The allegedly alternative theories of Phyletic Gradualism and Punctuated Equilibria are examined as regards the nature of their differences. The explanatory value of both models is determined by establishing their actual connection with reality. It is concluded that they are to be considered complementary rather than mutually exclusive at all levels of infraspecific, specific, and supraspecific evolution. So, in order to be described comprehensively, the pathways of evolution require at least two distinct models, each based on a discrete range of (...) real phenomena. [Phyletic Gradualism; Punctuated Equilibria; evolutionary theories; divergence models; additive speciation; microevolution; macroevolution; anagenesis.]. (shrink)

The author assumes that the biological evolution must reflect itself also in the energetic processes of the organism. Several concept are discussed, in view of a characterization of the energetic economy of the organism. Two of these are thought to have particular significance related to evolution: the energetic efficiency and the capacity for energetic production . E is the ratio of the performed useful work to the amount of energy “spent”; P is the ratio of the performed useful work to (...) the product of the mass of the living system and time. An evolution of both E and P during the animal phylogenesis is assumed. The evolution of E is generally evident at the level of more elementary metabolic processes, while that of P at the level of more complex functions or of the organism as a whole. In many cases, the increase of P is associated with a decrease of E. The main evolutionary feature of biological energetic economy is the increase of the capacity for energetic production. This holds true even if the increase of P can be achieved only at the expense of a reduction of the energetic efficiency, of a “waste” of energy, especially in the most highly developed systems of the organism.L'évolution biologique doit se refléter, selon l'avis de l'auteur, aussi dans les processus énergétiques de l'organisme. On discute quelques notions qui pourraient caractériser l'économie énergétique de celui-ci. Deux de celles-ci ont une signification évolutive particulière: le rendement énergétique et la capacité de production énergétique . E est le rapport du travail util effectué à la quantité d'énergie “dépensée”; P est le rapport du travail util effectué au produit de la masse du système vivant avec de le temps. L'auteur considère qu'il y a une évolution des deux grandeurs au cours de la phylogénèse animale. L'évolution d'E se manifeste spécialement au niveau des processus métaboliques élémentaires, tandis que celle de P au niveau des fonctions plus complexes ou de l'organisme entier. Dans beaucoup de cas, l'accroissement de P entraîne une diminution de E. Le trait évolutif principal de l'énergétique biologique c'est l'accroissement de la capacité de production énergétique, même si cela suppose une réduction du rendement, une “dissipation” d'énergie, surtout dans les systèmes les plus développés de l'organisme.Die biologische Evolution soll sich, nach dem Erachten des Verfassers, auch in den energetischen Vorgange des Organismus kundtun. Es werden einige Begriffe erörtert, welche den Energiehaushalt des Organismus kennzeichnen können. Zwei von diesen Begriffen haben eine besondere entwicklungsgeschichtliche Bedeutung: die energetische Leistung und das Vermögen zur Energieproduktion . E ist das Verhältnis der geleisteten nützlichen Arbeit zur verbrauchten Energiemenge; P ist das Verhältnis der nützlichen Arbeit zum Produkt von Masse des lebenden Systems und Zeit. Der Verfasser ist der Meinung, dass es eine Evolution von E und P während der tierischen Phylogenesis gäbe. Die Evolution von E äussert sich meist in der Ebene der elementaren metabolischen Vorgänge, hingegen die von P an komplexeren Funktionen. In zahlreichen Fällen, vermindert E während P wächst. Die evolutive Grundzug der biologischen Energetik ist das Anwachsen der Fähigkeit zur Energieproduktion, sogar wenn dieses nur auf Kosten einer Verminderung der energetischen Leistung, einer „Vergeudung“ der Energie verwirklichen kann. (shrink)

