The Human Age: The World Shaped by Us

by Diane Ackerman

  Using a cane, she moved smoothly and looked understandably elated, comfortable in motion, which is remarkable since Duckworth didn’t grow up learning to balance her pelvis and spine over prostheses while she walked. As an infant she learned to walk fearlessly, as babies instinctively do, around the age of thirteen months, when balance and strength are keen enough, and some baby fat has yielded to muscle.

  Although walking ultimately becomes unconscious, it’s a skill that requires us to tumble into and out of balance all the time. It takes countless hours of practice and encouragement, and a great many falls to do it expertly. Babies are like tiny petulant stilt-walkers. To walk, you step forward with one foot, which tilts you off balance, then you catch yourself before you fall too far, quickly rebalance, and fall in the opposite direction, catch yourself, and start falling again as you make a so-called straight line across the room or street. Walking is really a series of recovered falls. In time we learn to do it expertly, without noticing that it’s an evolutionary circus act. Over time, a lovely pendulum swing develops, as the hips roll out of balance and back in again, over and over, without the walker paying it any mind. Its rhythm is naturally iambic (a short unstressed syllable followed by a long stressed one), which could be why so many poets, from Shakespeare to Wordsworth, wrote poems in iambs; maybe they composed while strolling. Fortunately, the pelvis and backbone are engineered to make the skill (strolling, not composing poetry) relatively easy.

  However, relearning to walk as an adult means unlearning old balancing tricks and mastering new ones, based on the current shape of your body, while fully aware that you could fall and badly injure yourself. Also, injuries aren’t always symmetrical—Duckworth’s were complex (right leg missing at the hip, left leg below the knee). Blades like Pistorius’s wouldn’t have suited her lifestyle, in which she needed to feel equally comfortable on airplanes, behind a desk, at a podium, or climbing stairs. Her revolutionary ankle joints and legs rely on robotic software—microprocessors, accelerometers, gyroscopes, and torque angle sensors—to mimic the delicate teamwork of muscles and tendons in the ankle when someone walks.

  The day of the cyborg has certainly arrived, with goggles for skiers and snowboarders offering a dashboard display of data, GPS, camera, speedometer, altimeter, and Bluetooth phone; plus voice control and gaze control for cyclists. Will it be safe to ski or bike with data dancing before your eyes, or while posting photos on Facebook? Probably not. But safer than looking down at a smartphone and back up at the slopes, while dizzily jockeying between the sensory and tech worlds. The virtual reality that Star Trek promised us is starting to become commonplace. We can don a headset that stimulates all five senses simultaneously, and walk along a street in ancient Rome or Egypt, so immersed in the look, smell, and feel of the place that it seems real.

  I’ve yet to meet anyone sporting Google Glass, the voice-controlled miniature screen in a flexible frame that hovers piratically above one eye, projecting e-mail and maps onto your visual field. But, whether or not it catches on as techno-fashion, it’s already a triumph in operating rooms around the world. The first surgeon who wore it simply videotaped an operation to share with colleagues. Since then, surgeons have been actively consulting Glass during operations to view X-rays or medical data without turning away to look. The cyborg doctor has eyes in the back of his head, and four or more hands. At the University of Alabama at Birmingham (UAB), Dr. Brent Ponce, wearing a Google Glass, began a shoulder replacement surgery while the built-in camera showed the surgical field to Dr. Phani Dantuluri, a veteran surgeon watching on his computer monitor in Atlanta. As the doctors discussed the case, Dantuluri could reach into the surgical field that Ponce saw on his heads-up display: ghostly hands floated over the body, pinpointed an anatomical feature or demonstrated how to reposition an instrument, as he consulted in real time. Invented by a UAB neurosurgeon, Barton Guthrie, who was frustrated by the limits of teleconferencing, VIPAAR (Virtual Interactive Presence in Augmented Reality) offers a safety net in diverse situations: teaching surgeons, guiding a resident’s hands, piloting difficult procedures in regional hospitals anywhere in the world, and also assisting emergency operations at an Antarctic base or in space.

