Twenty years have passed since Gould and Lewontin published their critique of ‘the adaptationist program’ – the tendency of some evolutionary biologists to assume, rather than demonstrate, the operation of natural selection. After the ‘Spandrels paper’, evolutionists were more careful about producing just-so stories based on selection, and paid more attention to a panoply of other processes. Then came reactions against the excesses of the anti-adaptationist movement, which ranged from a complete dismissal of Gould and Lewontin’s contribution to a positive (...) call to overcome the problems. We now have an excellent opportunity for finally affirming a more balanced and pluralistic approach to the study of evolutionary biology. (shrink)
This article discusses various dangers that accompany the supposedly benign methods in behavioral evoltutionary biology and evolutionary psychology that fall under the framework of "methodological adaptationism." A "Logic of Research Questions" is proposed that aids in clarifying the reasoning problems that arise due to the framework under critique. The live, and widely practiced, " evolutionary factors" framework is offered as the key comparison and alternative. The article goes beyond the traditional critique of Stephen Jay Gould and Richard C. Lewontin, (...) to present problems such as the disappearance of evidence, the mishandling of the null hypothesis, and failures in scientific reasoning, exemplified by a case from human behavioral ecology. In conclusion the paper shows that "methodological adaptationism" does not deserve its benign reputation. (shrink)
Scientific Realism (SR) has three crucial aspects: 1) the centrality of the concept of truth, 2) the idea that success is a reliable indicator of truth, and 3) the idea that the Inference to the Best Explanation is a reliable inference rule. It will be outlined how some realists try to overcome the difficulties which arise in justifying such crucial aspects relying on an adaptationist view of evolutionism, and why such attempts are inadequate. Finally, we will briefly sketch some of (...) the main difficulties the realist has to face in defending those crucial aspects, and how such difficulties are deeply related: they derive from the inability of SR to satisfyingly avoid the sceptical challenge of the criterion of truth. Indeed, SR seems not to be able to fill the so-called ‘epistemic gap’ (Sankey 2008). In fact, the epistemic gap cannot be filled in no way other than obtaining a criterion of truth, but such a criterion cannot be obtained if the epistemic gap obtains. (shrink)
Strong adaptationists explore complex organic design as taskspecific adaptations to ancestral environments. This strategy seems best when there is evidence of homology. Weak adaptationists don't assume that complex organic (including cognitive and linguistic) functioning necessarily or primarily represents taskspecific adaptation. This approach to cognition resembles physicists' attempts to deductively explain the most facts with fewest hypotheses. For certain domainspecific competencies (folkbiology) strong adaptationism is useful but not necessary to research. With grouplevel belief systems (religion) strong adaptationism degenerates into (...) spurious notions of social function and cultural selection. In other cases (language, especially universal grammar) weak adaptationism's 'minimalist' approach seems productive. (shrink)
This contribution to the adaptationism debate elaborates the nature of constraints and their importance in evolutionary explanation and argues that the adaptationism debate should be limited to the issue of how to privilege causes in evolutionary explanation. I argue that adaptationist explanations are deeply conceptually dependent on developmental constraints, and explanations that appeal to constraints are dependant on the results of natural selection. I suggest these explanations should be integrated into the framework of historical causal explanation. Each strategy (...) explicitly appeals to some aspect of the evolutionary process, while implicitly appealing to others. Thus, adaptationists and anti-adaptationists can offer complementary causal explanations of the same explanandum. This eliminates much of the adaptationism debate and explains why its adversaries regularly agree with each other more than they would like. The adaptationism issue that remains is a species of the general issue of how to privilege causes in explanation. I show how a proposed solution to this general problem might be brought to bear on evolutionary explanations, and investigate some difficulties that might arise due to the nature of the evolutionary process. (shrink)
