The Human Genome Project is nearing completion, and shortly we will have access to the complete genetic sequence of an average human being. Hopes are high that the sequence will contribute profoundly to medicine in particular, but also to our understanding of our evolutionary past. Of course, detractors have long insisted that because the HGP represents a victory for formalism in biology, determining the function of DNA sequences will remain an outstanding problem for at least the next several decades. Moreover, (...) it is not clear that having the complete sequence will be significantly useful to biologists seeking to understand gene function in the first place. What can we expect in the postgenomic era? ;I reject the very idea that a complete, encapsulated sequence of a human genome is foundational to biological understanding. I set my investigation within the framework of the ancient debate between preformationists and epigenecists. I survey and conceptually analyze arguments on both sides, especially as they relate to the separation of genetics and embryology in the early part of the twentieth century. I identify modern variants of both preformationism and epigenesis, and note their reconciliation in the form of a Modern Consensus on development established after the neo-Darwinian Synthesis in biology in the 1940s. ;Drawing on recent work in molecular and developmental biology, I challenge the seeming intuitiveness of the Modern Consensus and its subsumption of developmental concerns under the aegis of molecular genetics. I then propose and defend an alternative synthesis of preformationism and epigenesis, and of genetics and developmental biology, according to which development does not reduce to mere gene activation. I underscore the practical benefit of my perspective through a lengthy discussion of the psychiatric genetics approach to schizophrenia. (shrink)

This paper argues that the consensus physicalist antireductionism in the philosophy of biology cannot accommodate the research strategy or indeed the recent findings of molecular developmental biology. After describing Wolperts programmatic claims on its behalf, and recent work by Gehring and others to identify the molecular determinants of development, the paper attempts to identify the relationship between evolutionary and developmental biology by reconciling two apparently conflicting accounts of bio-function – Wrights and Nagels (as elaborated by Cummins). Finally, the paper seeks (...) a way of defending the two central theses of physicalist antireductionism in the light of the research program of molecular developmental biology, by sharply reducing their metaphysical force. (shrink)

The use of informational terms is widespread in molecular and developmental biology. The usage dates back to Weismann. In both protein synthesis and in later development, genes are symbols, in that there is no necessary connection between their form (sequence) and their effects. The sequence of a gene has been determined, by past natural selection, because of the effects it produces. In biology, the use of informational terms implies intentionality, in that both the form of the signal, and the response (...) to it, have evolved by selection. Where an engineer sees design, a biologist sees natural selection. (shrink)

I begin by examining how genetics drivesschizophrenia research, and raise both familiar andrelatively novel criticisms of the evidence putativelysupporting the genetic basis of schizophrenia. Inparticular, I call attention to a set of concernsabout the effects of placentation on concordance ratesof schizophrenia in monozygotic twins, which furtherweakens the case for schizophrenia''s so-called stronggenetic component. I then underscore two criticalpoints. First, I emphasize the importance of takingseriously considerations about the complexity of bothontogenesis and the development of hereditarydiseases. The recognition of developmentalconstraints and (...) supports is crucial, for attention todevelopment exposes the naivete of too many models ofgene action in the aetiology of disease. Secondly, Iattend to those schizophreniologists who ignoremethodological criticisms and thus presume a geneticbasis for schizophrenia, and then seek the schizophrenic genotype lacking an adequatephenotype. In response I attempt to demonstrate thenecessity of a sustained effort at characterizing thephenotype of schizophrenia as an enabling conditionfor the whole enterprise of psychiatric genetics – andfor psychiatry itself. Without the organism-levelphenotype, research at the level of genes will remainunproductive – assuming of course that research at thegenetic level is appropriate at all. (shrink)

Many scientists and philosophers of science are troubled by the relative isolation of developmental from evolutionary biology. Reconciling the science of development with the science of heredity preoccupied a minority of biologists for much of the twentieth century, but these efforts were not corporately successful. Mainly in the past fifteen years, however, these previously dispersed integrating programmes have been themselves synthesized and so reinvigorated. Two of these more recent synthesizing endeavours are evolutionary developmental biology and developmental systems theory. While the (...) former is a bourgeoning and scientifically well-respected biological discipline, the same cannot be said of DST, which is virtually unknown among biologists. In this review, we provide overviews of DST and EDB, summarize their key tenets, examine how they relate to one another and to the study of epigenetics, and survey the impact that DST and EDB have had on biological theory and practice. (shrink)