  A lively pair of glasses, even with all the digital trimmings, is still only an accessory. At the end of the day, you remove it and become mortal again. We yearn to supersize and supervise our powers with no intermediary, but intimately, naturally, without fuss, as if such marvels were our birthright. The next small step, a world closer, will be thought-controlled contact lenses floating on the eyes like high-tech continents. Will they cling invisibly, or twinkle like the glass eyes of a doll? The final step, who knows when, will be the silk of silicon sliding along our neurons. Then, without disappearing, only virtually visible, our computer worlds will fully mesh with us. Will we feel haunted sometimes, or merely worry about affording the latest update?

  It’s a strange paradox to imagine, yet highly possible, maybe even inevitable, but by delegating more physical and mental tasks to robots and computers, we might also weaken various skills and aptitudes—math, musculature, memory—while perfecting new ones. We may soon have to master multitasking spatially, as we cross midtown streets while scrolling through and answering e-mails hovering in the air, which we’ve conjured up on our iGlasses, just by batting our eyelashes. In time, brain and body would adapt.

  We’ve always crafted new technologies to help us live better or longer, but in the past few decades that’s accelerated dramatically. We’ve stepped up the pace of our romance with machines, wedding them to our bodies as never before, and saturating our lives with techno-marvels, from genetic tests to organ transplants, satellite communications to genetic engineering, brain scans to mood enhancers. They’ve amused and nettled our lives to such an extent that a new branch of anthropology has arisen to study the phenomenon.

  Amber Case practices “cyborg anthropology,” a field in which scientists study how both humans and robots interact with objects, and how that changes the culture in which we live. For example, the way cell phones affect human relationships, and how we now interact techno-socially instead of socially. Old-fashioned social relationships, in which one gets together with friends, are regarded as “analog.”

  “So, for instance,” Case explains, “we have these things in our pockets that cry, and we have to pick them up and soothe them back to sleep, and then we have to feed them every night by plugging them into the wall, right? And at no other time in history have we had these really strange nonhuman devices that we take care of as if they are real.”

  Cyborgs may be growing plentiful, but even more of us are chimeras—DNA (and sometimes body parts) from two or more creatures lodged inside one body. The ease with which mythic humans and animals breed and swap bodies speaks to our prior intimacy with the rest of nature, acknowledging animals as part of our extended family. We’ve adopted the term “chimera” from the Greek monstrosity Homer sang of in the Iliad, a savage sky-beast said to be part lion, goat, and serpent, that blasted fire from her mouth and terrorized the land until a hero named Bellerophon chased her on his winged horse, Pegasus, and rose above her fiery blasts to kill her. It’s the sort of fiend that haunts many cultures, all claiming that some unholy union of different species—a lion, snake, and eagle, for instance—has produced a dragon, a sphinx, a griffin, a medusa. In Greek mythology we find satyrs, overly lustful woodland goat-men, and the perfumed and tuneful sirens, bird-women who lured men to their doom. There are Chinese tales of families that descend from the marriage of a shape-shifting dragon and a human. Siberian shamans owe their magical power to the marriage of men and swans. Native American lore declares that the first people of the Earth were part animal. In fairy tales brides and grooms marry animals. Often the chimeras (mermaids, for instance) exist at the limits of the known world, where heroes and explorers go to prove their courage. Despite the countless children’s books filled with delightful thinking, talking, personality-ridden animals, t
he idea of a real-life part-human being trapped in the body of another animal seems diabolical to most people, so horrifying that it was the Greek gods’ favorite way of punishing humans.

  As exotic as it sounds, we already have a great many natural chimeras among us, including all the people who secretly harbor Neanderthal and Denisovan genes. We absorb other people all the time. When we pass along a cold sore or flu, the virus carries some of our protein and releases it inside the other person, where the immune system stows it for future reference. HIV and other retroviruses are especially good at installing pieces of one person’s DNA inside another person’s chromosomes. By exchanging body fluids we even swap gene fragments with our partner, and become a chimera as our self starts including bits of their immune system. We don’t just get under a mate’s skin, we absorb him or her. As the immunologist Gerald N. Callahan explains, we’re probably swapping gene fragments with other people “a lot more often than we realize. Infection becomes communication, memorization, chimerization. Over the course of an intimate relationship, we collect a lot of pieces of someone else. Until one day what remains is truly and thoroughly a mosaic, a chimera—part man, part woman, part someone, part someone else.”

