A common belief is that evolution generally proceeds towards greater complexity at both the organismal and the genomic level, numerous examples of reductive evolution of parasites and symbionts notwithstanding. However, recent evolutionary reconstructions challenge this notion. Two notable examples are the reconstruction of the complex archaeal ancestor and the intron‐rich ancestor of eukaryotes. In both cases, evolution in most of the lineages was apparently dominated by extensive loss of genes and introns, respectively. These and many other cases of reductive evolution (...) are consistent with a general model composed of two distinct evolutionary phases: the short, explosive, innovation phase that leads to an abrupt increase in genome complexity, followed by a much longer reductive phase, which encompasses either a neutral ratchet of genetic material loss or adaptive genome streamlining. Quantitatively, the evolution of genomes appears to be dominated by reduction and simplification, punctuated by episodes of complexification. (shrink)

This paper addresses the question of whether animals have souls and the ability to experience God after death within the limitations of their nature. Plausible explanations for the natural origin of life and for the development of subsequent complexity are increasingly being advanced by molecular biologists. Christian tradition and scholasticism teach that the human body is animated by the soul which is the agent of vital activities. This teaching is incompatible with the claim for a natural origin for life. At (...) some stage in the evolution of chordates and cephalopods a sense of self-awareness and an ability to distinguish between pleasure and the absence of pleasure would have arisen permitting the potential for ensoulment. The premise that evolution was gradual but ensoulment was discontinuous predicates the irrational conclusion that for one generation the parents were animals without souls and their children humans, made in the image of God, and with souls. Biological gradualism is incompatible with a sudden ensoulment dichotomy both in the evolutionary history of humans and for a maturing foetus, human or animal. Gradualism must apply to both body and soul. A Christian interpretation of physicalism, however, provides an alternative to dualism and resolves the paradoxes and difficulties relating to animals. (shrink)

A common method of improving how well understood a theory is, is by comparing it to another theory which has been better developed. Radical interpretation is a theory which attempts to explain how communication has meaning. Radical interpretation is treated as another time dependent theory and compared to the time dependent theory of biological evolution. Several similarities and differences are uncovered. Biological evolution can be gradual or punctuated. Whether radical interpretation is gradual or punctuated depends on how the question is (...) framed: on the coarse-grained time scale it proceeds gradually, but on the fine-grained time scale it proceeds by punctuated equilibria. Biological evolution proceeds by natural selection, the counterpart to this is the increase in both correspondence and coherence. Exaption, mutations, and spandrels have counterparts metaphor, speech errors, and puns respectively. Homologous and analogs have direct counterparts in specific words. The most important differences originate from the existence of a unit of inheritance occurring in biological evolution - there is no such unit in language. (shrink)

I identify two versions of the scientific anti-realist’s selectionist explanation for the success of science: Bas van Fraassen’s original and K. Brad Wray’s newer interpretation. In Wray’s version, psycho-social factors internal to the scientific community – viz. scientists’ interests, goals, and preferences – explain the theory-selection practices that explain theory-success. I argue that, if Wray’s version were correct, then science should resemble art. In art, the artwork-selection practices that explain artwork-success appear faddish. They are prone to radical change over time. (...) Theory-selection practices that explain theory-success in science are however not faddish. They are mostly stable; that is, long-lived and consistent over time. This is because scientists (explicitly or implicitly) subscribe to what I will call the testability norm: scientific theories must make falsifiable claims about the external physical world. The testability norm and not psycho-sociology explains the theory-selection practices that explain theory-success in science. Contra Wray, scientific anti-realists can then maintain that the external physical world (as expressed in the testability norm) explains theory-success. (shrink)

