Leonardo’s Brain: What a Posthumous “Brain Scan” Six Centuries Later Reveals about the Source of Da Vinci’s Creativity
By Maria Popova
One September day in 2008, Leonard Shlain found himself having trouble buttoning his shirt with his right hand. He was admitted into the emergency room, diagnosed with Stage 4 brain cancer, and given nine months to live. Shlain — a surgeon by training and a self-described “synthesizer by nature” with an intense interest in the ennobling intersection of art and science, author of the now-legendary Art & Physics — had spent the previous seven years working on what he considered his magnum opus: a sort of postmortem “brain scan” of Leonardo da Vinci, performed six centuries after his death and fused with a detective story about his life, exploring what the unique neuroanatomy of the man commonly considered humanity’s greatest creative genius might reveal about the essence of creativity itself.
Shlain finished the book on May 3, 2009. He died a week later. His three children — Kimberly, Jordan, and filmmaker Tiffany Shlain — spent the next five years bringing their father’s final legacy to life. The result is Leonardo’s Brain: Understanding Da Vinci’s Creative Genius (public library | IndieBound) — an astonishing intellectual, and at times spiritual, journey into the center of human creativity via the particular brain of one undereducated, left-handed, nearly ambidextrous, vegetarian, pacifist, gay, singularly creative Renaissance male, who Shlain proposes was able to attain a different state of consciousness than “practically all other humans.”
Noting that “a writer is always refining his ideas,” Shlain points out that the book is a synthesis of his three previous books, and an effort to live up to Kafka’s famous proclamation that “a book must be the axe for the frozen sea inside us.” It is also a beautiful celebration of the idea that art and science belong together and enrich one another whenever they converge.
To understand Leonardo’s brain, Shlain points out as he proves himself once again the great poet of the scientific spirit, we must first understand our own:
The human brain remains among the last few stubborn redoubts to yield its secrets to the experimental method. During the period that scientists expanded the horizons of astronomy, balanced the valences of chemistry, and determined the forces of physics, the crowning glory of Homo sapiens and its most enigmatic emanation, human consciousness, resisted the scientific model’s persistent searching.
The brain accounts for only 2 percent of the body’s volume, yet consumes 20 percent of the body’s energy. A pearly gray, gelatinous, three-pound universe, this exceptional organ can map parsecs and plot the whereabouts of distant galaxies measured in quintillions of light-years. The brain accomplishes this magic trick without ever having to leave its ensorcelled ovoid cranial shell. From minuscule-wattage electrical currents crisscrossing and ricocheting within its walls, the brain can reconstruct a detailed diorama of how it imagines the Earth appeared four billion years ago. It can generate poetry so achingly beautiful that readers weep, hatred so intense that otherwise rational people revel in the torture of others, and love so oceanic that entwined lovers lose the boundaries of their physical beings.
Shlain argues that Leonardo — who painted the eternally mysterious Mona Lisa, created visionary anatomical drawings long before medical anatomy existed, made observations of bird flight in greater detailed than any previous scientist, mastered engineering, architecture, mathematics, botany, and cartography, might be considered history’s first true scientist long before the word was coined for Mary Somerville, presaged Newton’s Third Law, Bernoulli’s law, and elements of chaos theory, and was a deft composer who sang “divinely,” among countless other domains of mastery — is the individual most worthy of the title “genius” in both science and art:
The divergent flow of art and science in the historical record provides evidence of a distinct compartmentalization of genius. The river of art rarely intersected with the meander of science.
Although both art and science require a high degree of creativity, the difference between them is stark. For visionaries to change the domain of art, they must make a breakthrough that can only be judged through the lens of posterity. Great science, on the other hand, must be able to predict the future. If a scientist’s hypotheses cannot be turned into a law that can be verified by future investigators, it is not scientifically sound. Another contrast: Art and science represent the difference between “being” and “doing.” Art’s raison d’être is to evoke an emotion. Science seeks to solve problems by advancing knowledge.
Leonardo’s story continues to compel because he represents the highest excellence all of us lesser mortals strive to achieve — to be intellectually, creatively, and emotionally well-rounded. No other individual in the known history of the human species attained such distinction both in science and art as the hyper-curious, undereducated, illegitimate country boy from Vinci.
Using a wealth of available information from Leonardo’s notebooks, various biographical resources, and some well-reasoned speculation, Shlain sets out to perform a “posthumous brain scan” seeking to illuminate the unique wiring of Da Vinci’s brain and how it explains his unparalleled creativity.