The word ``deme'' was coined by the botanists J.S.L. Gilmour and J.W.Gregor in 1939, following the pattern of J.S. Huxley's ``cline''. Its purposewas not only to rationalize the plethora of terms describing chromosomaland genetic variation, but also to reduce hostility between traditionaltaxonomists and researchers on evolution, who sometimes scorned eachother's understanding of species. A multi-layered system of compoundterms based on deme was published by Gilmour and J. Heslop-Harrison in1954 but not widely used. Deme was adopted with a modified meaning byzoologists (...) leading the evolutionary synthesis – Huxley, Simpson, Wright,and Mayr. Connections are shown between Gilmour's ideas around definingthe deme, his role in founding the Systematics Association, and his chapter``Taxonomy and Philosophy'' in the book The New Systematics. Thishistorical episode raises questions about the role of carefully-definedwords in scientific practice. (shrink)

Darwin proposed that evolutionary novelties are environmentally induced in organisms “constitutionally” sensitive to environmental change, with selection effective owing to the inheritance of constitutional responses. A molecular theory of inheritance, pangenesis , explained the cross‐generational transmission of environmentally induced traits, as required for evolution by natural selection. The twentieth‐century evolutionary synthesis featured mutation as the source of novelty, neglecting the role of environmental induction. But current knowledge of environmentally sensitive gene expression, combined with the idea of genetic accommodation of mutationally (...) and environmentally induced change, supports a revival of Darwin's original theory that is consistent with modern molecular and population genetics. †To contact the author, please write to: Smithsonian Tropical Research Institute, c/o Escuela de Biología, Universidad de Costa Rica, Costa Rica; e‐mail: [email protected]. (shrink)

The argument is put forward that genetic mutations are viable then only, when the changed pattern of growth and/or metabolism is accommodated by the taxon-specific biochemistry of the organisms, i.e. by adaptive, somatic/physiological plasticity. The range of somatic plasticity under changing environmental conditions, therefore, has a certain predictive value for the kind of mutations that are likely to be viable.

Chance has been a focus of attention ever since the beginning of population genetics, but neutrality has not, as natural selection once appeared to be the only worthwhile issue. Neutral change became a major source of interest during the neutralist–selectionist debate, 1970–1980. It retained interest beyond this period for two reasons that contributed to its becoming foundational for evolutionary reasoning. On the one hand, neutral evolution was the first mathematical prediction to emerge from Mendelian inheritance: until then evolution by natural (...) selection was considered the alternative to the fixity of species; now it appears to be the alternative to continuous change. Second, neutral change generated a set of clear predictions on standing variation. These could be used as a reference for detecting more elusive alternative mechanisms of evolution including natural selection. In the wake of the transition from Mendelism to genomics, the combination of coalescent theory, DNA sequence variation, and numerical analysis made it possible to integrate contingent aspects of the history of species into a new null model, thus opening a new dimension in the concept of population that the Modern Synthesis formerly considered as a mere gene pool. (shrink)

