by Michio Kaku
Other clues can be found in an animal’s behavior, though sifting out conscious acts from those that are evolved and mindless can be difficult. Tool use is an instructive case. Australian “firehawk” raptors sometimes fly bundles of flaming sticks out of forest fires and into neighboring landscapes, to flush out prey. Maybe that means the raptors are capable of considering a piece of the physical environment, and imagining a new purpose for it. Or maybe something more rote is going on.
Crows are among the most sophisticated avian technologists. They have long been known to shape sticks into hooks, and just last year, members of one crow species were observed constructing tools out of three separate sticklike parts. In Japan, one crow population has figured out how to use traffic to crack open walnuts: the crows drop a nut in front of cars at intersections, and then when the light turns red, they swoop in to scoop up the exposed flesh.
As Singh and I talked, the crow grew bored with us and turned back to the window, as though to inspect its faint reflection. In 2008, a magpie—a member of crows’ extended family of corvids, or “feathered apes”—became the first nonmammal to pass the “mirror test.” The magpie’s neck was marked with a bright dot in a place that could be seen only in a mirror. When the magpie caught sight of its reflection, it immediately tried to check its neck.
Singh told me this crow would soon move upstairs, to one of the roof’s exposed cages, where the birds have more space to test their still-fragile wings, in view of an open sky that must surely loom large in a bird’s consciousness. With luck, it would quickly return to the spirited life preferred by wild crows, which sometimes play like acrobats in high winds and ski down snowy surfaces. (Birds that die at this hospital are buried along a riverbed outside Delhi, an apt touch in the case of the crows, which sometimes hold funerals—or, if not funerals, postmortems, where they gather around their dead like homicide detectives discerning cause of death.)
I asked Singh how he felt when he released birds on the rooftop. “We are here to serve them,” he said, and then noted that not all the birds leave right away. “Some of them come back and sit on our shoulders.”
Crows are not among the shoulder-perchers, but Singh sometimes sees former crow patients hovering around the hospital. They might be looking for him. Crows recognize individual human faces. They are known to blare vicious caws at people they dislike, but for favored humans, they sometimes leave gifts—buttons or shiny bits of glass—where the person will be sure to notice, like votive offerings.
If these behaviors add up to consciousness, it means one of two things: either consciousness evolved twice, at least, across the long course of evolutionary history, or it evolved sometime before birds and mammals went on their separate evolutionary journeys. Both scenarios would give us reason to believe that nature can knit molecules into waking minds more easily than previously guessed. This would mean that all across the planet, animals large and small are constantly generating vivid experiences that bear some relationship to our own.
* * *
The day after I visited the bird hospital, I left Delhi by car, on a road that follows the Yamuna River south and east, away from its icy source among the serrated ridges of the Himalayas. Delhi’s sewage has blackened long stretches of the Yamuna, making it one of the world’s most polluted rivers. From the road, I could see plastic bottles floating on its surface. In India, where rivers have a special place in the spiritual imagination, this is a metaphysical defilement.
Millions of fish once swam in the Yamuna River, before it was desecrated by the human technosphere, which now reaches into nearly every body of water on Earth. Even the deepest point in the ocean is littered with trash: a grocery bag was recently seen drifting along the bottom of the Mariana Trench.
We last swam in the same gene pool with the animals that evolved into fish about 460 million years ago, more than 100 million years before we split from birds. The notion that we are kin across this expanse of time has proved too radical for some, which is one reason the ever-changing universe described by Darwin has been slow to lodge in the collective human consciousness. And yet, our hands are converted fins, our hiccups the relics of gill-breathing.
Scientists have sometimes seemed to judge fish for their refusal to join our exodus out of the water and into the atmosphere’s more ethereal realm of gases. Their inability to see far in their murky environment is sometimes thought to be a cognitive impairment. But new evidence indicates that fish have minds rich with memories; some are able to recall associations from more than ten days earlier.
They also seem to be capable of deception. Female trout “fake orgasms,” quivering as though they’re about to lay eggs, perhaps so that undesired males will release their sperm and be on their way. We have high-definition footage of grouper fish teaming up with eels to scare prey out of reefs, the two coordinating their actions with sophisticated head signals. This behavior suggests that fish possess a theory of mind, an ability to speculate about the mental states of other beings.
A more troubling set of behaviors has emerged from experiments designed to determine whether fish feel pain. One of the most intense states of consciousness, pain is something beyond the mere detection of damage. Even the simplest of bacteria have sensors on their external membranes; when the sensors detect trace amounts of dangerous chemicals, the bacteria respond with a programmed flight reflex. But bacteria have no central nervous system where these signals are integrated into a three-dimensional experience of the chemical environment.
