PICTURE A BIOLOGIST removing from the incubator an egg containing a nearly developed young chicken. Fourteen days ago this egg consisted of a single cell (the world’s largest single cell is an unfertilized ostrich egg). Now it has divided into hundreds of millions of cells, a whirlpool of protoplasm rearranging itself to prepare for life outside. The biologist cracks the shell and sacrifices the chick.
Word travels fast through the body, but hours may pass before the far outposts surrender their hold on life. From the tiny heart the biologist extracts a few muscle cells, still living though in a dead embryo, and drops them in saline solution. Under the microscope they appear as long, spindly cylinders, crisscrossed like sections of railroad track. Their destiny is to throb, and they persist even in the anarchic world beyond the body. Now isolated from the chick, each cell continues its pitiful and useless palpitations.
Ungoverned by a pacemaker, the cardiac cells beat spasmodically, in a rhythm approximate to the chick’s normal 350 beats per minute. As the observer watches over a period of hours, however, something marvelous takes place. Instead of five independent heart cells contracting at their own pace, at first two, then three, and then all the cells pulse together in unison. Five beats converge into one. How do cells communicate the urge for unity, and why?
Some species of fireflies show a similar pattern. A wanderer discovers a tribe of them flickering haphazardly in a forest clearing. As she watches, one by one the fireflies synchronize until soon she sees not dozens of twinkling lights but one light, switched on and off, with fifty branch locations. Heart cells and fireflies both sense an innate rightness about playing the same note at the same time.
Wherever we look, it seems, community is the order of the day. At the smallest observable levels cooperation prevails, and we could neither breathe nor eat without it. Producing the oxygen by which we live requires colonies of bacteria to aid plant photosynthesis, and our digestion relies on similar colonies to help break down what we eat. Recent studies have determined that the human body contains about as many bacteria, thirty-nine trillion, as the person’s “own” cells. We encompass an entire ecosystem, called the human microbiome.
Hosts and guests alike must cooperate together to produce a functioning person. What mysterious force unites the cells in my body so that they all act like Paul Brand (with a few rebellious exceptions)?
Unity is the foundation of bodily life, where every heart cell obeys in tempo or the animal dies. How does the roaming white blood cell in the bat’s wing know which cells to attack as invaders and which to welcome as friends? No one yet knows, but the body’s cells have a near infallible sense of belonging.
The body senses infinitesimal differences with an unfailing scent. My body knows which cells belong to Paul Brand and maintains constant vigilance against intruders. The first transplant recipients did not die because their new kidneys failed, but rather because their bodies would not be fooled. Though the new kidney cells looked and acted in every respect like the old ones, they did not belong. Transplant surgeons must now give the recipient immunosuppressant drugs for the rest of the patient’s life in order to lull the guards and keep them from sounding an alarm against the transplanted organ.
To complicate the process of identity, the composite of Paul Brand today—bone cells, fat cells, blood cells, muscle cells—differs almost entirely from my components two decades ago. All cells have turned over their mission to fresh recruits (except for nerve cells and brain cells, most of which do not get replaced). More like a fountain than a sculpture, my body maintains its continuity while constantly being renewed. Somehow my body knows the new cells belong and welcomes them.
Occasionally children are born without an immune system, the “bubble boy” syndrome. Until recent advances in therapy, they had to spend their lives in a plastic tent, untouched by other humans. NASA rigged up a bulky spacesuit for one such child, who then tugged behind him a golf cart-size contraption that scrubbed the air of impurities. Lacking a sense of shared identity, this unfortunate boy’s cells welcomed all intruders, including lethal bacteria and viruses.
The secret to membership lies locked away inside each cell nucleus, chemically coiled in a strand of DNA. The three billion letters of DNA spell out instructions that, if printed in a tiny font, would fill three hundred books of a thousand pages each. (Each letter counts: a mistake in only two letters can cause a disease like cystic fibrosis.) A nerve cell may operate according to instructions from volume four and a kidney cell from volume twenty-five, yet each carries the whole compendium, its credential of membership in the body. The entire body could be reassembled from information in any one of the body’s cells—which forms the basis for cloning and for the evolving technology of stem cell transplants.