Recent definitions of the botanical terms ecotype, ecospecies and coenospecies are briefly reviewed. Examples of ecospecies are discussed and the following new definitions are proposed: Groups with the same chromosome number between which there are well-defined morphological, ecological and geographical differences and which, under artifical or natural conditions are capable of only limited gene-exchange. Groups with different chromosome numbers between which there are well-defined ecological and geographical differences and which are capable of only limited gene-exchange. Groups forming genetically distinct components (...) of ecospecies, adapted to special types of environment and capable of unlimited gene-exchange. Groups forming polyploid components of an ecospecies.The probable modes of origin ofg-ecospecies anda-ecospecies are explained; and the importance of the recognition by taxonomists ofa-ecospecies, which may differ morphologically hardly at all, is. emphasized.Examples of the uses of the terms are given, and it is suggested that their application to animals as well as plants would be of interest.Neuere Definitionen der botanischen Begriffe „ecotype”, „ecospecies” und “coenospecies” werden kurz besprochen. Beispiele von ecospecies werden erörtet, und folgende neue Begriffsbestimmungen vorgeschlagen: Gruppen mit gleicher Chromosomenzahl, zwischen denen morphologische, ökologische und geographische Unterschiede deutlich festzustellen sind, und bei denen in künstlichen oder natürlichen Zuständen nur beschränkter Genaustausch stattfinden kann. Gruppen mit ungleicher Chromosomenzahl, zwischen denen ökologische und geographische Unterschiede deutlich festzustellen sind, und bei denen nur beschränkter Genaustausch stattfinden kann. Gruppen, die genetisch unterschiedene Bestandteile von ecospecies bilden, die für besondere Typen von Milieu geeignet sind, und bei denen unbeschränkter Genaustausch stattfinden kann. Gruppen, die polyploiden Bestandteile einer ecospecies bilden.Die wahrscheinlichen Enstehungsarten derg-ecospecies und dera-ecospecies werden beschrieben, und es wird für besonders wichtig erklärt, dass die Systematiker den Begriffa-ecospecies anerkennen, denn diese mögen sich morphologisch äusserst wenig unterscheiden.Beispiele für den Gebrauch der Begriffe werden angeführt, und es wird vorgeschlagen, dass es interessant wäre, sie nicht nur bei Pflanzen sondern auch bei Tieren zu verwenden.Nous avons brièvement étudié dans l'article ci-dessus les récentes définitions des ternies botaniques „ecotype” „ecospecies”, et „coenospecies”. Nous avons discuté quelques exemples d'ecospecies et nous avons proposé les nouvelles définitions suivantes: Groupes avec le même nombre de chromosomes, entre lesquels il y a des différences morphologiques, écologiques et géographiques nettement déterminées; ils ne sont capables que d'un échange limité de gènes dans des conditions artificielles ou naturelles. Groupes avec différents nombres de chromosomes, entre lesquels il y a des différences écologiques et géographiques nettement déterminées, et qui ne sont capables que d'un échange limité de gènes. Groupes formant des composants d'ecospecies génétiquement distincts, adaptés à des types spéciaux de milieux et qui sont capables d'un échange illimité de gènes. Groupes formant des composants polyploïdes d'une ecospecies.Les origines probables desg-ecospecies et desa-ecospecies y sont expliquées; nous avons mis en relief l'importance de l'identification par les taxonomistes d'a-ecospecies, qui peuvent à peine présenter des différences morphologiques.Nous donnons des exemples d'emplois de ces termes, et nous suggérons que leurs applications aux animaux aussi bien qu'aux plantes pourraient présenter un intérêt certain. (shrink)

I criticize the particular argument for evolutionary progressivism which is based on the concept of a series of "dominant life forms." My procedure is to show that there is no rigorous definition for the concept of "dominant life form." I examine several attempts to define this concept by Julian Huxley and a new formulation of the concept by G. G. Simpson and show that none of the criteria either of these men develop for determining which groups of organisms can be (...) classified as dominant are adequate to exclude any groups of organisms from the classification. The concept proves so broad as to be meaningless. Since it is a key concept in the particular argument for progressivism that I discuss, the criticism of the concept demonstrates the argument to be invalid. (shrink)

In 1847, the British polymath William Whewell pointed out that the sciences for which he, in 1837, had coined the term “palætiological” have much in common and that they may reflect light upon each other by being treated together. This recommendation is here put into practice in a specific way, to wit, not by comparing the palaetiological sciences that Whewell distinguished himself but by comparing the general historical development of the scientific study of the four broad palætiological domains that he (...) enumerated in 1847: the solar system, the Earth, its vegetable and animal creation, and man. For wide and various as their subjects are, it will be found that [the palætiological sciences] have all certain principles, maxims, and rules of procedure in common; and thus may reflect light upon each other by being treated together. William Whewell ( 1847, 1, p. 640). (shrink)

