Adaptationism

A functional approach to evolutionary morphology is emphasized in this paper. This perspective differs from the current structuralist trend, which emphasizes the constraining role of developmental paths. In addition, the present approach agrees with the adaptationist paradigm. It is further argued that three types of phenomena are better understood in this light: i.- the existence of evolutionary trends, ii.- the maintenance of certain structural features within a given taxon, and iii.- the irreversibility of evolution.

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)

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.

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)

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)

The concepts of form and function have traditionally been defined in terms of biology and then extended to other disciplines. Stephen T. Asma examines the various interpretations of form and function in science and philosophy, reflecting on the philosophical presuppositions underlying the work of Geoffroy, Cuvier, Darwin, and others. -/- In the continental tradition of Canguilhem and Foucault, Asma's treatment of the historical form/function dispute analyzes the complex interactions among ideologies, metaphysical commitments, and research programs. Following Form and Function is (...) a significant contribution to the history of science, history of philosophy, and disputes within contemporary biology. (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)

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)

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)

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.

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)

Is there any way to reconcile the adaptationist’s image of natural selection as an engine of optimality with the more complex image of its dynamics we get from population genetics? This has long been an important strand in the controversy surrounding adaptationism, yet debate has been hampered by a tendency to conflate various different ways of thinking about maximization. Here I distinguish four varieties of maximization principle. I then discuss the logical relations between these varieties, arguing that, although they may (...) seem similar at face value, none entails any of the others. I then turn briefly to the status of each variety, arguing that, while each type of maximization principle faces serious problems, the problems are subtly different for each type. In the last section, I reflect on what is at stake in the debate. (shrink)

Hamilton introduced two conceptions of social fitness, which he called neighbour-modulated fitness and inclusive fitness. Although he regarded them as formally equivalent, a re-analysis of his own argument for their equivalence brings out two important assumptions on which it rests: weak additivity and actor's control. When weak additivity breaks down, neither fitness concept is appropriate in its original form. When actor's control breaks down, neighbour-modulated fitness may be appropriate, but inclusive fitness is not. Yet I argue that, despite its more (...) limited domain of application, inclusive fitness provides a distinctively valuable perspective on social evolution. (shrink)

One key aim of Grafen’s Formal Darwinism project is to formalize ‘modern biology’s understanding and updating of Darwin’s central argument’. In this commentary, I consider whether Grafen has succeeded in this aim.

The scientific study of living organisms is permeated by machine and design metaphors. Genes are thought of as the ‘‘blueprint’’ of an organism, organisms are ‘‘reverse engineered’’ to discover their functionality, and living cells are compared to biochemical factories, complete with assembly lines, transport systems, messenger circuits, etc. Although the notion of design is indispensable to think about adaptations, and engineering analogies have considerable heuristic value (e.g., optimality assumptions), we argue they are limited in several important respects. In particular, the (...) analogy with human-made machines falters when we move down to the level of molecular biology and genetics. Living organisms are far more messy and less transparent than human-made machines. Notoriously, evolution is an opportunistic tinkerer, blindly stumbling on ‘‘designs’’ that no sensible engineer would come up with. Despite impressive technological innovation, the prospect of artificially designing new life forms from scratch has proven more difficult than the superficial analogy with ‘‘programming’’ the right ‘‘software’’ would suggest. The idea of applying straightforward engineering approaches to living systems and their genomes— isolating functional components, designing new parts from scratch, recombining and assembling them into novel life forms—pushes the analogy with human artifacts beyond its limits. In the absence of a one-to-one correspondence between genotype and phenotype, there is no straightforward way to implement novel biological functions and design new life forms. Both the developmental complexity of gene expression and the multifarious interactions of genes and environments are serious obstacles for ‘‘engineering’’ a particular phenotype. The problem of reverse-engineering a desired phenotype to its genetic ‘‘instructions’’ is probably intractable for any but the most simple phenotypes. Recent developments in the field of bio-engineering and synthetic biology reflect these limitations. Instead of genetically engineering a desired trait from scratch, as the machine/engineering metaphor promises, researchers are making greater strides by co-opting natural selection to ‘‘search’’ for a suitable genotype, or by borrowing and recombining genetic material from extant life forms. (shrink)

