Human Brain Evolution

The evolution of the human brain and cognitive ability is one of the central themes of physical/biological anthropology. This book discusses the emergence of human cognition at a conceptual level, describing it as a process of long adaptive stasis interrupted by short periods of cognitive advance. These advances were not linear and directed, but were acquired indirectly as part of changing human behaviors, in other words through the process of exaptation (acquisition of a function for which it was not originally selected). Based on studies of the modem human brain, certain prerequisites were needed for the development of the early brain and associated cognitive advances. This book documents the energy and nutrient constraints of the modern brain, highlighting the significant role of long-chain polyunsaturated fatty acids (LC-PUFA) in brain development and maintenance. Crawford provides further emphasis for the role of essential fatty acids, in particular DHA, in brain development, by discussing the evolution of the eye and neural systems.

This is an ideal book for Graduate students, post docs, research scientists in Physical/Biological Anthropology, Human Biology, Archaeology, Nutrition, Cognitive Science, Neurosciences. It is also an excellent selection for a grad student discussion seminar.

Foreword: Evolution, Encephalization, Environment vii
Phillip V. Tobias

Introduction xiii
Kathlyn M. Stewart and Stephen C. Cunnane

Contributors xix

Chapter 1 Macroevolutionary Patterns, Exaptation, and Emergence in the Evolution of the Human Brain and Cognition 1
Ian Tattersall

Introduction 1

Natural Selection 1

Macroevolution 2

Patterns in Human Evolution 3

Symbolic Cognition 5

Exaptation and Emergence 8

Large Brains and Aquatic Resources 9

References 10

Chapter 2 Long-Chain Polyunsaturated Fatty Acids in Human Brain Evolution 13
Michael A. Crawford

Introduction – Lipids and Evolution 13

The Evolution of Complex Life Forms 14

The Language of Lipids 15

DHA 17

Evolution of Homo sapiens 20

DHA and Neural Pathways? 22

A Comment on AA 24

The Third Phase of Earth’s Life History – AA and Reproduction in Mammals 25

Darwin and the Conditions of Existence 26

Implications 27

Conclusion 28

Acknowledgments 28

Notes 28

References 28

Chapter 3 Human Brain Evolution: A Question of Solving Key Nutritional and Metabolic Constraints On Mammalian Brain Development 33
Stephen C. Cunnane

Introduction 33

Brain Evolution in Hominins 35

Need for a New Paradigm 38

Brain Development 40

Energy Requirements of the Brain 41

Nutrients and Brain Function 44

Brain-Selective Nutrients 46

Critical Importance of Baby Fat in Humans 52

Gene – Nutrient Interactions 57

Conclusions 59

Acknowledgments 61

References 61

Chapter 4 Metabolic and Molecular Aspects of the Critical Role of Docosahexaenoic Acid in Human Brain Function 65
J. Thomas Brenna

Docosahexaenoic Acid (DHA) Molecular Structure 65

DHA and Neural Function 66

Metabolic and Biophysical Considerations 68

Functional Importance of DHA in Retinal and Neural Membranes 70

Dietary Need for Preformed DHA 71

DHA Intake During Pregnancy and Lactation: Effects on Higher CNS Functions of the Mother and Infant 73

Summary 74

References 74

Chapter 5 Lessons From Shorebased Hunter-Gatherer Diets Iin East Africa 77
Frits A.J. Muskiet and Remko S. Kuipers

Introduction 77

Our Genetic Background 78

Adaptation to the Conditions of Existence 79

Western Diets and the Human Genome 81

Brain-Selective Nutrients in Health and Disease 83

Dietary Fatty Acids at the Land–Water Interface 84

Tanzanian Breast Milk Fatty Acids Versus Western Recommendations 89

Estimated Fatty Acid Intakes from Shore-Based Paleolithic Diets 93

Conclusions 96

Notes 97

References 97

Appendix 103

Chapter 6 Thyroid Hormone, Iodine and Human Brain Evolution 105
Sebastiano Venturi and Michel E. Bégin

Introduction 105

Thyroid Hormone Metabolism and Function 105

Fetal Development 108

Antioxidant Activity of Iodine 108

Dietary Sources of Iodine 110

Iodine Defi ciency Disorders 111

Human Brain Evolution 113

Thyroid Hormone, Iodine, and Human Brain Evolution 117

Conclusion 118

References 119

Chapter 7 Food For Thought: The Role of Coastlines and Aquatic Resources in Human Evolution 125
Jon M. Erlandson

Introduction 125

Food for Thought 126

Human Nutrition and Physiology 127

Archaeological Evidence for the Antiquity of Fishing 128

Conclusions 132

Acknowledgments 133

Notes 133

References 133

Chapter 8 The Case for Exploitation of Wetlands Environments and Foods By Pre-Sapiens Hominins 137
Kathlyn M. Stewart