The rights and wrongs of adaptationism areoften discussed by appeal to what I call theartefact model. Anti-adaptationistscomplain that the use of optimality modelling,reverse engineering and other techniques areindicative of a mistaken and outmoded beliefthat organisms are like well-designedartefacts. Adaptationists (e.g. Dennett 1995)respond with the assertion that viewingorganisms as though they were well designed isa fruitful, perhaps necessary research strategyin evolutionary biology. Anti-adaptationistsare right when they say that techniques likereverse engineering are liable to mislead. This fact does not undermine the (...) artefact modelprecisely because the same techniques misleadus for the same reasons when they are appliedunreflectively to artefacts. Thoseadaptationists who hold only that it isworthwhile to investigate organisms as thoughthey were artefacts and thoseanti-adaptationists who criticise simplisticdesign models have far more in common than thelabels attached to their positions mightsuggest. (shrink)
Evolutionary psychologists attempt to infer our evolved psychology from the selection pressures present in our ancestral environments. Their use of this inference strategy?often called ?adaptive thinking??is thought to be justified by way of appeal to a rather modest form of adaptationism, according to which the mind's adaptive complexity reveals it to be a product of selection. I argue, on the contrary, that the mind's being an adaptation is only a necessary and not a sufficient condition for the validity of (...) adaptive thinking, and that evolutionary psychology's predictive project is in fact committed to an extremely strong and highly implausible form of adaptationism. According to this ?strong adaptationism,? the macroevolutionary trajectory of a population is determined by, and therefore predictable on the basis of, the selection pressures acting upon it. Not only is this form of adaptationism prima facie highly implausible, it requires making a number of naïve and likely false assumptions concerning the nature of heritable phenotypic variation in natural populations. In particular, it assumes that phenotypic variation is inevitably small in its extent, unbiased in its direction, and copious in its quantity. Because it is unlikely that these conditions obtain as a general rule, and even more unlikely that they obtained in early human populations, I conclude that there is little reason to believe that adaptive thinking can be used to infer the current structure of our minds from evidence of past selection pressures. (shrink)
Elliott Sober (1987, 1993) and Orzack and Sober (forthcoming) argue that adaptationism is a very general hypothesis that can be tested by testing various particular hypotheses that invoke natural selection to explain the presence of traits in populations of organisms. In this paper, I challenge Sobers claim that adaptationism is an hypothesis and I argue that it is best viewed as a heuristic (or research strategy). Biologists would still have good reasons for employing this research strategy even if (...) it turns out that natural selection is not the most important cause of evolution. (shrink)
This paper critically examines Jerry Fodor's latest attacks on evolutionary psychology. Contra Leda Cosmides and John Tooby, Fodor argues (i) there is no reason to think that human cognition is a Darwinian adaptation in the first place, and (ii) there is no valid inference from adaptationism about the mind to massive modularity. However, Fodor maintains (iii) that there is a valid inference in the converse direction, from modularity to adaptationism, but (iv) that the language module is an exception (...) to the validity of this inference. I explore Fodor's arguments for each of these claims, and the interrelations between them. I argue that Fodor is incorrect on point (i), correct on point (ii), partially correct on point (iii), and incorrect on point (iv). Overall, his critique fails to show that adopting a broadly Darwinian approach to cognition is intellectually indefensible. (shrink)
This chapter contains sections titled: * I Introduction * II One Preliminary * III Adaptationist Theories * IV Punishment Theories * V Commitment Signaling * VI Group Selection * V Conclusion * Notes * References.