In a recent paper, Chris Haufe paints a provocative portrait of the late paleontologist Stephen Jay Gould. His principal aim is to resolve a “paradox” arising from a prima facie inconsistent pair of commitments: Gould believed that the biological facts could have been otherwise, and Gould believed that there are evolutionary laws. In order to resolve this paradox, Haufe makes two substantive claims: Gould was aware of the challenges that the Replay Thesis posed for a law-centered science of evolution, even (...) early in his career, and Gould endeavored to meet these challenges by deploying the “species-as-particles approach.” In this paper, I put pressure on both of these claims. By examining the goals and methods of Gould’s first “nomothetic research program,” the science of form, I show that it does not fit the picture of nomothetic science that Haufe illustrates. Additionally, I show that no straightforward connection exists between Gould’s understanding of contingency and his adoption of the species-as-particles approach. I propose that Gould’s career can be usefully split into three periods, each of which employed a distinct strategy for establishing distinctively paleontological contributions to evolutionary theory. (shrink)

This paper reviews and clarifies five misunderstandings about cultural evolution identified by Henrich et al.. First, cultural representations are neither discrete nor continuous; they are distributed across neurons that respond to microfeatures. This enables associations to be made, and cultural change to be generated. Second, ‘replicator dynamics’ do not ensure natural selection. The replicator notion does not capture the distinction between actively interpreted self-assembly code and passively copied self-description, which leads to a fundamental principle of natural selection: inherited information is (...) transmitted, whereas acquired information is not. Third, this principle is violated in culture by the ubiquity of acquired change. Moreover, biased transmission is less important to culture than the creative processes by which novelty is generated. Fourth, there is no objective basis for determining cultural fitness. Fifth, the necessity of randomness is discussed. It is concluded that natural selection inappropriate is an explanatory framework for culture. (shrink)

A common method of making a theory more understandable is to compare it to another theory that has been better developed. Radical interpretation is a theory that attempts to explain how communication has meaning. Radical interpretation is treated as another time-dependent theory and compared to the time-dependent theory of biological evolution. The main reason for doing this is to find the nature of the time dependence; producing analogs between the two theories is a necessary prerequisite to this and brings up (...) many problems. When the nature of the time dependence is better known it might allow the underlying mechanism to be uncovered. Several similarities and differences are uncovered, and there appear to be more differences than similarities. (shrink)

The Darwinian concept of natural selection was conceived within a set of Newtonian background assumptions about systems dynamics. Mendelian genetics at first did not sit well with the gradualist assumptions of the Darwinian theory. Eventually, however, Mendelism and Darwinism were fused by reformulating natural selection in statistical terms. This reflected a shift to a more probabilistic set of background assumptions based upon Boltzmannian systems dynamics. Recent developments in molecular genetics and paleontology have put pressure on Darwinism once again. Current work (...) on self-organizing systems may provide a stimulus not only for increased problem solving within the Darwinian tradition, especially with respect to origins of life, developmental genetics, phylogenetic pattern, and energy-flow ecology, but for deeper understanding of the very phenomenon of natural selection itself. Since self-organizational phenomena depend deeply on stochastic processes, self-organizational systems dynamics advance the probability revolution. In our view, natural selection is an emergent phenomenon of physical and chemical selection. These developments suggest that natural selection may be grounded in physical law more deeply than is allowed by advocates of the autonomy of biology, while still making it possible to deny, with autonomists, that evolutionary explanations can be modeled in terms of a deductive relationship between laws and cases. We explore the relationship between, chance, self-organization, and selection as sources of order in biological systems in order to make these points. (shrink)

Tinbergen’s classic “On Aims and Methods of Ethology” (_Zeitschrift für Tierpsychologie, 20_, 1963) proposed four levels of explanation of behavior, which he thought would soon apply to humans. This paper discusses the need for multilevel explanation; Huxley and Mayr’s prior models, and others that followed; Tinbergen’s differences with Lorenz on “the innate”; and Mayr’s ultimate/proximate distinction. It synthesizes these approaches with nine levels of explanation in three categories: phylogeny, natural selection, and genomics (ultimate causes); maturation, sensitive period effects, and routine (...) environmental effects (intermediate causes); and hormonal/metabolic processes, neural circuitry, and eliciting stimuli (proximate causes), as a respectful extension of Tinbergen’s levels. The proposed classification supports and builds on Tinbergen’s multilevel model and Mayr’s ultimate/proximate continuum, adding intermediate causes in accord with Tinbergen’s emphasis on ontogeny. It requires no modification of Standard Evolutionary Theory or The Modern Synthesis, but shows that much that critics claim was missing was in fact part of Neo-Darwinian theory (so named by J. Mark Baldwin in _The American Naturalist_ in 1896) all along, notably reciprocal causation in ontogeny, niche construction, cultural evolution, and multilevel selection. Updates of classical examples in ethology are offered at each of the nine levels, including the neuroethological and genomic findings Tinbergen foresaw. Finally, human examples are supplied at each level, fulfilling his hope of human applications as part of the biology of behavior. This broad ethological framework empowers us to explain human behavior—eventually completely—and vindicates the idea of human nature, and of humans as a part of nature. (shrink)

