Leonardo's Foot

by Carol Ann Rinzler

  In China, the legendary Huangdi (Yellow Emperor), who ruled in the area of the Yellow River sometime between 2697 and 2590 BCE, is credited with creating language characters, ships, carts, medicine, music, and a system of measures whose smallest standard unit was the width of a person’s thumb at the knuckle. To eliminate variation, and the inevitable question—“Whose finger?”—the system was standardized relatively quickly under another legendary leader, Yu The Great, (c. 2200–2100 BCE), whose other claim to fame was to prevent flooding of the Yellow River by dredging channels to send the overflow waters east into the Bohai Sea and from there into the Yellow Sea.

  Among citizens along the Mediterranean and in Mesopotamia, the area of southwest Asia that corresponds roughly to modern Iraq, the basic unit of length was the cubit (from the Latin cubitum meaning elbow), roughly the length of an adult (usually male) forearm from elbow to outstretched fingertip, a distance between 18–22 inches, depending on whose forearm one used. Arabs, Egyptians, Greeks, Jews, and Persians divided their cubits into smaller units, also based on body parts and also highly variable. For all of them, the smallest unit was the digit, always roughly an inch long, but never exactly so. The Arab digit appears to have been 0.9 inches; the Hebrew, 0.75 inches; the Persian, 0.8. The next unit up, the palm, was measured in multiples of finger widths, and after that, the cubit in multiples of palms. In Rome, for example, four digiti (finger widths) equaled one palmus; four palmi–“i” is the plural of the Latin masculine singular “us”—or sixteen digiti equaled one pes (foot).

  Other body-based measurements of length include the yard (3 feet), once put at the distance from the tip of your nose to the end of the middle finger on your outstretched arm; the span (nine inches), the width of a fully extended hand measured from the tip of the thumb to the tip of the little finger; the fathom, the distance from the tip of the middle finger on one outstretched arm straight across your body to the tip of the middle finger on the other outstretched arm; and the mile, from the Latin mille passuum or 1,000 paces, a pace in Rome being equal to five pes, making the original Roman mile 4,867 feet long (11.68 × 5 × 1,000/12).

  The differences from system to system, so small at the digit stage, widened as the length increased, often enough to affect important details such as an architect’s ability to assume the size of the materials required to build a building or an army’s determination of how far in the distance the enemy waited. The Egyptians solved the problem with measuring sticks, wooden rods, or bars of exact length. The originals of these highly prized instruments were kept in the local equivalent of City Hall or City Temple and made available for copying, so that duplicates could be distributed to ensure that a cubit here was also a cubit there. Then the Romans further standardized the rules by introducing the uncia, which means one-twelfth and which we translate as inch. By common consent, the early Roman digiti is believed to have been about 0.73 inches long; the palmus, 2.9 inches; and the foot—the pes—about 11.68 inches, not quite 12, but close enough. After that, the concept of the twelve-inch pes gained increasing acceptance, and obviously still rules most of our measuring rules.

  With some local tweaks.

  The Britons, who used the furlong (660 feet) to measure property, changed the Roman mile of 1,000 pes to the British mile: eight furlongs or 5,280 feet, a move legalized by Parliament in 1592. Before the Norman Conquest, Anglo Saxons had their own variety of foot lengths including one equal to 12 inches, one equal to 13 inches (two shaftments), and the pes naturalis (natural foot), equal to slightly less than 10 inches, about the length of a foot that fits a modern U.S. size 9.5 or 10 shoe. The 12-inch foot, arriving with the Normans in 1066, is said to have been certified 50 years later during the reign of Henry I, along with the 3-foot long yard, described as “the measure of the king’s own arm.”

  Clearly, each of these measurements, including the nearly 12-inch Roman pes, depended on the person serving as a model having been a fairly tall male. But when the Romans and their mathematically inclined descendents were measuring things in the length of some man’s fingers and feet, exactly how tall was a “fairly tall” man?

  Remember, based on the Vitruvian proportions, the ideal man’s foot is exactly one sixth as long as he is high. Measure the foot in any drawing of Leonardo’s Vitruvian Man, then measure the man’s height, and you will find that, yes, the height of the figure is six times the length of the foot. But the Roman human foot was obviously shorter than the pes because an ideal Vitruvian Man with an 11.68-inch foot—exactly the length of the foot that fits a modern American size 13 shoe—would be only slightly less than 6 feet tall (6 × 11.68 = 70.08 inches).

