it clarifies the relation between the DNA-centric theory and the ‘unfolding’ theory of development; (4) it argues that (given what we now know about developmental processes and genetic activity) the DNA-centric theory should be abandoned in favour of a pluralistic (but not holistic) theory of the inheritance of features. According to this pluralistic theory, the reliable reoccurrence of phenotypes must be explained by appealing not only to processes responsible for the reliable reoccurrence of genetic developmental factors but also to processes responsible for the reliable reoccurrence (or persistence) of nongenetic developmental factors. (shrink)

This paper aims to offer a new argument in defence bacterial species pluralism. To do so, I shall first present the particular issues derived from the conflict between the non-theoretical understanding of species as units of classification and the theoretical comprehension of them as units of evolution. Secondly, I shall justify the necessity of the concept of species for the bacterial world, and show how medicine and endosymbiotic evolutionary theory make use of different concepts of bacterial species due to their (...) distinctive purposes. Finally, I shall show how my argument provides a new source of defence for bacterial pluralism. (shrink)

Although the theory of memetics appeared highly promising at the beginning, it is no longer considered a scientific theory among contemporary evolutionary scholars. This study aims to compare the genealogy of memetics with the historically more successful gene-culture coevolution theory. This comparison is made in order to determine the constraints that emerged during the internal development of the memetics theory that could bias memeticists to work on the ontology of meme units as opposed to hypotheses testing, which was adopted by (...) the gene-culture scholars. I trace this problem back to the diachronic development of memetics to its origin in the gene-centered anti-group-selectionist argument of George C. Williams and Richard Dawkins. The strict adoption of this argument predisposed memeticists with the a priori idea that there is no evolution without discrete units of selection, which in turn, made them dependent on the principal separation of biological and memetic fitness. This separation thus prevented memeticists from accepting an adaptationist view of culture which, on the contrary, allowed gene-culture theorists to attract more scientists to test the hypotheses, creating the historical success of the gene-culture coevolution theory. (shrink)

RESUMENEl desarrollo embriológico es un fenómeno que ha inspirado la especulación filosófica desde temprano en la historia del pensamiento. Desde los tiempos de Aristóteles dos modelos conceptuales antitéticos se han utilizado tradicionalmente para comprender la embriogénesis: o el embrión posee ya una forma o estructura, o ésta se forma de nuevo en cada generación. Nuestro objetivo en este artículo es mostrar que el contraste entre la posición preformacionista y epigenética persiste a pesar de los formidables avances teóricos y experimentales de (...) la biología del desarrollo contemporánea. El preformacionismo y la epigénesis han perfeccionado constantemente sus posiciones en el curso de la historia con el fin de responder a los retos conceptuales de la época. Este continuo proceso de transformación ha dado lugar a una convergencia parcial entre las dos posiciones. Sin embargo, vamos a argumentar que, a pesar de los esfuerzos por conciliar ambas posturas, esta antinomia, que se erige como una de las más fundamentales de la biología, no será fácil de superar. ABSTRACTThe process of development of the embryo has inspired philosophical speculation since the advent of Western thought. Since the time of Aristotle two antithetical conceptual models have traditionally been used to understand embryogenesis: either form or structure is preformed in the embryo or it is newly formed with each generation. Our aim in this article is to show that the contrast between the pre-formationist and epigenetic positions persists despite the formidable theoretical and experimental advances of contemporary developmental biology. Pre-formationism and epigenesis have constantly refined their positions in the course of history in order to answer the conceptual challenges of each epoch. This process of continuous transformation has resulted in a partial convergence of the two positions. However, we shall argue that, despite the partial successes of this process of continuous convergence, one of the most fundamental antinomies in biology persists. (shrink)

This inaugural handbook documents the distinctive research field that utilizes history and philosophy in investigation of theoretical, curricular and pedagogical issues in the teaching of science and mathematics. It is contributed to by 130 researchers from 30 countries; it provides a logically structured, fully referenced guide to the ways in which science and mathematics education is, informed by the history and philosophy of these disciplines, as well as by the philosophy of education more generally. The first handbook to cover the (...) field, it lays down a much-needed marker of progress to date and provides a platform for informed and coherent future analysis and research of the subject. -/- The publication comes at a time of heightened worldwide concern over the standard of science and mathematics education, attended by fierce debate over how best to reform curricula and enliven student engagement in the subjects There is a growing recognition among educators and policy makers that the learning of science must dovetail with learning about science; this handbook is uniquely positioned as a locus for the discussion. -/- The handbook features sections on pedagogical, theoretical, national, and biographical research, setting the literature of each tradition in its historical context. Each chapter engages in an assessment of the strengths and weakness of the research addressed, and suggests potentially fruitful avenues of future research. A key element of the handbook’s broader analytical framework is its identification and examination of unnoticed philosophical assumptions in science and mathematics research. It reminds readers at a crucial juncture that there has been a long and rich tradition of historical and philosophical engagements with science and mathematics teaching, and that lessons can be learnt from these engagements for the resolution of current theoretical, curricular and pedagogical questions that face teachers and administrators. (shrink)