As a Christian, I believe that the Designer of DNA further challenged the human race to a new and higher purpose: membership in a spiritual Body. The community that the New Testament calls the Body of Christ differs from every other human group: unlike a social or political body, joining it requires an identity transfer, analogous to an infusion of DNA. Jesus described the process to Nicodemus as being “born again” or “born from above,” indicating that spiritual life requires an identity change as drastic as a person’s first entrance into the world. We become, quite literally, God’s children.
“By him we cry, ‘Abba, Father.’ The Spirit himself testifies with our spirit that we are God’s children,” wrote the apostle Paul (Romans 8:15-16). We are “in him” and he is “in us,” the New Testament says in several places. We members take on Christ’s name and identity, and he asks from us the same kind of loyalty and unity that my own body’s cells give to me.
That common identity links all members of Christ’s Body with a unifying bond. I sense that bond when I meet strangers in India or Africa or California who share my loyalty to the Head; instantly we become brothers and sisters, fellow cells in Christ’s Body.
In a healthy church, unity trumps diversity. Paul, who as a faithful Pharisee used to thank God every day that he was not born a slave, a Gentile, or a woman, changed dramatically. “There is neither Jew nor Gentile, neither slave nor free, nor is there male and female, for you are all one in Christ Jesus,” he told the fractious Galatians (3:28). Such ethnic and gender categories melt away in significance compared to the new identity that we share.
The process of joining Christ’s Body may at first seem like a renunciation. I forfeit autonomy. Ironically, however, renouncing my old value system—in which I had to compete with other people on the basis of power, wealth, and talent—and committing myself to the Head abruptly frees me. My sense of competition fades. No longer do I have to compete through life, looking for ways to prove myself. Instead, I have the singular goal of pleasing God, of living for an audience of One. More, I can partner with other cells in the Body to accomplish God’s work in the world.
Driving home one evening during a heavy downpour, I suddenly see a small, dark shape scurrying out onto the road—probably an armadillo or opossum. Before that thought even registers, my foot has instinctively tapped the brake pedal.
I feel the sickening, out-of-control sensation of a skid coming on as the rear of the car hydroplanes off to the right. My hands grip the steering wheel more tightly. In response to a few quick jerks of my wrist, the car fishtails and finally straightens out. Once I have steering back under control, I breathe deeply and slow down until my anxiety subsides.
The entire incident lasts maybe three seconds. When I arrive home, I will recount to my wife what happened: an animal crossed a rain-slicked highway, and I arrested a dangerous skid just in time. Those are the external events, simple and matter-of-fact. The rest of the way home, still keyed up from the adrenaline pumping through my body, I think back on a few of the internal events.
Few parts of my body went untouched by the momentary crisis. My brain relied on a reflex response to direct my foot onto the brake pedal. At the same time, my hypothalamus ordered up chemicals that, with lightning speed, equipped me to cope.
Vision intensified as my pupils dilated and my eyes widened to admit more light and a larger visual field. My heart beat faster and contracted more forcefully, even as vascular muscles relaxed in order to allow blood vessels to widen for increased blood flow. My muscles went on alert. The makeup of my blood changed: more blood sugars surged in to provide emergency reserves for those muscles, and clotting materials multiplied in preparation for wound repair. Bronchial tubes in my lungs flared open to allow a faster oxygen transfer.
On the skin, blood vessels contracted, bringing on a pale complexion (“white as a ghost”); the reduced blood flow lowered the danger of surface bleeding in case of injury and freed up more blood for the muscles. The electrical resistance of skin changed as a protective response against potential bacterial invaders. Sweat glands activated to increase the traction of my palms on the steering wheel.
Meanwhile, nonessential functions slowed down. Digestion nearly came to a halt—blood assigned to that and to kidney filtration was redeployed for more urgent needs.
Fear, relief, heightened awareness—I felt all these sensations, and for the next twenty miles or so they made me a better driver. Yet inside my body a full-scale campaign had been launched to equip me for the classic alternatives of fight or flight. And what skilled executive coordinated the different responses of trillions of cells? A single chemical messenger called adrenaline.