The Darwinian theory of evolution is itself evolving and this book presents the details of the core of modern Darwinism and its latest developmental directions. The authors present current scientific work addressing theoretical problems and challenges in four sections, beginning with the concepts of evolution theory, its processes of variation, heredity, selection, adaptation and function, and its patterns of character, species, descent and life. The second part of this book scrutinizes Darwinism in the philosophy of science and its usefulness in (...) understanding ecosystems, whilst the third section deals with its application in disciplines beyond the biological sciences, including evolutionary psychology and evolutionary economics, Darwinian morality and phylolinguistics. The final section addresses anti-Darwinism, the creationist view and issues around teaching evolution in secondary schools. The reader learns how current experimental biology is opening important perspectives on the sources of variation, and thus of the very power of natural selection. This work examines numerous examples of the extension of the principle of natural selection and provides the opportunity to critically reflect on a rich theory, on the methodological rigour that presides in its extensions and exportations, and on the necessity to measure its advantages and also its limits. Scholars interested in modern Darwinism and scientific research, its concepts, research programs and controversies will find this book an excellent read, and those considering how Darwinism might evolve, how it can apply to the human sciences and other disciplines beyond its origins will find it particularly valuable. Originally produced in French (Les Mondes Darwiniens), the scope and usefulness of the book have led to the production of this English text, to reach a wider audience. This book is a milestone in the impressive penetration by Francophone scholars into the world of Darwinian science, its historiography and philosophy over the last two decades. Alex Rosenberg, R. Taylor Cole Professor of Philosophy, Duke University Until now this useful and comprehensive handbook has only been available to francophones. Thanks to this invaluable new translation, this collection of insightful and original essays can reach the global audience it deserves. Tim Lewens, University of Cambridge. (shrink)

The term adaptive radiation has been recurrently used to describe evolutionary patterns of several lineages, and has been proposed as the main driver of biological diversification. Different definitions and criteria have been proposed to distinguish an adaptive radiation, and the current literature shows disagreements as to how radiating lineages should be circumscribed. Inconsistencies increase when authors try to differentiate a clade under adaptive radiation from clades evolving under ‘regular’ speciation with adaptation, a pattern anticipated and predicted by the evolutionary theory (...) in any lineage. The most important disagreement is as to which evolutionary rate authors analyze to characterize a radiation; a discussion embedded in a prevailing inability to provide mechanistic explanations of the relationship among evolutionary rates. The union of pattern and process in the same term, the inadequacy of reported null hypotheses, and the frequent use of ad hoc comparisons between lineages have also contributed to the lack of consensus. A rigorous use of available terms and the articulation of solid criteria with objective methodologies in distinguishing evolutionary patterns are imperative. Given the difficulties in detecting adaptation, the use of the ‘adaptive’ term to qualify a radiation should be avoided unless methodologically tested. As an unambiguous method to distinguish radiating lineages, the statistical detection of significant increases in taxonomic diversification rates on monophyletic lineages can be considered a distinctive signature of a radiation. After recognizing this pattern, causal hypotheses explaining them can be stated, as well as correlates with other rates of evolution. (shrink)