  Today, the United States has no shortage of men whose height tops 6 feet and whose shoe size may run well into the teens. Or larger. At 7 feet 1 inches tall, weighing 325 well-buffed pounds, Shaquille O’Neal wears a size 22 shoe—15 and 11/16 inches long to fit over his 14 and 11/16 inch-long feet that are almost but not quite one-sixth of his height.

  A slew of anthropometric studies calculating human body measurements in earlier times in order to identify and compare anthropological remains puts the normal height of persons living in Europe and around the Mediterranean neighborhood during the time of the ancient Romans at about 5 feet 3 inches. True, Julius Caesar and his grandnephew Caius Julius Caesar Octavianus, better known simply as Octavius, the first emperor of the Roman Empire, are both said to have stood a majestic 5 feet 7 inches. But even they would not have had that size 13 foot.

  So here’s the question: Was the Roman man whose foot became the measure of the pes not only a legend but also a giant in his own time?

  Or were his feet simply pes planus, lacking a normal arch when standing and thus leaving a longer impression on the floor.

  In short, did Leonardo’s perfect Vitruvian Man have perfectly flat feet?

  Notes

  (1)In December 2011, Ebay item number 290466164613 offered a “Vintage Dr.Scholl’s Foot-Eazer,” marked “Dr. Scholl’s Foot-Eazer. Pat. No. 1575645, Silveroid Made in U.S.A.” for $9.99 plus $6 shipping. Minus the skeleton foot.

  (2)From the first edition in 1889 of The Merck Manual, straight through to the fifth edition in 1923, the series pretty much comprised catalogues of materia medica, that is, remedies, including Merck products. The Merck editors did not even mention flatfeet until the eighth edition (1950) when the recommended treatment for pes valgo planus (flatfoot) was “correction of the anatomic deformities through use of any of the following: adhesive strapping, arch supports, external shoe corrections (i.e. Denverheel and metatarsal bars), padding of insole with felt, operative intervention.” For pes cavus (high-arched foot), it was “a sponge rubber bar placed across an insole just behind the metatarsal heads, or a leather bar applied similarly to the outside of the sole of the shoe.” The ninth edition (1956) added warm soaks, hot and cold foot baths, and aspirin for flatfoot. The tenth edition (1961) translated aspirin into a more sophisticated “acetylsalicylic acid.” To deal with any discomfort, Merck still advised keeping the foot “in a relatively normal position while walking by an arch support made of sponge rubber,” but added that “[m]etal or plastic is used for older people with concomitant tarsal osteoarthritis.” In the fourteenth edition (1982), the words pes planovalgus are out. There is nary a mention of flatfeet, but cavus, highly arched feet, and pronation (inward leaning of the foot) are prominent in the entry on “metatarsal-phalangeal articulation pain (lesser toes)” including “excessive eversion of the subtalar joint (rolling in of the ankles)” for which “[o]rthotics should be prescribed to redistribute and relieve pressure from the affected articulation.” Five years later, pes cavus and planovalgus are back in the index for the fifteenth edition (1987), to be treated with corrective shoes, including arch supports. By the eighteenth edition (2006), all these terms are gone, gone, gone, replaced by the really sophisticated talipes equinovarus and talipes calcaneovalgus; casting and surgery—the Ponseti duo—have been added to the list of possible remedies. Ditto fo
r the nineteenth edition (2011).

  4

  DIET

  “A man hath no better thing under the sun, than to eat, and to drink, and to be merry.”

  Song of Solomon

  HOW DO YOU SCULPT A HUMAN FOOT?

  The question is more complicated than you might think. In 1897, E. H. Bradford, a Boston doctor, founding member and one-time president of the American Orthopedic Association, wrote that, “Anyone whose attention has been called to the subject of the shape of the human foot will find it of interest to examine the feet in a collection of statues.” Having done so, Dr. Bradford concluded that every sculptor since the dawn of time had each chosen one of three types of feet.

  The “barbaric and Egyptian type,” he wrote, was a straight foot with straight toes and no natural curves, modeled on people who went barefoot or wore sandals. The “classical type” found in Greek, Roman, and modern (i.e., late nineteenth century) statues was modeled on people who either went barefoot or “wore the cothurnus,” a laced high boot with a thick sole, sometimes called a buskin and often worn by actors. This foot had the proper curves, with the big toe slightly separated from the other four. Finally, the modern pseudo-classical type, based on the feet of the “races that have worn shoes,” was similar to the classical, but shorter and fatter with the big toe bent in toward the other four.

  As you can see, in all three drawings the second toe is longer than the big toe.

  Now look at the toes on the right foot of the Vitruvian Man. Unlike the toes on the ideal Buddha’s foot, all exactly the same length, the toes in Leonardo’s drawing are more true to life, or at least true to the life of the three of every four human beings whose genes dictate that the first toe should be larger and longer than the other four. One in five of us gets a different genetic message, making the second toe longer than the first, a feature clearly visible on the foot of God in Michelangelo’s Creation of Adam panel on the ceiling of the Sistine Chapel (whether this represents the reality of Michelangelo’s own foot or that of a male model is a mystery). Three in every one hundred humans have a longer third toe. Only two of every hundred have toes that look like those on the Buddha’s foot with at least the first three equal in length.

  These patterns of toe length occur on both male and female feet, but finger length is sexually dimorphic, meaning it is gender-related, different in men and women. At birth, a baby boy’s ring finger is usually longer than his index finger; for baby girls, the reverse is true. In 1998, John Manning of the School of Biological Sciences at the University of Liverpool attributed this difference to the infant’s exposure to sex hormones in the womb. In 2011, by manipulating the levels of testosterone and estrogen available to mouse fetuses, Zhengui Zheng and Martin Cohn of the Howard Hughes Medical Institute and the Department of Molecular Genetics and Microbiology at the University of Florida College of Medicine were able to demonstrate that Manning was right. Prenatal exposure to testosterone appears to turn on genes that increase cell division in the fourth toe on the mouse’s five toe-back paw, a digit comparable to our human ring finger, making it longer than the second toe, comparable to our index finger. Estrogen does the opposite, slowing cell division and producing a shorter fourth toe.

  This was a fascinating discovery. Few take it seriously when palm readers and fortune tellers link finger length to specific characteristics such as aggression or infertility, but when reputable scientists suggest the same thing … that matters. After Manning’s studies, several hundred serious medical researchers began to investigate the possibility that there might actually be a link between the index-to-ring-finger-size ratios and a plethora of human health conditions ranging from autism to sperm counts, sexual orientation, gender-related cancers, and, of course, athletic prowess. No such links have yet been proven, but Zheng and Cohn’s data does open the door to a more reliable understanding of fetal exposure to chemicals in utero and thus to better predictions of fetal (and maybe adult) health.

  Length aside, the big toe is always wider and sturdier than the others, and that is also a big deal.

  Along with three firm bone-and-muscle arches, the big toe stabilizes your foot and literally puts the spring in your step. Begin to move ahead, and your foot flexes at joints that connect the long metatarsal bones in the middle of your foot to the shorter bones at the back of your toes. The entire foot bends forward, and your big toe, assisted by the four smaller ones, pushes you off the ground and sends you on, a subject of major importance to those who study biomechanics, the science of the ways in which your body moves. This discipline advanced by leaps and bounds at the beginning of the twentieth century due to the invention of motion pictures, which made it possible to film and then analyze, frame by frame, the movement of humans and other animals. As the Australian podiatric blogger Cameron Kippen, a self-described “retired academic, general bum, freelance writer, blogger and broadcaster” known as Toeslayer to his fans, notes, “An early pioneer of human movement was the comedian Charlie Chaplin who filmed many of his sequences backwards then ran them forward to accentuate the movement and expression.”1

  The big toe is so important to your movement and balance that a replacement for a lost toe appears to have been among the first prosthetics. Two such devices are still extant, one at the Egyptian Galleries of the British Museum in London, another at the Egyptian Museum in Cairo. The one in London, discovered at Thebes, is known as the Greville Chester toe after Reverend Greville Chester who acquired it for the museum 1881. The toe is made of linen-based papier-mâché covered with plaster tinted to look like skin and designed to fit a right foot. As Jacqueline Finch of the University of Manchester’s KNH Centre for Biomedical Egyptology reported in The Lancet in 2011, a three-year examination of the artificial toe conducted by the British Museum between 1989 and 1992 concluded that “[b]ased on the ‘spin characteristics of the linen’ the toe could be dated to a time prior to 600 BCE.” The second Egyptian false big toe, Finch continued, was even older, with a more complex structure. This one, again from Thebes, “was fastened onto the right foot of the female owner, who was identified as Tabaketenmut from around 950—710 BCE and was the daughter of a priest…. the carver seems to have been conscious of the anatomy and function of the foot. The inclusion of a hinge perhaps was intended to mimic the flexion of the metatarsophalangeal joint. Deliberate chamfering on the front edge shows an attempt to avoid rubbing against the navicular bone on the top of the foot, and the underside of the toe is flat for stability.” Finch found two volunteers “with similar amputation sites,” asked them to try on replicas of the two ancient Egyptian artificial toes, and found that they performed “extremely well” for motion and balance.

  Your big toe can be useful in another way. In the event of digital disaster, the short, blunt, two-bone, one-joint appendage may be a lifesaver for your hand because it (the toe) can be amputated from your foot and grafted on to replace a lost two-bone, one-joint thumb, thus restoring your grasp.2 Transferring your big toe from your foot to your hand may bar you from serving in the American armed forces because the U.S. Department of Defense thinks that having fewer than ten toes leaves you less balanced and less able to run to or from battle. But given the choice between one less toe and one new opposable thumb, the finger that makes it possible to perform such vital tasks as writing with a pen or opening jars, who would hesitate?

  There is, of course, a price to pay for all these benefits.

  Despite its virtues, the big toe is a place where good food sometimes goes to do bad things, triggering the arthritic pain in the toe called gout and in the process linking the digit to etymology, nutrition, genetics, sociology, the medical hierarchy, the green pharmacy, food and drug laws, and last, but certainly not least, one really important war.

  Naming, not taming, the beast

  A disease isn’t really official until you give it a name. Until then, it is, in the words of the very old vaudeville joke, “that thing you had before that you have again.”

  When a ne
w, presumably infectious, disease appeared in the early 1980s, some doctors referred to it as lymphadenopathy because it caused swollen lymph glands. It seemed to strike only gay men, so others called it gay cancer or GRID, short for gay-related immune deficiency, but when the acronym AIDS for acquired immunodeficiency syndrome was proposed at a Washington conference in the summer of 1982, it stuck. By fall, when the CDC began to include AIDS in its Morbidity and Mortality Weekly Report (MMWR), a weekly compilation of public health reports, recommendations, and announcements, the cause, nature, and treatment of the disease were still a mystery, but now at least a mystery with a proper name.

  AIDS was named within a year or two. That sometimes excruciating pain in your toe? Not so fast.

  In the beginning and for some time after that, gout was known as podagra, from the Greek words pod meaning foot and agra meaning catch or trap. Podagra was also the name of a minor goddess, the daughter of Dionysus (Bacchus), the god of wine, and Aphrodite (Venus), the goddess of love. Given the fact that peoples across the Mediterranean blamed the aching toe on too much wine and—victims being mostly male—too much dalliance with the ladies, Podagra was the perfect avatar.

  The first written description of podagra is commonly thought to be in Egyptian hieroglyphics in the Ebers Papyrus (c. 1500 BCE), the general treatise on disease and remedies named for Georg Ebers, the German Egyptologist who found the document in Thebes in 1873. Today, the Ebers Papyrus resides in the Library of the University of Leipzig, its antiquity rivaled only by the Edwin Smith Papyrus, a text on surgical treatment whose date, depending on your source, is either 1600 BCE or 3000–2500 BCE. This second scroll was discovered by American Egyptologist Edwin Smith, by coincidence born in 1822, the year Egyptian hieroglyphics were deciphered by Jean-François Champollion, the French scholar considered to be the Father of Egyptology. Champollion, who used the Rosetta stone to crack the code, was once considered the first to have done the job, but in 2004, archeologists at University College London discovered that Arab scholars had been there, done that, more than 1,000 years earlier, well before Smith bought the document from traders—read thieves—in Luxor in 1862. The scroll is now at the New York Academy of Medicine in Manhattan.