The Human Age (32 page)
We now grasp that a wafer of skin can be retrained to do just about anything. It’s a new category of raw material, like wood or stone, with potent gifts. An ebony tree growing in Africa may provide shade to humans, and a lofty haven for a leopard gnawing a carcass, but its dark grain also gives rise to clarinets, piano keys, violin fingerboards, and music. The old idea of skin as a sacred cloak with two main jobs—to seal off the vulnerable organs inside us and define
our individuality—has given way to a sense of how mingling, malleable, and porous the body really is. At the cellular level, we’re stunningly mutable, not just in our lifestyles, which we always knew, but in our bits and pieces. A butler can change his mind, via his neurons, and become a gandy dancer. A dash of skin can become fresh neurons for a Parkinson’s-stricken monk. What to do with cells is increasingly more a question of imagination than material.
Spearheaded by pioneers like Bonassar and Lipson, Anthropocene engineering has penetrated the world of medicine and biology, revolutionizing how we regard the body. In these vistas, electricity, architecture, and chemistry slant together and tell tales never heard before.
We baby boomers grew up with a cartload of absolutes, handed down from generation to generation of biologists, the most daunting one, perhaps, being that we’re born with all the brain cells we’ll ever have, because the brain doesn’t mint new cells. Yet now we have proof that it does, even in old age. We’ve spent the last decade blowing up a lot of similar assumptions, and I wonder what other rigid ideas will topple. Bonassar offers me another quite mysterious one.
“We were told, over and over,” he says with relish, “that the heart is an organ that positively can’t regenerate. Yet an amazing study has turned that idea upside down.”
In this study, he explains, heart transplant patients received hearts from a donor of a different gender—mostly men receiving women’s hearts. In theory, one should be able to examine the heart recipient, look at the cells in his borrowed heart, and find female cells from the donor. But it turns out that, on autopsy, if these men bore their transplanted hearts for more than a decade, almost half of the heart cells were mysteriously replaced by male cells. The mechanism isn’t clear—but the new paradigm is. The heart’s metronome tissues, which we always believed couldn’t regenerate, actually can. No one knows if the cell-swap is a fusion or whether the female cells were forcibly displaced. Either way, it’s overturned the handcart of possibility, and furrowed many brows. If organs as elemental as brain
and heart can be persuaded to regenerate, and others, like ears and corneas, can be fashioned from living ink, how will that change us as a species? Will the printing of organs affect our evolution? Could it alter our genes? I’m curious to know what Bonassar thinks.
The possibility intrigues him, too. “The real question,” he says, “is what the evolutionary pressure of these therapies might be. Would faulty genes become more prevalent, because they could be fixed? I wear contact lenses, but if I were a caveman and my eyesight was as bad as it was when I was five, I would have been in serious trouble. Now it doesn’t matter. We could replace our defective parts, live longer, and feel healthier.” Then he adds a provocative afterthought: “Yet physically we could be much weaker and more flawed genetically.”
Suppose we don’t just repair and enhance ourselves, suppose we live longer as a result? The primary focus of the work in Bonassar’s lab—cartilage for arthritis, cartilage for traumatic injury, disks for back pain—is medical solutions for ailments that tend to afflict people long after they’ve had children, when evolution has stopped bedeviling them to breed. Would the ability to be fit for a decade longer present an evolutionary advantage? Would people take more risks? How will we regard the body’s bits and pieces, and safeguard them, if we know we can cheaply replace them? We replace heart valves or heart tissue to extend life, but what if you can cure arthritis, and keep people active and sexual well into their seventies and eighties?
Think geriatric cyborgs and chimeras. Grandpa’s going to be saying a lot more interesting things than
Where are my teeth!
Just staying active for an added decade may alter our society as a whole far more than fixing a particular defect in the heart, liver, brain, or kidney.
