Leonardo's Foot Read online

  Moving farther down the body, Vitruvius’ other perfectly proportioned measurements include:

  From the breast to the hairline: the man’s height.

  The width of the breast: ¼ the man’s height.

  The root of the penis: at half the height of a man (this measurement is often omitted from the Vitruvian list).

  From the armpit to the elbow: the man’s height.

  From the elbow to the tip of the hand: the man’s height.

  The length of the forearm (from elbow to wrist): ¼ the man’s height.

  From the wrist to the tip of the fingers: the man’s height.

  From one fingertip to the other with the arms outstretched: equal to the man’s height.

  From the wrist to the tip of the fingers: the man’s height.

  The foot: as long as the man is tall.

  With all this in mind, Vitruvius then laid out rules for the overall geometric diagram of the male body: “… if a man be placed flat on his back, with his hands and feet extended, and a pair of compasses centered at his navel, the fingers and toes of his two hands and feet will touch the circumference of a circle described therefrom. And just as the human body yields a circular outline, so too a square figure may be found from it. For if we measure the distance from the soles of the feet to the top of the head, and then apply that measure to the outstretched arms, the breadth will be found to be the same as the height, as in the case of plane surfaces which are perfectly square.”

  Take a ruler marked off in centimeters, measure a picture of the Vitruvian Man, and you will see that Leonardo drew the man exactly as Vitruvius proposed.

  With maybe one interesting added detail.

  Artists are not known for their modesty. In Lives of the Most Excellent Painters, Sculptors, and Architects (1550), Giorgio Vasari (1511–1674), the architect, artist, and author known for his important biographies of Renaissance painters and sculptors, described da Vinci as “an artist of outstanding physical beauty” and a man “endowed by heaven with beauty, grace and talent.”

  Dutch portraitist, illustrator, and activist Siegfried Woldhek (he once headed the Netherlands branch of the World Wildlife Fund and Dutch Birdlife International) believes that Leonardo used his own features as the face of the Vitruvian Man. In 2008, at a TED (Technology, Entertainment and Design) conference in California sponsored by the non-profit Sapling Foundation, Woldhek described how after combing through more than 120 male portraits by da Vinci he found three—The Musician, the Vitruvian Man, and the well-known drawing of an old man—in which the features conform to the descriptions of da Vinci’s at ages 33, 38, and 63, the approximate ages of the three portraits.

  In other words, the perfect face of the perfect Vitruvian Man may really be Leonardo da Vinci’s.

  From there to here

  Over the centuries since Vitruvius wrote his rules and da Vinci made them immortal, the marvelous human foot has walked its way into the English language.

  For example, sometimes we mistakenly set off on the wrong foot when, to be successful, we should put our best foot forward and start off on the right foot, a trio of locutions that track back to the ancient relationship between left (sinistre) and right (dextra). By the way, if you think that many of the people in Egyptian paintings seem to have their feet on wrong, you’re right. In Egyptian art, only the royals had both a right foot and a left foot; lesser mortals were drawn with two left feet, then, as now, a descriptor for an inelegant person.

  We say that timid people have cold feet, those with a hidden fault have feet of clay. The decisive will put their foot down, the bold jump in with both feet and, regardless of the fall, always land on their feet. Those in a hurry hot foot it along. If someone fails to give us a proper answer to a proper question, we will hold his feet to the fire. And leaving people who have treated us badly—or, in the more mellifluous words of Matthew 10:14, those “whosoever shall not receive you nor hear your words”—we shake the dust off our feet.

  Finally, at The End, most of us leave this world carried out feet first so that our ghost will not be tempted to return. Unless the feet in question are attached to the body of a priest, one who is carried from the church head first, looking back at his congregation to which he expects to return … at least in spirit.

  As we humans became the dominant species, it has been common to credit our progress to the evolution of our increasingly more complex brain with its highly specialized folds and grooves and multiple connections. In fact, we stood straight before we began to think straight, and in the process, our two feet with their fifty-two bones, sixty-six joints, and 200 assorted muscles and tendons have influenced not only our language, but also our culture, our politics, and of course our medicine.

