Neural Reuse and the Evolution of Higher Cognition Andrew Brigham A thesis submitted in partial fulfillment of the requirements for the PhD in Philosophy Department of Philosophy Faculty of Arts University of Ottawa © Andrew Brigham, Ottawa, Canada, 2019 Acknowledgements I wish to thank my thesis supervisor, Professor Vincent Bergeron, for supporting me throughout the graduate program, offering advice about topics, grants, teaching, and selecting committee members. Moreover, Professor Bergeron was meticulous with his comments on my thesis and read and re-read each chapter thoroughly. I could not have completed this project without his continuous support and motivation. I’m grateful to my thesis committee, Dr. Andrew Sneddon, Dr. Patrice Philie, Dr. Andrew Brook, and my external examiner, Dr. Muhammad Ali Khalidi. Each provided extensive comments which improved the quality of the thesis, correcting errors, organization, flow, and raising important objections. Most importantly, I must thank my wife, Leigha, whose encouragement and incentive for me to finish strong never ceased. And to my three children, Eva, Scott, and Landen, each of whom provided valuable distractions along the way. ii Abstract Harvard psychologist Steven Pinker recently examined a problem with understanding human cognition, particularly how the processes of biological evolution could explain the human ability to think abstractly, including the higher cognitive abilities for logic and math (hereafter, HCAs). Pinker credits the formulation of the problem of understanding human cognition and the evolutionary development of HCAs to the co-discoverer of evolution by natural selection, Alfred Russell Wallace. Pinker states the following response to the question raised by Wallace: …Nonetheless it is appropriate to engage the profound puzzle [Wallace] raised; namely, why do humans have the ability to pursue abstract intellectual feats such as science, mathematics, philosophy, and law, given that opportunities to exercise these talents did not exist in the foraging lifestyle in which humans evolved and would not have parlayed themselves into advantages in survival and reproduction even if they did? Wallace claimed that while ancestral cognitive operations, such as those operations for perception and motor control, were the product of evolution, he disagreed with Charles Darwin’s view that HCAs are the product of evolution by natural selection. Wallace is not the only one to doubt that HCAs are the product of evolution. Contemporary philosopher Thomas Nagel also rejects the view that HCAs are the product of evolution. Comparable to Wallace, although Nagel accepts that older operations of the brain, such as perception and motor control, are the product of evolution, Nagel denies that higher types of cognitive operations are the product of evolution. The aim of this dissertation is to argue that HCAs are the product of evolutionary processes, both natural selection and other mechanisms of change. The reason HCAs are the product of evolution is because HCAs are carried out by the neural reuse of older evolved brain regions. Neural reuse is the view that brain regions can be recruited for multiple cognitive uses. Ancestral brain regions, such as regions for perceptual and motor functions, can be reused for carrying out HCAs, such as language, logic, and math. iii Table of Contents Chapter 1. Introduction …………………………………………………………………………...1 Chapter 2. Neural Reuse: Defense of Premise (2) ………………………………………………33 Section I. Neural Reuse: Predictions and Evidence……………………………...............33 Section A. The Neural Recycling Hypothesis…………………………………...42 Section II. Neural Reuse: Evolution……………………………………………………..49 Section A. Cognitive Homologies……………………………………………….49 Section B. The Evolvability Problem……………………………………………57 Section C. Neural Reuse and Natural Selection: Three Strategies..……………..59 Section III. General Objections and Responses……………………………………...…..62 Section IV. Conclusions……………………………………………………………….…63 Chapter 3. More on Neural Reuse: Defense of Premise (2)……………………………………..64 Section I. Traditional Cognitive Science and Embodied Cognitive Science…………….64 Section A. Embodied Cognitive Science: Body as Constraint…………………..66 Section B. Embodied Cognitive Science: Body as Distributor…………….…….68 Section II. Neural Reuse and Higher Cognitive Abilities………………………….…….71 Section A. Neural Reuse and Language…………………………………………71 Section B. Neural Reuse and Mathematics………………………………………77 Section C. Neural Reuse and Sub-Cortical Structures……………………..…….83 Section III. General Objections and Responses………………………………….………91 Section IV. Conclusions………………………………………………………….………94 iv Interlude. A Response to the Evolutionary Argument Against Naturalism……………...95 Chapter 4. Scientific Inference: Defense of Premise (4)………………………….