Leonardo was an outlier in a number of ways — socially, culturally, biologically, and in some seemingly unimportant yet, as Shlain explains, notable ways bridging these various aspects of life. For instance:
Leonardo was a vegetarian in a culture that thought nothing of killing animals for food. His explanation for his unwillingness to participate in carnivory was that he did not want to contribute to any animal’s discomfort or death. He extended the courtesy of staying alive to all living creatures, and demonstrated a feeling of connectedness to all life, which was in short supply during a time that glorified hunting.
He was also the only individual in recorded history known to write comfortably backwards, performing what is known as “mirror writing,” which gives an important clue about the wiring of his brain:
Someone wishing to read Leonardo’s manuscripts must first hold the pages before a mirror. Instead of writing from left to right, which is the standard among all European languages, he chose to write from right to left — what the rest of us would consider backward writing. And he used his left hand to write.
Thoroughly confusing the issue was the fact that sometimes he would switch in mid-sentence, writing some words in one direction followed by other words heading in the opposite direction. Another intriguing neurological datum: Careful examination of two samples of his handwriting show the one written backward moving from right to left across the page is indistinguishable from the handwriting that is not reversed.
Leonardo’s quirks of penmanship strongly suggest that his two hemispheres were intimately connected in an extraordinary way. The traditional dominance pattern of one hemisphere lording it over the other does not seem to have been operational in Leonardo’s brain. Based on what we can extrapolate from the brains of people who share Leonardo’s ability to mirror-write, the evidence points to the presence of a large corpus callosum that kept each hemisphere well informed as to what the other was doing.
Further evidence that his corpus callosum — that thick bundle of fibers connecting the left and right hemispheres, consisting of more than 200 million neurons — was “afairly bursting with an overabundance of connecting neurons” comes from his unusually deft fusion of art and science. For instance, Shlain points out, no other artist in history labored so obsessively over perfecting the geometrical details of the science of perspective.
Before delving into Leonardo’s specific neuroanatomy, Shlain points out that because our brains have the maximum number of neurons at the age of eight months and because a dramatic pruning of our neurocircuitry unfolds over the next decade, those early years are crucially formative in our cognitive development and warrant special attention. (Tolstoy captured this beautifully when he wrote, “From a five-year-old child to my present self there is only one step. From a new-born infant to a five-year-old child there is an awesome distance.”)
Leonardo’s own childhood was so unusual and tumultuous that it calls for consideration in examining his brain development. The illicit child of a rich playboy from the city and a poor peasant girl from the picturesque Tuscan town of Vinci, he grew up without a real father — an ambitious notary, his father refused to marry Leonardo’s mother in order to avoid compromising his social status. The little boy was raised by a single mother in the countryside. Eventually, his father arranged for his mother to marry another man, and he himself married a sixteen-year-old girl. Leonardo was taken from his mother and awkwardly included in his father’s household as a not-quite-son. But the father-figure in his life ended up being his kindly uncle Francesco, whom the boy grew to love dearly. He remained in contact with his mother throughout his life and evidence from his notebooks suggests that, like Andy Warhol, he invited her to live with him as she became elderly.
Shlain points to two perplexities that stand out in Leonardo’s upbringing: First, contemporary psychologists agree that removing young children from their mothers makes for substantial attachment and anxiety issues throughout life, producing emotionally distant adults. Secondly, Leonardo’s illegitimacy greatly limited his education options, as the Church, in one of its many strokes of gobsmacking lack of the very compassion it preaches, decreed that children born to unwed parents were not eligible for enrollment in its cathedral schools. Shlain writes:
Outside of the prohibitively expensive alternative of private tutors, admission to one of these schools was the only means to learning the secret code that opened the doors of opportunity.
That secret code was knowledge of Latin and Greek, without which it was practically impossible to participate in the making of the Renaissance. And yet Leonardo had an especially blistering response to those who dismissed his work due to his lack of education:
They will say that because of my lack of book learning, I cannot properly express what I desire to treat of. Do they not know that my subjects require for their exposition experience rather than the words of others? And since experience has been the mistress, and to her in all points make my appeal.
(More than half a millennium later, Werner Herzog would go on to offer aspiring filmmakers similarly spirited advice.)
Creativity is a combination of courage and inventiveness. One without the other would be useless.
