How New Humans are Made: Cells and Embryos, Twins and Chimeras, Left and Right, Mind/Self/Soul, Sexnd Schizophrenia »

It is not okay to call something a miracle without even trying to understand it. This is human developmental biology (human embryology, in terms of cells and molecules) for everyone curious enough to see it through, from the perspective of the business of becoming human - as individuals and as species; making new humans; how it happens (cells do it, ALL of it); and common variations of the process.

It cannot be made quite simple and be kept quite true, but we will move as far toward simple as we can without losing touch with sound evidence. Variations from the "normal" version of the process, particularly malformations and twinning and chimerism, figure prominently in the story because there is no better way to learn about the usual than to study the unusual and see what differences in the endings these observable differences at the beginnings can make.

In this book, when technical terminology is the only way, or the best way, to say what needs to be said, it is defined and explained - making the words a worthwhile part of what is here to be learned.

This book defines its own new field. We cannot claim to understand how anything [human] works [as human], with no effort at understanding the emergence of its form and functions. Old and new unanswered questions are waiting to be dug out from under old unquestioned answers about how becoming human unfolds. We will also address some popular and weighty, but deeply empty assertions about the circumstances and mechanisms of our beginnings and our ceaseless becoming. We will find fundamental questions from "the humanities" unanswerable except from biology. Human developmental biology is a foundational discipline within the humanities.

Foreword vii

Acknowledgments ix

Introduction 1

Chapter 1 Orientation 12

Chapter 2 Human, by [Cellular & Developmental] Definition: Emergence: of Mind, of Self, of Soul, of Person 37

Chapter 3 Genetic Twin Studies of Schizophrenia: Mind/Brain Asymmetry, Multifactorial Inheritance and Epigenetic Variation 64

Chapter 4 Reviewing/Reciting The Orthodoxy 94

Chapter 5 On The Zygosity of Twins 105

Chapter 6 Most Twins are Not Twins 119

Chapter 7 Natural History and Epidemiology of Twins and Twinning 129

Chapter 8 the Chorion, the Amnion and the Vertebrate Body Plan 168

Chapter 9 Each of Us was Once a Single Cell ... or Two: Meiosis, Gametogenesis, Syngamy, Embryogenesis... 191

Chapter 10 Getting to the Bottom of Creation's Best Trick: How Human Lives Begin 233

Chapter 11 Timing Is Everything 252

Chapter 12 Twins and Handedness and [Illusions of] Mirror-Imaging 261

Chapter 13 Twins and Malformations 278

Chapter 14 Twins and Teeth and (the Realities of) Mirror-Imaging 289

Chapter 15 The Oddest of Couples: Boy-Girl Twins 306

Chapter 16 The Weinberg Tautology and The Lingering Perfume of Red Herring 318

Chapter 17 Twinning and Spontaneous Chimerism 341

Chapter 18 Finding the Right Answer is Much Easier: After Finding the Right Question 368

Chapter 19 Normal Embryogenesis of Left and Right, and Twins and Chimeras 389

Epilogue: The Logic of DNA Genotyping and Forensic Implications of Chimerism 407

Summary 415

Bibliography 421

Glossary 430

Index 485