  However the affair turns out, we’re invisibly changed for having known each other. This may not be a pleasant thought if the DNA belongs to an old flame you never want to see again as long as you live and can’t bear the thought of hauling around in your car, let alone your cells. Best not to dwell on that. Think instead of Mom’s DNA, or a sweetheart’s, still alive inside you as a miniature portrait.

  The human chimeras known as twins provide a glimpse of how confusing a world full of clones might be, but twins are too numerous to regard as oddities. At the end of her life, my mother needed regular bone marrow transplants, through which she had donor cells in her bloodstream. By that time, she was already a chimera, because moms retain cells from their fetuses. She would also have stored cells from my father, who stored her cells, too. But, to the best of my knowledge, he didn’t contain cells from pig valves, cat gut, or monkey glands—though the last might have been a temptation, since it was in high vogue when he was a young man.

  In the pre-Viagra 1920s, men hoping to improve their virility flocked to the French surgeon Serge Voronoff, who grafted thin slices of monkey testicles onto their scrotums. Later he transplanted monkey ovaries into women, including, allegedly, the U.S. coloratura soprano Lily Pons, who was a frequent guest at his monkey farm on the Italian Riviera. Over five hundred such operations brought Voronoff fame and great wealth, until, in time, he was denounced as nothing more than a witch or magician. But people didn’t fret about hitching their testicles and ovaries to monkey glands.

  Today, the monkey gland craze is as passé as Rudolph Valentino, but so many of us have pieces of other nonhuman creatures inside us, it’s surprising that we don’t inadvertently oink, clop, or bleat in embarrassing moments. We think nothing of strolling around with cow and horse valves in our hearts. Raising genetically modified pigs that are more compatible with human tissue, we harvest the blood-thinner heparin from their intestines, and insulin from their pancreases. The fibrous tissue in the spaces between the cells in a pig’s bladder, once viewed as mere cushions, are so rich with growth factors that they’re used to “fertilize” war-ravaged human muscles and help them regrow.

  When Corporal Isaias Hernandez, a nineteen-year-old marine deployed in Iraq, had 70 percent of his thigh muscle torn off by a roadside bomb, doctors assumed they’d be amputating the leg. The remains of his thigh looked to him like a half-eaten meal at a Kentucky Fried Chicken restaurant: “You know, like when you take a bite of the drumstick down to the bone?” Quickly scarring over, his thigh sparked constant pain, and doctors prescribed amputation followed by a prosthetic as his only hope.

  Then he became a chimera. Volunteering to be part of a clinical research trial, in 2004, he allowed surgeons to insert a paper-thin slice of pig’s bladder, known as extracellular matrix, into the ragged thigh muscle. It began to regenerate. Today, without pain, he—like others—uses a regrown thigh to walk, sit, kneel, bike, climb, and enjoy a normal life. He’ll always be part pig, the part his surgeons refer to affectionately as “pixie dust.”

  Is there much difference between ingesting and implanting? We swallow snake and spider venom, and gila monster spit to calm an unruly heart, and cone shell venom for pain. For birth control, millions of women ingest mare’s urine. Our foremost antibiotics come from a cavalcade of fungi. Then there are the coatings, capsules, and liquid additives that go into medicines, concocted from the skin, cartilage, connective tissues, and bones of animals. If we’re comfortable with implanting horse valves in our faulty hearts and pig tissue in our thighs, if we get past the basic idea of raising animals to butcher for their organs and amending our bodies with pieces from lower orders, what else might we think of? Borrowing a spare stomach from a cow so that we can digest food more quickly and lose weight?

  Maybe embedding parts from other animals doesn’t seem to bother us because, on the atomic level, we’re living beings composed of nonliving parts. Hence the graveside reminder, “from dust to dust.” Maybe we see it as the ultimate domestication of animals and taming of the soil, which we began long ago in our collective memory, little by little widening their uses. Gradually we’ve gone from animals sleeping under our roof to animals sleeping under our ribs without feeling alarmed. Oh, that again, the cow is in my bone house. Maybe in our desperate hours we gladly extend the idea of kinship from, say, my brother’s kidney to a sheep’s kidney.

