Abstract
It is worth wondering whether a Darwinian view of the mind and its problems is the next step in the evolution of our understanding of mental disorders. After all, our views on the etiology and treatment of psychological disorders have been revolutionized (and mostly for the better) many times in the past 150 years. Inefficacious and harmful treatments have been, for the most part, abandoned for methods based on evidence gathered from careful studies, including randomized control studies. Conceptualizations involving humors, evil spirits, and cold mothers have been replaced by theories based on scientific evidence involving genes, personality predispositions, and developmental factors. Notions of mental illnesses as strictly personal events requiring intense one-on-one therapy have been replaced by contextual approaches involving precipitating factors and requiring systemic interventions. Advances in pharmacological and cognitive-behavioral treatments, quantitative and molecular genetics, and neuroscience have transformed psychopathology to a point that the grandfathers of abnormal psychology—the Freuds, Kraepelins, and Greys—would barely recognize it.
And yet, so much remains to be done. The genetic contribution to psychological disorders is undeniable but nebulously complex. Efficacious treatments can be difficult to implement outside of teaching hospitals, for various economic and professional guild reasons. Despite extensive research, some disorders remain highly resistant to treatment. Neuroscience has difficulty incorporating the important notions of precipitating and contextual factors into its methodology. Adding to this, psychological disorders remain highly stigmatized and misunderstood. Diagnoses are clouded by vigorous disagreements about what constitutes pathology, and diagnostic practices are mostly nothing but a relabeling of presenting problems. But, perhaps more importantly, there is no overarching theory of mental disorders.
In our Abnormal Psychology classroom, we typically begin one of the lectures by asking the question “If it is true that at least 25% of people experience a serious mental disorder at some point in their lives, how can it be that evolution has left us with a mind prone to such serious problems?” This question has led to interesting discussions about whether some of the disorders should be considered disorders in the first place, whether there is a mismatch between our evolved minds and our current social and biotic environments, whether some of the disorders would have negatively affected our fitness in ancestral environments, and whether some of the negative fitness effects resulting from a disordered mind have been balanced by positive effects, either in individuals themselves or their relatives. These are some of the questions that are addressed in Maladapting Minds.
The overarching question in Maladapting Minds is whether a Darwinian approach will lead to the next revolution in our understanding of psychological disorders. And if so, what will the revolution look like? Will it be one in which Darwinian thinking simply provides a better heuristic to think about the issues, or will it transform the field so that the types of questions asked and the solutions provided will be completely different from what they are today? The contributors vary in their opinions, some wondering if anything will change, and others postulating that nothing will ever be the same. Geoffrey Miller, in his crafty Foreword, believes that evolutionary considerations have had little impact on psychiatry so far, and we agree. Despite promising beginnings, provided in large part by the work of Nesse, Williams, and Hagen, little has changed. Perhaps reflecting how slowly things change in medicine, evolution is now part of the curriculum in basic medicine, but not in the psychiatry specialization.
This book provides an extremely thoughtful and balanced view on the big question (i.e., will evolution change psychiatry?) and on more applied questions (e.g., is there such a thing as prepared fear that is related to certain phobias?). With the exception of perhaps one chapter, this volume was well conceived and a pleasure to read.
Adriaens and De Block, the editors of the book, provide an excellent introduction to the main issues facing evolutionary approaches to mental illnesses, such as whether mental disorders are unique to humans, what are the best evolutionary models to consider (e.g., adaptation, mismatch, trade-off, etc.), whether mental disorders are unique to (or more frequent in) contemporary societies, and whether it is possible to arrive at a naturalist definition of pathology. They conclude with the suggestion that an interdisciplinary awareness is necessary in order to pave the way for advances in how we conceptualize, diagnose, and treat psychological disorders.