The ninety-year-olds I’ve known haven’t run marathons, even with gleaming new hips and knees, but they’ve inhaled a lot of sky on daily walks. Even bioprinted cartilage needs exercise. Looking forward to a walkabout through drifting avenues of snow, I say
good-bye to Bonassar and slip into my parka. As I stride down the hallway and into the atrium, the building’s smart sensors work and a little breeze runs before me like an invisible serpent. Hail begins lightly rattling against the windows. A vague thought, as elusive as the smell of violets, nags at me. A dark cloud passes over, and I feel aware of how aging, like winter weather, can chill the bones. For a moment, that thought hangs like an icicle, tapering and cold. Then my mind reels through hopeful images: an incubator full of spinal disks, the flexible necks of dachshunds, the long open labs of students with eager minds, the children with new ears, and the warming plate where collagen marbles land on their way to reshaping our future biology, and I swear I hear spring buzzing like a red-winged blackbird.
A
t no point in my conversation with Bonassar did we discuss if people will
mind
the idea of artificial body parts. No need to. They’re already a commonplace feature of the new normal. Not long ago the idea of a cyborg was pure science fiction, and we couldn’t get enough of the Six Million Dollar Man (who inspired many a roboticist),
Star Trek
’s Captain Picard (who has an artificial heart), or the species of moody Replicants in
Blade Runner
. Now we think nothing of strolling around with stainless steel knees and hips; battery-operated pacemakers and insulin pumps; plastic stents; TENS pain units that disrupt pain signaling in the nerves; cochlear implants to restore hearing; neural implants for cerebral palsy, Parkinson’s, or damaged retinas; polymer and metal alloy teeth; vaccines hatched in eggs; chemically altered personalities; and, of course, artificial limbs. A great many of us are bionic (I have a 5 cm titanium screw in my foot), and bionic hands, arms, legs, skin, hearts, livers, kidneys, lungs, ears, and eyes are all available. Visible cyborgs who move among us may grab our attention and curiosity, but they don’t scare us anymore, and they’re becoming commonplace.
On a windy November day in 2012, software designer Zac Vawter climbed 103 floors of Chicago’s Willis Tower, the tallest building in the western hemisphere. From its Skydeck, 1,353 feet in the air, one can view four states and the pounded blue metal of Lake Michigan fanned out below. Breathing hard toward the end, with the 2,100th step he reached the Skydeck and strode straight into history.
It was a climb that challenged the stamina and knees of all 2,700 people who joined him to help raise money for the Rehabilitation Institute of Chicago. But what makes Vawter remarkable is that he did it using a gleaming new bionic leg. Surpassing even that is how he did it—by controlling the device with his thoughts.
A thirty-one-year-old father of two, Vawter lost his right leg in a motorcycle accident in 2009. Afterward he went through a pioneering procedure in which the residual nerves that once ruled his lower leg were “reassigned”—they were rerouted to control his hamstring. For months he flew to Chicago to work with engineers, therapists, and doctors to adjust the bionics and refine both his physical and mental technique.
As he pictured himself climbing—lifting his leg, bending his knee, flexing his ankle—electrical impulses from his brain flashed to his hamstring, which signaled a deftly designed assembly of motors, belts, and chains to lift his ankle and knee in unison, and he began taking the stairs step-over-step in the normal way. Just focusing hard doesn’t work; he had to intend to walk. The bionic leg is designed to read an owner’s intent, whether he’s walking, standing, or sitting. So if he’s seated and wants to stand up, he just pushes down and the leg pushes back, propelling him up.
Like any athlete, he had to prepare for months, while scientists tailor-made the prototype leg and he practiced the mind-feel of stair-climbing. In time, the brain accepted the robotics as an extension of his body image and took it into account when judging, say, whether or not he might fit through an open door. Yet when the climb was over and he flew home to Washington, he had to leave the leg in Chicago for researchers to continue tinkering with until it’s even
more reliable. Bionic arms are already popular, and if an arm fails someone might drop a glass of milk, or, more alarmingly, a baby, or a flaming match. If a bionic leg fails, they could tumble down a flight of stairs. So the technology has to be safe. RIC expects the FDA to approve such bionic legs within the next five years.
As long as humans have walked the Earth, we’ve been driven by a need to stretch into the environment; tools and technology have always been an innate part of that quest. Now we’re comfortable with, and excited by, the promise of connecting our brains to the world outside of the body. iPads and cell phones that store phone numbers, calendars, to-do lists, photos, documents, and memories for us—external brains the size of a notepad—are just the beginning.
Oh, where did I leave my memories?
