Leonardo's Brain

by Leonard Shlain

  Another puzzle: At the conclusion of a passage which contains an elaborate description of a temple of Venus, Leonardo adds, “[S]etting out from the coast of Cilicia towards the south you discover the beauty of the island of Cyprus,” and on the reverse of the same sheet he affirms the visibility of Cyprus from the southern shores of Cilicia.

  Leonardo’s descriptions of Egypt, Ethiopia, and Arab lands are also uncannily accurate:

  The Egyptians, the Ethiopians and the Arabs when crossing the Nile are accustomed to attach two bags to the sides of the bodies of their camels, that is wine-skins of the shape shown underneath.

  The sketch included in the text depicts “five camels thus equipped crossing a river, the last with a rider,” according to MacCurdy.

  Leonardo was also familiar with the way the sands drifted in Egypt and Arabia to make their enormous sand dunes.

  To explain these anomalies, Jean Paul Richter in 1888 proposed that Leonardo may have slipped away from Florence before assuming his duties in Milan and journeyed to these places. Adding Sardinia and then Egypt to the itinerary, however, would have been a stretch. MacCurdy struggles to make these hypotheses fit with the other detailed information we have on Leonardo’s whereabouts at the time.

  MacCurdy also puzzles over the fact that:

  On the cover of Manuscript L of the Institute, which, as time references show, was written in the year 1502, is a note: “Rhodes has in it five thousand houses.” Where and when Leonardo obtained this knowledge is a matter in which there is nothing to sustain conjecture. The second reference occurs on folio 10b of the Leicester Manuscript, where it is stated that in “eighty-nine” there was an earthquake in the sea of Atalia near Rhodes, which caused the bed of the sea to open, and that such a torrent of water poured through this opening that it was more than three hours before the sea returned to its former level. On the assumption, which seems an entirely reasonable one, that by the year “eighty-nine” Leonardo meant [1489], Richter directs attention to the evidence in an unpublished Arabic manuscript at Paris of the occurrence of a terrible earthquake in the year 867 of the Mohammedan Era, which corresponds to the year 1489.

  As before, there is nothing to sustain conjecture as to how Leonardo acquired this knowledge. Perhaps, as it has been suggested, Leonardo was writing these as fantasies. MacCurdy examines this view:

  The theory that Leonardo was trying his hand at a romance in these letters that describe imaginary travels is unlikely, as the letters do not seem to be couched in this vein at all. They are too matter of fact, beginning as they do with excuses for the non-performance of official duties and proceeding with descriptions . . .

  According to MacCurdy, geographer Douglas Freshfield has disputed Richter’s conclusions regarding the Armenia letters, characterizing Leonardo’s sketch map of the sources of the Tigris and Euphrates as “very rough but, for the time, accurate.”

  MacCurdy goes on to write:

  So following on the lines which his own researches in geology among the rocks and river cuttings in the regions of the Arno had revealed, he envisaged in a passage of sustained descriptive power at the commencement of the Leicester Manuscript a time when, as is shown by the fact of shells and bones of great fishes being found in the sides of mountains, the waters of the Black Sea covered much of what is now the valley of the Danube and much else of Eastern Europe and Asia Minor. He then mentions the spurs of Mount Taurus and also Mount Caucasus, and again on the folio 31a of the same manuscript, Mount Taurus and the mountains of Armenia.

  The manuscript in which these passages occur was written from twenty to thirty years after what would be the latest possible date for the composition of the Armenian letters, if it were admitted that they were records of the writer’s own experiences. There is, however, no word in either passage, which can be construed as indicating any firsthand knowledge, or anything that would serve to indicate that any record of these scenes was graven upon the tablets of memory.

  Richter, Freshfield, and MacCurdy never consider the possibility that perhaps Leonardo had the skill to enter a space-time consciousness, discard the rational left brain, and acquire a quantum look at the world. Perhaps he never physically visited these places. Perhaps his ability to remote-view the world extended into the past as well.

  Art critic Kenneth Clark proposed that Leonardo had a “super fast eye.” Clark marvels at the phenomenon, mentioning it several times throughout his book, Leonardo da Vinci. Highlighting examples to illustrate Leonardo’s quickness of sight, Clark dwells on two. In the first, Leonardo was able to slow down the rapid fluttering of a bird’s wings in his mind’s eye and carefully draw the sequence of winged flight. In the second, Leonardo could gaze at falling water and, with his “super fast eye,” freeze the image of the water in mid-fall and then draw its flow, arrested for an instant. But Leonardo went even further. He made a drawing that showed water falling into a pond, and then included in his image how the falling water roiled the undersurface! No other artist in history has ever been able to accomplish either of these feats.