The concept of developmental constraint was at the heart of developmental approaches to evolution of the 1980s. While this idea was widely used to criticize neo-Darwinian evolutionary theory, critique does not yield an alternative framework that offers evolutionary explanations. In current Evo-devo the concept of constraint is of minor importance, whereas notions as evolvability are at the center of attention. The latter clearly defines an explanatory agenda for evolutionary research, so that one could view the historical shift from ‘developmental constraint’ (...) towards ‘evolvability’ as the move from a concept that is a mere tool of criticism to a concept that establishes a positive explanatory project. However, by taking a look at how the concept of constraint was employed in the 1980s, I argue that developmental constraint was not just seen as restricting possibilities (‘constraining’), but also as facilitating morphological change in several ways. Accounting for macroevolutionary transformation and the origin of novel form was an aim of these developmental approaches to evolution. Thus, the concept of developmental constraint was part of a positive explanatory agenda long before the advent of Evo-devo as a genuine scientific discipline. In the 1980s, despite the lack of a clear disciplinary identity, this concept coordinated research among paleontologists, morphologists, and developmentally inclined evolutionary biologists. I discuss the different functions that scientific concepts can have, highlighting that instead of classifying or explaining natural phenomena, concepts such as ‘developmental constraint’ and ‘evolvability’ are more important in setting explanatory agendas so as to provide intellectual coherence to scientific approaches. The essay concludes with a puzzle about how to conceptually distinguish evolvability and selection. (shrink)

This is the first volume of a projected three-volume set on the subject of innateness. The extent to which the mind is innate is one of the central questions in the human sciences, with important implications for many surrounding debates. By bringing together the top nativist scholars in philosophy, psychology, and allied disciplines these volumes provide a comprehensive assessment of nativist thought and a definitive reference point for future nativist inquiry. The Innate Mind: Structure and Content, concerns the fundamental architecture (...) of the mind, addressing such question as: What capacities, processes, representations, biases, and connections are innate? How do these innate elements feed into a story about the development of our mature cognitive capacities, and which of them are shared with other members of the animal kingdom? The editors have provided an introduction giving some of the background to debates about innateness and introducing each of the subsequent essays, as well as a consolidated bibliography that will be a valuable reference resource for all those interested in this area. The volume will be of great importance to all researchers and students interested in the fundamental nature and powers of the human mind. Together, the three volumes in the series will provide the most intensive and richly cross-disciplinary investigation of nativism ever undertaken. They point the way toward a synthesis of nativist work that promises to provide a new understanding of our minds and their place in the natural order. (shrink)

In 1993, biologist Margie Profet captured the attention of the popular press with the publication of her radical thesis: menstruation has a function. Traditional theories, she claims, typically view menstruation as a functionless by-product of cyclic flux. The details of Profet's functional account are similarly radical: she argues that menstruation has been naturally selected to defend the female reproductive tract from sperm-borne pathogens. There are a number of weaknesses in Profet's evolutionary analysis. However, I focus on a set of pragmatic (...) problems that arise prior to any details of her evolutionary account. In arguing for the importance of pragmatic considerations, I draw from the linguistic analyses of Nelson Goodman. I conclude that critical investigation of the evolutionary details of Profet's pathogen defense account will be more feasible if and when biologists more frequently feature the female system of pathogen defense in their inductive generalisations. The system needs to be better entrenched before its functional components, such as menstruation, can be thoroughly investigated. (shrink)

