Rethinking Evolutionary Psychology

A. Goldfinch

• Publisher: Palgrave Macmillan
• Year: 2015
• Print ISBN: 9781137442901
• eBook ISBN: 9781137442918
• Topic: Philosophy
• Subtopic: Mind & Body in Philosophy

Rethinking Evolutionary Psychology identifies, champions and vindicates a streamlined evolutionary psychology. It offers a new way of thinking that moves decisively away from theoretical and critical excess. Where standard accounts often obscure and distort, this book emphasizes and develops evolutionary psychology's heuristic credentials.

1

Evolutionary Psychology as a Paradigm

1.0 Introduction

We have evolved by natural selection. Even if not everything about an organism is an adaptation for survival and reproduction, it seems inescapable that organisms are well adapted, at least to the environment in which they evolved. Most consent to that proposition. But there is disagreement, often quite animated disagreement, as to what implications this has for psychology.

Our ancestors faced a multitude of recurrent survival and reproduction problems. In order to survive and reproduce, one must locate and secure resources; avoid pathogens; avoid predators; find a mate; counter threats from mate poachers; form and maintain coalitions and relationships; establish and protect one’s status in a societal hierarchy; and so on. These problems are known as ‘adaptive problems’ and solutions to these problems promote reproductive success.

One proposal, perhaps the dominant view, is that selection favoured one or a few general-purpose psychological mechanisms, general learning and decision-making mechanisms sufficient to generate multiple behavioural solutions to multiple adaptive problems. If this is the case, applying evolutionary perspectives to psychology might have limited mileage.

An alternative proposal is that some or many of the problems were solved by dedicated psychological adaptations. Just as we inherit physiological specialisations, so too we might inherit psychological specialisations. If this is the case, this opens up the possibility that evolutionary theory can open up new lines of research in psychology. This is the possibility evolutionary psychologists pursue.

Quite reasonable, isn’t it? If selection pressures have favoured physiological adaptations, then they might also favour psychological adaptations, and that this perspective might be useful in understanding psychology in some way. In a way, pursuit of this line of thought is ‘inevitable’ (de Waal, 2001). Of course, whether this kind of thinking is actually useful needs to be established.

Yet despite its apparent reasonableness, evolutionary psychology has been subject to a firestorm of criticism and controversy, often from philosophers of science. Dawkins observes that evolutionary psychology is ‘subject to a level of implacable hostility, which seems far out of proportion to anything sober reason or even common politeness might sanction’ (2005: 975). This book’s introduction already observed some flashes of this deeply motivated hostility and as we go along we shall witness similar expressions.

So we have something of a puzzle: evolutionary psychology’s underlying impulse—to hypothesise possible adaptive problems and to hypothesise possible psychological adaptive solutions—seems reasonable and yet evolutionary psychology is widely dismissed wholesale in philosophy and by many practitioners in the social sciences.

To begin to understand this puzzle, this controversy, is to understand that evolutionary psychology is frequently presented as much more than simply operationalising a set of ideas to illuminate our understanding of psychology. In introductory paragraphs and articles, theoretical manifestos and introductions to edited volumes, evolutionary psychology is presented as something of a game-changer. Something revolutionary. More precisely, it is frequently characterised in terms of commitments to particular views about evolution, to a particular view about the mind, as being an explanatory project, as being a metatheory for psychology in particular and the behavioural sciences more broadly, and as having a public policy agenda.

More than a research programme in the evolutionary behavioural sciences going about its daily business, it is championed as a ‘scientific revolution’ in psychology and the social sciences—as an all-encompassing view of science and, indeed, the world. We are assured that evolutionary psychology is ‘becoming the unifying paradigm upon which the entire field of psychology can be based’ (Fitzgerald and Whitaker, 2010: 284). ‘Evolutionary psychology represents a true scientific revolution, a profound paradigm shift in the field of psychology’ (Buss, 2005a: xxiv; see also Buss, 1995). And as you might already be realising, such a packaging of strong views is likely to magnetise not only supporters, but also opponents.

To understand how the underling impulse of evolutionary psychology, its heartbeat, is cashed out into a paradigm is to understand what its main theoretical and methodological tenets are commonly purported to be. This is the task we shall undertake in this short chapter, which sets the stage for the remaining chapters and forms a roadmap for the controversies that lay ahead.