  Leonardo also made a drawing of a pendulum that included multiple images of its swinging. In an uncannily correct representation, if a strobe light were concentrated on the pendulum, there would have been more images of the pendulum as it swung faster at its base than at its extremities. Leonardo personified this increase in images, indicating that the pendulum is swinging faster as it nears its fulcrum than when it extends near its extremities.

  Instead of ascribing to Leonardo a “super fast eye,” perhaps we need to think of him as someone who perceived time differently. If he was capable of achieving a space-time consciousness, then he should have been able to draw a bird’s trajectory in slow motion or stop time to accurately portray water caught in midair. He could then complete the work by revealing how it appeared under the water as well.

  Leonardo was capable of thinking in extended reaches of time as well as space. For centuries, stonemasons were aware that trapped in rocks retrieved from quarries high in the mountains were fossilized creatures from the depths of the sea. Yet no one ever seriously questioned how or why the fossils of sea creatures could be found high in the rocks of mountains, far from water. The accepted explanation was the flood described in the Old Testament. That this huge amount of water carried these fossils inland seemed a satisfactory answer to everyone—except for Leonardo.

  The insight that the rocks were immeasurably older than the biblical reckoning would have required a perspective about time unimaginable for anyone living in fifteenth-century Europe. He or she would have had to imagine that the tops of mountains were once the seabed, and that the present seabed once formed—in a very distant past—the peaks of mountains somewhere else.

  Leonardo was the first person in the historical record to suggest that the Earth was much older than anyone had previously imagined. His opinion preceded those of two geologists by three hundred years: Georges-Louis Leclerc, Comte de Buffon, who first posed that the Earth was seventy-five thousand years old; and then Charles Lyell, who proposed that it was billions of years old. Did a space-time consciousness play a role in Leonardo’s ability to conceive of immense passages of time?

  Other peculiarities of Leonardo’s life and work habits begin to make sense if we think of him as an early space-time traveler. (Leonardo’s perception of time may explain why he thought that it was nothing out of the ordinary to deliver the second version of Virgin of the Rocks to the friars, who had been dissatisfied with his first version—some twenty-five-odd years later!)

  Start and finish are words that belie the ingrained notions we have about linear time. The fact that Leonardo started but abandoned so many works makes more sense if we think of him as an artist who did not necessarily see things in terms of standard time. This may provide an alternative explanation for a puzzling trait that has given centuries of biographers conniptions trying to explain it.

  Leonardo was the first artist to use an “exploded” view when depicting the
relationships of the organs and muscles of the human body to one another. By showing the upper layer stripped away from the next layer, but still hovering a respectable distance above the layer below, he was able to convey relationships of one part to another that would be difficult to understand if viewed in only one perspective. He also used cross-section and exploded views to illustrate his many engineering drawings. Similarly, he was the first to supply a view of the body from multiple different angles simultaneously, as if the viewer were moving around the stationary object.

  Leonardo’s ability to see the Earth as viewed from space may have helped Copernicus to overturn the Ptolemaic Earth-as-center-of-the-universe type of medieval thinking. Copernicus asked: How would the sun appear from the vantage point of Mars instead of Earth? He initiated his revolutionary theory based on the answer to this novel question. It was a perspectivist question that Leonardo was prone to ask.

  Chapter 16

  Leonardo’s Brain

  In women, the measurements of the corpus callosum, measured as a whole or for specific measurements of any seven subdivisions of the callosum, are larger.

  —H. Steinmetz et al.

  Leonardo understood that the creative process was predominantly a female process. The male part of procreation was short, easy, and beyond his power of analysis. The female part was long, complex, and a possible subject for investigation.

  —Kenneth Clark

  “It’s a fine day, let us go out and kill something!” cries the typical male instinctively. “There is a living thing, it will die if it is not cared for,” says the average woman almost equally instinctively.

  —Olive Schreiner, feminist

  Let us consider the differences among the brains of straights, gays*, women, and left-handers. Amplifying the functional results of these quirks of brain arrangement is the recent finding that there are differences in the relative size of the corpus callosum between right-handed heterosexual males (hereafter referred to by the acronym RHHM) and left-handed heterosexual men, women, gay men, and lesbians. The corpus callosum is the largest single structure in the human brain, containing over 200 million connecting neurons. It coordinates the differing feelings, desires, proclivities, opinions, and sensory experiences of the two hemispheres, so that the entity called “I” can present a unified, coherent response to the outside world. The corpus callosum consists of several anatomically distinct component cables, the largest of which is the anterior commissure.

  * The word homosexual is emotionally freighted and unclear. The homo is the Greek prefix for “same,” rather than, as most people would assume, “man.” The term is inexact, sometimes including bisexuals and transgenders. I prefer to use the term exclusive same sex preference, or ESSP. I will refer to homosexual men (ESSP) as gays, homosexual women (ESSP) as lesbians, and heterosexual men and women as straights. I will also identify bisexuals when I am discussing them.