The evolution of the biosphere has led to creation of astrophysical and telluric stable perfect system biotic regulation, which based on a high degree of closure of natural cycles. The development of human beings as bio-social, beyond the biological patterns, break these closed cycles, and dramatically broke the biotic regulation of the biosphere. As results — sustainable biosphere has become unsustainable anthroposphere. As with the origin of life physico-chemical regularities of the structure of matter turned out to be “mastered” life, (...) as soon as with the emergence of anthroposphere physical-chemicalbiological regularities of evolution are complemented by social ones. The result of the violation of natural biotic regulation broke a global environmental crisis that boomerang begins it is dangerous to human. It is theoretically possible to overcome this ecological crisis by the transition from the Neolithic paradigm of “nature conquest”, to the organization of “crisis management” of the biosphere by the activity of the society restore and “repair” the damaged processes in the biosphere. This requires a new organization in all areas of human activity, i.e., a fundamentally new paradigm of human behavior on the planet. Development within the paradigm of the Neolithic culture, leads to an increasing accumulation of non-degradable waste, determines the fatal instability of anthroposphere and, therefore, unsustainable development of civilization. It is a mistake to assume that human’s dependence on nature is reduced — it takes a different form. The forces of human as an intelligence being, “recollecting himself”, about the offense with lifesupporting bioshere’ systems, and based on the concept of controlled evolution, to assist nature to restore the disturbed natural regulations of biospheric processes. For this it need to find out what the thresholds for allowable violations of natural processes are already accomplished, and develop a plan of action for the reduction of disturbances, relying on the regenerative potential of living nature and resources of the human mind. (shrink)

The aim of this dissertation is to create a naturalistic philosophical picture of creative capacities that are specific to our species, focusing on artistic ability, religious reflection, and scientific study. By integrating data from diverse domains within a philosophical anthropological framework, I have presented a cognitive and evolutionary approach to the question of why humans, but not other animals engage in such activities. Through an application of cognitive and evolutionary perspectives to the study of these behaviors, I have sought to (...) provide a more solid footing for philosophical anthropological discussions of uniquely human behavior. In particular, I have argued that art, religion and science, which are usually seen as achievements that are quite remote from ordinary modes of reasoning, are subserved by evolved cognitive processes that serve functions in everyday cognitive tasks, that arise early and spontaneously in cognitive development, that are shared cross-culturally, and that have evolved in response to selective pressures in our ancestral past. These mundane cognitive processes provide a measuring rod with which we can assess a diversity of cultural phenomena; they form a unified explanatory framework to approach human culture. I have argued that we can explain uncommon thoughts in terms of interactions between common minds. This dissertation is subdivided into four parts. Part I outlines the problem of human uniqueness, examining theories on how humans conceptualize the world, and what their mental tool box looks like. Part II discusses the evolutionary and cognitive origins of human artistic behavior. Part III focuses on the cognitive science of religion, especially on how it can be applied to the reasoning of theologians and philosophers of religion. Part IV considers the cognitive basis of scientific practice. (shrink)

James Shapiro’s view of evolution is inspired by looking at the molecular mechanisms of mutation. Finding these systems to be intelligent and the mutations non-gradual, Shapiro concludes that neither the role of DNA in development, nor and the role of natural selection in evolution are what we thought them to be. The cases discussed are interesting and may require some modification of theory in biology, but this reviewer finds many of Shapiro’s conclusions unwarranted.

Christian ethics accentuates in manifold ways the unique character of human nature. Personalists believe that the mind is never reducible to material and physical substance. The human person is presented as the supreme principle, based on arguments referring to free-willed actions, the immateriality of both the divine spirit and the reflexive capacity, intersubjectivity and self-consciousness. But since Darwin, evolutionary biology slowly instructs us that morality roots in dispositions that are programmed by evolution into our nature. Historically, Thomas Huxley, “Darwin's bulldog,” (...) agreed with Darwin on almost everything, except for his gradualist position on moral behavior. Huxley's “saltationism” has recently been characterized by Frans de Waal as “a veneer theory of morality.” Does this mark the end of a period of presenting morality as only the fruit of socialization processes (nurture) and as having nothing in common with nature? Does it necessarily imply a corrosion of personalist views on the human being or do Christian ethics have to become familiar again with their ancient roots? (shrink)

