A Natural History of Mind The role of Evolutionary explanations in psychology By Russi! Durrant A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy in psychology. Department ofPsychology The University of Canterbury 1998 Acknowledgements I should like to thank firstly my two supervisors Brian Haig and Jim Pollard, for their relaxed supervisory styles and their encouraging and thoughtful comments on my work. I should also like to thank all those who contributed in various ways to the completion of this project. My especial thanks to Jo, Alice, Chris, Simon, Jonnyand James. Finally, my thanks to Sco and Pat for putting everything in perspective. Contents Introduction 1 (1) Explanation, theory appraisal and the growth of science: A realist perspective 7 The aims ofscience 8 A Realist approach to science 12 Anti-realism 14 The challenge from empiricism 15 The challenge from relativism 16 The challenge from the history ofscience 18 Realism defended 19 The status of non-observables 19 The role ofsuper-empirical values 20 A closer look at the theory dependence ofobservation 22 Rescuing truth: an optimistic reappraisal of the history ofscience 25 Theory appraisal and the role of global research programmes in science 27 Scientific research programmes 29 Features ofglobal research programmes in science 35 Internal characteristics 35 External characteristics 39 Theory appraisal in science 42 Relationships between theories 50 The nature of scientific explanation 51 The received view 51 Problems with the received view 53 The causal-mechanistic approach to explanation 55 Explanation as unification 57 The pragmatics of explanation 60 The role ofglobal research programmes in scientific explanations 63 Progress and conceptual change in science 64 Summary 67 (2) The nature of psychology 69 Is psychology a science? 70 The domain ofpsychology 75 A naturalist-realist perspective 79 Systems of psychological explanation 86 Psychology as a disunified science 86 Reductionism in psychology 89 Global research programmes in psychology 91 Progress and conceptual change in psychology 93 Summary 95 (3) The evolutionary programme in psychology 96 The structure of the evolutionary programme 97 Historical Overview 104 ethology and the emergence ofsociobiology 112 Human behavioural ecology 119 Evolutionary psychology 123 Criticisms of evolutionary psychology: getting the best out of evolutionary theory for psychology 130 Mind or behaviour? 131 TheEEA 132 Reconstructing human cognitive architecture: degrees of domain specificity 133 Ignoring groups: evolutionary psychology and the social environment 137 Summary 139 (4) Challenges to the evolutionary research programme in psychology: An overview 141 (5) Ethical issues in the evolutionary research programme in psychology 145 Class and evolutionary theory 148 Sexism and evolutionary theory 153 Evolutionary theory and racism 156 The role ofnon-epistemic values and the acceptability of the evolutionary research programme 158 (6) Anthropomorphism: the role of comparative psychology in the evolutionary programme 162 Challenges to the role of comparative psychology in the evolutionary programme 163 A limited defense of comparative explanations 166 Problems with cognitive explanations of animal behaviour 172 Summary 175 (7) The use of adaptation explanations in the evolutionary programme in psychology 176 Adaptation and natural selection 177 Challenges to the adaptationist programme 179 A general defense of adaptationism 187 The use of adaptation explanations in psychology 191 Methodological problems 192 The problem of taxonomy 199 Alternative explanations: the scope of adaptationism in psychology 200 Summary 212 (8) Explaining diversity: The role of culture as an alternative source of explanation in psychology 213 Nativism V s. Empiricism: the role of learning and environment in evolutionary explanations 213 Culture as an alternative explanation 217 Is culture unique to humans? 219 Does culture represent a truly alternative explanation? 222 Explaining individual differences from an evolutionary perspective 223 Explaining culture 225 Summary 229 (9) Explaining jealousy: A case study 230 The nature of jealousy 231 General features ofjealousy 232 Responses to jealousy 233 Modifying variables 235 Gender differences 235 Cross-cultural aspects ofjealousy 237 Jealousy in open marriages 238 Legal and social structures 238 An evolutionary approach to jealousy 239 Criticisms ofevolutionary approaches to jealousy 249 Cognitive theories of jealousy 253 Social-cognitive perspectives 256 Socio-cultural approaches 258 Explaining jealousy: Relating the alternative perspectives 259 What is the best explanation ofjealousy? 