Revaluation of the problem of natural teleology seems an important precondition for elucidating our environmental crisis and for formulating an 'econological ethics', because it calls for a recognition of an intrinsic value in nature and organisms. Therefore, it is necessary to show that the concept of natural teleology is not in contradiction with scientific theories, in particular not with the theory of evolution. In this paper I shall argue that there is a fundamental misunderstanding about the concepts of teleology and (...) chance in modern thinking. This as a result of a radical transformation of the Aristotelian concept of teleology by Christian theologians during the Middle Ages. This confusion resulted in the rejection of teleology from evolution and in an exaggeration of the role of chance. However, not a solution for the problem of teleology is given here, but only an attempt to prove that neither the fossil-record, nor the role of chance in evolution can give adequate arguments for the negation of teleology in evolution. That is not to say that, therefore there exists teleology in evolution, but the problem of teleology in nature cannot, be solved by the scientific theory of evolution, but only be elucidated by philosophical analysis. At the end of the paper it is argued that teleology must be rather presupposed in evolution. (shrink)

In the received view of the history of the Modern Evolutionary Synthesis, paleontology was given a prominent role in evolutionary biology thanks to the significant influence of paleontologist George Gaylord Simpson on both the institutional and conceptual development of the Synthesis. Simpson's 1944 Tempo and Mode in Evolution is considered a classic of Synthesis-era biology, and Simpson often remarked on the influence of other major Synthesis figures – such as Ernst Mayr and Theodosius Dobzhansky – on his developing thought. Why, (...) then, did paleontologists of the 1970s and 1980s – Stephen Jay Gould, Niles Eldredge, David M. Raup, Steven Stanley, and others – so frequently complain that paleontology remained marginalized within evolutionary biology? This essay considers three linked questions: first, were paleontologists genuinely welcomed into the Synthetic project during its initial stages? Second, was the initial promise of the role for paleontology realized during the decades between 1950 and 1980, when the Synthesis supposedly "hardened" to an "orthodoxy"? And third, did the period of organized dissent and opposition to this orthodoxy by paleontologists during the 1970s and 1980s bring about a long-delayed completion to the Modern Synthesis, or rather does it highlight the wider failure of any such unified Darwinian evolutionary consensus? (shrink)

This paper analyzes the development of evolutionary theory in the period from 1918 to 1932. It argues that: (i) Fisher's work in 1918 constituted a not fully satisfactory reduction of biometry to Mendelism; (ii) there was a synthesis in the 1920s but that this synthesis was mainly one of classical genetics with population genetics, with Haldane's The Causes of Evolution being its founding document; (iii) the most important achievement of the models of theoretical population genetics was to show that natural (...) selection sufficed as a mechanism for evolution; and (iv) Haldane formulated a prospective evolutionary theory in the 1920s whereas Fisher and Wright formulated retrospective theories of evolutionary history. (shrink)

A foundational idea of evo‐devo is that morphological variation is not isotropic, that is, it does not occur in all directions. Instead, some directions of morphological variation are more likely than others from DNA‐level variation and these largely depend on development. We argue that this evo‐devo perspective should apply not only to morphology but to evolution at all phenotypic levels. At other phenotypic levels there is no development, but there are processes that can be seen, in analogy to development, as (...) constructing the phenotype (e.g., protein folding, learning for behavior, etc.). We argue that to explain the direction of evolution two types of arguments need to be combined: generative arguments about which phenotypic variation arises in each generation and selective arguments about which of it passes to the next generation. We explain how a full consideration of the two types of arguments improves the explanatory power of evolutionary theory. Also see the video abstract here: https://youtu.be/Egbvma_uaKc. (shrink)

A common complaint of biologists is that their subject receives poor treatment from philosophers—it gets but a fraction of the attention accorded to physics and chemistry, and what little it does receive, is usually of the type where ‘All swans are white’ is taken to be a paradigmatic example of the state of biological thinking. It cannot be denied that this complaint is, to a great extent, justified; however, there are some notable breaches in the wall of ignorance and silence, (...) amongst which must be numbered The Ascent of Life by T.A. Goudge. In this book, starting from what is obviously a very wide knowledge of biology, Goudge attempts a careful and thorough analysis of one of the major achievements of biological thought, evolutionary theory. The conclusions that Goudge draws are many; nevertheless, one can discern running through them a common theme, namely that whilst evolutionary theory is indeed a legitimate branch of science, to assume that it is a science of the same nature as physics and chemistry would be a grave error. Goudge argues that, despite certain similarities to other branches of science, the essential aims, methods and results of evolutionary theory are peculiar unto itself. (shrink)

