Leonardo's Brain Read online

  Leonardo’s Brain

  Understanding da Vinci’s Creative Genius

  Leonard Shlain

  Lyons Press is an imprint of Rowman & Littlefield

  Distributed by NATIONAL BOOK NETWORK

  Copyright © 2014 by Leonard Shlain

  All rights reserved. No part of this book may be reproduced or transmitted in any form by any means, electronic or mechanical,

  including photocopying and recording, or by any information storage and retrieval system, except as may be expressly permitted in writing from the publisher.

  British Library Cataloguing-in-Publication Information available

  Library of Congress Cataloging-in-Publication Data available

  ISBN 978-1-4930-0335-8 (hardcover)

  eISBN 978-1-4930-1557-3 (eBook)

  The paper used in this publication meets the minimum requirements of American National Standard for Information Sciences—Permanence of Paper for Printed Library Materials, ANSI/NISO Z39.48-1992.

  To my incredible wife, Ina Gyemant

  Contents

  Copyright

  Note to Reader

  Author’s Note

  Preface

  Chapter 1: Art/Science

  Chapter 2: Medicis/Popes

  Chapter 3: Milan/Vatican

  Chapter 4: Mind/Brain

  Chapter 5: Leonardo/Renaissance Art

  Chapter 6: Renaissance Art/Modern Art

  Chapter 7: Duchamp/Leonardo

  Chapter 8: Leonardo the Trickster

  Chapter 9: Creativity

  Chapter 10: Fear, Lust, and Beauty

  Chapter 11: Leonardo/Theories

  Chapter 12: Leonardo/Inventions

  Chapter 13: Emotions/Memory

  Chapter 14: Space and Time/Space-Time

  Chapter 15: Leonardo/Remote Viewing

  Chapter 16: Leonardo’s Brain

  Chapter 17: Leonardo/Asynchrony

  Chapter 18: Evolution/Extinction

  Acknowledgments

  Photographs

  Notes

  Index

  About the Author

  Note to Reader

  On September 6, 2008, our father entered emergency surgery and was diagnosed with stage 4 brain cancer and given nine months to live. The prospect of losing our father, a simultaneously larger-than-life and loving and fully present figure, took our breath away. Up until that fateful day, he had been diligently finishing this book that he had worked on for seven years, Leonardo’s Brain.

  Our days were spent eating meals together, searching for silver brain-cancer bullets, shuttling between radiation and daily blood transfusions, and writing this book. So whether we were reading or talking about his book, or the tumor we were trying to shrink in his head, we were always talking about Leonardo’s Brain in one form or another.

  These days were especially high-definition. He reached out to people he hadn’t seen in years, and they would pick him up at home, take him out for a fabulous lunch with a glass of wine, and reconnect. After this, he would sit in the blood transfusion chair at the hospital and then go home and get back to writing. He was trying to download all his ideas and knowledge before it was too late.

  He finished the book on Monday, May 3, 2009. It was akin to watching a long-distance runner cross the finish line. On Thursday, May 6, we spent the evening selecting quotes from a large list of favorites he kept in a document, placing two or three atop every chapter, like putting dewdrops on the leaves of a Japanese tea ceremony orchid.

  On Friday, May 7, Ina, his wife and our stepmother, called all three children and his two best friends to his bedside. She said he had something he wanted to tell all of us. We gathered around him, but this time he couldn’t speak. Still, we could see the thoughts dancing in his eyes. He looked frustrated at not being able to find words, but then he started to look amazed. He kept saying “Wow.” Then he started to slip away.

  He died Monday, May 11, 2009, at 5:40 a.m.

  Leonardo’s Brain is not only one of his grandest intellectual journeys, akin to his books Art & Physics, The Alphabet Versus the Goddess, and Sex, Time, and Power, but it also kept him alive.

  He loved more than anything else to share. As his children, we are honored to share this book with you.

  Kimberly (Shlain) Brooks, Jordan Shlain, and Tiffany Shlain

  Author’s Note

  Dear Reader,

  In the months before September 6, 2008, I noticed that I was having trouble buttoning my sleeves with my right hand more than my left, even though I am right-handed. When I came down for breakfast that morning, I could barely speak. My alarmed wife, Ina, called my son, Jordan, a doctor, who scheduled an emergency MRI. I emerged to find my friend Brian Anderson, a neurosurgeon, at my bedside. He told me in a serious voice that I would need emergency brain surgery in two hours.

  The brain tumor was large and malignant. Even though I knew that the tremendous difficulty I was having speaking and moving my right side was as a result of brain swelling secondary to the surgery, at the time I was not so sure I would recover. Thankfully, I did.

  The reason I am telling you of this development, dear reader, is to let you know that I am determined to finish this book. Tiffany Shlain, my youngest daughter, who lives near me, has assured me that she will be there for any help I need. Most of it is written, and the last few chapters are in my head. I had planned to make this book as accurate as possible, and to meticulously go over every fact and date to ensure that there are no errors. Alas, there is not enough time left for me to guarantee that, so I ask for your tolerance if the book slips on a detail, or if an endnote is missing.