  In recent studies, neuroscientists have revealed that the “standard” brain arrangement present in the majority of straight, right-handed, non-musician males has many exceptions. Shuttling back and forth between Renaissance descriptions of Leonardo’s eccentricities and these modern neurological findings provides a scaffold upon which to begin to erect the diagram of his particular brain. But first we must examine the most common wiring diagrams present in the average human.

  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.

  All of the above statements refer, of course, to bell-shaped distribution curves. There will always be some lefties, women, and gays who have more specialized brains than most right-handed straight men; and there will be some right-handed straight men who have less-lateralized brains for language and handedness. But in general, these characteristics of brain anatomy tend to hold true for the population at large.

  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.

  The import of these differing arrangements becomes manifest when an RHHM has a significant stroke, injury, or tumor in his left brain. The resulting handicap precipitates a profound social catastrophe. He loses his ability to communicate and experiences a devastating paralysis on his dominant side. His opposite arm, forearm, and hand—as well as his thigh, leg, and foot—lack dexterity, resulting in a gross loss of maneuverability. The same size defect in a right- or left-handed woman, left-hander, or a gay or lesbian will not produce the same degree of disability. Further, a member of any of the three subgroups would recover from the left lobe’s affliction sooner than would the afflicted RHHM. Amplifying these results is the recent finding that there are differences in the relative size of the corpus callosum between RHHMs and right- and left-handed women, left-handed heterosexual men, and gays and lesbians.

  Although among neuroscientists there smolders a low-level controversy over these findings, the weight of evidence in the scientific literature supports the finding of Sandra Witelson and others, who studied the MRI scans of numerous men and women and discovered that the anterior commissure of women can be as much as 30 percent larger than that of men. Also, its shape differs. Further studies indicate that the size of the anterior commissure in gay men is half again as large as the difference from women and straight men; that is, if women are 30 percent larger than men, then the corpus callosum—along with the anterior commissural—in gays is, on average, 15 percent larger than straight men. And to add an arabesque to Witelson’s findings: Recently she has reported that these two entities, in both left-handed men and women, are larger than in right-handed men.

  These two discoveries—more specialized brains, and smaller anterior commissures in RHHMs when compared to women, gays, and lefties—are related. Each quirk exaggerates the significance of the other.

  The only emotions that have drifted over to take up residence to the left of the corpus callosum are happy ones. Joy, optimism, cheerfulness, and a sense of well-being paradoxically seem to have taken leave of the more-negative emotions associated with the right brain to find a home in the left frontal lobe. Even laughter resides on that side, according to neuroscientist Antonio Damasio. All of these emotions are in close proximity to the Great Decider, the Executor. So, too, are they separated from the emotions that have to do with sex and nurturing small children that reside on the right side. The division between emotions to the right and to the left is most extreme in RHHMs when compared to the three subgroups of women, gays, and lefties.

  The asymmetry in the emotional functions of the two hemispheres, combined with the left brain’s hegemony over words, leads to the inescapable conclusion that individuals with larger connections containing more neurons between the left and right brain should translate into a facility to express emotions. More neurons means more links between feelings and words. And more emotional centers located in near proximity to language modules would also increase emotional expressiveness.

  As this information has leaked out through the popular media, the response among women and men has been predictable. Women apprised of the disparity and made aware of their larger anterior commissures discussed these revelations among themselves. Some encouraged the sisterhood to feel compassion for emotionally impoverished men. No wonder, they said, that so many men are emotionally barren and have such a difficult time experiencing various emotional states.

  The men, in contrast, heaved a sigh of rel
ief. Here, at last, was confirmation that it was okay to groan, take a deep breath, and affect the deer-in-the-headlights expression whenever a woman announces that it is time to have a discussion concerning their relationship: a moment traditionally dreaded by the males. The stereotype that women are more “in touch” with their emotions had some basis in experience, and now it had basis in science.

  These recent findings concerning brain organization give us substantial clues in deciphering the wiring arrangement of the subject of this book: the particular brain of a possibly gay, left-handed, nearly ambidextrous, and singularly creative Renaissance male. The outlier, Leonardo da Vinci.

  The question of Leonardo’s sexuality is pertinent. Members of this one select group, ESSPs, did not conform to the standard model of the RHHM. In fact, they represented the complete opposite.

  In Sex, Time, and Power, I put forth my Theory of Eights: 8 percent of human males are ESSP; 8 percent of males are left-handed. (Only 5 percent of human females figure into this statistic.) Another most peculiar percentage: 8 percent of males are born with the gene for color blindness, or color deficiency. (Less than .01 percent of females are burdened by this abnormality.) And finally, 8 percent of males are bald in their prime. (Rarely does a woman lose her hair.)