Most of us tuck our prosthetic memories in pockets, purses, and briefcases. On campus, the students tote spare hippocampi in their backpacks. We may fear losing our memory as we age, but at any age we’re anxious about losing our prosthetic memories. Many people aren’t at ease without obsessively “checking”—a verb once applied to OCD behavior (Did I turn off the stove? Close the garage? Shut the door tightly?). Relentless digital “checking behavior” has joined the closet of neurotic compulsions, and we’ve added these phobias to our quiver:
nomophobia
/
mobophobia
(the fear of leaving your cell phone at home),
phantom vibrations
(thinking your cell phone is vibrating even though no one is calling), and
FOMO
(
f
ear
o
f
m
issing
o
ut, and so relentlessly checking Facebook).
Continuous partial attention
(focusing halfheartedly) has become pervasive as we’re tugged at by ringtones, text-tunes, incoming-mail pings, calendar flags, update alerts, new-post beeps, pop-ups, and the nagging possibility that something more engrossing may appear.
Our ancestors adapted to nature according to the limits of their senses. But over the eons, we’ve been extending our senses through visionary and stylish inventions—language, writing, books, tools, telescopes, telephones, eyeglasses, cars, planes, rocket ships—and, in the process, we’ve redefined how we engage the world but also
how we think of ourselves. This even extends to our metaphors. We used to picture the body as a factory. Today that’s sea-changed and scientists picture factories as primitive forms of cells. We used to compare the brain to a computer. Now DARPA has a SyNAPSE program whose goal is building “a new kind of computer with similar form and function to the mammalian brain.”
Our cells dance with their own electric, and as they’re immersed in ambient networks and signals—the
everyware
—we’re becoming part of an invisible weave that’s different from the one we used to picture as the seamless web of nature. This is part of the new natural. It slips beneath our radar for things weird, experimental, nonhuman. Anthropocene humans can merge with technology and not be regarded as alien.
Not only humans. When a puppy called Naki’o fell asleep in a puddle on a cold Nebraska night, he woke with frostbite on all four paws. As his condition worsened, Orthopets, a Denver company that specializes in prosthetics for animals, turned Naki’o into the world’s first bionic dog. Equipped with four prosthetic limbs, he runs and romps normally with his owner—despite not being able to feel the ground—and has become the spokesdog for Orthopets, which has also equipped a front-legless Chihuahua with two wheels (he’s a big hit in nursing homes). Other bionic animals include a wounded bald eagle, found starving in an Alaska landfill and given a new upper beak; a dolphin mutilated in a crab trap and unable to steer until it got a prosthetic tail; a green sea turtle with replacement flippers after a surfboard injury; and a baby orangutan, born with clubfeet, fitted successfully with therapy braces.
Clearly, these attachments were all prosthetics. But should we consider the first spears to be tools or imaginary prosthetics? Attacked by slashing bears, tigers, and other beasts with razory teeth and claws, our ancestors fought back by crafting teeth and claws of their own, ones they could detach and hurl from a distance. What a novel idea! Imagine a wolf flinging its teeth, one by one, at its prey. Stone axes were tools, but also prosthetic hands built stronger and
bigger and sharper than a hominid’s own. The first clothing was also a prosthetic, an artificial body part: skin. When cavemen and -women wore draped animal hides for warmth, tying them with sinew, no matter how much they tanned the clothing first, it would have yielded a whiff of other creatures. They slept under borrowed scents, in a cave permeated by sweet gamy odors that mingled with each person’s personal bouquet. Today we’re so far from the origins of our clothing that it’s become impersonal, and we don’t feel the powerful magic of being enrobed in another animal’s skin or a plant’s fibers.
Early humans probably devised crutches for the lame, but the first prosthetics are spoken of in the ancient sacred Indian poem the
Rig Veda
, where they belonged to the warrior queen Vishpla. After she lost a leg in battle, she still insisted on fighting, so some sort of iron leg was fashioned for her. The Greek historian Herodotus tells of a shackled Persian soldier who escaped by cutting off his foot and replacing it with a copper and wooden one. In the Cairo Museum, there’s a mummy from the reign of Amenhotep II (fifteenth century BC), whose big toe on the right foot was amputated and replaced by a superbly carved wooden replica tied on with leather straps. She’s believed to have been a royal woman suffering from diabetes, and the artful toe was designed to help her both on Earth and in the afterlife.