It is shown in a literature review, that in the Typostrophic Theory autonomous mechanisms in the organism are considered as the factors which play a decisive role in orienting and controlling the evolutionary process. Selection is a controlling factor of only minor importance. The Synthetic Theory, on the other side, says that phylogenetic changes are not random or controlled by “internal factors” but can always be considered as adaptive remodellings. They are achieved by selection acting on the variation within populations. (...) Ecological, historical and “bautechnische” factors are considered as limiting mechanisms in the evolutionary process. They are discussed in detail in the text. (shrink)

Sociobiology is the scientific study of why organisms sometimes associate with other organisms. This paper surveys recent research on the reasons for altruism and aggression. It also considers the contributions an individual's genes and its environment make to its behavior, and it reviews functional theories for the evolution of cannibalism, polygamy, homosexuality, and infanticide in humans and other animals. Finally mention is made of the limited and generally negative attitude of sociobiology to religion.

The extended evolutionary synthesis intends to offer a new framework for understanding evolution based mainly on empirical and theoretical findings of current studies, including heredity and evolutionary developmental biology. In this essay, we present and develop the following objections about the terminology associated with the EES literature: despite using the term "extension," EES protagonists claim new evolutionary processes, reformulate conceptual networks, and modify central assumptions of the evolutionary synthesis. Therefore, the difference between ES and EES should not be described in (...) terms of a set-subset relationship ; despite using the term "synthesis," the EES leads, at least in the short term, to a pluralism of approaches in evolutionary biology. Thus, we argue that the EES should not be described as a synthesis, but as a broad and plural interpretative framework encompassing different approaches. These objections are not directed to the proposed changes, but to the interpretation of these changes as a mere expansion of the previous evolutionary framework, as well as to the interpretation of the EES as a synthesis. Based on these objections, we seek to present some explanations for the use of the term "extended synthesis" among its protagonists. (shrink)

Starting from the early decades of the twentieth century, evolutionary biology began to acquire mathematical overtones. This took place via the development of a set of models in which the Darwinian picture of evolution was shown to be consistent with the laws of heredity discovered by Mendel. The models, which came to be elaborated over the years, define a field of study known as population genetics. Population genetics is generally looked upon as an essential component of modern evolutionary theory. This (...) article deals with a famous dispute between J. B. S. Haldane, one of the founders of population genetics, and Ernst Mayr, a major contributor to the way we understand evolution. The philosophical undercurrents of the dispute remain relevant today. Mayr and Haldane agreed that genetics provided a broad explanatory framework for explaining how evolution took place but differed over the relevance of the mathematical models that sought to underpin that framework. The dispute began with a fundamental issue raised by Mayr in 1959: in terms of understanding evolution, did population genetics contribute anything beyond the obvious? Haldane's response came just before his death in 1964. It contained a spirited defense, not just of population genetics, but also of the motivations that lie behind mathematical modelling in biology. While the difference of opinion persisted and was not glossed over, the two continued to maintain cordial personal relations. (shrink)

There are two motivations commonly ascribed to historical actors for taking up statistics: to reduce complicated data to a mean value (e.g., Quetelet), and to take account of diversity (e.g., Galton). Different motivations will, it is assumed, lead to different methodological decisions in the practice of the statistical sciences. Karl Pearson and W. F. R. Weldon are generally seen as following directly in Galton’s footsteps. I argue for two related theses in light of this standard interpretation, based on a reading (...) of several sources in which Weldon, independently of Pearson, reflects on his own motivations. First, while Pearson does approach statistics from this "Galtonian" perspective, he is, consistent with his positivist philosophy of science, utilizing statistics to simplify the highly variable data of biology. Weldon, on the other hand, is brought to statistics by a rich empiricism and a desire to preserve the diversity of biological data. Secondly, we have here a counterexample to the claim that divergence in motivation will lead to a corresponding separation in methodology. Pearson and Weldon, despite embracing biometry for different reasons, settled on precisely the same set of statistical tools for the investigation of evolution. (shrink)