Two decades ago, the eminent evolutionary biologist George C. Williams and his physician coauthor, Randolph Nesse, formulated the evolutionary medicine research program. Williams and Nesse explicitly made adaptationism a core component of the new program, which has served to undermine the program ever since, distorting its practitioners’ perceptions of evidentiary burdens and in extreme cases has served to warp practitioner’s understandings of the relationship between evolutionary benefits/detriments and medical ones. I show that the Williams and Nesse program more particularly (...) embraces the panselectionist variety of adaptationism (the empirical assumption that non-adaptive evolutionary processes are causally unimportant compared to natural selection), and argue that this has harmed the field. Panselectionism serves to conceal the enormous evidentiary hurdles that evolutionary medicine hypotheses face, making them appear stronger than they are. I use two examples of evolutionary medicine texts, on neonatal jaundice and on asthma, to show that some evolutionary medicine practitioners have allowed their fervent panselectionism to directly shape their recommendations for clinical practice. I argue that this escalation of panselectionism’s influence is inappropriate under Williams’ and Nesse original stated standards, despite being inspired by their program. I also show that the examples’ conflation of clinical and evolutionary considerations is inappropriate even under Christopher Boorse’s controversial evolution-rooted concepts of disease and health. (shrink)
This chapter focuses on the issue of methodological usefulness of a strong versus weak adaptationist position in attempting to gain significant insight and to make scientifically important advances and discoveries in human cognition. Strong adaptationism holds that complex design is best explained by task-specific adaptations to particular ancestral environments; whereas weak adaptationism claims that we should not assume that complex design is the result of such narrowly determined task- or niche-specific evolutionary pressures in the absence of substantial corroborating (...) evidence. It argues that in cases of certain domain-specific cognitive competencies strong adaptationism has proven useful but not necessary to recent progress in the field. In other cases, a weak adaptationist strategy has been arguably most productive in advancing scientific understanding, without precluding that the structures uncovered by other means are actually adaptations. (shrink)
Godfrey-Smith ( 2001 ) has distinguished three types of adaptationism. This article builds on his analysis, and revises it in places, by distinguishing seven varieties of adaptationism. This taxonomy allows us to clarify what is at stake in debates over adaptationism, and it also helps to cement the importance of Gould and Lewontin’s ‘Spandrels’ essay. Some adaptationists have suggested that their essay does not offer any coherent alternative to the adaptationist programme: it consists only in an exhortation (...) to test adaptationist hypotheses more thoroughly than was usual in the 1970s. Here it is argued that the ‘Spandrels’ paper points towards a genuinely non-adaptationist methodology implicit in much evolutionary developmental biology. This conclusion helps to expose the links between older debates over adaptationism and more recent questions about the property of evolvability. (shrink)
Debate about adaptationism in biology continues, in part because within “the” problem of assessing adaptationism, three distinct problems are mixed together. The three problems concern the assessment of three distinct adaptationist positions, each of which asserts the central importance of adaptation and natural selection to the study of evolution, but conceives this importance in a different way. As there are three kinds of adaptationism, there are three distinct "anti-adaptationist" positions as well. Or putting it more formally, there (...) are three different dimensions here, and strongly adaptationist views, strongly anti-adaptationist views, and moderate views are possible for each dimension. (shrink)
The so-called "adaptationism" of mainstream evolutionary biology has been criticized from a variety of sources. One, which has received relatively little philosophical attention, is developmental biology. Developmental constraints are said to be neglected by adaptationists. This paper explores the divergent methodological and explanatory interests that separate mainstream evolutionary biology from its embryological and developmental critics. It will focus on the concept of constraint itself; even this central concept is understood differently by the two sides of the dispute.