259 The relations between alternative approaches 264 Pragmatic concerns 270 Summary 272 (10) The role of evolutionary explanations in psychology 274 The current status of psychological science 274 The explanatory coherence of the evolutionary research programme in psychology: Past, present, and future 277 Levels of analysis and evolutionary explanations in psychology 285 Explanatory relevance and explanatory salience 289 The evolutionary programme and the future of psychology 292 References 296 Abstract Evolutionary theory has been employed to explain psychological and social phenomena for over a hundred years. However, despite various claims that evolutionary theory should be considered the dominant theoretical framework for psychology, mainstream psychologists have resisted the widespread use of evolutionary explanations in their domain. This thesis aims to clarify the role of evolutionary explanations in psychology. In particular, I demonstrate that a clearer understanding of the role of evolutionary explanations in psy~hology is obtained by drawing on some recent literature in the philosophy of science. Evolutionary theory, I argue offers a coherent, unifying, explanatory framework for psychology, and evolutionary explanations should have a more prominent role in psychological science than they have had in the past. However, mainstream psychological theory will not be entirely replaced by theories drawn from the evolutionary research programme. The relationship between evolutionary explanations and other sorts of explanations in psychology is clarified, and some suggestions as to what evolutionary theory offers the future of psychology are forwarded. 1 Introduction Humans are the product of evolution. Our opposable thumb, bipedal stance, and colour vision are all the result of millions of years of selection under ecological conditions where these characteristics proved favorable in fulfilling reproductive goals. The anatomical and physiological features of our bodies are clearly explicable in tenns of evolutionary theory. Evolution by natural selection can explain why we possess a grasping hand with an opposable thumb, why we walk upright, and why we see the world in colour. In all motile organisms certain ways of behaving, but not others, are also likely to prove beneficial in tenns of increasing reproductive success. Ultimately behaviour is regulated by brain processes. In organisms with complex nervous systems, brain processes can be conceptualised as the physiological instantiations of psychological mechanisms.' Certain ways of perceiving and thinking about the world, of making decisions, and of integrating behaviour are likely to prove more reproductively successful than are others. It follows that evolutionary theory should be able to explain why humans think and behave in the way that they do. The logical conclusion is that evolutionary theory should be able to provide satisfactory explanations of human psychological and behavioral phenomena. Psychology should be considered as a branch of biology. The sort of argument outlined above has been forwarded by numerous biologists, philosophers, anthropologists and psychologists since the publication of Darwin's The Origin of the Species by Means of Natural Selection. Darwin himself clearly viewed the emotional, behavioural, and psychological characteristics of humans as specific instances of evolution by natural selection at work. Evolutionary theory for Darwin, Huxley, Romanes, and others provided a means of explaining the nature and organization of the human mind just as it provided explanations for physiological, anatomical and behavioural phenomena in humans and other animals. About a hundred years later, the development of sociobiology, to the consternation of many social scientists, offered a way of explaining the patterns of social behaviour in humans and other animals by reference to evolutionary theory. For E. O. Wilson, as with Darwin, psychology could be clearly conceptualised as a biological science. Just 2 over a decade later, and in the wake of a voluminous raft of criticism directed at sociobiology, evolutionary psychologists were beginning to make similar claims. For evolutionary psychologists, however, the mind was seen as the level to which evolutionary explanations should be directed. The seemingly diverse behaviour manifest in humans was explained as the product of innate psychological mechanisms, explicable ultimately in terms of evolutionary forces. As with Darwin and Wilson, psychology was, and is, viewed by evolutionary psychologists as part of biological science. Evolutionary theory is, or should be, the unifying theoretical paradigm in the psychological sciences. Mainstream psychologists, however, have been, and remain, unconvinced. Humans may be the product of evolution it is conceded, but