With the advent of the Human Genome Project there have been many claims for the genetic origins of complex human behavior including insanity, criminality, and intelligence. But what does it really mean to call something 'genetic'? This is the fundamental question that Sahotra Sarkar's book addresses. The author analyses the nature of reductionism in classical and molecular genetics. He shows that there are two radically different kinds of reductionist explanation: genetic reduction (as found in classical genetics) and physical reduction (found (...) in molecular genetics). This important book clarifies the meaning of the term 'genetic', shows how molecular studies have affected genetics, and provides the philosophical background necessary to understand the debates over the Human Genome Project. It will be of particular interest to professionals and students in the philosophy of science, the history of science, and the social studies of science, medicine, and technology. (shrink)

'...a challenging and useful book, both because it provokes a careful scrutiny of one's own basic ideas regarding evolutionary theory, and because it cuts across so many biological disciplines.' -The Quarterly Review of Biology 'In my view, this work exemplifies Theoretical Biology at its best...here is rampant speculation that is consistently based on cautious reasoning from the available data. Even more refreshing is the absence of sloganeering, grandstanding, and 'isms'.' -Biology and Philosophy 'Epigenetics is fundamental to understanding both development and (...) gene expression, and not surprisingly, evolutionary biologists have long been fascinated with its proper place in evolutionary theory...Enter Jablonka and Lamb, who provide a thoughtful review of the recent molecular literature and suggest a number of potential consequences.' -EvolutionSince first publication of this controversial book, much of the initial opposition to the ideas it contained has been replaced by a general, although often grudging, acceptance of them. Advances in knowledge, especially at the molecular level, have enhanced general awareness and interest in epigenetics and the evolution of systems that store and transmit information and put any of the authors' speculations on a more solid basis. This paperback edition contains a new Preface that sets out the major changes in the scientific world and in the authors' own thinking that have occurred since the book was published. A new Appendix provides a selected bibliography of the many books and articles about epigenetic inheritance and its role in evolution that have appeared since first publication. (shrink)

The question of the influence of genes on behavior raises difficult philosophical and social issues. In this paper I delineate what I call the Developmentalist Challenge (DC) to assertions of genetic influence on behavior, and then examine the DC through an indepth analysis of the behavioral genetics of the nematode, C. elegans, with some briefer references to work on Drosophila. I argue that eight "rules" relating genes and behavior through environmentally-influenced and tangled neural nets capture the results of developmental and (...) behavioral studies on the nematode. Some elements of the DC are found to be sound and others are criticized. The essay concludes by examining the relations of this study to Kitcher's antireductionist arguments and Bechtel and Richardson's decomposition and localization heuristics. Some implications for human behavioral genetics are also briefly considered. (shrink)

Evolutionary developmental biology (evo-devo) offers both an account of developmental processes and also new integrative frameworks for analyzing interactions between development and evolution. Biologists and philosophers are keen on evo-devo in part because it appears to offer a comfort zone between, on the one hand, what some take to be the relative inability of mainstream evolutionary biology to integrate a developmental perspective; and, on the other hand, what some take to be more intractable syntheses of development and evolution. In this (...) article, I outline core concerns of evo-devo, distinguish theoretical and practical variants, and counter Sterelny's recent argument that evo-devo's attention to development, while important, offers no significant challenge to evolutionary theory as we know it. (shrink)

The Developmental Systems approach to evolution is defended against the alternative extended replicator approach of Sterelny, Smith and Dickison (1996). A precise definition is provided of the spatial and temporal boundaries of the life-cycle that DST claims is the unit of evolution. Pacé Sterelny et al., the extended replicator theory is not a bulwark against excessive holism. Everything which DST claims is replicated in evolution can be shown to be an extended replicator on Sterelny et al.s definition. Reasons are given (...) for scepticism about the heuristic value claimed for the extended replicator concept. For every competitive, individualistic insight the replicator theorist has a cooperative, systematic blindspot. (shrink)

Evolutionary genetics is concerned with natural selection and neutral drift, to the virtual exclusion of almost everything else. In its current focus on DNA variation, it reduces phenotypes to symbols. Varying phenotypes, however, are the units of evolution, and, if we want a comprehensive theory of evolution, we need to consider both the internal and external evolutionary forces that shape the development of phenotypes. Genetic systems are redundant, modular and subject to a variety of genomic mechanisms of “turnover” (transposition, gene (...) conversion, unequal crossingover, slippage and so on). As such the construction and spread of novel combinations of modules by turnover, in particular within gene promoters, contributes significantly to the evolution of phenotypes. Furthermore, redundancy, turnover and modularity lead to ever more complex networks of genetic interactions and ever more functions for a given module. The significant interaction between genomic turnover and natural selection leads to a molecular coevolution between interacting modules and hence facilitates the establishment of biological novelties. BioEssays 22:1153–1159, 2000. © 2000 John Wiley & Sons, Inc. (shrink)