  I have poured myself into this book by reading and synthesizing an enormous amount of background information about Leonardo and the evolutionary development of the brain. In this book I aim to present original theories that weave together the different aspects of Leonardo’s life (and brain) that have not yet been considered by previous scholars from the fields of psychology, art history, and science. In doing so, I hope to stimulate new thinking about Leonardo and humankind alike.

  Leonard Shlain

  Mill Valley, California

  April 2009

  Great art can communicate before it is understood.

  —T. S. Eliot

  It seems to me that in the question of truth and beauty one finds what is really the deepest root of the relationship between science and art.

  —David Bohm, quantum physicist

  The artist is the antennae of the race.

  —Ezra Pound

  Preface

  Another book about Leonardo da Vinci? Is there no end to authors, poets, historians, art critics, scientists, and psychiatrists rooting around in this cultural giant’s extensively overexamined life? Can we not let this poor soul’s psyche rest in peace? I would answer, “Well, not yet.” Scholars have scrutinized both Leonardo’s life and work with a perspective particular to each of their specialties and interests. I intend to scrutinize Leonardo utilizing the knowledge others have gained, but seen from a perspective none have previously employed—that of a general and vascular surgeon with an abiding interest in brain science, and, in particular, the division of functions between the two hemispheres of the brain. I am convinced that many of the mysteries of the human condition are a result of this split-brain duality. It forms a paradox best represented by the English first-person singular “I.” This perpendicular straight line with no subsidiary parts seems the perfect icon for the self-contained human being “I.” The vertical stroke creates a division between everything within the waterproof bag we call our skin, and everything on the other side of that bag.

  But neuroscientists have learned that what we think of as the singular “I” can more accurately be con
strued as a sharp line cleaving the two, sometimes competing and sometimes cooperating, halves of a person’s cerebral hemispheres. In truth, we are Siamese twins conjoined at the corpus callosum—the broad band of fibers that connects the right and left halves of the brain in all vertebrates. Each of the halves of a human brain can generate opinions, perceptions, likes, and dislikes different from those of its yoked twin across the way. There is a long history in literature and art of two personas existing within one body, epitomized by Robert Louis Stevenson’s two characters operating within the confines of one body that sometimes manifested as Dr. Jekyll, and other times as Mr. Hyde. Only recently has it been possible to assign to each of them their own individual anatomical mailing addresses.

  Despite the many different theories about how the brain processes information and generates the sublime mystery of human consciousness, no neuroscientist disputes the fact that the human brain differs from those of other animals in the unparalleled degree to which its two cortical hemispheres have specialized their functions.

  Human creativity, I will argue, must be intimately bound up in this unique arrangement. But why are some individuals more creative than others? If, as many have conjectured, the brains of the truly creative are wired differently than those of the plodding masses, then it is a worthy exercise to compare the wiring diagram of an average person’s brain with that of a creative genius.

  But how would a researcher choose among the many creative people presently alive? Some would opt for the latest winner of the Nobel Prize in Physics. Others would propose the greatest contemporary composer. Still others would advocate that the head encircled by the magnetic doughnut should be the winner of a prestigious art prize, such as the Rome Prize.

  Rather than attempt to contrast the average brain with a renowned contemporary creative genius, I have decided to choose the one individual whom the majority of inhabitants of the Western world would agree was the most creative person who ever lived—Leonardo da Vinci.

  Ah, but someone is quick to point out that the exact site where Leonardo was buried in France is presently unknown. Besides, his brain decomposed along with the rest of him nearly five hundred years ago. These are not insurmountable obstacles. Twenty-first-century strides in neurocognitive research will allow me to investigate one of the mysteries about Leonardo that remains unexplored: How was Leonardo’s brain organized? What extraordinary neuroconfiguration did he possess that allowed him to attain his singular place in history?

  To solve this mystery, I must pursue two entirely different stories. One story will be about the life and works of Leonardo; the other will be about the evolution of brains. This two-strand braid will make up roughly the first two-thirds of the book, creating the foundation for the third part of the book, which will explore the effect of brain organization on creativity and suggest new directions toward which the human species is evolving.

  An exposition of the environmental pressures that caused the human brain to evolve so differently from the brains of other mammals leads to a discussion of the unique human arrangement of a split brain, with each hemisphere assigned different functions. The ratio of right-hand/left-brain-dominant individuals compared to left-hand/right-brain dominance is 90 percent, a percentage that has remained stable throughout history and across differing cultures. If being right-handed was such an advantage for humans, why are not all humans right-handed? Or, alternatively, why not a fifty-fifty ratio? What was the evolutionary advantage of a dominant cerebral hemisphere in the first place? Why not the ambidextrous model used with great success by the majority of other animals?