Part 1 of the book deals with particular evolutionary hypotheses, such as whether there is a fear module that leads to particular phobias and whether imprinting can lead to paraphilias. Faucher and Blanchette (Chapter 1) argue for flexibility rather than modularity with regard to human fear mechanisms; they note that novel stimuli (e.g., a pen) can be just as readily detected and processed as evolutionarily relevant stimuli (e.g., a snake), casting doubt on the current evolutionary models of phobias. Aronsson (Chapter 2) cogently argues that imprinting, a well-studied learning phenomenon, has not been considered as a possible contributor to paraphilias, such as fetishism, citing interesting studies on how mate choice is affected by early exposure. Machery (Chapter 3) discusses the notion of dissociations—that different brain functions can be studied separately from others—and whether the study of developmental disorders can inform the study of “normal” functioning. Geerts and Brüne (Chapter 4) argue, like Tinbergen (1963) did a long time ago (but that part is often forgotten), that a careful study of behavior and its proximate causes can inform ultimate questions. They do so by applying ethological techniques to the study of depression (for example, demonstrating that depressed people often induce rejection in others, countering some adaptationist hypotheses of depression).
Part 2 of the book is about the tricky notion of mental disorders. Wakefield (Chapter 5) starts it off brilliantly with a defense of his notion of disorders as harmful dysfunctions. Although Wakefield's proposal is simple, its ramifications are complex and have resulted in much confusion. We have enjoyed reading Wakefield's responses to critics over the years, if only because of his systematic and thoughtful approach. Even evolutionary psychologists are not immune to confusion about functions and dysfunctions. A colleague of ours gave a talk at an evolutionary psychology conference a few months ago about psychopathy. He was presenting a test of a functional hypothesis for psychopathy, and an audience member questioned whether something as abhorrent and damaging as psychopathy could ever be considered functional. Her point was (we think) that if something as destructive as psychopathy could ever be considered not to be a disorder, then there must be something wrong with Wakefield's notion of disorders. One wonders if we all forget, at one point or another, that evolution does not care about our happiness.
Nesse and Jackson (Chapter 6) discuss the making and the remaking of the Diagnostic and Statistical Manual of Mental Disorders, noting that psychiatry does not distinguish between symptoms and diseases, nor does it even discriminate between protective responses and diseases. They make a strong argument that diagnosis requires an identification of causes. They produced our favourite sentence in the book: “Living is a sequence of episodes in which organisms attempt to reach goals and avoid losses” (p. 185). No poetry here, and certainly not uplifting, but it is hard to come up with a truer sentence of what it is all about.
Nettle (Chapter 7) provides a nice counterpoint to Nesse and Jackson. He wonders if it is in fact too hard to distinguish, in practice, between the normal and the abnormal, between function and dysfunction. He makes an argument similar to one made many years ago by Cosmides and Tooby (1999), that subjective distress is really what matters to clinicians—the notion of treatable conditions. It doesn't matter whether a “condition” is functional or dysfunctional, or whether it falls in the realm of disease or not. What matters is helping a suffering person. That is a fair point, but we believe a better understanding of dysfunction will serve as a good starting point to help fix what is broken.
Roe and Murphy (Chapter 8) close this section with a somewhat puzzling argument. They state that medicine does not care about evolved function, instead suggesting that medicine and psychiatry should be concerned with mechanistic (proximal) function only. They argue that we don't know much about reproductive success associated with many mental disorders, something that is clearly not true (and something that might not be relevant in the first place). They further write, “We suggest that homeostasis, not survival value, is what guides physiological answers to questions about causal explanations of biological systems” (p. 227). A thorough reading of Tinbergen (1963) might be beneficial here.
Part 3 contains three very good chapters that did not fit nicely in the first two parts. Focquaert and Braeckman (Chapter 9) propose an evolutionary model of autism spectrum disorder, suggesting that the sex difference in prevalence is the result of differential selection pressures on empathy. Price's (Chapter 10) contribution is a tribute to Gregory Bateson, who wrote about interpersonal relationship processes, in which positions of power and control are defined. Price uses this approach to make a hypothesis about depression: People with depression are unable to get up, like losers in a fight, giving relationship power to others—a novel and largely untested idea. Burns (Chapter 11) discusses the possibility that schizophrenia is a social brain disorder, in the sense that social consciousness is an important and complex trait, and when that trait does not develop properly, something akin to schizophrenia results. One wonders then if it is possible that every major and complex human skill has a disordered equivalent. After all, things that need to be built will sometimes malfunction.
We highly recommend this book for anyone interested in the application of evolutionary thinking to psychological disorders. It is a great read. We also recommend the book for teaching, especially with students who already have some background in evolutionary psychology. Can anything make sense in psychiatry and abnormal psychology without the light of evolution? These fields have advanced tremendously without it, but taking the next step might require it.