Ce travail pose la question des critères de la „progression biologique“ , d'après les documents fossiles, dans le monde des organismes, c'est-à-dire de ce perfectionnement qui ne s'arrête pas à l'intérieur du cadre d'un phylum donné, comme le „perfectionnement de l'adaptation“, mais qui conduit, au-de-là de phylums de rang différent, à des types supérieurs, par exemple, des Poissons pas les Amphibies et les Reptiles jusqu'aux Mammifères ou aux Oiseaux. Deux groupes de critères y sont recensés en détail, leur contenu est (...) exposé, et on les examine pour voir s'ils caractérisent sans ambiguïté la „progression biologique“. Le premier groupe comprend les critères de „différenciation croissante“ et „d'intégration harmonique”. Ils sont fondés sur la différenciation morphophysiologique ou plus exactement sur la „totalité” des organismes, c'est-à-dire leur multiplicité dans l'unité. Le second groupe de critères, à savoir „indépendance croissante du milieu” et „autonomie individuelle croissante”, part des relations de l'organisme au milieu et aux autres formes vivantes et souligne la „subsistence” des individus, c'est-à-dire leur plus ou moins grande indépendence ou leur stabilité interne. Comme „totalité” et „subsistence” sont les éléments décisifs d'une définition biologique de l'individu, on peut dire que la „progression biologique“ d'un organisme est d'autant plus élevée que sa totalité et subsistence et par là son être individuel sont plus accusés.Tous les critères mentionnés ne sont pas uniformes. Les motifs de leur imprécision sont divers. Tout d'abord, il n'y a pas encore de définition unique et complète de l'individu biologique, de sorte qu'on ne peut circonscrire d'une manière univoque ce qui confère à un organisme une individualité plus forte ou moins forte. Ensuite les lignées au-delà desquelles s'accomplissent des perfectionnements, et dont l'une reste intérieur au phylum , tandis que l'autre le transcende , sont entrelacées si intimement et d'une façon si particulière qu'elles ne se laissent pas séparer franchement et décrire rigoureusement selon leurs signes distinctifs. Tout représentant d'un phylum, peu importe son palier, est en effet nécessairement inséré dans un milieu et en quelque façon spécialisé. Il n'existe pas des types à caractères phylétiques purs, qui ne montrent dans aucune direction un „perfectionnement de l'adaptation”, mais seulement des marques caractéristiques de la „progression biologique”. Enfin nous ne connaissons pas les restes fossiles que le développement ou la formation des grands phylums du règne animal, à savoir du rameau des Vertébrés et des divers groupes des Invertébrés, mais non pas le plus intéressant et le plus important, leur „progression biologique” jusqu'au degré d'organisation qu'ils présentent déjà à l'époque du Silurien ou plutôt du Cambrien. C'est cela seulement qui permettrait une vue plus profonde sur la nature de la „progression biologique”.Die Arbeit stellt die Frage nach den Kriterien des fossil belegten Biologischen Aufstiegs” der Organismenwelt, d.h. derjenigen Vervollkommnung, die sich nicht innerhalb des Rahmens eines gegebenen Bauplans hält, wie die „Anpassungsvervollkommnung”, sondern über verschiedenrangige Baupläne hinweg zu höheren Typen führt, z.B. von den Fischen über die Amphibien und Reptilien zu den Säugern bzw. Vögeln. Ausführlich werden zwei Gruppen von Kriterien besprochen, ihr Inhalt dargelegt und ihre Eindeutigkeit zur Charakterisierung des „Biologischen Aufstiegs” untersucht. Die erste Gruppe umfasst die Kriterien der „zunehmenden Differenzierung” und „harmonischeren Integration”. Diese legen die morphologisch-physiologische Differenzierung oder genauer die „Ganzheit” der Organismen zugrunde, d.h. ihre Vielheit in der Einheit. Die zweite Kriteriengruppe, nämlich „zunehmende Umweltunabhängigkeit” und „zunehmende individuelle Autonomie”, geht von den Beziehungen des Organismus zur Umwelt und zu andern Lebensformen aus und betont die „Subsistenz” der Individuen, d.h. ihr grösseres oder geringeres Losgelöstsein oder ihre Selbständigkeit. Da nun „Ganzheit” und „Subsistenz” die entscheidenden Elemente einer biologischen Definition des Individuums sind, lässt sich sagen, dass der „Biologische Aufstieg” eines Organismus um so höher ist, je stärker seine