The paper aims at proposing an extended notion of epigenesis acknowledging an actual causal import to the phenotypic dimension for the evolutionary diversification of life forms. “Introductory remarks” section offers introductory remarks on the issue of epigenesis contrasting it with ancient and modern preformationist views. In “Transmutation of forms: phenotypic variation, diversification, and complexification” section we propose to intend epigenesis as a process of phenotypic formation and diversification dependent on environmental influences, independent of changes in the genomic nucleotide sequence, and (...) occurring during the whole life span. Then, “Evolvability and phenotypic evolution” section focuses on phenotypic plasticity and offers an overview of basic properties that allows biological systems to be evolvable—i.e. to have the potentiality of producing phenotypic variation. Successively, the emphasis is put on environmentally-induced modifications in the regulation of gene expression giving rise to phenotypic variation and diversification. After some brief considerations on the debated issue of epigenetic inheritance, the issue of culture is considered. The key point is that, in the case of humans and of the evolutionary history of the genus Homo at least, the environment is also, importantly, the cultural environment. Thus, “Bio-cultural feedback” section argues that a bio-cultural feedback should be acknowledged in the “epigenic” processes leading to phenotypic diversification and innovation in Homo evolution. Finally, “Brain plasticity and cultural neural reuse” section introduces the notion of “cultural neural reuse”, which refers to phenotypic/neural modifications induced by specific features of the cultural environment that are effective in human cultural evolution without involving genetic changes. Therefore, cultural neural reuse may be regarded as a key instance of the bio-cultural feedback and ultimately of the extended notion of epigenesis proposed in this work. (shrink)

Science is a dynamic process in which the assimilation of new phenomena, perspectives, and hypotheses into the scientific corpus takes place slowly. The apparent disunity of the sciences is the unavoidable consequence of this gradual integration process. Some thinkers label this dynamical circumstance a ‘crisis’. However, a retrospective view of the practical results of the scientific enterprise and of science itself, grants us a clear view of the unity of the human knowledge seeking enterprise. This book provides many arguments, case (...) studies and examples in favor of the unity of science. These contributions touch upon various scientific perspectives and disciplines such as: Physics, Computer Science, Biology, Neuroscience, Cognitive Psychology, and Economics. (shrink)

In “The Origin of Species,” Darwin describes a hypothetical example illustrating that large, slowly reproducing mammals such as the elephant can reach very large numbers if population growth is not affected by regulating factors. The elephant example has since been cited in various forms in a wide variety of books, ranging from educational material to encyclopedias. However, Darwin’s text was changed over the six editions of the book, although some errors in the mathematics persisted throughout. In addition, full details of (...) the problem remained hidden in his correspondence with readers of the Origin. As a result, Darwin’s example is very often misinterpreted, misunderstood or presented as if it were a fact. We show that the population growth of Darwin’s elephant population can be modeled by the Leslie matrix method, which we generalize here to males as well. Darwin’s most often cited figure, about 19 million elephants after 750 years is not a typical outcome, actually a very unlikely result under more realistic, although still hypothetical situations. We provide a recursion formula suggesting that Darwin’s original model corresponds to a tribonacci series, a proof showing that sex ratio is constant over all age classes, and a derivation of a generating function of the sequence. (shrink)

In 1877, the young Alfred Espinas defended a philosophical study, ‘doctorat ès lettres’, at the Sorbonne University, entitled Des Sociétés animales. This was to become one of the principal sources of French organicist sociology. The paradox, however, is that this work seems to be fundamentally a study of natural science. Espinas tried to justify his position theoretically through two types of reciprocally exclusive and uncomplementary arguments. The first one consists in showing that only certain kinds of animal groupings belong legitimately, (...) if not academically, to sociology. The second one has a greater audacious and uncontrollable dimension. It consists in asserting that all pluricellular organisms are true societies. In this article we first focus on the role played by cellular theory in such a ‘sociologization’ of biology, concerning the extension of sociology. Second, we examine the importance of such confusion within the fields of extension, in aiming to explain the conceptual transfers between social sciences and life sciences, in the second half of the 19th century. (shrink)

Historians and biologists identify the debate between mechanists and vitalists over the nature of life itself with the arguments of Driesch, Loeb, and other prominent voices. But what if the conversation was broader and the consequences deeper for the field? Following the suspicions of Joseph Needham in the 1930s and Francis Crick in the 1960s, we deployed tools of the digital humanities to an old problem in the history of biology. We analyzed over 31,000 peer-reviewed scientific papers and learned that (...) bioexceptionalism participated in a robust discursive landscape throughout subfields of the life sciences, occupied even by otherwise unknown biologists. (shrink)

Pluralism is popular among philosophers of biology. This essay argues that negative judgments about universal biology, while understandable, are very premature. Familiar life on Earth represents a single example of life and, most importantly, there are empirical as well as theoretical reasons for suspecting that it may be unrepresentative. Scientifically compelling generalizations about the unity of life must await the discovery of forms of life descended from an alternative origin, the most promising candidate being the discovery of extraterrestrial life. Nonetheless, (...) in the absence of additional examples of life, we are best off exploring the microbial world for promising explanatory concepts, principles, and mechanisms rather than prematurely giving up on universal biology. Unicellular microbes are by far the oldest, metabolically most diverse, and environmentally tolerant form of life on our planet. Yet somewhat ironically, much of our theorizing about life still implicitly privileges complex multicellular eukaryotes, which are now understood to be highly specialized, fragile latecomers to Earth. The problem with pursuing a pluralist approach to understanding life is that it is likely to blind us to the significance of just those entities and causal processes most likely to shed light on the underlying nature of life. (shrink)