1 Adaptationism is a research strategy that seeks to identify adaptations and the specific selective forces that drove their evolution in past environments. Since the mid-1970s, paleontologist Stephen J. Gould and geneticist Richard Lewontin have been critical of adaptationism, especially as applied toward understanding human behavior and cognition. Perhaps the most prominent criticism they made was that adaptationist explanations were analogous to Rudyard Kipling's Just So Stories. Since storytelling is an inherent part of science, the criticism refers to (...) the acceptance of stories without sufficient empirical evidence. In particular, Gould, Lewontin, and their colleagues argue that adaptationists often use inappropriate evidentiary standards for identifying adaptations and their functions, and that they often fail to consider alternative hypotheses to adaptation. Playing prominently in both of these criticisms are the concepts of constraint, spandrel, and exaptation. In this article we discuss the standards of evidence that could be used to identify adaptations and when and how they may be appropriately used. Moreover, building an empirical case that certain features of a trait are best explained by exaptation, spandrel, or constraint requires demonstrating that the trait's features cannot be better accounted for by adaptationist hypotheses. Thus, we argue that the testing of alternatives requires the consideration, testing, and systematic rejection of adaptationist hypotheses. Where possible, we illustrate our points with examples taken from human behavior and cognition. Key Words: adaptation; ADHD; brain allometry; constraint; epistemology; evolutionary psychology; exaptation; female orgasm ; optimization; special design; waist-hip ratio. Footnotes1 The authors contributed equally to this paper. Order of authorship was determined alphabetically. Correspondence may be addressed to any of the authors. (shrink)
Two critiques of simple adaptationism are distinguished: anti-adaptationism and extended adaptationism. Adaptationists and anti-adaptationists share the presumption that an evolutionary explanation should identify the dominant simple cause of the evolutionary outcome to be explained. A consideration of extended-adaptationist models such as coevolution, niche construction and extended phenotypes reveals the inappropriateness of this presumption in explaining the evolution of certain important kinds of features—those that play particular roles in the regulation of organic processes, especially behavior. These biological or (...) behavioral ‘levers’ are distinctively available for adaptation and exaptation by their possessors and for co-optation by other organisms. As a result they are likely to result from a distinctive and complex type of evolutionary process that conforms neither to simple adaptationist nor to anti-adaptationist styles of explanation. Many of the human features whose evolutionary explanation is most controversial belong to this category, including the female orgasm. (shrink)
Debates over adaptationism can be clarified and partially resolved by careful consideration of the ‘grain’ at which evolutionary processes are described. The framework of ‘adaptive landscapes’ can be used to illustrate and facilitate this investigation. We argue that natural selection may have special status at an intermediate grain of analysis of evolutionary processes. The cases of sickle-cell disease and genomic imprinting are used as case studies.
It is often thought that if an adaptationist explanation of some behavioural phenomenon is true, then this fact shows that a culturist explanation of the very same phenomenon is false, or else the adaptationist explanation preempts or crowds out the culturist explanation in some way. This chapter shows why this so-called competition thesis is misguided. Two evolutionary models are identified — the Information Learning Model and the Strategic Learning Model — which show that adaptationist reasoning can help explain why cultural (...) learning evolved. These models suggest that there will typically be a division of labor between adaptationist and culturist explanations. It is then shown that the Strategic Learning Model, which has been widely neglected by adaptationist thinkers, has important and underappreciated implications for a question that has long been contentious in the behavioural sciences — the question of the malleability of human nature. (shrink)
In our target article, we discussed the standards of evidence that could be used to identify adaptations, and argued that building an empirical case that certain features of a trait are best explained by exaptation, spandrel, or constraint requires the consideration, testing, and rejection of adaptationist hypotheses. We are grateful to the 31 commentators for their thoughtful insights. They raised important issues, including the meaning of “exaptation”; whether Gould and Lewontin's critique of adaptationism was primarily epistemological or ontological; the (...) necessity, sufficiency, or utility of design evidence, phylogenetic analyses, homology, and molecular genetics in distinguishing exaptations from adaptations; whether adaptationists accept adaptationist hypotheses too quickly; and the real utility of adaptationism to human behavioral science. We organize our response along the major points of the target article, in some situations defending our original claims and in others modifying them. While debate on these issues will undoubtedly continue, we are cautiously optimistic that the main points of the target article (as modified by our response) will help move the debate in a positive direction. (shrink)
I identify a number of problematic aspects of Christiansen & Chater's (C&C's) contribution. These include their suggestion that subjacency and binding reflect non-domain-specific mechanisms; that proto-language is a ; and that non-adaptationism requires overly rich innate structures, and is incompatible with acceptable evolutionary processes. It shows that a fully UG (Universal Grammar)-free version of the authors' neo-adaptationism would be incoherent.
Methodological analysis shows that the concepts of fitness and adaptation are more complex than the literature suggests. Various arguments against adaptationism are inadequate since they are couched in terms of unduly simplistic notions.
We describe delusional disorder–jealous type (“morbid jealousy”) with the adaptationist perspective used by Darwinian psychiatrists and evolutionary psychologists to explain the relatively common existence and continued prevalence of mental disorders. We then apply the “harmful dysfunction” analysis to morbid jealousy, including a discussion of this disorder as (1) an end on a continuum of normal jealousy or (2) a discrete entity. (Published Online November 9 2006).