I interpret the leading proponents of evolutionary psychology—Leda Cosmides, John Tooby, David Buss and others—as presenting evolutionary psychology as a package of views:

(T1) Evolutionary theory, with an emphasis on natural selection and adaptation

(T2) The possibility of psychological adaptations

(T3) Empirical adaptationism

(T4) Inference from empirical adaptationism to massive modularity

(T5) Methodological adaptationism

(T6) Metatheory for psychology and the behavioural sciences

(T7) Public policy agenda

The distinction between empirical and methodological adaptationism is owing to Godfrey-Smith (2001). Godfrey-Smith discusses these distinctions with respect to evolutionary biology but they’re equally applicable to evolutionary psychology. Leading evolutionary psychologists seem to have no trouble subscribing to both empirical and methodological adaptationism, and there’s plenty of evidence they do.

We’ll go through each of these tenets in order. In doing so, we will not only be able to see precisely where and how the paradigmatic framework emerges, but also to see clearly and to anticipate precisely at which junctures controversy and heated resistance to the paradigm can arise. This is important: in the sceptical literature one is often treated to a battery of objections against evolutionary psychology, and without knowing the sequence of tenets that form the evolutionary psychology paradigm and how they relate to one another it can be unclear just how destabilising any particular objection is. And given sceptical writings often codify a number of objections against evolutionary psychology, this can, quite naturally, lead to a wholesale dismissal of evolutionary psychology—even if the objections tabled might not, in fact, justify such a judgement.

1.1 Natural Selection and Adaptation

The modern evolutionary synthesis, the synthesis of Darwin’s theory of evolution by natural selection and Mendelian inheritance, forms the basic theoretical foundation of evolutionary psychology. This synthesis is currently the consensus framework of modern evolutionary biology. The modern evolutionary synthesis has many components and concepts, which are well known and can be found in many textbooks. Instead of repeating them, I’ll only identify the concepts most directly relevant to evolutionary psychology.

1.1.1 Evolution by Natural Selection

Biological evolution is a change in the characteristics of a population over time. More precisely, a standard definition is that evolution occurs precisely when there is a change in the gene frequencies found in a population (Sober, 2000). Populations evolve, not individuals—individuals survive and reproduce. Several processes drive evolutionary change: natural selection (heritable variation in fitness), genetic drift (gene frequencies can change owing to chance alone), migration (gene flow) and mutation. In the classical view, within a population, selection and drift decrease genetic variation, while mutation and migration increase genetic variation (Culver, 2009).

Evolutionary psychologists focus on natural selection. Evolution by natural selection is the process of preserving and increasing the frequency of fitness-enhancing characteristics or traits in a population. For selection to occur in a population, three conditions must obtain. First, variation: individuals in a population must differ with respect to the relevant trait in question. Without variation, all individuals will have the same trait value, and will thereby be indistinguishable with respect to that trait. Second, heritability: the variation found in the population must be heritable to some degree. Non-heritable traits, and the advantages they provide, cannot be passed on from one generation to the next. Third, differential fitness: individuals must have a probability of reproduction that is a function of the trait value in question. Although this classic formulation presents selection as acting on individual organisms, one can view selection as acting on genes, groups or species.

1.1.2 Adaptations and By-products

Natural selection results in the evolution of adaptations, where selection increases the frequency of beneficial alleles in a population to the point of fixation. An adaptation can be defined as an inherited and reliably developing trait that was selected for because it helped solve an adaptive problem—a recurring problem of survival or reproduction (Buss, 2008; see also Stearns 1986 and Tooby and Cosmides 1992). More precisely,

Characteristic c is an adaptation for doing task t in a population if and only if members of the population now have c because, ancestrally, there was selection for having c and c conferred a fitness advantage because it performed task t (Sober, 2000: 85).

This way of defining an adaptation—adaptation as an historical concept—represents a ‘reasonable consensus on what it is to be an adaptation’ (Godfrey-Smith, 1998: 191). This is also how the concept is commonly defined in evolutionary psychology. Accordingly, this book adopts that definition. For a discussion of other ways of defining adaptation, see Shanahan (2004).

Adaptations are to be distinguished from their by-products. A by-product is a trait that evolved not because it was selected for, but because it was connected to another trait that was selected for. By-products do not function to solve adaptive problems: the sound of the heart pumping blood and the white colour of bones are non-functional by-products of selection.

1.1.3 Adaptations Advantageous on Balance

To be selected for a trait need not be advantageous under every scenario. Rather, all that is required is that the trait is advantageous overall. For example, a child’s enlarged skull displays signs of being an adaptation, as a larger brain is correlated with greater cognitive power. But this makes birth complicated. And dangerous: there’s a risk of childbirth death. Yet the enlarged skull is advantageous on balance, and so could have been selected for.