  Man-made chimeric creatures are a staple in laboratories—mice and other animals bred or grafted with human immune systems, kidneys, skin, muscle tissue—as a common way to study human diseases. Scientists have created sheep with organs that are 40 percent human, monkeys with part-human brains, and mice in which a quarter of the brain cells were human (fortunately they still behaved like mice, but who knows what strange mists galloped across their thoughts). Yet people balked when Japanese scientists announced that, given a year, they could grow a perfect human heart or kidney by tucking a human stem cell into a pig’s embryo, then lodging the embryo in a healthy pig’s womb. Pig valves in humans, no problem. But a pig with human organs?

  It’s a sign of our times that the problem with “chimeric embryos” isn’t technological but ethical. It’s doable, but it’s not permissible. Nations would have to agree on what a human being should be, and that’s not so obvious anymore. For the first time, we’re asking ourselves: how far are we willing to engineer the world and ourselves? We still feel human when partially enhanced by prostheses, somewhat chimeric, or controlling wearable technology by eyelash-flicks or thoughts. The question has become one of degree. How replaceable are we, yet still legally and attractively human? And where is the line of disgust between enhanced human and monstrous?

  Canada has passed the Assisted Human Reproduction Act, which bans the creation of chimeras. The bioethicist Françoise Baylis of Dalhousie University in Halifax, Nova Scotia, helped draft Canada’s guidelines on chimeras.

  “We don’t treat all humans well, and we certainly don’t treat animals well,” she insists. “So how do we treat these new beings?”

  In the United States, the National Academy of Science permits chimeras but warns against allowing chimeras to breed, because breeding two part-human chimeras could potentially lead to the grotesque (though almost certainly fatal) possibility of a human embryo growing inside another animal. Remember Rome’s fabled origin, when Romulus and Remus were raised by wolves? Suppose a wolf actually gave birth to a human? Or a sheep did? Almost ten years ago, Esmail Zanjani of the University of Nevada, Reno, announced that he had injected human stem cells into sheep embryos halfway through gestation, and the lambs emerged with human cells throughout their tissues. And not just a few cells. Some of the organs were nearly half human. Only the organs. No two-legged sheep with opposable thumbs emerged. Staring at them in photographs, I found t
hey looked eerily human, with long faces, jelly roll falling over the forehead, and down-turned eyes. Would dogs detect an odor both human and sheep?

  What scientists still don’t know is if transplanted human stem cells would change an animal’s inherent behaviors, attributes, or personality. As bioethicists rightly argue, the last thing we need is the horror of humanized monkeys or other animals. With less than one-thousandth the brain volume of humans, there’s little danger of mice developing our cognitive abilities. But in an animal closer to us on the evolutionary tree, say, a chimpanzee or bonobo, the merger might just work, especially if the DNA were mixed in the earliest stages of development. What would the orangutan Budi make of monkeys with part-human brains, I wonder?

  A laboratory chimera poses a moral paradox. The more human its cells, the better it will serve for testing human cures. Too human, and it’s trapped between worlds, a claustrophobic prisoner. Writing in 1876, when the Industrial Revolution had really begun to pick up steam, one British novelist warned of just such a possibility.

  In H. G. Wells’s classic novel The Island of Dr. Moreau, a shipwrecked man, rescued by a passing boat, relates a gruesomely fascinating tale of escaping from a nameless Indonesian island populated by sentient monsters whom Dr. Moreau has created through transfusions, transplants, grafts, and other bizarre techniques to create human-animal chimeras. They’re hyena-swine, hog-men, leopard-men, ape-men, little sloth people, and other “Beast Folk,” some of whom have founded their own colony in the jungle, worship Moreau, and have evolved moral bylaws. The novel shocked Victorian England, which was reeling from a slew of new technologies and from Darwin’s idea that humans descended from apes. The vogue for vivisection provoked controversy, as did eugenics, and the ethical limits of scientific experiments. Wells’s novel brought all of those into question, and also explored British colonialism, the essence of identity, the depravity of torture, and maybe most of all the peril one faces by interfering with nature. In later years, Wells described the wildly successful novel as “an exercise in youthful blasphemy.”