Strong adaptationists would explain complex organic designs as specific adaptations to particular ancestral environments. Weak adaptationists don't assume that complex organic functioning represents evolutionary design in the sense of niche-specific adaptation. For some domain-specific competencies (folkbiology) strong adaptationism is useful, not necessary. With group-level belief systems (religion), strong adaptationism can become spurious pseudo-adaptationism. In other cases (language), weak adaptationism proves productive.
In recent times evolutionary psychologists have offered adaptation explanations for a wide range of human psychological characteristics. Critics, however, have argued that such endeavors are problematic because the appropriate evidence required to demonstrate adaptation is unlikely to be forthcoming, therefore severely limiting the role of the adaptationist program in psychology. More specifically, doubts have been raised over both the methodology employed by evolutionary psychologists for studying adaptations and about the possibility of ever developing acceptably rigorous evolutionary explanations of human psychological (...) phenomena. We argue that by employing a wide range of methods for inferring adaptation and by adopting an inference to the best explanation strategy for evaluating adaptation explanations, these two doubts can be adequately addressed. We illustrate how this approach can be fruitfully employed in evaluating claims about the evolutionary origins of language, and conclude with a brief discussion of the future of evolutionary psychology. (shrink)
Andrews et al. effectively argue that, despite prominent criticism, adaptationism can be a viable research strategy. We agree. In our complementary commentary, we discuss the neglected method of inference to the best explanation and argue that it is a valuable addition to the adaptationist's methodological practice.
Adaptationism has for decades been the topic of sophisticated debates in philosophy of biology but methodological adaptationism has not received as much attention as the empirical and explanatory issues. In addition, adaptationism has mainly been discussed in the context of evolutionary biology and not in fields such as zoophysiology and systems biology where this heuristic is also used in design analyses of physiological traits and molecular structures. This paper draws on case studies from these fields to discuss (...) the productive and problematic aspects of this heuristic in different research practices, in functional as well as evolutionary studies on different levels of biological organization. Gould and Lewontin’s Spandrels-paper famously criticized adaptationist methodology for implying the risk of generating ‘blind spots’ with respect to non-selective effects on evolution. Some have claimed that this bias can be accommodated through the testing of evolutionary hypotheses. Although this is an important aspect of overcoming naïve adaptationism, I argue that the issue of methodological biases is broader than the question of testability. I demonstrate the productivity of adaptationist heuristics but also discuss the deeper problematic aspects associated with the methodological imperialism that is part of the strong adaptationist position. (shrink)
Ryan Nichols in his recent article ‘A genealogy of early Confucian moral psychology’ argues that the discussion of Confucius and Mencius on moral emotions can be provided an evolutionary analysis. Nichols’ argument is based on the evolutionary value of kin-relations and the origin of emotions toward kin in human society. In this article I argue that Nichols’ argument is flawed because he endorses an adaptationist program of human moral psychology. The adaptationists treat kin-relations and our emotions toward kin as a (...) straightforward result of natural selection and adaptation. They ignore any non-adaptationist interpretation of biological traits. As more and more evolutionary biologists discover that the adaptationist program is too simplistic to understand the diverse evolutionary pathways of living beings, Nichols’ project is not justified due to its reliance on this problematic adaptationist program. (shrink)