1.1.4 Adaptations and Constraints

Natural selection optimises under constraints. ‘Adaptationist models do predict optimality, but this optimality is always constrained optimality’ (Sansom, 2003: 497; original emphasis). Genetic and developmental constraints can prevent certain traits and designs being realisable. Coordination constraints with extant mechanisms can prevent the evolution of certain traits and designs. Prohibitive costs can also rule out the evolution of certain traits and designs. Furthermore, ‘Local optima can prevent the evolution of better adaptive solutions that might, in principle, exist in potential design space’ (Buss et al., 1998: 538). In other words, the required fitness chain between one solution and a better solution might not obtain. Buss et al. (1998) invite us to think of selection as building adaptations through a relentless mountain-climbing process. On top of a neighbouring mountain a better design might be found ‘but selection cannot reach it if it has to go through a deep fitness valley to get there’ (ibid.: 538).

1.1.5 Adaptation/Adaptive Distinction

We need to distinguish between a trait being an adaptation and a trait being adaptive.

An adaptation is a character favoured by natural selection for its effectiveness in a particular role; that is, it has an evolutionary history of selection. To be labelled as adaptive, a character has to function currently to increase reproductive success (Laland and Brown, 2002: 132, original emphasis).

Hence, ‘To say that a trait is an adaptation is to make a claim about the cause of its presence; to say that it is adaptive is to comment on its consequences for survival and reproduction’ (Sober, 1993: 211). It follows that a trait can be an adaptation without being adaptive, and a trait can be adaptive without being an adaptation.

The adaptation/adaptive distinction highlights the possibility of a mismatch between adaptations and novel environments. Evolutionary psychologists stress that our contemporary environment differs from our ancestral environment. When an organism’s environment changes speedily and significantly, behaviours that were adaptive in the previous environment can become dysfunctional or deleterious in the new environment, undermining reproductive success. Some evolutionary psychologists call such behaviour ‘maladaptive’ (e.g. Tooby and Cosmides, 2005). Sterelny (1995) adopts and illustrates the distinction between adaptive and maladaptive behaviours with the memorable example of hedgehogs responding to danger by rolling into balls: an effective response to dangers from its natural predators, but a poor response to the danger of cars. More on this in the next chapter.

1.2 The Possibility of Psychological Adaptations

It’s common to think of the outcomes of selection as being exclusively physiological. Many physiological traits—hearts, livers, lungs and so on—are widely seen as having been shaped by natural selection for the survival and reproduction of their possessors. But why shouldn’t the same be true of psychological traits? As Dawkins notes, the claim that psychology is on the same footing as the body where selection is concerned is ‘exceedingly modest’ (2005: 978).

A guiding principle of evolutionary psychology, what I call its symmetry principle, is that there is no reason to suppose that only physiological traits can be selected for. This enables us to move from physiological adaptations to psychological adaptations. As with physiology, so too with psychology: ‘Just as a shared set of digestive mechanisms both enable and constrain the diverse diets of human populations, so do a comparable set of behavioral mechanisms enable and constrain our social-cultural behavior’ (Barkow, 2006: 21–2).

Physiologists have divided the body up into different physical organs, based largely on the purported functions of organ. As with physiology, so too with psychology: we can do this with psychology, too, with psychological ‘organs’. As Cosmides and Tooby (1997a) put it,

Our body is divided into organs, like the heart and the liver, for exactly this reason. Pumping blood through the body and detoxifying poisons are two very different problems. Consequently, your body has a different machine for solving each of them. The design of the heart is specialized for pumping blood; the design of the liver is specialized for detoxifying poisons. Your liver can’t function as a pump, and your heart isn’t any good at detoxifying poisons. For the same reason, our minds consist of a large number of circuits that are functionally specialized.

Hence, we can hypothesise that a particular psychological trait exists in the form that it does because it solved a specific problem of survival or reproduction recurrent in ancestral populations. For example, we can hypothesise that fear of snakes is an adaptation, taking the form that it does because it solved a specific and recurring problem in ancestral populations, namely the threat of being poisoned by snake bites (Öhman and Mineka, 2001). As those who possessed this trait would enjoy a fitness advantage over those who didn’t possess the trait, the trait would be selected for and become prevalent in ancestral populations.

As our physiological adaptations are species-typical, appearing in normally developing members of the human species, our psychological adaptations are also held to be species-typica...

Table of contents

• Cover
• Halftitle
• Title
• Copyright
• Contents
• Acknowledgements
• Introduction
• 1 Evolutionary Psychology as a Paradigm
• 2 Subverting the Paradigm
• 3 Evolutionary Psychology and Novel Predictions
• 4 Reframing Evolutionary Psychology as a Heuristic Programme
• 5 Restructuring the Debate
• Conclusions
• References
• Index