In his recent book on Darwinism, Daniel Dennett has offered up a species of a priori selectionism that he calls algorithmic. He used this view to challenge a number of positions advocated by Stephen J. Gould. I examine his algorithmic conception, review his unqualified enthusiasm for the a priori selectionist position, challenge Dennett's main metaphors (cranes vs. skyhooks and a design space), examine ways in which his position has lead him to misunderstand or misrepresent Gould (spandrels, exaptation, punctuated equilibrium, contingency (...) and disparity), and discuss recent results in developmental biology that suggest that an a priori position does not fill the demands of an evolutionary biology. I conclude by insisting that evolutionary biology is many leveled, complicated, and is carried on an ever shifting and expanding empirical base that when disregarded results in caricature. (shrink)

Many attempts have been made at supporting either one of the allegedly complementary divergence models Phyletic Gradualism and Punctuated Equilibria by patterns found in specific fossil sequences. However, assessing each model's connection with reality via such “individual case histories” appears not to constitute a relevant approach. Instead, in order to correctly establish the possible merits of both concepts, the claims of each have to be verified against general evolutionary theory. This is being pointed out herein by analyzing cladogenesis at the (...) specific level as an example. [Phyletic Gradualism; Punctuated Equilibria; evolutionary theory; divergence models; case histories; additive speciation.]. (shrink)

I respond to Stanley Klein's critique of my essay “Quantum Reality, the Emergence of Complex Order from Virtual States, and the Importance of Consciousness in the Universe,” arguing in support of the necessity to derive a quantum perspective of evolution rather than adhering to an essentially classical view. In response to Klein's criticism of my concept of a cosmic morality, the origins of that concept are traced back to Zeno of Citium. I wholeheartedly embrace Klein's suggestion that the new science (...) inspires views of the human condition that can help us make the world a better place. (shrink)

This book is divided in two parts, the first of which shows how, beyond paleontology and systematics, macroevolutionary theories apply key insights from ecology and biogeography, developmental biology, biophysics, molecular phylogenetics, and even the sociocultural sciences to explain evolution in deep time. In the second part, the phenomenon of macroevolution is examined with the help of real life-history case studies on the evolution of eukaryotic sex, the formation of anatomical form and body-plans, extinction and speciation events of marine invertebrates, hominin (...) evolution and species conservation ethics. The book brings together leading experts, who explain pivotal concepts such as Punctuated Equilibria, Stasis, Developmental Constraints, Adaptive Radiations, Habitat Tracking, Turnovers, (Mass) Extinctions, Species Sorting, Major Transitions, Trends, and Hierarchies – key premises that allow macroevolutionary epistemic frameworks to transcend microevolutionary theories that focus on genetic variation, selection, migration and fitness. Along the way, the contributing authors review ongoing debates and current scientific challenges; detail new and fascinating scientific tools and techniques that allow us to cross the classic borders between disciplines; demonstrate how their theories make it possible to extend the Modern Synthesis; present guidelines on how the macroevolutionary field could be further developed; and provide a rich view of just how it was that life evolved across time and space. In short, this book is a must-read for active scholars and, because the technical aspects are fully explained, it is also accessible for non-specialists. Understanding evolution requires a solid grasp of above-population phenomena. Species are real biological individuals, and abiotic factors impact the future course of evolution. Beyond observation, when the explanation of macroevolution is the goal, we need both evidence and theory that enable us to explain and interpret how life evolves at the grand scale. (shrink)