So how did Leonardo muster the courage and inventiveness to turn the dismal cards he was dealt into the supreme winning hand of being history’s greatest genius? Shlain argues that while we can speculate about how much more remarkable work Leonardo may have done had he been able to command the respect, resources, and recognition “of one who claims noble blood, a university position, and powerful friends in high places,” there is an even more powerful counteragent to be made — one that resonates with Nietzsche’s ideas about the value of difficulty and bespeaks the immeasurable benefits of what Orson Welles called “the gift of ignorance,” or what is commonly known as “beginner’s mind”:
A strong counterargument can also be put forth that it was precisely his lack of indoctrination into the reigning dogma taught in these institutions that liberated him from mental restraints. Unimpeded by the accretion of misconceptions that had fogged the lens of the educated, Leonardo was able to ask key questions and seek fresh answers. Although he could not quote learned books, he promised, “I will quote something far greater and more worthy: experience, the mistress of their masters.” He disdained “trumpets and reciters of the works of others,” and tried to live by his own dictum: “Better a small certainty, than a big lie.” He referred to himself as omo sanza lettere — an “unlettered man” — because he had not received the kind of liberal arts schooling that led to the university. Somewhere in his late thirties and early forties, Leonardo made a concerted effort to teach himself Latin. Long lists of vocabulary words appear in his notebooks. Anyone who has tried to learn a foreign language in adulthood knows how difficult the task can be.
One silver lining to his lack of formal education and attentive parenting is that he was never trained out of his left-handedness as was the practice during the Middle Ages and the Renaissance — something that turned out to be crucial in the anatomy of his genius.
But Leonardo’s social disadvantages didn’t end with education. Based on evidence from his notebooks and biographical accounts from a handful of contemporaries, he was most likely homosexual — at a time when it was not only a crime but a “sin” punishable by death. Even in his fashion and demeanor, Leonardo appeared to be the Walt Whitman of his day — in other words, a proto-dandy who “fell into the flamboyant set.” Shlain quotes Anonimo Gaddiano, a contemporary of Leonardo’s:
He wore a rose colored tunic, short to the knee, although long garments were then in fashion. He had, reaching down to the middle of his breasts, a fine beard, curled and well kept.
Leonardo was also unorthodox in his universal empathy for animals and philosophical stance against eating them — a complete anomaly in a carnivorous era when the poor longed for meat and the rich threw elaborate feasts around it, showcasing it as a status symbol of their wealth and power. Instead, Leonardo was known to buy caged birds whenever he saw them in the town’s shops and set them free.
But Leonardo’s most significant source of exceptionalism goes back to his handedness. Left-handedness might still be an evolutionary mystery, but it is also an enduring metaphor for the powers of intuition. For Leonardo, the physical and the intuitive were inextricably linked:
Leonardo intuited that a person’s face, despite appearing symmetrical, is actually divided into two slightly different halves. Because of the crossover in sensory and motor nerves from each side of the face within the brain, the left hemisphere controls the muscles of the right side of the face and the right hemisphere controls the muscles of the left side. The majority of people are left-brained/right-handed, which means that the right half of their face is under better conscious control than their left. In contrast, the left half of the face connects to the emotional right brain, and is more revealing of a person’s feelings. Right-handers have more difficulty trying to suppress emotional responses on the left side of their face.
In a recent psychology experiment, a group of unsuspecting college students were ushered into a photographer’s studio one at a time and informed that they were to pose for a picture to be given to members of their family. The majority of these right-handed students positioned themselves unaware that they were turning the left side of their face toward the camera’s lens. All of them smiled.
Brought back a second time, the researchers informed them that, now, they were to pose for a job application photo. In this case, they adopted a more professional demeanor, and the majority of right-handers emphasized the right side of their face. The results of this experiment, along with several others of similar design, strongly suggest that unconsciously, most people know that the right side of their face is best to present to the outside world. They are also subliminally aware that their left side is a more natural reflection of who they really are.
Leonardo understood these subtleties of expression. Mona Lisa is best appreciated by observing the left side of her face.
One of Leonardo’s great artistic innovations was his inclusion of the subject’s hands in a portrait. Up to that point, portraiture included only the upper chest and head, but Leonardo saw in the expressiveness of hands a gateway to the subject’s state of mind, his psychological portraiture implicitly invalidating the mind-body split and painting consciousness itself.