  To track how we got from there to here, begin by imagining yourself back in time, at a moment before history when you, an early hominin, are sitting on the ground, munching happily on berries—or as a team of scientists from the Max Planck Institute for Evolutionary Anthropology in Leipzig suggested in 2012, hard foods including grasses, grains, and tree bark. Your bottom is firmly flat on the ground; your trunk is perpendicular to the ground. Unlike four-legged mammals such as your dog or cat who sit with their front legs set straight from shoulder to ground to balance their bodies, your front legs—your arms—are free so that you can lift your food to your mouth rather than lowering your mouth to the food.

  When you finish eating and are ready to move forward, you walk or run on two rear feet and perhaps the knuckles of your front feet, as apes and monkeys still do. Your big toe has not yet moved in close to the other four, so above ground, in the trees, you can still use all four limbs with their opposable thumbs to grasp the branches, and your long arms to swing you from tree to tree through a canopy that looks nothing like the dreamy “murmuring pines and hemlock” Henry Wadsworth Longfellow created for the heroine of Evangeline, A Tale of Acadie, (1847), an epic poem that is one of the most popular works in American literature and the bane of school children who were made to memorize as many lines as they could cram into their heads. Instead, this forest was a tropical landscape similar to a modern rainforest that for tens of millions of years before you arrived on the scene, seemed to create a band all around the planet, skipping the oceans.

  Now imagine that in the blink of an eye, evolutionarily-speaking, the canopy disappears; the forest, a place where more than 80 percent of the land was covered with trees, is gone. Instead you now inhabit a landscape known as the original savannah, a land of grass plus mini-forests, clumps of trees that take up less than half of any given area. Blink again, and the tree clumps are even more widely spaced in what is now a vast ocean of tall grass, the modern savannah that once covered nearly two-thirds of the African continent.

  Anthropologists had long believed that the first savannah appeared less than 4 million years ago. But in 2011, geologists from the University of Utah traced chemical markers in the soil to describe and date the ratio of grass to trees in East Africa where fossils of the oldest known human ancestor have been identified, and concluded that savannahs existed 2 million years earlier than previously imagined.

  Clearly, this change in the landscape was a problem for the “you” of this imagined scenario. Unable to digest grass, you suddenly find the food supply restricted to a less-plentiful store of fruit- and vegetable-bearing plants and trees. And to add insult to injury, at ground level, having once had your whole kingdom before your eyes, you can no longer see beyond your nose because the grass is taller than you are.

  What to do? How to adapt?

  Stand up.

  Of course, it did not happen that quickly nor did we stand up just to look over the grass. Think of it instead as our moving step by step through the multiple frames required to make a Disney cartoon or as a modern pixel character moves his arm, and then multiply those frames over hundreds of thousands if not millions of years. Then at the end, multiply the frames yet again because as every toddler demonstrates, standing up is hard to
do. To rise on two legs and then stay upright you must constantly make small adjustments to your balance. Walking or running is geometrically more complicated. You have to push off with your foot (actually the big toe), bounce back and forth on your ankles, and lift and extend and lower your knee, all in an unconsciously coordinated and perfectly smooth sequence that some have described as “controlled falling”—pause in mid-step and you are likely to trip and fall.

  But once you master the trick, the rewards are obvious.

  First, standing up makes you taller. On the ground, it is now easier to peer over what’s in front of you and thus easier to check out what’s happening around you. Standing up frees your arms to carry things; the hunter–gatherers can now lug home more prey or plants over longer distances than if they had to carry the booty on their backs or in their teeth, and the warriors can also fight more effectively with hands free to scratch, punch, or swing a club. In the searing African afternoon, you may be more comfortable because standing up presents more of your body surface to whatever cooling breezes may drift pleasantly by. Finally, standing up exposes the front of your body, making sexual display inevitable, which is likely to help to continue the species. But no advance comes free of some regret.