An important question facing contemporary philosophy of science is whether the natural sciences in terms of their historical records exhibit distinguishing developmental patterns or structures. At least two philosophical stances are possible in answering this question. The first pertains to the plurality of the individual sciences. From this stance, the various sciences are analyzed individually and compared with one another in order to derive potential commonalities, if any, among them. The second stance involves a general philosophy of science in which (...) a thorough theory of the natural sciences is developed. The latter stance strives to account for more than possible commonalities among the sciences but also to provide a broad-spectrum philosophical framework to account for, or to explicate, the nature of science itself and its progress. In this paper, the second stance is taken in which an evolutionary philosophy of science is proposed. To that end, Thomas Kuhn’s evolutionary philosophy of science is initially discussed and critiqued. An evolutionary philosophy of science is then proposed based on a revision of Kuhn’s evolutionary philosophy of science in terms of George Gaylord Simpson’s various tempos and modes for biological evolution. Next, two historical case studies from the biological sciences are reconstructed to illustrate the robustness of the proposed evolutionary philosophy of science for explicating the progress of the natural sciences. A concluding section discusses the proposed evolutionary philosophy of science with respect to providing a broad-spectrum framework or general philosophy of science for understanding the nature and progress of the natural sciences. (shrink)

For principled and substantially philosophical reasons, based largely on his reform of natural history by inverting the Paleyan notion of overarching and purposeful beneficence in the construction of organisms, Darwin built his theory of selection at the single causal level of individual bodies engaged in unconscious struggle for their own reproductive success. But the central logic of the theory allows selection to work effectively on entities at several levels of a genealogical hierarchy, provided that they embody a set of requisite (...) features for defining evolutionary individuality. Genes, cell lineages, demes, species, and clades-as well as Darwin’s favoured organisms-embody these requisite features in enough cases to form important levels of selection in the history of life. R. A. Fisher explicitly recognized the unassailable logic of species selection, but denied that thsi real process could be important in evolution because, compared with the production of new organisms within a species, the origin of new species is so rare, and the number of species within most clades so low. I review this and other classical arguments against higher-level selection, and conclude that they are invalid in practice for interdemic selection, and false in principle for species selection. Punctuated equilibrium defines the individuality of species and refutes Fisher’s classical argument based on cycle time. In the second part of the paper, I argue that we have failed to appreciate the range and power of selection at levels above and below the organismic because we falsely extrapolate the defining properties of organisms to these other levels, and then regard the other levels as impotent because their effective individuals differ so much from organisms. We would better appreciate the power and generality of hierarchical models of selection if we grasped two key principles: first, that levels can interact in all modes, and not only in the negative style that, for heuristic and operational reasons, has received almost exclusive attention in the existing literature; and second, that each hierarchical level differs from all others in substantial and interesting ways, both in the style and frequency of patterns in change and causal modes. (shrink)

Darwinism is defined here as an evolving research tradition based upon the concepts of natural selection acting upon heritable variation articulated via background assumptions about systems dynamics. Darwin’s theory of evolution was developed within a context of the background assumptions of Newtonian systems dynamics. The Modern Evolutionary Synthesis, or neo-Darwinism, successfully joined Darwinian selection and Mendelian genetics by developing population genetics informed by background assumptions of Boltzmannian systems dynamics. Currently the Darwinian Research Tradition is changing as it incorporates new information (...) and ideas from molecular biology, paleontology, developmental biology, and systems ecology. This putative expanded and extended synthesis is most perspicuously deployed using background assumptions from complex systems dynamics. Such attempts seek to not only broaden the range of phenomena encompassed by the Darwinian Research Tradition, such as neutral molecular evolution, punctuated equilibrium, as well as developmental biology, and systems ecology more generally, but to also address issues of the emergence of evolutionary novelties as well as of life itself. (shrink)

Christian ethics accentuates in manifold ways the unique character of human nature. Personalists believe that the mind is never reducible to material and physical substance. The human person is presented as the supreme principle, based on arguments referring to free‐willed actions, the immateriality of both the divine spirit and the reflexive capacity, intersubjectivity and self‐consciousness. But since Darwin, evolutionary biology slowly instructs us that morality roots in dispositions that are programmed by evolution into our nature. Historically, Thomas Huxley, “Darwin's bulldog,” (...) agreed with Darwin on almost everything, except for his gradualist position on moral behavior. Huxley's “saltationism” has recently been characterized by Frans de Waal as “a veneer theory of morality.” Does this mark the end of a period of presenting morality as only the fruit of socialization processes (nurture) and as having nothing in common with nature? Does it necessarily imply a corrosion of personalist views on the human being or do Christian ethics have to become familiar again with their ancient roots? (shrink)