Fish have many more kinds of sensors than bacteria do. Their sensors flare when the water temperature spikes, when they come into contact with corrosive chemicals, when a hook rips through their scales and into their flesh. In the lab, when trout lips are injected with acid, the fish do not merely respond at the site. They rock their entire bodies back and forth, hyperventilating, rubbing their mouths against their tanks’ sides or gravel bottoms. These behaviors cease when the fish are given morphine.
Such actions call the ethics of the research itself into question. But the experiences of lab fish are nothing compared with those endured by the trillions of aquatic animals that humans yank, unceremoniously, out of oceans and rivers and lakes every year. Some fish are still alive, hours later, when they’re shoveled into the sickly lit, refrigerated intake tubes of the global seafood supply chain.
Fish pain is something different from our own pain. In the elaborate mirrored hall that is human consciousness, pain takes on existential dimensions. Because we know that death looms, and grieve for the loss of richly imagined futures, it’s tempting to imagine that our pain is the most profound of all suffering. But we would do well to remember that our perspective can make our pain easier to bear, if only by giving it an expiration date. When we pull a less cognitively blessed fish up from the pressured depths too quickly, and barometric trauma fills its bloodstream with tissue-burning acid, its on-deck thrashing might be a silent scream, born of the fish’s belief that it has entered a permanent state of extreme suffering.
The Jains tell a story about Neminath, a man from deep antiquity who is said to have been sensitive to the distress calls of other animals. He developed his unusual fondness for animals while tending cattle in pastures on the banks of the Yamuna River, in his home village of Shauripur, which I reached four hours after leaving Delhi.
Neminath is one of twenty-four Jain “Fordmakers,” prophetlike figures who crossed a metaphorical river, freeing themselves from the cycle of birth and rebirth, before showing others the way to enlightenment. The Fordmakers’ life stories tend to emphasize their nonviolent natures. One is said to have floated perfectly still in the womb, sending not so much as a ripple through the amniotic fluid, to avoid harming his mother.
Only a few Fordmakers are confirmed historical figures, and Neminath is not one of them. The Jains say Neminath left his village for good on the day of his wedding. That morning, he mounted an elephant, intent on riding it to the temple where he was to be w
ed. On the way, he heard a series of agonized screams, and demanded to know their origin. Neminath’s elephant guide explained that the screams came from animals that were being slaughtered for his wedding feast.
This moment transformed Neminath. Some versions of this story say he freed the surviving animals, including a fish that he carried, in his hands, back to the river. Others say he fled. All agree that he renounced his former life. Rather than marry his bride, he set out for Girnar, a sacred mountain in Gujarat, 40 miles from the Arabian Sea.
* * *
My own ascent up Girnar began before dawn. It followed the usual topography of enlightenment. I was to climb 7,000 steps, all built into the mountain, by nine in the morning, so as not to be late for a ritual at an ancient temple near the peak.
The trail was only 50 miles from Gir National Park, where, the day before, I’d seen two Asiatic lions, nearly indistinguishable cousins of Africa’s lions. Once the region’s apex predator, the Asiatic lion almost went extinct during the British empire’s colonization of India, when no viceroy could visit a maharaja’s palace without a hunt in the local forest. Even today, the Asiatic lion still ranks among the rarest of the large feline predators, rarer even than its neighbor to the north, the snow leopard, which is so scarce that a glimpse of one padding down a jagged Himalayan crag is said to consummate a spiritual pilgrimage.
I did my best to put the lions, which have recently expanded to Girnar’s forests, out of my mind as I passed small huts and tents in the dark, at the trail’s base. Daylight brought langur monkeys onto the trailside boulders. One watched a vendor set up his stall to offer food and water to passing Jain pilgrims. The monkey waited until the man’s back was turned, at which point he scampered in to grab a banana. In Gir National Park, I’d seen deer using these monkeys as a treetop surveillance system. The monkeys sat high in the trees, keeping watch for leopards and lions, which blend into the woodland’s pre-monsoon palette of amber and gold. Monkeys that spotted a stalking cat let out a specific call. Deer weren’t the only ones that recognized and used these calls; the lion tracker who had been with me in the park did too.
On the hike up Girnar, barefoot women kept passing me, wearing iridescent saris in bright shades of orange, green, or pink. Their delicate silver anklets tinkled as they went. When I reached a trail marker that said I was still 1,000 steps from the temple, I removed my pack and hopped up onto a wall, letting my legs dangle.
Two switchbacks below, an aged Jain monk in a white robe was struggling up the steps. He looked lonely, and seemed to be having trouble breathing. When Jain monks and nuns renounce worldly life, they sever all family ties. They embrace their children one last time, and vow never to see them again, unless chance brings them together on the rural back roads where the monks and nuns wander for the rest of their lives, carrying all their possessions on their back.