Ganzheit und Subsistenz und damit sein Individuumsein ist.Eindeutigkeit kommt allen genannten Kriterien nicht zu. Die Gründe für ihre Unschärfe sind verschiedener Art. Zunächst gibt es noch keine eindeutige und vollständige Definition des biologischen Individuums, so dass sich nicht eindeutig umreissen lässt, was einem Organismus eine stärkere oder weniger starke Individualität verleiht. Dann sind die Linien, über die sich Vervollkommnungen vollziehen und von denen die eine innerhalb des Bauplans bleibt , die andere aber über ihn hinausführt so innig und in so eigenartiger Weise miteinander verflochten, dass sie sich nicht sauber scheiden und in ihren charakteristischen Merkmalen genau beschreiben lassen. Jeder Vertreter eines Bauplans, ganz gleich von welcher Ranghöhe, ist nämlich notwendig in eine Umwelt eingepasst und irgendwie spezialisiert. Es gibt keine Typen mit reinen Bauplanmerkmalen, die nach keiner Richtung hin eine „Anpassungsvervollkommnung”, sondern nur Merkmale des „Biologischen Aufstiegs” aufweisen. Schliesslich kennen wir fossil nur die Entfaltung oder Ausgestaltung der Grossbaupläne des Tierreichs, nämlich des Wirbeltierstammes und der verschiedenen Gruppen der Wirbellosen, nicht aber das Interessanteste und Wichtigste, nämlich ihren „Biologischen Aufstieg” zu der organisatorischen Höhe, mit der sie sich im Silur bzw. im Kabrium bereits vorstellen. Das erst würde einen tieferen Einblick in das Wesen des „Biologischen Aufstiegs” vermitteln.This article deals with the question of the criteria for the “biological ascent” of the organic world, resting on fossil evidence. That is, of that improvement which is not only restricted to the framework of a given “general structure” as is the “improvement of adaptation”, but which also leads beyond general structures of differentiated levels to a higher type,e.g. from the fishes through the amphibians and reptiles to the mammals or birds. Two groups of criteria are discussed at length, their content exposed and their univocity for the characterisation of this “biological ascent” is examined. The first group includes the criteria of “increasing differentiation” and “more harmonious integration”. The basis for these is the morphological-physiological differentiation, or more exactly, the “totality” of the organisms,i.e., their variety-in-unity. The second group of criteria, “increasing independence of environment” and “increasing individual autonomy”, is derived from the relationships of the organism to its environment and to other living forms, and stresses the “subsistence” of individuals,i.e., their greater or lesser degree of independence or self-sufficiency. Now since “totality” and “subsistence” are the decisive elements in a biological definition of the individual, it may be said that the “biological ascent” of an organism is higher, the more perfect its totality and subsistence and therefore its individuality is.The criteria mentioned are not univocal. The reasons for this lack of clarity are varied. First of all, there is no univocal and complete definition of the biological individual, so that it cannot be exactly stated just what gives an organism a more or less perfect individuality. Then the lines, along which improvements are made, and according to which the one remains within the general structure and the other goes beyond the general structure , are so intimately and singularly bound together, that they cannot be cleanly distinguished, and their characteristic notes exactly described. For each representative of a general structure, regardless of its level, is necessarily fitted into an environment and somehow or other specialised. There are no types with only notes of the general structure which show in no direction an “improvment of adaption”, but only the signs of “biological ascent”. Finally, we only have fossil evidence for the development or deployment of the “great general structures” of the animal world, namely that of the vertebrates and of the different groups of invertebrates, not for the most interesting and most important, that is, their “biological ascent” to the level of organisation with which they are found in the Silurian or Cambrian periods. Only that would give us a deeper insight into the essence of “biological ascent”. (shrink)