In this paper, I will take advantage of the controversy on the legitimacy of adaptationism in evolutionary biology to further investigate the nature of adaptationistic thinking, or biological explanations in general. To this end, first I will look at the famous and provocative criticism made by Gould and Lewontin (1979) against then-prevalent adaptationism --- a research strategy for accounting for the origin of traits of organisms seemingly adapted to the environment by appealing primarily to natural selection. Then I (...) will consider its counterarguments put forward by Dennett (1995), one of the proponents of adaptationism, in order toscrutinize the intrinsically hypothetical character of adaptationistic thinking. By amplifying Dennett’s points, I will finally reach the conclusion that there are two senses --- objective and subjective --- in which adaptationistic thinking is said to be hypothetical, which nonetheless do not prevent it from qualifying as scientific practice. In the process, I will also gain an insight into the sense in which the theory of natural selection is said to be mechanistic, as a spin-off. (shrink)
Since the late 1990s, the characterization of complete DNA sequences for a large and taxonomically diverse set of species has continued to gain in speed and accuracy. Sequence analyses have indicated a strikingly baroque structure for most eukaryotic genomes, with multiple repeats of DNA sequences and with very little of the DNA specifying proteins. Much of the DNA in these genomes has no known function. These results have generated strong interest in the factors that govern the evolution of genome architecture. (...) While adaptationist ‘just so’ stories have been offered, recent theoretical analyses based on mathematical population genetics strongly suggest that non-adaptive processes dominate genome architecture evolution. This article critically synthesizes and develops these arguments, explicating a core argument along with several variants. It provides a critical assessment of the evidence that supports these arguments’ premises. It also analyses adaptationist responses to these arguments and notes potential problems with the core argument. These theoretical analyses continue the molecular reinterpretation of evolution initiated by the neutral theory in 1968. The article ends by noting that some of these arguments can also be extended to evolution at higher levels of organization which raises questions about adaptationism in general. This remains a puzzle because there is probably little reason to doubt that many organismic features are genuine adaptations. 1 Introduction2 Preliminaries: Senses of Adaptationism3 Genome Architecture3.1 Surprises of early eukaryotic genetics3.2 Genome structure, post-20014 The Case against Adaptationism4.1 Just so stories versus population genetics4.2 The core argument4.3 Three variants of the core argument4.4 Examples: Non-adaptive features of the genome5 Adaptationist Responses6 Concluding Remarks. (shrink)
Attempts to explain human behavior that appeal to economic rationality share many of the same ontological as- sumptions and methodological practices that the so-called ‘adaptationist program’ in biology was criticized for. This program in biology was largely abandoned by biologists as poorly motivated, and replaced with the active testing of both adaptive and non-adaptive hypotheses regarding the spread and maintenance of traits in populations. This development was largely welcome by the biological community, despite having required the development of new tools, (...) both conceptual and method- ological. Many analysts of contemporary microeconomic practice criticize the assumptions and practices employed therein as similarly poorly motivated. Close attention to these criticisms reveal them to have more than superficial similarities to the critiques of adaptationism in biology. These similarities extend to some macroeconomics researchers recent suggestions of ways that hypotheses regarding the causes of people’s actions might be tested; as yet, however, these suggestions have not been embraced by the field as a whole. By attending to the ways in which biological practice has moved beyond the adaptationist program, similar changes in economic practice may be motivated. (shrink)
The adaptationist framework is necessary and sufficient for unifying the social and natural sciences. Gintis's “beliefs, preferences, and constraints” (BPC) model compares unfavorably to this framework because it lacks criteria for determining special design, incorrectly assumes that standard evolutionary theory predicts individual rationality maximisation, does not adequately recognize the impact of psychological mechanisms on culture, and is mute on the behavioural implications of intragenomic conflict. (Published Online April 27 2007).