Evolutionary stasis is discussed in light of the idea that the common output of every successful evolution is the creation of the entities that are increasingly resistant to further change. The moving force of evolution is entropy. This general aspiration for chaos is a cause of the mortality of organisms and extinction of species. However, being a prerequisite for any motion, entropy generates (by chance) novelties, which may happen to be (by chance) more resistant to further decay and thus survive. (...) The entities that change rapidly disappear. All existing entities are endowed with an ability to resist further change. In simple organisms, the stasis is primarily achieved by means of the high fidelity of DNA reproduction. In organisms with a large genome and complex development, the achievable fidelity of genome reproduction fails to guarantee homeorhetic reproduction: there is more mutation than reproduction. Such species must be capable of surviving and remain phenotypically unchanged at continuous changes of their genes. This capability (canalization or robustness) reflects a global degeneracy of the link structure-function: there are more genotypes than phenotypes. Hence, function (i.e. meaning), not structure, is selected. The selection for successful ontogenesis in a varying environment creates developmental robustness to mutational and environmental perturbations and, consequently, to the halt of evolution. Evolution is resistance to entropy, the adaptation to environment being only one of the means of this resistance. Everything essential in biology is determined not by physical causality but by semantic rules and goal-directed programs. This principal operates on various levels of biological organization. (shrink)

Have the large-scale evolutionary patterns illustrated by the fossil record been driven by fluctuations in environmental opportunity, by biotic factors, or by changes in the types of phenotypic variants available for evolutionary change? Since the Modern Synthesis most evolutionary biologists have maintained that microevolutionary processes carrying on over sufficient time will generate macroevolutionary patterns, with no need for other pattern-generating mechanisms such as punctuated equilibrium or species selection. This view was challenged by paleontologists in the 1970s with proposals that the (...) differential sorting and selection of species and clades, and the effects of biotic crises such as mass extinctions, were important extensions to traditional evolutionary theory. More recently those interested in macroevolution have debated the relative importance of abiotic and biotic factors in driving macroevolutionary patterns and have introduced comparative phylogenetic methods to analyze the rates of change in taxonomic diversity. Applying Peter Godfrey-Smith’s distinction between distributional explanations and explanations focusing on the origin of variation, most macroevolutionary studies have provided distributional explanations of macroevolutionary patterns. Comparative studies of developmental evolution, however, have implicated the origin of variants as a driving macroevolution force. In particular, the repatterning of gene regulatory networks provides new insights into the origins of developmental novelties. This raises the question of whether macroevolution has been pulled by the generation of environmental opportunity, or pushed by the introduction of new morphologies. The contrast between distributional and origination scenarios has implications for understanding evolutionary novelty and innovation and how macroevolutionary process may have evolved over time. (shrink)

Plusieurs aspects de l’histoire évolutive sont envisagés. Les grands événements font intervenir des facteurs externes qui jouent au hasard. Les grandes séries évolutives montrent des sélections directionnelles constantes, qui orientent les changements morphologiques. Les équilibres ponctués et leur forte réintroduction de hasards sont critiqués. L’histoire des mammifères montre des évolutions répétées dans de multiples lignées de caractères nouveaux, qui suggèrent des contraintes de développement. Les progrès récents en biologie du développement expliquent comment les variations phénotypiques sont délimitées, réduisant fortement le (...) nombre des chemins évolutifs possibles. Cette diminution de la part du hasard rend l’évolution plus compréhensible. Several aspects of evolutionary history are here taken into consideration. Great events call for external factors, which operate largely by chance. Long evolutionary series manifest directional selections that are constant, orienting morphological changes. Punctuated equilibria and their strong reintroduction of chance factors are criticized. The history of mammals evinces repeated evolutions within multiple lineages of new characters, which suggest developmental constraints. Recent advances in developmental biology explain how phenotypic variations are limited, reducing considerably the number of possible evolutionary paths. This diminution of the role of chance makes evolution more comprehensible. (shrink)