We experience the effects of adrenaline every day: a clap of thunder startles us, we hear a bit of shocking news, we drive through a dangerous neighborhood, we stumble and nearly fall. Adrenal reactions occur so smoothly and synchronously that we rarely, if ever, stop to reflect on all the elements involved. Yet adrenaline is just one of many hormones at work in my body coaxing a cooperative response from diverse cells.
Medicine has coined a wonderful word to describe how the body unites its many cells to serve the whole: homeostasis. A physician and writer named Dr. Walter Cannon introduced the term in his classic study The Wisdom of the Body and also coined the term “fight-or-flight response.” He viewed the body as a community that consciously seeks out the most favorable conditions for itself. It corrects imbalances in fluids and salts, mobilizes to heal itself, and deploys resources on demand, all with the goal of maintaining a dependable milieu interieur, as the French call it.
You can see homeostasis on vivid display in modern hospitals, where monitors record a patient’s pulse and other vital functions. I visit a patient in a hospital room. As I enter, red numerals glow a steady 70, her resting pulse. She notices my presence and greets me, the flurry of emotional responses shooting her pulse up to 91. She reaches over to shake my hand, and the rate surges past 100. During my visit, the numbers rise and fall in concert with her moods and actions. A sneeze causes the most violent reaction of all, a pulse of 110.
Cells are constantly calling out their needs, and the body responds to each demand. Kidneys adjust to the body’s needs, increasing or decreasing the amount of fluid and minerals eliminated. After unusual exertion, they may stop the outflow altogether to prevent dehydration; hence a triathlete may not urinate for twenty-four hours after a race.
Sweat. I could write an entire chapter on that model of homeostasis. What a lizard wouldn’t give for warm blood and sweat glands! On brisk mornings the reptile must wriggle over to the sunlight and warm up before it can start climbing trees and catching flies. If the lizard overheats, it frantically scuttles toward shade. In humans, however, an efficient cooling system uses sweat to cool our bodies to a constant internal temperature so that sensitive organs can maintain a milieu interieur. Otherwise, we could hardly function in a climate where temperatures exceed eighty degrees Fahrenheit.
The Japanese physiologist Yas Kuno spent thirty years studying sweat, and in 1956 he published a 416-page book, Human Perspiration. He found the body to be so sensitive that a change of one-tenth of a degree in temperature sets off alarms in the skin’s thermoreceptors. Humans have the finest cooling system of all mammals; most animals will run fevers on a hot day. A marathon runner may shed three to five quarts of fluid in a three-hour race, but inside his temperature will hardly waver. (Animals compensate, though. A dog or tiger pants, creating its own internal fan. An elephant finds a water hole and wades in for a hose-down.)
All these operations—heart rate, fluid control, perspiration—adapt second by second as the body seeks the very best state. Hormone-like compounds, the prostaglandins, bathe the body’s cells: one lowers blood pressure and another raises it; one initiates inflammation, another inhibits it. These messenger fluids travel from cell to cell, visiting nearly every tissue of the body, linking isolated cells and organs into units of a coordinated response.
Until recently, anatomists believed that glands such as the adrenal and pituitary sent out their hormonal instructions independently. New discoveries point to reliance on the brain at virtually every point. Instructions on growth, on deployment of resources, and on how to meet a crisis all originate in the head, which senses the needs of the entire body.
In the human body, the sense of belonging extends two ways: a cell follows orders from the brain, while also recognizing a bond with every other cell in the body. So too in the spiritual Body. God calls me into an organic community, and I join a Body that binds me to other diverse cells. “We will grow to become in every respect the mature body of him who is the head, that is, Christ. From him the whole body, joined and held together by every supporting ligament, grows and builds itself up in love, as each part does its work” (Ephesians 4:15-16).
The word another hints at a kind of cell-to-cell cooperation, and we cannot escape the word in the New Testament. It appears as a relentless leitmotif. “Accept one another,” we are told. “Serve one another” by “washing one another’s feet.” We are to confess our sins to one another, pray for one another, forgive one another, teach and admonish one another, comfort one another, and bear one another’s burdens.
Jesus left us the most inclusive command of all: “Love one another as I have loved you.” When we obey the Head, following the orders that coordinate the Body’s many parts, unity results.
