THE DESCENT OF MADNESS Drawing on evidence from across the behavioural and natural sciences, this book advances a radical new hypothesis: that madness exists as a costly consequence of the evolution of a sophisticated social brain in Homo sapiens. Having explained the rationale for an evolutionary approach to psych- osis, the author makes a case for psychotic illness in our living ape relatives, as well as in human ancestors. He then reviews existing evolutionary theor- ies of psychosis, before introducing his own thesis: that the same genes causing madness are responsible for the evolution of our highly social brain. Jonathan Burns’ novel Darwinian analysis of the importance of psychosis for human survival provides some meaning for this form of suffering. It also spurs us on to a renewed commitment to changing our societies in a way that allows the mentally ill the opportunity of living. The Descent of Madness will be of interest to those in the fields of psychiatry, psychology, sociology and anthropology, and is also accessible to the general reader. Jonathan Burns is chief specialist psychiatrist at the Nelson Mandela School of Medicine. His main areas of research include psychotic illnesses, human brain evolution and evolutionary origins of psychosis. THE DESCENT OF MADNESS Evolutionary Origins of Psychosis and the Social Brain Jonathan Burns First published 2007 by Routledge 27 Church Road, Hove, East Sussex BN3 2FA Simultaneously published in the USA and Canada by Routledge 270 Madison Ave, New York, NY 10016 Routledge is an imprint of the Taylor & Francis Group, an informa business © 2007 Jonathan Burns This edition published in the Taylor & Francis e-Library, 2007. “To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.” All rights reserved. No part of this book may be reprinted or reproduced or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers. This publication has been produced with paper manufactured to strict environmental standards and with pulp derived from sustainable forests. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging in Publication Data Burns, Jonathan, 1968– The descent of madness : evolutionary origins of psychosis and the social brain / Jonathan Burns. p. ; cm. Includes bibliographical references. ISBN-13: 978–1–58391–742–8 (hardback) ISBN-10: 1–58391–742–X (hardback) ISBN-13: 978–1–58391–743–5 (pbk.) ISBN-10: 1–58391–743–8 (pbk.) 1. Psychoses—Etiology. 2. Mental illness—Diagnosis. 3. Evolution. I. Title. [DNLM: 1. Psychotic Disorders—etiology. 2. Evolution. 3. Hominidae—psychology. 4. Psychotic Disorders—genetics. 5. Social Behavior. WM 200 B967d 2006] RC512.B87 2006 616.89—dc 2006016382 ISBN 0–203–01211–9 Master e-book ISBN ISBN13: 978–1–58391–742–8 (hbk) ISBN13: 978–1–58391–743–5 (pbk) For Eliza whose love, companionship, wisdom and patience keep me sane and enrich my every day. CONTENTS Acknowledgements viii 1 Introduction 1 2 A history and pre-history of madness 21 3 Evolutionary principles of the origins of psychosis 44 4 Evolutionary genetics of psychosis 60 5 A social brain for a social world 71 6 The evolution of the social brain 100 7 Schizophrenia and the social brain 122 8 The dysconnectivity hypothesis of schizophrenia 143 9 Evolutionary ontogeny of schizophrenia 162 10 The costly legacy of an evolved social brain 180 Glossary 203 Notes 205 References 214 Index 259 vii ACKNOWLEDGEMENTS In the several years it has taken me to formulate and clarify my thinking and to write this book, there are many individuals to whom I am greatly indebted. As a psychiatric registrar in Cape Town, I was first introduced to the evolutionary approach to mental disorders by Dave Kibel my consultant – he loaned me his copy of Evolutionary Psychiatry by Anthony Stevens and John Price – and for planting this seed of interest I am truly grateful. I first met John Price in London a few years later at a Human Behaviour and Evolution Society meeting and I thank him for our conversations and correspondence on that occasion and in the years since. It was John who encouraged me to write a paper on brain evolution and psychosis that marked the beginnings of this book project. Tim Crow has had a profound influence on me over the last 5 or 6 years and I owe him special appreci- ation. For our conversations, email exchanges and good-natured disagree- ment on certain issues, I offer him my thanks and humbly acknowledge his genius. To Martin Brüne, I am grateful for friendship and great discussions – also for his helpful comments at different stages of the writing process. Richard Byrne, James Rilling, Sarah Hrdy and Jane Goodall all contributed (either verbally or in writing) their