In recent years, several prominent biologists have pointed to the relatively new field of evolutionary developmental biology (EvoDevo) as evidence of an Extended Synthesis in evolutionary biology. More particularly, these biologists claim that theoretical and empirical EvoDevo research is extending the Modern Synthesis framework of evolutionary theory through investigation of evolutionarily important concepts that are not part of the framework developed during the 20th century. To describe the current changes in evolutionary biology as an Extended Synthesis, however, is incorrect. Through (...) review of Extended Synthesis arguments and analysis of the same biological concepts used to support these arguments, I argue that the foundation of the Modern Synthesis framework, theoretical population genetics, faces significant, perhaps insurmountable challenges from the concepts highlighted by EvoDevo research. As the foundation of the Modern Synthesis framework will require considerable remodeling—if possible—in light of the concepts emphasized by EvoDevo, it is incorrect to describe the ongoing changes in evolutionary biology as an Extended Synthesis. (shrink)

From its inception Darwinian evolutionary biology has been seen as having a problematic relationship of fact and theory. While the forging of the modern evolutionary synthesis resolved most of these issues for biologists, critics continue to argue that natural selection and common descent are “only theories.” Much of the confusion engendered by the “evolution wars” can be clarified by applying the concept of phenomena, inferred from fact, and explained by theories, thus locating where legitimate dissent may still exist. By setting (...) such analysis in the context of research traditions, it is possible to gain further insight into the complex interplay of facts, phenomena, and theories. Two case studies are explored to assess the value of such approaches, one from within evolutionary biology, the Baldwin effect, and one from outside, intelligent design. (shrink)

In the 1940s, the ‘modern synthesis’ (MS) of Darwinism and genetics cast genetic mutation and recombination as the source of variability from which environmental events naturally select the fittest, such ‘natural selection’ constituting the cause of evolution. Recent biology increasingly challenges this view by casting genes as followers and awarding the leading role in the genesis of adaptations to the agency and plasticity of developing phenotypes—making natural selection a consequence of other causal processes. Both views of natural selection claim to (...) capture the core of Darwin’s arguments in On the Origin of Species. Today, historians largely concur with the MS’s reading of Origin as a book aimed to prove natural selection the cause (vera causa) of adaptive change. This paper finds the evidence for that conclusion wanting. I undertake to examine the context and meaning of all Darwin’s known uses of the phrase vera causa, documenting in particular Darwin’s resistance to the pressure to prove natural selection a vera causa in letters written early in 1860. His resistance underlines the logical dependence of natural selection, an unobservable phenomenon, on the causal processes producing the observable events captured by the laws of inheritance, variation, and the struggle for existence, established in Chapters 1–3 of Origin. (shrink)

Between 1946 and 1960, a new phenomenon emerged in the field of bacteriology. "Bacterial sex," as it was called, revolutionized the study of genetics, largely by making available a whole new class of cheap, fast-growing, and easily manipulated organisms. But what was "bacterial sex?" How could single-celled organisms have "sex" or even be sexually differentiated? The technical language used in the scientific press -- the public and inalienable face of 20th century science -- to describe this apparently neuter organism was (...) explicit: the cells "copulated," had "intimate contract," "conjugal unions," and engaged in "ménage à trois" relationships. And yet, to describe bacteria as sexually reproducing organisms, the definition of sex itself had to change. Despite manifold contradictions and the availability of alternative language, the notion of sexually active (even promiscuous) single-celled organisms has persisted, even into contemporary textbooks on cell biology and genetics. In this paper I examine the ways in which bacteria were brought into the genetic fold, sexualized, and given gender; I also consider the issues underlying the durability of "bacterial sex.". (shrink)

Common folks “have” emotions and talk to others; and sometimes they make “their” emotions the topic of such talk. The emotions seem to be “theirs,” since they can be conceived of as private states ; and they can be topicalized, because we seem to be able to attribute or lend a conventionalized public form to some inner state or event. This is the way much of our folk-talk and folk-thinking about emotions, the expression thereof, the role of language in these (...) expressions, and communication in general are organized. However, as we have shown, such talk serves the purpose of communicating effectively and reaching mutual understanding. (shrink)

There are several different ways in which chance affects evolutionary change. That all of these processes are called “random genetic drift” is in part a due to common elements across these different processes, but is also a product of historical borrowing of models and language across different levels of organization in the biological hierarchy. A history of the concept of drift will reveal the variety of contexts in which drift has played an explanatory role in biology, and will shed light (...) on some of the philosophical controversy surrounding whether drift is a cause of evolutionary change. (shrink)

The evolutionary synthesis of the 1930s and 1940s integrated the study of biological microevolution and biological macroevolution into the theoretically consistent and hugely productive field of evolutionary biology. A similar synthesis has yet to occur for the study of culture, and the social sciences remain fragmented and theoretically incompatible. Here, it is suggested that a Darwinian theory of cultural evolution can promote such a synthesis. Earlier non-Darwinian theories of cultural evolution, such as progress theories, lacked key elements of a Darwinian (...) theory of cultural evolution that are necessary to promote a synthesis, while other contemporary theories of cultural evolution, such as memetics, make too stringent neo-Darwinian assumptions that are inconsistent with evidence regarding cultural transmission. Several examples are given which indicate the beginnings of an evolutionary synthesis for culture, where patterns of cultural macroevolution have been explained in terms of underlying cultural microevolutionary forces. Finally, it is argued that experimental simulations of cultural evolution can play an important role in this emerging synthesis. (shrink)

The T/t locus was a major focus of study by mouse geneticists during the 20th century. In the 70s, as the study of cell surface antigens controlling transplantation antigens was taking off, several laboratories hypothesized that alleles of this locus would control cell surface antigens important for embryonic development. One such antigen, the embryonal carcinoma F9 antigen was said to be an example. Other antigens were described on sperm and embryos that were said to be controlled by alleles at the (...) T/t complex. These findings were later found to be false. The history of the findings and their refutation is described. (shrink)

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)