Progress has become a suspect concept in evolutionary biology, not the least because the core concepts of neo-Darwinism do not support the idea that evolution is progressive. There have been a number of attempts to account for directionality in evolution through additions to the core hypotheses of neo-Darwinism, but they do not establish progressiveness, and they are somewhat of an ad hoc collection. The standard account of fitness and adaptation can be rephrased in terms of information theory. From this, an (...) information of adaptation can be defined in terms of a fitness function. The information of adaptation is a measure of the mutual information between biota and their environment. If the actual state of adaptation lags behind the state of optimal adaptation, then it is possible for the information of adaptation to increase indefinitely. Since adaptations are functional, this suggests the possibility of progressive evolution in the sense of increasing adaptation. Keywords: evolution, information, adaptation, fitness, entropy, progress.. (shrink)

Selection type theories solve adaptation problems. Natural selection, clonal selection for antibody production, and selective theories of higher brain function are examples. An abstract characterization of typical selection processes is generated by analyzing and extending previous work on the nature of natural selection. Once constructed, this abstraction provides a useful tool for analyzing the nature of other selection theories and may be of use in new instances of theory construction. This suggests the potential fruitfulness of research to find other theory (...) types and construct their abstractions. (shrink)

The phenomena of adaptation, observed on cave-dwelling organisms, fitting themselves to the particular conditions of the caves, must not be explained in lamarckistish sense. They are phenomena of general organical reductions. As primary inducements, they compel some species, which have been made helpless in consequence of happening reductions to retire themselves spontaneously in caves. Trogloditism is therefore no cause of the peculiar decay of notorious cave-dwellers, on the contrary, it is the last stage of incessant phenomena, induced by reductions . (...) The reductions arise independently from the cave, the cave is only a fitting place of existence, in which the decaying organisms introduced themselves afterwards.Diejenigen Erscheinungen, die in der Anpassung zu den speziellen Verhältnissen der Höhlen bei den Höhlenorganismen zu beobachten sind, sollen nicht im Sinne lamarckistischer Auffassung erklärt werden. Es sind dies allgemeine organische Reduktionserscheinungen, die als primäre Ursachen einzelne Arten veranlassen, sich mit dem Auftreten der sie hilflos machenden Reduktionserscheinungen willkürlich in die Höhlen zurückzuziehen. Der Trogloditismus ist demnach keine Ursache der speziellen Verkümmerung der allbekannten Höhlenbewohner, sondern eine Endstation der mit den Reduktionen eingeleiteten fortdauernden Erscheinungen . Die Reduktionen treten von der Höhle unabhängig auf, die Höhle stellt nur den entsprechendsten Lebensraum dar, in welchen sich diese verkümmerten Organismen nachträglich eingefügt haben. (shrink)

I want to explore four different exercises of interpretation: (1) the interpretation of texts (or hermeneutics), (2) the interpretation of people (otherwise known as "attribution" psychology, or cognitive or intentional psychology), (3) the interpretation of other artifacts (which I shall call artifact hermeneutics), (4) the interpretation of organism design in evolutionary biology--the controversial interpretive activity known as adaptationism.

In this paper I argue the best examples of the methods in the evolutionary social sciences don’t actually resemble either of the two methods called “Adaptive Thinking” or “Reverse Engineering” described by evolutionary psychologists. Both AT and RE have significant problems. Instead, the best adaptationist work in the ESSs seems to be based on and is aiming at a different method that avoids the problems of AT and RE: it is a behavioral level method that starts with information about both (...) the trait in question and knowledge of the EEA. I describe some examples from the literature, and suggest how a behavioral level ESS might still contribute to the discovery and understanding of human psychology. Finally, I describe some remaining problems for adaptationist reasoning of this kind. (shrink)

Evolutionary psychologists often try to “bring together” biology and psychology by making predictions about what specific psychological mechanisms exist from theories about what patterns of behaviour would have been adaptive in the EEA for humans. This paper shows that one of the deepest methodological generalities in evolutionary biology—that proximate explanations and ultimate explanations stand in a many-to-many relation—entails that this inferential strategy is unsound. Ultimate explanations almost never entail the truth of any particular proximate hypothesis. But of course it does (...) not follow that there are no other ways of “bringing together” biology and psychology. Accordingly, this paper explores one other strategy for doing just that, the pursuit of a very specific kind of consilience. However, I argue that inferences reflecting the pursuit of this kind of consilience with the best available theories in contemporary evolutionary biology indicate that psychologists should have a preference for explanations of adaptive behavior in humans that refer to learning and other similarly malleable psychological mechanisms—and not modules or instincts or any other kind of relatively innate and relatively non-malleable psychological mechanism. (shrink)