Since the 1940s, microbiologists, biochemists and population geneticists have experimented with the genetic mechanisms of microorganisms in order to investigate evolutionary processes. These evolutionary studies of bacteria and other microorganisms gained some recognition from the standard-bearers of the modern synthesis of evolutionary biology, especially Theodosius Dobzhansky and Ledyard Stebbins. A further period of post-synthesis bacterial evolutionary research occurred between the 1950s and 1980s. These experimental analyses focused on the evolution of population and genetic structure, the adaptive gain of new functions, (...) and the evolutionary consequences of competition dynamics. This large body of research aimed to make evolutionary theory testable and predictive, by giving it mechanistic underpinnings. Although evolutionary microbiologists promoted bacterial experiments as methodologically advantageous and a source of general insight into evolution, they also acknowledged the biological differences of bacteria. My historical overview concludes with reflections on what bacterial evolutionary research achieved in this period, and its implications for the still-developing modern synthesis. (shrink)

This article scrutinizes in detail much of the extant historiography on the controversy between biometricians and Mendelians, considering in particular how this controversy is related to the evolutionary synthesis. While the historiographic critique concentrates on William Provine’s standard account, it also extends to the proposal by Donald MacKenzie and Barry Barnes. What Provine and these sociologists of scientific knowledge have in common is a set of unquestioned assumptions about the nature of Darwinism, about William Bateson’s anti-Darwinism, and about the very (...) idea of an evolutionary “synthesis.” While these assumptions make for a compelling history of the synthesis, they engender an endemically asymmetrical perspective and bias historiography toward the mere confirmation of antecedent expectations, which renders the years from 1859 to 1929 an age of ignorance and misunderstanding. In contrast, a return to what was probably the original meaning of evolutionary “synthesis” allows for a symmetrical account. It yields an appreciation of the positive contributions made both by Mendelians and biometricians to the gradual development of Darwinism. The article concludes with a synopsis of this alternative account. (shrink)

William Keith Brooks was an American zoologist at Johns Hopkins University from 1876 until his death in 1908. Over the course of his career, Brooks staunchly defended Darwinism, arguing for the centrality of natural selection in evolutionary theory at a time when alternative theories, such as neo-Lamarckism, grew prominent in American biology. In his book The Law of Heredity, Brooks addressed problems raised by Darwin’s theory of pangenesis. In modifying and developing Darwin’s pangenesis, Brooks proposed a new theory of heredity (...) that sought to avoid the pitfalls of Darwin’s hypothesis. In so doing he strengthened Darwin’s theory of natural selection by undermining arguments for the inheritance of acquired characteristics. In later attacks on neo-Lamarckism, Brooks consistently defended Darwin’s theory of natural selection on logical grounds, continued to challenge the idea of the inheritance of acquired characteristics, and argued that natural selection best explained a wide range of adaptations. Finally, he critiqued Galton’s statistical view of heredity and argued that Galton had resurrected an outmoded typological concept of species, one which Darwin and other naturalists had shown to be incorrect. Brooks’s ideas resemble the “biological species concept” of the twentieth century, as developed by evolutionary biologist Ernst Mayr and others. The late-nineteenth century was not a period of total “eclipse” of Darwinism, as biologists and historians have hitherto seen it. Although the “Modern Synthesis” refers to the reconciliation of post-Mendelian genetics with evolution by natural selection, we might adjust our understanding of how the synthesis developed by seeing it as the culmination of a longer discussion that extends back to the late-nineteenth century. (shrink)