Introduction 137

Hominid Exploitation of Wetlands Environments and Resources 139

Early Hominins: Colonization of New Environments 144

Plio-Pleistocene Climate Instability and Use of Wetlands Resources 147

Intensification of Wetlands Vegetation Exploitation 149

The Shift to High-Quality Foods 151

Preconditions for Encephalization 155

Precessional Forcing, Drying Lakes/Rivers, and Die-Offs of Aquatic Faunas 157

Mammal Meat: A Later Hominin Adaptation? 158

Postscript: H. heidelbergensis and H. sapiens 160

Summary 161

Acknowledgments 162

References 162

Chapter 9 Brain Size in Carnivoran Mammals That Forage at the Land–Water Ecotone, with Implications for Robust Australopithecine Paleobiology 173
Alan B. Shabel

Introduction 173

Methods 177

Results 177

Discussion 183

Acknowledgments 186

References 186

Chapter 10 Coastal Diet, Encephalization, and Innovative Behaviors in the Late Middle Stone Age of Southern Africa 189
John Parkington

Introduction 189

Changes 190

Climate Change 196

A New Narrative 198

References 200

Chapter 11 Human Brain Evolution: A New Wetlands Scenario 203
Stephen C. Cunnane and Kathlyn M. Stewart

Human Brain Evolution 203

Neurochemical and Nutritional Evidence 203

The Fossil Evidence 204

Plausibility, Prediction, and Parsimony 205

Salient Points 206

Conclusion 207

Reference 207

Index 209

"This is an ideal book for Graduate students, post docs, research scientists in Physical/ Biological Anthropology, Human Biology, Archaeology, Nutrition, Cognitive Science, Neurosciences. It is also an excellent selection for a grad student discussion seminar." (Human Evolution, 1 March 2013)

"This volume... is a puissant move away from the heavy, earthbound view of hominid evolution and a move toward a greater emphasis upon the role of water and waterways in hominid development, survival, and diversification." (Phillip Tobias, Foreward, Human Brain Evolution)

Stephen C. Cunnane, Ph.D., holds the Canada Research Chair in Brain Metabolism and Aging and is the Director of the Research Centre on Aging at Sherbrooke University Geriatric Institute. He sits on the editorial boards of iiuinerous journals, including Nutrition, British Journal of Nutrition and Journal of Nutritional and Environmental Medicine.

Kathlyn M. Stewart, Ph.D. is a Research Scientist in Paleobiology and former Head of Paleobiology at the Canadian Museum of Nature. Specializing in environmental change and human adaptation, she has extensive field experience in Africa.

A multidisciplinary treatment of the importance of aquatic foods in human brain evolution

The evolution of the human brain and cognitive ability is one of the central themes of physical/biological anthropology. Based on studies of the modern human brain, certain prerequisites were needed for the development of the early brain and associated cognitive advances. Important prerequisites included polyunsaturated fatty acids and other brain selective nutrients, which are found in highest quantity in fish and shellfish. Early hominins were able to access these foods when frequenting wetlands, particularly lake and river margins. Increased consumption of this high-quality diet over time exaptively diverted energy to the brain, and was a catalyst for brain growth. The later exploitation of marine shellfish and fish is roughly correlated with the emergence of Homo sapiens, and cognitive advance associated with changing human behaviors.

Human Brain Evolution: The Influence of Freshwater and Marine Food Resources documents the energy and nutrient constraints of the modern brain, highlighting the significant role of brain selective nutrients in brain development and the evolution of neural systems. There is a particular focus on two long-chain polyunsaturated fatty acids (LC-PUFA) in brain development and maintenance—docosahexaenoic acid (DHA) and arachidonic acid (AA). These nutrients are found in the highest quantity in fish and shellfish, and this volume further discusses fossil, morphological, and isotopic evidence for hominin consumption of these foods over time.

The contributors to this volume come from several fields—paleoanthropology, nutrition, neurochemistry, archaeology, and paleobiology—providing a multidisciplinary approach to the complex and challenging topic of the evolution of the brain. The first half of this volume focuses specifically on the biochemical and nutritional requirements of encephalization of the human brain, best acquired opportunistically (exaptively) through consumption of fish and/or shellfish. The second half provides multidisciplinary evidence on the exploitation of initially, freshwater and later, marine fish and shellfish, by successive hominin taxa. These persuasive, thought-provoking discussions and arguments provide the basis for a new perspective and help the reader understand the vital role freshwater and marine foods have in human brain function and, hence, evolution.

Human Brain Evolution is essential reading for graduate students, postdoctoral students, and research scientists in physical/biological anthropology, human biology, archaeology, nutrition, cognitive science, and the neurosciences. It is also an excellent supplemental text for biological anthropology or a graduate student discussion seminar.