……104 Section I. Scientific Confirmation and Explanation……………………………104 Section II. Hypothetico-Deductive Model…………………………………...…105 Section A. Defense of Premise (4): H-D Model…………………….….112 Section III. Inference to the Best Explanation………………………………….116 Section A. Defense of Premise (4): IBE Model……………………..….130 Section IV. General Objections and Responses………………………...………133 Section V. Conclusions…………………………………………………………134 Chapter 5. Objections, Responses, and Conclusions……………………………...……136 Section I. Brigham’s Argument: Assessing Objections……………..………….136 Section A. Wallace’s General Objections……………………………....139 Section B. Wallace’s Descriptive Objections………………….……….145 Section C. Nagel’s General Objections……………………….………..147 Section D. Nagel’s Descriptive Objections………….………………....149 Section II. General Reponses and Conclusions…………………………….…..153 Bibliography………………………………………………………………………...….155 v List of Figures Figure 1. Functional Fingerprints………………………………………………………………..36 Figure 2. Functional Connectivity Graphs………………………………………………………39 Figure 3. Spatial Bias Graph…………………………………………………………………….78 Figure 4. Motion Bias Graph A………………………………………………………………….82 Figure 5. Motion Bias Graph B………………………………………………………………….82 vi Chapter 1 Introduction Harvard psychologist Steven Pinker recently examined a problem with understanding human cognition, particularly how the human ability to think abstractly, including the higher cognitive abilities for logic and math (hereafter, HCAs) could be the product of evolution.1 Pinker credits the formulation of that problem of understanding human cognition and the evolutionary development of HCAs to the co-discoverer of evolution by natural selection, Alfred Russell Wallace. Pinker states the following response to the question raised by Wallace: …Nonetheless it is appropriate to engage the profound puzzle [Wallace] raised; namely, why do humans have the ability to pursue abstract intellectual feats such as science, mathematics, philosophy, and law, given that opportunities to exercise these talents did not exist in the foraging lifestyle in which humans evolved and would not have parlayed themselves into advantages in survival and reproduction even if they did?2 Wallace claimed that while ancestral cognitive operations, such as those operations for perception and motor control, were the product of evolution, he disagreed with Charles Darwin’s view that HCAs are the product of evolution.3 To clarify the question about whether or not HCAs are the product of evolution, some terms require definition. Biological evolution is a process of change over time and includes three ideas.4 The first idea is that evolution refers to descent with modification: all living things are all related and the diversity and relationship of species to one another is the product of a long 1 Steven Pinker, “The cognitive niche: Coevolution of intelligence, sociality, and language,” accessed November 12, 2016, http://www.pnas.org/content/early/2010/05/04/0914630107.full.pdf. 2 Ibid., 186-90. 3 Alfred Russell Wallace, Darwinism: An Exposition of the Theory of Natural Selection With some of its Applications (London: MacMillan, 1889), 462-463, accessed November 17, 2016, https://archive.org/details/darwinism00unkngoog. 4 Ernst Mayr, What Evolution Is (New York: Basic Books, 2001), 8; Carl Zimmer and Douglas J. Emlen, Evolution: Making Sense of Life (Colorado: Roberts and Company Publishers, 2013), 3-5. 1 history of change through genetic inheritance.5 The second idea is that evolution describes the tree of life when species split from various lineages and the changes that took place. The third idea of evolution refers to the mechanisms that may cause evolution, including natural selection, sexual selection, and genetic drift.6 Natural selection is an important concept in this project and is a mechanism whereby the differential reproduction of individuals can cause some genetic traits to spread within a population.7 Traits that increase reproductive success, or fitness, often pass on to future generations. For example, within a herd of zebra, differential reproduction causes differences in the mutations that cause running speed.8 Some zebra within the population run faster than other zebra because of the mutations they acquired. The mutation responsible for the increase in speed causes fitness-enhancing behavior, meaning that the zebra with increased speed will likely reproduce more offspring than the slower zebra. The implication of this differential reproduction is that over time the mutation causing the increase in speed will dominate the population. The trait that promotes fitness will become an adaptation within that species of zebra. While natural selection is an important mechanism for causing