thoughts and insights on human brain evolution and abnormal ape behaviour – I thank them sincerely. And Louis Sass read and offered important suggestions on Chapter 5 for which I am grateful. Many of the ideas discussed in this book were developed during the open review process of my paper ‘An evolutionary theory of schizophrenia – cortical connectivity, metarepresentation and the social brain’ published in Behavioral and Brain Sciences (BBS) in December 2004. I thank the follow- ing individuals who contributed to this open review process (and whose responses are printed in the same volume): Conrado Bosman, Enzo Brunetti and Francisco Aboitiz; André Aleman and René Kahn; Martin Brüne; Tim Crow; Paul Gilbert; Valerie Hardcastle; Ralph Hoffman, Michelle Hampson, Maxine Varanko and Thomas McGlashan; Matthew Keller; Randolph Nesse; Jaak Panksepp and Joseph Moskal; Vadim Rotenberg; Roger Sullivan and John Allen; Rolf Verleger and Rebekka Lencer; and viii ACKNOWLEDGEMENTS Glenn Weisfeld. I would also like to acknowledge the wise counsel and welcome encouragement offered by the late Professor Jeffrey Gray, past editor of BBS, during the review process of my paper. His personal warmth and intellectual acuity are sorely missed. While a research fellow in the Department of Psychiatry in Edinburgh during 2001 and 2002, I was fortunate enough to work alongside a number of individuals who are considered leaders in the field of schizophrenia research. Eve Johnstone, David Cunningham-Owens and Steve Lawrie all contributed either directly or indirectly to my thinking and the preparation of this book. To them I extend my gratitude and, in particular, I thank Eve for tolerating my forays away from her project in pursuit of evolutionary ideas. It was in her department that I came to appreciate the significance of the social brain and its disturbance in psychotic illness. I also thank David Semple for the many hours of stimulating discussion out in the rain and for his friendship – many of the ideas I have elaborated in this book were percolated in this intellectual coffee-pot! I am grateful to my editor Joanne Forshaw and the team at Routledge for their support throughout the preparation of this book. Thank you for guiding me expertly through the process and for your patience with my delays in delivering the manuscript. I am grateful to Sebastian Faulks and Hutchinson Publishers for permission to quote material from Human Traces. The extracts are reprinted in Chapter 10 by permission of The Random House Group Ltd. My mother, Sarah Burns, created two of the illustrations: Figures 6.1 (the primate family tree) and 6.2 (the nut-cracking chimpanzee). I thank her for these wonderful contributions and I am profoundly grateful to both my parents for the multitude of ways in which they have positively influenced my life. As well as providing me with a powerful model of how to live an honest, humane and socially responsible life, they have also instilled a love and respect for the natural world and a curiosity about the workings of the human mind. In my three sons, Noah, Aidan and Luke, I experience true delight every day – they are a boisterous and spirited trio, my three musketeers – my only regret in writing this book is the time it has stolen from being with them. And finally I thank my wife, Eliza, who is the brainy, beautiful and gutsy woman of my life. For her integrity, courage and com- mitment to real relationship and real community I salute her. For being an awesome mother to our sons I thank her. And for loving me and making me a better man I offer my eternal gratitude. She is the perfect psychiatrist’s psychiatrist! ix 1 INTRODUCTION THE MEANING OF MADNESS The meaning of madness is one of the greatest enigmas of the human condi- tion. From before the written word there is evidence that those in our midst of unsound mind and aberrant behaviour have perplexed and unsettled us. Whether we examine archaeological clues, the themes of oral traditions and folklore or the literature of both New World and Old World societies we are struck by the fact that madness has always been a fascination and a challenge for society. Themes of mental suffering and disrupted reasoning pervade our literary and artistic heritage and continue, even into this liberal enlightened age, to evoke strong passions. Why is it that madness holds such a fascination to human societies the world over? What is it about the ‘imbalance’ of those afflicted that spurs us on to write about, paint, dramatize and immortalize in our legends carica- tures of suffering people? There are several contributory aspects of human nature that fuel this preoccupation.