Mental images are one of the more obvious aspects of human conscious experience. Familiar idioms such as “the mind's eye” reflect the high status of the image in metacognition. Theoretically, a defining characteristic of mental images is that they can be analog representations. But this has led to an enduring puzzle in cognitive psychology: How do “mental pictures” fit into a general theory of cognition? Three empirical problems have constituted this puzzle: The incidence of mental images has been unpredictable, innumerable (...) ordinary concepts cannot be depicted, and images typically do not resemble things well. I argue in this paper that theorists have begun to address these problems successfully. I argue further that the critical theoretical framework involves thinking of mental images as information within a cognitive system that is fundamentally adaptive. The main outline of the adaptationist framework was evident in the school of thought known as American Functionalism, but adaptationism has formed a consistent pattern of theorizing across many authors and decades. I briefly describe Functionalism and then present seven basic claims about imagery that were common in the years before the predominance of behaviorism. I then show how these claims have reappeared and been further articulated in modern cognitive psychology. I end with a brief integration of some of the basic elements of an adaptationist theory of imagery. (shrink)
Strong adaptationists explore complex organic design as task-specific adaptations to ancestral environments. Its strategy seems best when there is evidence of homology. Weak adaptationists don't assume that complex organic functioning necessarily or primarily represents task-specific adaptation. Its approach to cognition resembles physicists' attempts to deductively explain the most facts with fewest hypotheses. For certain domain-specific competencies strong adaptationism is useful but not necessary to research. With group-level belief systems strong adaptationism degenerates into spurious notions of social function and (...) cultural selection. In other cases weak adaptationism's “minimalist” approach seems productive. (shrink)
Andrews et al. present a form of instrumental adaptationism that is designed to test the hypothesis that a given trait is an adaptation. This epistemological commitment aims to make clear statements about behavioural natural kinds. The instrumental logic is sound, but it is the limits of our empirical imagination that can cause problems for theory construction.
The target article shows that the application of the evolutionary theory to psychopathology should not necessarily consist in finding hidden adaptive benefits for each psychiatric syndrome. However, in rejecting lax adaptationism, Darwinian psychiatrists should not forget that the search for adaptive behavioral polymorphisms can be a powerful antidote against the normative attitude of mainstream psychiatry and its growing tendency to medicalize human diversity. (Published Online November 9 2006).
Rather than starting with traits and speculating whether selective forces drove evolution in past environments, we propose starting with a candidate gene associated with a trait and testing first for patterns of selection at the DNA level. This can provide limitations on the number of traits to be evaluated subsequently by adaptationism as described by Andrews et al.
Methodological analysis shows that the concepts of fitness and adaptation are more complex than the literature suggests. Various arguments against ‘adaptationism’ are inadequate since they are couched in terms of unduly simplistic notions.
The debate over the relative importance of natural selection as compared to other forces affecting the evolution of organisms is a long-standing and central controversy in evolutionary biology. The theory of adaptationism argues that natural selection contains sufficient explanatory power in itself to account for all evolution. However, there are differing views about the efficiency of the adaptation model of explanation. If the adaptationism theory is applied, are energy and resources being used to their optimum? This book presents (...) an up-to-date view of this controversy and reflects the dramatic changes in our understanding of evolution that have occurred in the last twenty years. The volume combines contributions from biologists and philosophers, and offers a systematic treatment of foundational, conceptual, and methodological issues surrounding the theory of adaptationism. The essays examine recent developments in topics such as phylogenetic analysis, the theory of optimality and ess models, and methods of testing models. (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)
Recent work on the heat-shock protein Hsp90 by Rutherford and Lindquist (1998) has been included among the pieces of evidence taken to show the essential role of developmental processes in evolution; Hsp90 acts as a buffer against phenotypic variation, allowing genotypic variation to build. When the buffering capacity of Hsp90 is altered (e.g., in nature, by mutation or environmental stress), the genetic variation is "revealed," manifesting itself as phenotypic variation. This phenomenon raises questions about the genetic variation before and after (...) what I will call a "revelation event": Is it neutral, nearly neutral, or non-neutral (i.e., strongly deleterious or strongly advantageous)? Moreover, what kinds of evolutionary processes do we take to be at work? Rutherford and Lindquist (1998) focus on the implications of non-neutral variation and selection. Later work by Queitsch, Sangster, and Lindquist (2002) and Sangster, Lindquist, and Queitsch (2004) raises the possibility that Hsp90 buffering may play the role that was played by drift in Sewall Wright's shifting balance model, permitting transition from one adaptive peak to another. However, Ohta (2002) suggests that much of this variation may be nearly neutral, which in turn, would imply a strong role for drift as well as selection. The primary goal of this paper is to illuminate the alternative scenarios and the processes operating in each. At the end, I raise the possibility of a synthesis between evo-devo and nearly neutral evolution. (shrink)