  Once having stood up, your ancestors, the early hominins, pushed along toward full human-ness, perhaps by rewarding the person who made the best use of his (or her) ability to protect the clan, get the food, and use his (or her) freed arms to swat that faster sabre tooth tiger with a club. In other words, although our climbing the evolutionary ladder has always been attributed to our bigger brain, much anthropology and archeology tell us that the sturdy foot came first.

  The anthropology of an upright posture

  Ask the next ten people you meet to describe an archeologist, writes Jeremy Sabloff, president of the Santa Fe Institute, and those who don’t say Indiana Jones—or Harrison Ford—are likely to “describe a person digging in the middle of an excavation (probably dressed in khaki and wearing a pith helmet!) as dirt flies in all directions.”

  He’s right. Archeologists really are people who like to play in the dirt and with rocks, preferably rocks with fossils inside. Even in an era of technological advances such as the proton magnetometer, a tool you move across the ground to sense any anomaly such as an iron spear or a fired clay pot or an indentation (think, tomb) underneath, eventually you have to dig up what’s there, dust it off, chisel away the excess, and study what’s left, hoping to find a new clue to how humans became or began to behave human.

  Sometimes the rocks tell a tale no one expects, which is what happened to Raymond Dart.

  Raymond Arthur Dart (1893–1988) was born in Brisbane, Australia, on February 4, 1893, during a moment of high drama. The Brisbane River was flooding and, as The Brisbane Courier reported two days later, “the first Saturday of February 1893, has proved the most memorable in the calendar for many years past; we hope it will remain the most memorable for many years to come. On every vantage ground around Brisbane crowds gathered yesterday to witness the imposing and fearsome sight … Hundreds of wooden houses, once the happy homes of owner or occupier, careered upon the flood often remaining whole till they struck Victoria Bridge, when they crashed like matchboxes and broke away into shapeless masses of wood and iron … Steamers were driven ashore or laid on the tops of wharves.” More to the personal point, the flood waters surged as high as second-floor windows, through one of which the attending midwife is said to have floated the newborn Dart and his mother out to a waiting rowboat.

  Having survived the flood, Dart grew up on the family farm which he is reported to have loathed even as a child. He planned to escape as soon as possible, perhaps to serve as a medical missionary in China, but World War I intervened. Having earned two degrees in biology from the University of Queensland and two medical degrees from St. Andrew’s College in Sydney, he enlisted in the Australian Army Medical Corps in 1917. Two years later he was discharged in London where fellow Australian Grafton Elliot Smith (1871–1937), an authority on anatomy and the evolution of the human brain and chair of anatomy at University College in London, soon hired Dart as a senior demonstrator, the British term for research or teaching assistant. Three years after that, Smith urged Dart to apply for the position of professor of anatomy at the new University of the Witwatersrand in Johannesburg, South Africa.

  The teacher’s suggestion did not please the student. Dart “hated” the idea of leaving London’s libraries and laboratories to join a “new and ill-equipped University,” complaining that he had “lived a pioneer’s life for quite long enough in my younger [sic] days.” But Smith prevailed, and in January 1923, just before his thirtieth birthday, Dart arrived in South Africa.

  Once ensconced in his new position, he turned pragmatic. Now his aim was to build an anatomical collection of local finds such as the plethora of baboon skulls turning up at a limestone mine near a small city called Taung about twenty-eight miles west of Johannesburg. One day in September 1924, as he was getting dressed to serve as best man at a wedding to be held in his home, two new boxes of rocks arrived. With the groom literally tugging at one sleeve and his wife tugging at the other, Dart opened the boxes.