This brings us back to Leonardo’s own brain. Shlain’s most salient point has to do with the splitting of the brain into two functionally different hemispheres, an adaptation that catapulted us ahead of all other creatures in intellectual capacity and also accounted for Leonardo’s singular genius. Reflecting on findings from studies of split-brain patients, Shlain explains:
The most sublime function of the left hemisphere — critical thinking — has at its core a set of syllogistic formulations that undergird logic. In order to reach the correct answer, the rules must be followed without deviation. So dependent is the left brain on rules that Joseph Bogen, the neurosurgeon who operated on many of the first split-brain patients, called it the propositional brain: It processes information according to an underlying set of propositions. In contrast, he called the right hemisphere the appositional brain, because it does just the opposite: It processes information through nonlinear, non-rule-based means, incorporating differing converging determinants into a coherent thought. Bogen’s classification of the brain into two different types, proposition versus apposition, has been generally accepted by neuroscientists, and it appears often in neurocognitive literature.
The right brain’s contribution to creativity, however, is not absolute, because the left brain is constantly seeking explanations for inexplicable events. Unfortunately, although many are extremely creative, without the input of the right hemisphere, they are almost universally wrong. It seems that there is no phenomenon for which the left brain has not confabulated an explanation. This attribute seems specific for the left language lobe.
Echoing Hanna Arendt’s assertion that the ability to ask “unanswerable questions” is the hallmark of the human mind and F. Scott Fitzgerald’s famous aphorism that “the test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function,” Shlain describes how this interplay illuminates the creative process:
The first step in the creative process is for an event, an unidentified object, an unusual pattern, or a strange juxtaposition to alert the right brain. In a mysterious process not well understood, it prods the left brain to pose a question. Asking the right question goes to the heart of creativity. Questions are a Homo sapiens forte. Despite the amazing variation in animal communication, there is only one species that can ask a question and — most impressively — dispute the answer. But Mother Nature would not have provided us with language simply to ask a question. She had to equip us with a critical appendage that could investigate those questions. That appendage was the opposable thumb. Thumbs have a lot to do with curiosity, which in turn leads to creativity
Building on previous research on the four stages of the creative process, Shlain outlines the role of the two hemispheres which, despite working in concert most of the time, are subject to the dominance of the left hemisphere:
Natural Selection gave the left hemisphere hegemony over the right. Under certain circumstances, however, the minor hemisphere must escape the control of the major one to produce its most outstanding contribution — creativity. For creativity to manifest itself, the right brain must free itself from the deadening hand of the inhibitory left brain and do its work, unimpeded and in private. Like radicals plotting a revolution, they must work in secret out of the range of the left hemisphere’s conservatives.
After working out many of the kinks in the darkness of the right hemisphere’s subterranean processes, the idea, play, painting, theory, formula, or poetic metaphor surfaces exuberantly, as if from beneath a manhole cover that was overlaying the unconscious, and demands the attention of the left brain. Startled, the other side responds in wonderment.
When a creative impulse arises in the right hemisphere, Shlain writes, it is ferried over to the left side of the brain via the mighty corpus callosum — the largest and most poorly understood structure in the human brain, and a significant key to the mystery of Leonardo’s extraordinary creativity in attaining the two grand goals of his life: to study and discern the truth behind natural phenomena, and to communicate that truth with astounding artistry.
But Shlain’s most intriguing point about Leonardo’s brain has to do with the corpus callosum and its relation to the gendered brain. We already know that “psychological androgyny” is key to creativity, and it turns out that the corpus callosum has a major role in that. For one thing, Shlain points out, there are differences in the size of that essential bundle of fibers between right-handed heterosexual males, or RHHM, and all other variants of handedness, gender, and orientation — left-handed heterosexual males, heterosexual women of both hand dominances, and homosexual men and women.
The notion of the gendered brain is, of course, problematic and all sweeping statistical generalizations tend to exist on bell-shaped curves, with outliers on either side. Still, Shlain relays some fascinating findings:
The most dichotomous brain — that is, where the two hemispheres are the most specialized — belongs to a right-handed heterosexual male. Approximately 97 percent of key language modules reside in his left hemisphere, making it unequivocally his dominant lobe. This extreme skewing is not present to the same degree in women, both right- and left-handed; gays and lesbians; and left-handers of both sexes.
Females, right- or left-handed, have a more even distribution between the lobes regarding language and brain dominance. Right-handed women still have the large majority of their language modules in their left brains, but whereas an RHHM would most likely have 97 percent of his wordsmithing skills concentrated in the left lobe, a woman would be more likely to have a lesser percentage (about 80 percent) in the left brain, and the remaining 20 percent in the right brain.