  The right brain (in right-handers) best processes information that is for the most part emotional and spatial. The left brain (in right-handers) processes information that is primarily rule-driven and temporal. Similar to the Chinese yin/yang symbol, each major side contains within its core a small essence of its opposite. When discussing the brain, distinctions are never black and white. There is considerable crossover in function. Not all language centers are in the left brain, and not all spatial judgments are processed in the right brain. Nevertheless, our present and past can be better understood if we examine human history using this dualistic model.

  The right- and left-brain functions are commonly associated with the dualities of masculine/feminine, active/passive, particular/general, focused/holistic, and rational/intuitive. The arrangement of a masculine side of the brain and a feminine side promotes a psychic hermaphroditism in both men and women, making the human sexes unlike any other species. Every man has an animus and an anima just as every woman has an anima and an animus. I will apply this understanding of how human brains are organized to speculate on the design of Leonardo’s brain.

  The final section of the book will build upon the re-creation of Leonardo’s brain to launch into a discussion of human consciousness (after all, I am a California author!). The question I will try to answer is whether Leonardo, because of the unique arrangement of his neural cabling, was able to access a qualitatively different state of consciousness than practically all other humans.

  I am a synthesizer by nature in an age when the information explosion has resulted in compartmentalized education and highly specialized professions. In an attempt to reverse this process, my passion is to integrate unrelated disciplines. Mimicking Leonardo’s diverse interests, Leonardo’s Brain will draw from a disparate group of thinkers, as well as the principles and discoveries of a wide range of endeavors: Classical philosophers, art historians, modern physics, enlightenment thinkers, sociobiology, paranormal investigations, evolutionary theory, neuroscientific discoveries, and many more will become strands in the complex tapestry I plan to weave. I do not profess to be an expert in any of these fields, but I have spent a considerable amount of time and effort trying to make myself one.

  I do profess a certain degree of expertise in matters concerning the brain. As a medical student, I had to learn the intricacies of neuroanatomy and neurophysiology. As an aspiring psychiatrist, I enjoyed studying the puzzle of consciousness and contemplating how the mind works. When I decided not to take a psychiatric residency and begin instead a surgery residency to become a vascular surgeon, I had to learn how the brain works.

  A writer is always refining his ideas, and this book represents the trajectory and culmination of thought that I laid out in my three previous books. Because I am not sure whether or not the reader has read them, I need, on occasion, to repeat a few of their themes. For readers of one or all of my books, an occasional déjà vu may surface from time to time.

  In Art & Physics: Parallel Visions in Space, Time, and Light, I proposed that the visionary artist is the first person in the culture to see the world in a new way. Later, or sometimes simultaneously, the revolutionary physicist has an insight of such import that it changes the way we think about the world. In that book, I had a chapter on Leonardo, which was the seed from which this book grew. The division between the right and left sides of the brain and its correspondence to the divisions between art and physics figured prominently in that book.

  My next book had a similar right-/left-brain theme. The Alphabet Versus the Goddess: The Conflict Between Word and Image examined what happened to gender relations when cultures discovered writing, particularly the alphabet. Every ancient culture worshipped goddesses. Then the three monotheistic religions came into being—Judaism, Christianity, and Islam—each founded on a sacred alphabetic book, and each denying the existence of goddesses. I wanted to understand what event in culture could have been so pervasive that it changed the sex of God. I concluded that learning how to read and write an alphabet reconfigured the brain, bolstering the dominance of the left hemisphere. Reading and writing, unlike speaking and listening, are primarily left hemispheric tasks. Whenever writing appears, women’s rights suffer, image information becomes an “abomination,” and goddesses disappear. Whenever images regain prominence in the culture over written words, as they did in the Dark Ages, the goddess (Mary) makes a comeba
ck. The Protestant Reformation, coincident with the sharp rise in literacy in the Renaissance, devalued the divinity of Mary; consequently, women’s rights suffered. Now, as our culture becomes more image-based, women are making incredible advances. Images are primarily processed by the right brain.

  I wrote my third book, Sex, Time, and Power: How Women’s Sexuality Shaped Human Evolution, because after examining gender relations in the context of the arrival of the written word, I began to wonder why humans had wandered so far away from the mating systems used by the other three million sexually reproducing species. The human female abandoned estrus (the recurring but periodic state of sexual excitation in most mammals) but gained menses, the menstrual flow that in humans exceeds the hundred or so other mammals out of four thousand exhibiting this trait. How astonishing! Although primarily a discourse on the evolution of humans, in this book, once again the split brain plays a prominent role.

  This book carries the question even further. Why do we have a split brain in the first place? Realizing that every virtue comes with a vice, I ask the question: Did divided hemispheres that served us well on the African Serengeti in the Pleistocene Epoch now possess a curse that could destroy us? How do we change as a species to extract ourselves from this dilemma? Thinking about the wiring in the brain of Leonardo provides a convenient jumping-off point. He had, from what we know, the most creative brain in history. And he was a vegetarian pacifist. He overcame his initial aggressive stance toward designing weapons. How do the rest of us achieve greater creativity while becoming more peaceful?