The “straw man” prior expectation of the dominant social psychology paradigm is that humans should behave with perfect rationality and high ethical standards. The more modest claim of evolutionary psychologists is that humans have evolved specific adaptations for adaptive problems that were reliably present in the ancestral environment. Outside that restricted range of problems, one should not expect optimal behavior.

Darwin begins On the Origin of Species by asking the reader to “reflect on the vast diversity of the plants and animals which have been cultivated” (1859, p. 7); almost five-hundred pages later, he closes by having the reader consider the “endless forms most beautiful and wonderful” that have evolved (1859, p. 490). Darwin contemplates diversity throughout the Origin and presents the principle of divergence as a way to explain it. Darwin formulated the principle of divergence around 1857 (Browne 1980), (...) at which point he began replacing his previous view of “limited perfect adaptedness” with a view of relative adaptedness (Ospovat 1981; Burian 1983). Proponents of perfect adaptedness, such as Paley and .. (shrink)

"Adaptation" has several meanings which have often been confused, including relations, processes, states, and intrinsic properties. It is used in comparative and historical contexts. "Adaptation" and "environment" may designate probabilistic concepts. Recognition of these points refutes arguments for the notions that: 1) all organisms are perfectly adapted; 2) organisms cannot be ill-adapted and survive or well-adapted and die; 3) adaptation is necessarily relative to the environment; 4) change in environment is necessary for evolution; 5) preadaptation implies teleology. Such notions are (...) associated with metaphysical ideas, and may affect the thinking of biologists. (shrink)

Psychopathy represents a unique set of personality traits including deceitfulness, lack of empathy and guilt, impulsiveness, and antisocial behavior. Most often in the literature, psychopathy is described as pathology — a disorder that has been linked to a variety of biological deficits and environmental risk factors. However, from an evolutionary perspective, psychopathy, while it could be a disorder, has been construed in the context of an adaptive strategy. In this article we will examine the strengths and weaknesses of two models (...) suggesting that psychopathy is an adaptive strategy, and one model suggesting that it is a form of pathology resulting from accumulated mutations. Overall, we do not find that there is strong enough evidence to draw firm conclusions about one theory over another, but we highlight some areas where future research may be able to shed light on the issue. (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)

In 1979, Lewontin and I borrowed the archi- tectural term “spandrel” (using the pendentives of San Marco in Venice as an example) to designate the class of forms and spaces that arise as necessary byproducts of another decision in design, and not as adaptations for direct utility in them- selves. This proposal has generated a large literature featur- ing two critiques: (i) the terminological claim that the span- drels of San Marco are not true spandrels at all and (ii) the (...) conceptual claim that they are adaptations and not byprod- ucts. The features of the San Marco pendentives that we explicitly defined as spandrel-properties—their necessary number (four) and shape (roughly triangular)—are inevitable architectural byproducts, whatever the structural attributes of the pendentives themselves. The term spandrel may be extended from its particular architectural use for two- dimensional byproducts to the generality of “spaces left over,” a definition that properly includes the San Marco pendentives. Evolutionary biology needs such an explicit term for features arising as byproducts, rather than adaptations, whatever their subsequent exaptive utility. The concept of biological span- drels—including the examples here given of masculinized genitalia in female hyenas, exaptive use of an umbilicus as a brooding chamber by snails, the shoulder hump of the giant Irish deer, and several key features of human mentality— anchors the critique of overreliance upon adaptive scenarios in evolutionary explanation. Causes of historical origin must always be separated from current utilities; their conf lation has seriously hampered the evolutionary analysis of form in the history of life. (shrink)