Shlain cites MRI research by Sandra Witelson, who found that the anterior commissure, the largest of the corpus callosum’s anatomically distinct “component cables,” can be up to 30% larger in women than in men, and other studies have found that it is 15% larger in gay men than in straight men. Taken together, these two findings about the corpus callosum — that RHHMs have more specialized brains and slimmer connecting conduits between the two hemispheres — reveal important deductive insight about Leonardo’s multi-talented brain, which fused so elegantly the prototypical critical thinking of the left hemisphere with the wildly creative and imaginative faculties of the right.
Evidence from his notebooks and life strongly suggests that Leonardo was what scientists call an ESSP — an individual with exclusive same-sex preference. He never married or had children, rarely referenced women in his writings and whenever he did, it was only in the context of deciphering beauty; he was once jailed for homosexual conduct and spent some time in prison while awaiting a verdict; his anatomical drawings of the female reproductive system and genitalia are a stark outlier of inaccuracy amid his otherwise remarkably medically accurate illustrations. All of this is significant because ESSP’s don’t conform to the standard brain model of RHHM. They are also more likely to be left-handed, as Leonardo was.
In fact, Shlain points out, left-handers tend to have a larger corpus callosum than right-handers, and artists in general are more likely to be left-handed than the average person — around 9% of the general population are estimated to be left-handed, and 30-40% of the student body in art schools are lefties.
A left-handed ESSP, Leonardo was already likely to have a larger corpus callosum, but Shlain turns to the power of metaphor in illuminating the imagination for further evidence suggesting heightened communication between his two hemispheres:
The form of language that Leonardo used was highly metaphorical. He posed riddles and buried metaphors in his paintings. For this to occur, he had to have had a large connection of corpus callosum fibers between his right hemisphere and his left. The form of language based on metaphor— poetry, for instance—exists in the right hemisphere, even though language is primarily a left hemispheric function. To accomplish the task of the poet, a significant connection must exist between the parts of the right hemisphere, and, furthermore, there must be many interconnections between the two hemispheres. These fibers must be solidly welded to the language centers in the left hemisphere so that poetic metaphors can be expressed in language. Leonardo used the metaphor in his writings extensively— another example of connected hemispheres.
And therein lies Shlain’s point: The source of Leonardo’s extraordinary creativity was his ability to access different ways of thinking, to see more clearly the interconnectedness of everything, and in doing so, to reach a different state of consciousness than the rest of us:
His ESSP-ness put him somewhere between the masculine and the feminine. His left-handedness, ambidexterity, and mirror writing were indications of a nondominant brain. His adherence to vegetarianism at a time when most everyone was eating meat suggests a holistic view of the world. The equality between his right and left hemispheres contributed to his achievements in art and science, unparalleled by any other individual in history. His unique brain wiring also allowed him the opportunity to experience the world from the vantage point of a higher dimension. The inexplicable wizardry present in both his art and his science can be pondered only by stepping back and asking: Did he have mental faculties that differed merely in degree, or did he experience a form of cognition qualitatively different from the rest of us?
I propose that many of Leonardo’s successes (and failures) were the result of his gaining access to a higher consciousness.
Significantly, Leonardo was able to envision time and space differently from the rest of us, something evidenced in both his art and his scientific studies, from revolutionizing the art perspective to predating Newton’s famous action-reaction law by two centuries when he wrote, “See how the wings, striking the air, sustain the heavy eagle in the thin air on high. As much force is exerted by the object against the air as by the air against the object.” Shlain poses the ultimate question:
When pondering Leonardo’s brain we must ask the question: Did his brain perhaps represent a jump toward the future of man? Are we as a species moving toward an appreciation of space-time and nonlocality?
With an eye to Leonardo’s unflinching nonconformity — his pacifism in an era that glorified war, his resolute left-handedness despite concentrated efforts at the time to train children out of that devilish trait, his vegetarianism and holistic faith in nature amid a carnivorous culture — Shlain turns an optimistic gaze to the evolution of our species:
The appearance of Leonardo in the gene pool gives us hope. He lived in an age when war was accepted. Yet, later in life, he rejected war and concentrated on the search for truth and beauty. He believed he was part of nature and wanted to understand and paint it, not control it.
We humans are undergoing a profound metamorphosis as we transition into an entirely novel species. For those who doubt it is happening, remember: For millions of years dogs traveled in packs as harsh predators, their killer instinct close to the surface. Then humans artificially interfered with the canine genome beginning a mere six thousand years ago. No dog could have predicted in prehistoric times that the huge, snarling member, faithful to a pack, would evolve into individual Chihuahuas and lap-sitting poodles.
Published November 17, 2014