Human society approaches such unity only rarely. Families achieve it sometimes, as in the powerful tug of loyalty that binds me to my children scattered around the world. During a crisis, such as an earthquake or a forest fire, a town or even an entire nation may join together in common cause.
Jesus prayed for an even richer experience of unity in his Body. He asked “that all of them may be one, Father, just as you are in me and I am in you. May they also be in us so that the world may believe that you have sent me” (John 17:21). Do we in the church catch the vision of that unity—a unity based not on social class or interest group or kinship or race, but on common belonging in Jesus Christ?
Sadly, we see many examples of disunity in the church. I have, though, seen what can happen when the Body truly welcomes a new member. Those scenes give me a lasting vision of God at work in the world. I will mention only one example.
John Karmegan came to me in Vellore, India, as a leprosy patient in an advanced state of the disease. We could do little for him surgically since his feet and hands had already been damaged irreparably. We could, however, offer him a job and a place to stay.
Because of one-sided facial paralysis, John could not smile normally. When he tried, the uneven distortion of his features would draw attention to his paralysis. People often responded with a gasp or a gesture of fear, and so he learned not to smile. Margaret, my wife, stitched his eyelids partly closed to protect his sight. Though grateful for her efforts, John grew more and more paranoid about what others thought of him.
Perhaps in reaction to his marred appearance, John acted out the part of a troublemaker. I remember many tense scenes in which we had to confront him with some evidence of stealing or dishonesty. He treated fellow patients cruelly and resisted authority, sometimes organizing hunger strikes against the leprosy hospital. By almost anyone’s reckoning, he was beyond rehabilitation.
Perhaps John’s very irredeemableness attracted my aging mother to him, for she often latched onto the least attractive specimens of humanity. She spent time with John and eventually led him into the Christian faith. He was baptized in a cement tank on the grounds of the leprosarium.
Conversion, however, did not temper John’s high dudgeon against the world. He gained some friends among fellow patients, but a lifetime of rejection and mistreatment had permanently embittered him against all nonpatients. One day, almost defiantly, he asked me what would happen if he visited the local Tamil-speaking church in Vellore.
I went to the leaders of the church, described John, and assured them that despite obvious deformities, he had entered a safe phase of the arrested disease and would not endanger the congregation. They agreed he could visit. “Can he take Communion?” I asked, knowing that the church used a common cup. They looked at each other, thought for a moment, and agreed he could also take Communion.
Shortly thereafter I took John to the church, which met in a plain, whitewashed brick building with a corrugated iron roof. I could hardly imagine the trauma and paranoia inside a leprosy patient who attempts for the first time to enter that kind of setting. As I stood with him at the back of the church, his paralyzed face showed no reaction, but his body’s slight trembling betrayed his inner turmoil. I prayed silently that no church member would show the slightest hint of rejection.
As we entered during the singing of the first hymn, an Indian man toward the back of the church turned and saw us. We must have made an odd couple: a white person standing next to a leprosy patient with patches of his skin in garish disarray. I held my breath.
And then it happened. The man put down his hymnal, smiled broadly, and patted the chair next to him, inviting John to join him. John could not have been more startled. Haltingly, he made shuffling half-steps to the row and took his seat. I breathed a prayer of thanks.
That one incident proved to be the turning point of John’s life. Years later I visited Vellore and made a side trip to a factory that had been set up to employ disabled people. The manager wanted to show me a machine that produced tiny screws for typewriter parts. As we walked through the noisy plant, he shouted at me that he would introduce me to his prize employee, a man who had just won the parent corporation’s all-India prize for the highest quality work with fewest rejects. As we arrived at his work station, the employee turned to greet us, and I saw the unmistakable crooked face of John Karmegan. He wiped the grease off his stumpy hand and grinned with the ugliest, loveliest, and most radiant smile I have ever seen. He held out for my inspection a palmful of the small precision screws that had won him the prize.
A simple gesture of acceptance may not seem like much, but for John Karmegan it proved decisive. After a lifetime of being judged on his damaged appearance, he had finally been welcomed on a different basis. God’s Spirit had prompted the Body on earth to adopt a new member, and at last John knew he belonged.