  “A thrill of excitement shot through me,” he wrote thirty-five years later in Adventures with the Missing Link (Harper, 1959). “On the very top of the rock heap was what was undoubtedly an endocranial cast or mold of the interior of the skull. Had it been only the fossilized brain cast of any species of ape it would have ranked as a great discovery, for such a thing had never before been reported. But I knew at a glance that what lay in my hands was no ordinary anthropoidal brain. Here in lime-consolidated sand was the replica of a brain three times as large as that of a baboon and considerably bigger than that of an adult chimpanzee. The startling image of the convolutions and furrows of the brain and the blood vessels of the skull were plainly visible. … But was there anywhere among this pile of rocks, a face to fit the brain?”

  Later that day, having done his duty as best man, Dart returned and “ransacked feverishly through the boxes. My search was rewarded, for I found a large stone with a depression into which the cast fitted perfectly. … I stood in the shade holding the brain as greedily as any miser hugs his gold, my mind racing ahead. Here I was certain was one of the most significant finds ever made in the history of anthropology.”

  Over the next three months, Dart dusted and cleaned and scraped away, sometimes with homemade tools such as sharpened knitting needles borrowed from his wife. By Christmas day, he had removed enough debris to show the face of a creature he christened the Taung Child because its teeth were obviously those of a very young individual; eventually, the age of the fossilized creature at the time of its death was put at two or three years.

  The Taung Child’s brain was similar in size to that of an adult chimpanzee, but the skull was not an ape’s—or at least not that of any known ape.

  Gaul, Julius Caesar famously wrote, was divided in three parts. Your skull is divided in two. The top part is the cranium, a curved dome created by six bones: the ethmoid, sphenoid, frontal, parietal, temporal, and the occipital that fuse in the first 18 months of life to form a helmet that protects the brain and frames the eyes and ears. Under that is the mandible, the hinged lower jaw whose joints make it possible for you to open and close your mouth so that you can eat and drink and speak intelligibly.

  Your cranium is round-ish, but not completely smooth because the muscles that move your jaws, head, neck, shoulders, and upper back are attached at specific points on the skull. On the ape or early hominin skull, these attachments produce significant bumps called ridges or crests. The sagittal crest on top anchors muscles that move the ape’s jaws. The characteristic brow ridge that gives gorillas their fearsome appearance secures muscles that help relieve the stress of chewing and grinding hard plant food. And the nuchal crest on the occipital bone at the back of an ape or early hominin head is where the neck and back muscles that keep the ape (or homin
in) head from falling forward are attached.

  Some early hominins had various smaller versions of the sagittal crest, the brow ridge and the nuchal crest, but the fully human Homo sapiens skull has a flat forehead in place of a brow ridge, a minimal sagittal ridge, and an equally small site line where the nuchal ligament attaches. Because you stand upright, your head is supported by your spine. The nuchal ligament is a back-up system stretching from the bottom of the occipital protuberance (the bump you can feel at the back of your skull right above your neck) down to the vertebra prominens, the seventh and last bone in your neck. Its job is to help keep your head from rattling about too vigorously when you run or jump or otherwise bounce your body.

  The foramen magnum is the opening at the back of the skull through which the spinal cord passes into the skull. In four-legged animals such as cats, dogs, horses, and cows, the foramen magnum is positioned so that the spinal cord forms a relatively straight horizontal line across the animal’s back and into its skull. Like this:

  But on the skull from the Taung quarry, the foramen magnum was farther down and toward the underside of the head, similar to the positioning of the head and foramen magnum on a creature such as a Neanderthal/Neandertal with a C-shape spine. Like this:

  Dart’s immediate conclusion was that the Taung Child stood upright, its back hunched and its head leaning forward, a step beyond the configuration of the four-legged animal’s spine and head, but not quite the arrangement of our own Homo sapiens’ S-shape thirty-three-vertebrae vertical spine with seven mobile cervical (neck) vertebrae; twelve thoracic (chest) vertebrae; five weight-bearing lumbar (lower back) vertebrae; five sacral vertebrae at the pelvis; and four caudal (tail) vertebrae that form the coccyx at the bottom of the spine. Like this: