Leonardo's Foot
Page 4
Below the waist, our two-footed stance has changed the shape of the pelvis. Our ilium, the largest bone in the pelvis and the place where abdominal muscles attach, is nearly twice as large as a chimpanzee’s, and it is wider and lower on the back, which has its own particular soft tissue. Monkeys and apes can sit up, but when they do their heads still lean forward because they lack the muscles needed to support the back and stabilize the hip and leg. Humans have three such muscles: the gluteus maximus, the gluteus medius, and the gluteus minimus, all packed tightly into our distinctively larger buttocks, a feature that separates us from most apes whose rear ends are generally flat. Maximus cushions us while sitting and helps us to turn or straighten our legs when hopping, jumping, or climbing. Medius, the middle, and minimus, the smallest, are both layered under maximus; they stabilize our upper body when we lift one foot, for example, while taking a step so that we do not tip over on the other one. “Old World monkeys,” a group that includes baboons, macaques, mandrills, and any of the approximately one hundred species of monkey that live in Africa, along the Arabian coast of the Red Sea, and in Asia from Afghanistan to Indonesia, do have brightly colored sometimes padded buttocks and genitalia. But they don’t have our strong gluteus muscles with their multiple connections to pelvis and legs, which as Robert Ardrey has observed, make possible “agility and all the turning and twisting and throwing and balance of the human body in an erect position,” not to mention empowering a very large industry devoted to the care and coddling of the human lower back.
Because we stand up on our legs with our arms free, there’s nothing surprising about bipedalism’s influences on these limbs. Some, but not all of these changes, produce a better survivor, one who can catch dinner or outrun a more ferocious diner.
As noted earlier, the quadruped ape’s arms are bigger and more powerful than ours. The long bones in the ape’s forearm—the humerus, the radius and the ulna—may be fused so the arms are stronger, and overall often longer than the back legs. To facilitate staying up once we stand up, the long bones in our human legs (the femur above the knee and the tibia, and fibula below) are longer and stronger than the long bones in our arms (the humerus between the shoulder and the elbow and the ulna and radius between the elbow and the wrist). The ratio between the length of the forelimbs and the length of the back limbs is called the intermembral index (IM or IMI). The formula for the IM is written like this:
There are seven basic IM ratios. For convenience, they may be grouped into three broad categories which modern zoologists can use to describe prosimian and primate limbs and thus tell how the modern animal moves through its environment; when examining fossils, anthropologists can use these measurements to speculate on how these long-ago creatures moved.
An IM equal to or close to 1 describes an animal whose front and back legs are of equal length. Primates and prosimians whose short arms and legs are equal in length walk on four legs on the ground and across tree limbs. Those with long limbs equal in length walk on four limbs, often on their toes. Animals with very long limbs that are equal in length climb and swing with all four limbs.
An animal with an IM greater than 1 has arms longer than its legs. These animals are likely to move by brachiating (from the Latin word bracchium meaning arm), swinging arm over arm through the trees. Chimpanzees and gorillas have arms longer than their legs and may also brachiate, but more commonly they are quadrupeds, walking on their rear feet and the knuckles of their front legs (orangutans, which are also quadrupeds, fold the front foot into a fist and walk on that rather than on the knuckles).
Finally, primates whose rear legs are longer than their arms have an IM lower than 1. These animals move by leaping from place. The primary primate exception to this rule, of course, is us, an entire species that walks erect on two firm and steady longer legs. In their summary of comparative limb structure published in the Journal of Anatomy in the summer of 2000, Bernard Wood and Brian Richmond of George Washington University called this inequality of limb length the most striking difference between apes and humans: “The great absolute and relative length of modern human lower limbs … increases stride length and thus the speed of bipedal walking.”
An important requirement for standing up safely on two legs is a skeleton that keeps the body balanced over the legs. Like apes, early hominids moved on four limbs, so they always had at least two limbs on the ground at once to balance their bodies. Ours is a more delicate task because our hips are wider apart. If our legs were also wide apart, we would have a hard time to keep from falling over. Our femur has evolved to an angle that brings the knee joint in closer to the middle of the body, an orientation known as valgus knee (“knock knees” are an extreme version of this orientation). With the knee in closer, our feet are positioned under the center of our body so we can stand up, as Lucy is believed to have done. Wood and Richmond write that her “bones are rife with evidence clearly pointing to bipedality.” Her femur is angled correctly; her knees are set with a prominent edge on the top to keep the knee from slipping out of place; the condyles (ends) of the bones are large enough to support the extra weight of standing on two legs instead of four; and her pelvis is wider and more stable. “The entire structure,” they conclude, “has been remodeled to accommodate an upright stance and the need to balance the trunk on only one limb with each stride.” As for the spring in that stride, we owe our bounce to our Achilles tendon, the tissue that ties our calf muscle to the bones in our heel and is vital for long distance running. Apes have no Achilles tendon; their calf muscles stretch right down to the bones in their feet.
Which brings us back, at last, to the fifty-two bones with which we began: our feet, two long, firmly arched pads with five perfectly adapted toes.
Start at the ankle, set squarely on our heel. Unlike a chimpanzee’s ankle, which flexes sufficiently to permit the foot to twist around a tree while climbing, ours is designed to keep the long bones in the lower leg straight over the foot, an appendage whose evolution has resulted in three unique characteristics: the position of the big toe, the firmness of the arch(es), and the full fall of the sole on the ground.
Unlike other primates, whose feet are as flexible as their hands with an opposable thumb-like first toe, our foot is relatively rigid with three distinct arches firm enough to absorb the shock as our foot strikes the ground and the force of our body’s weight crashes onto our feet. We are not the first to have had these arches, or something like them. In September 2011, Carol Ward of the University of Missouri School of Medicine and William Kimbel of Arizona State University reported that a metatarsal bone found with Lucy’s fossilized skeleton showed that Lucy, whom Ward calls “the poster girl for her group of ancient hominins,” had arch-stabilized feet and was perfectly capable of standing up and walking, though probably not as straight up or as efficiently as we do.
Farther forward on the foot, our toes are no longer fingers. They are shorter and closer together, and our big toe (the hallux, from the Latin allex meaning big toe) is not just another digit. Unlike the long first toe on an ape’s rear foot, ours is short, straight, and adducted, that is, moved in close to our other four (noticeably shortened) toes to help us balance when we stand and to lift and push our foot up and forward with each step. Together, the five toes absorb pressure as we walk or run.
Underneath our ankle, toes, and arch is the bottom of our foot, the sole, the final platform on which our body rests and by virtue of its shape and scent, for some an object of intense desire, about which more later. For the moment, it is enough to observe that we human beings are not only bipeds, we are plantigrade (from the Latin words planta meaning sole of the foot and gradus meaning step or walk). We stand on the whole foot, not on our heel or on the ball of our foot or on our toes. We are, quite simply, balanced on our feet.
Even now, it is widely believed that Homo sapiens owes its primacy as a species to an increasingly more complex brain. But here, as is so often the case, the common wisdom is wrong. What changed us fir
st was not the centuries-long evolution of our brain, but the transcendent moment when our hominin ancestors the Taung Child, Lucy, and all their friends and neighbors stood up on the African savannah or maybe next to an African stream. At the time, the brain that ruled their bodies was larger than an ape’s, but smaller than a human’s. Standing up immediately gave them entry to a new and larger universe brimming with a richer, more varied, higher protein diet, whether fish by the water as Alister Hardy proposed or flesh on land as most others accepted.
Either way, the new menu provided the energy required to enlarge the brain. With that bigger brain, as Robert Ardrey wrote, “We became man.” And walked into the future on our own two feet.
2
DISABILITY
“A true critic ought to dwell rather upon excellencies than imperfections.”
Joseph Addison, The Spectator (1711)
UNLIKE LEONARDO’S perfect Vitruvian foot, whose length from heel to toe equaled exactly one-sixth the height of the person to whom it was attached, our own feet are usually longer or shorter or wider or more narrow than the Roman ideal.
They may even be twisted out of shape. Every year around the world, about one in every 1,000 babies is born with a clubfoot, that is, a foot twisted up or down so that the sole cannot be placed flat on the floor. Clubfoot is our most common congenital lower limb deformity. In history—both real and mythological—it has tormented gods, kings, and commoners alike, so frequently in fact that even in the ancient world whose culture and law sanctioned a parent’s disposing of an imperfect infant, this one deformity was not a death sentence.
The Greek poet-philosopher Hermodorus of Ephesus (c. 6th–5th centuries BCE) is a bit player in this story, simply a man who carried a message from one town to another, unremarkable except for the fact that the message came from Plato and the town to which Hermodorus carried it was Rome where he helped to convert the ancient policy of dealing harshly with deformed infants from Roman custom into Roman law.
One day sometime around 459 BCE, Hermodorus did what philosophers usually do: He told other people how to behave, in this case proposing citizenship for freed men in Ephesus and the right to public office for their children. The very thought so offended the City elders that they exiled him.
Hermodorus’ friends were not amused.
His fellow philosopher Heraclitus (c. 535–475 BCE) said that the Ephesians “all deserve to have their necks broken as they grow up, so that the town should be left to minors because they drove away his friend Hermodorus, the best of them all, and gave as their reason for so doing that amongst them none should be more excellent than the rest; and if anyone were so, it should be elsewhere and amongst others.”
After which Heraclitus himself was tossed out of town “for misanthropy and refusal to smile.”
Several centuries later, Ephesus was the capital of Proconsular Asia, the Roman province comprising western Asia Minor, the peninsula between the Black Sea and the Mediterranean, a major transport center for goods from both Greece and Rome with roads leading to all the major cities along the way. Around the year 51 CE, Saul (5–c. 67 CE), who later became the disciple Paul, stopped off for a short visit on his way from Greece to Syria. Three years later, he returned to Ephesus. He was not pleased with what he found.
There was, for example, the matter of the Temple of Artemis (Diana), the Ephesians’ greatest monument. The temple was the largest open air theater in the contemporary world with a capacity of 50,000 spectators, just 7,545 fewer than the official capacity (including seats and standing room) of Yankee Stadium in New York. The newly named Paul opposed gods made by man, such as those embodied by the statues of the Greek and Roman deities. But the Ephesians said their statue of the goddess Artemis had fallen from the sky and was therefore divine. Besides, the temple provided asylum for debtors, a practice the Ephesians hotly defended before the Roman senate.
Clearly annoyed, Paul penned two scathing missives in which he berated the Ephesians for their obeisance to Cybele (goddess of nature and fertility, both linked, however delicately, to sexuality) and Dionysus a.k.a. Bacchus (the god of wine and celebration), as well as for their lust, lies, fraud, arguments, robbery, unnecessary litigation, their sexual behavior, and their decision to abandon their principles in favor of whatever the current ruling class ruled. He was equally contemptuous of the Ephesians’ wealth because he believed that fate punishes not by taking away a person’s possessions, but by granting the abundance that gives people the means by which to demonstrate their inevitable corruption.
Meanwhile, Hermodorus had long ago made it to Rome where he served as an advisor to the Decemvirate (from the Latin decemviri meaning ten men), the council charged in 455 BCE with creating the first written Roman code of law designed to deal even handedly with the rights of both the privileged and the less so. The Decemvirs began with ten bronze tablets of rules and regulations, but there was obviously need for more because a second commission, named five years later, filled another two with social and legal niceties such as the prohibition of marriage between members of different social classes (Table XI) and the promise that “whatever the People has last ordained shall be held as binding by law” (Table XII). With those additions, The Twelve Tables served Roman justice until 387 BCE when the invading Gauls sacked the city and destroyed the physical tablets. The Tables codified Roman law as follows:
Table I: Courts and trials
Table II: Trials
Table III: Debt
Table IV: Rights and duties of fathers
Table V: Guardianship and inheritance
Table VI: Ownership
Table VII: Land rights
Table VIII: Legal rules on injuries
Table IX: Public law
Table X: Sacred law
Table XI: Matters not previously covered
Table XII: Matters not previously covered
Perhaps the most troublesome of the Decemvirs’ new laws were the ones in Table IV, which, with Hermodorus’ advice, declared it to be a father’s duty to make sure that “if a child is born with a deformity he shall be killed.”
At the time, abandoning or killing deformed infants was accepted practice all across the Mediterranean world. Spartans, for example, already had such a custom, based on the laws promulgated by Lycurgus, who ruled Sparta sometime between 800 and 630 BCE—no one is absolutely certain of the dates. Some historians even consider him a legend rather than a real man, but still credit him with creating the city-state’s constitution.
In any event, disabled Greek and Roman newborns who survived into childhood or even managed somehow to make it into adulthood faced a life considered less than valuable. So much less in fact that the “games” at the Coliseum included tossing these children under the hooves of galloping horses and setting matches between blind adult gladiators or between blind and sighted ones.
This callous disregard for the disabled was not limited to the secular society. In Leviticus 21:17–23, the Higher Authority was pretty clear when he told Moses what to tell Aaron, the first priest of Israel, about who could do what in sacred places: “Whosoever be of thy seed throughout their generations that hath a blemish, let him not approach to offer the bread of his God. For whatsoever man he be that hath a blemish, he shall not approach: a blind man, or a lame, or he that hath anything maimed, or anything too long or a man that is broken-footed, or broken-handed, or crook-backed, or a dwarf, or that hath his eye overspread, or is scabbed or scurvy, or hath his stones crushed; no man of the seed of Aaron the priest that hath a blemish, shall come nigh in order to offer the offering of the Lord made by fire; he hath a blemish; he shall not come nigh to offer the bread of his God. He may eat the bread of his God, both of the most holy, and of the holy. Only he shall not go unto the veil, nor come nigh unto the altar, because he hath a blemish; that he profane not my Holy places; for I am the Lord who sanctify them.”
Why were these people so careless with their imperfect, but helpless infants? There are severa
l possibilities from the divine to the prosaic.
In pre-scientific society, where decisions were based on signs and symbols, a visibly deformed child signaled the displeasure of the gods and was therefore a threat to the family, the tribe, and the city. In a world where wars were fought primarily in hand-to-hand combat, the need for a strong and able cohort was obvious. In an agrarian society, the imperfect baby was one more mouth to feed, but one less hand (or foot) to work.
Then there was the thorny question of exactly when a human became human. Hippocrates believed that the human soul was present from the very beginning, in modern terms, from the moment of fertilization. Others thought otherwise, questioning whether a newborn was really a human being at all. Contrasting the human with the not-quite, Aristotle (c. 384–322 BCE) wrote in The History of Animals that a fetus begins with a “nutritive” soul similar to that of plants, moves on to a “sensitive” soul like an animal’s, and then finally develops a “rational” or intellectual soul. This theory, known as delayed hominization, was adopted as Catholic dogma in 1312 at the Council of Vienne in northern France. Thereafter, Catholics, while opposing abortion, did not consider it to be murder until 1588 when Pope Sixtus V issued the Bull Effraenatam [without restraint] directing that anyone who performed an abortion at any stage of pregnancy would be excommunicated and subject to whatever punishment the civil law prescribed for murderers. Three years later, Gregory XIV overturned this, limiting the punishment to excommunication and that only for the abortion of a “quickened” fetus.
For some, however, neither quickening nor the acquisition of an intelligent soul was enough to guarantee human-ness. Like Hippocrates, Aristotle believed that a male fetus looked human 40 days into a pregnancy and a female at 80–90 days (one way to justify the idea that men were naturally stronger and more intelligent than women). But he also thought that despite appearances a newborn was not fully human until one week after birth, thus conveniently providing a seven day window in which to dispose of severely disabled infants. Among the ancient Jews, the waiting period was thirty days, although a male child was named seven to eight days after birth when he is circumcised, marking the moment when a Jewish identity passes from father to son. In some parts of Japan, a child became a human being when its first cry told everyone that the infant’s spirit had arrived. Elsewhere naming became the important ritual, and eventually, for Christians, baptism.