The monk and I had the trail to ourselves for a moment. All was silent but for a buzzing sound that I traced to a spindly black wasp bobbing above a dense clump of bougainvillea. The last ancestor this wasp and I shared likely lived more than 700 million years ago. The insect’s appearance reinforced this sense of evolutionary remoteness. The elongated shape and micro-tiled matte finish of its eyes made it seem too alien to be conscious. But appearances can deceive: some wasps are thought to have evolved large eyes to observe social cues, and members of certain wasp species can learn the facial features of individual colony members.
Wasps, like bees and ants, are hymenopterans, an order of animals that displays strikingly sophisticated behaviors. Ants build body-to-body bridges that allow whole colonies to cross gaps in their terrain. Lab-bound honeybees can learn to recognize abstract concepts, including “similar to,” “different from,” and “zero.” Honeybees also learn from one another. If one picks up a novel nectar-extraction technique, surrounding bees may mimic the behavior, causing it to cascade across the colony, or even through generations.
In one experiment, honeybees were attracted to a boat at the center of a lake, which scientists had stocked with sugar water. When the bees flew back to the hive, they communicated the boat’s location with waggle dances. The hive’s other bees would usually set out immediately for a newly revealed nectar lode. But in this case, they stayed put, as though they’d consulted a mental map and dismissed the possibility of flowers in the middle of a lake. Other scientists were not able to replicate this result, but different experiments suggest that bees are capable of consulting a mental map in this way.
Andrew Barron, a neuroscientist from Macquarie University, in Australia, has spent the past decade identifying fine neural structures in honeybee brains. He thinks structures in the bee brain integrate spatial information in a way that is analogous to processes in the human midbrain. That may sound surprising, given that the honeybee brain contains only 1 million neurons to our brains’ 85 billion, but artificial-intelligence research tells us that complex tasks can sometimes be executed by relatively simple neuronal circuits. Fruit flies have only 250,000 neurons, and they too display complex behaviors. In lab experiments, when faced with dim mating prospects, some seek out alcohol, the consciousness-altering substance that’s available to them in nature in broken-open, fermenting fruit.
Many invertebrate lineages never developed anything beyond a rudimentary nervous system, a network of neurons dispersed evenly through a wormlike form. But more than half a billion years ago, natural selection began to shape other squirming blobs into arthropods with distinct appendages and newly specialized sensory organs, which they used to achieve liberation from a drifting life of stimulus and response.
The first animals to direct themselves through three-dimensional space would have encountered a new set of problems whose solution may have been the evolution of consciousness. Take the black wasp. As it hovered above the bougainvillea’s tissue-thin petals, a great deal of information—sunlight, sound vibrations, floral scents—rushed into its fibrous exoskull. But these information streams arrived in its brain at different times. To form an accurate and continuous account of the external world, the wasp needed to sync these signals. And it needed to correct any errors introduced by its own movements, a difficult trick given that some of its sensors are mounted on body parts that are themselves mobile, not least its swiveling head.
The neuroscientist Björn Merker has suggested that early animal brains solved these problems by generating an internal model of the world, with an avatar of the body at its center. Merker says that consciousness is just the multisensory view from inside this model. The syncing processes and the jangle and noise from our mobile bodies are all missing from this conscious view—some invisible, algorithmic Stanley Kubrick seems to edit them out. Nor do we experience the mechanisms that convert our desires into movements. When I wished to begin hiking up the mountain again, I would simply set off, without thinking about the individual muscle contractions that each step required. When a wasp flies, it is probably not aware of its every wing beat. It may simply will itself through space.
If one of the wasp’s aquatic ancestors experienced Earth’s first embryonic consciousness, it would have been nothing like our own consciousness. It may have been colorless and barren of sharply defined objects. It may have been episodic, flickering on in some situations and off in others. It may have been a murkily sensed perimeter of binary feelings, a bubble of good and bad experienced by something central and unitary. To those of us who have seen stars shining on the far side of the cosmos, this existence would be claustrophobic to a degree that is scarcely imaginable. But that doesn’t mean it wasn’t conscious.
* * *
When the monk arrived at the wall where I was resting, the wasp flew away, rising up toward the sun until I lost it in the light. The monk was wearing a white mask like those that some Jains wear to avoid inhaling insects and other tiny creatures. I nodded to him as he passed, and lay back against the warm stone of the mountain.
The monk was a white dot some six switchbacks up by
the time I hopped off the wall and continued the climb, my legs stiffened by the break. I reached the entrance to the temple complex with only fifteen minutes to spare. Its marble courtyard shone brilliant white, as though bleached by the mountain sun.
Ducking under a row of elegant golden medallions, I entered the temple’s interior chamber, where dozens of candles flickered in intricately carved wall niches, and on platforms that hung from the ceiling on chains. The stone ceiling was carved into a lotus flower, its delicate unfurling petals symbolizing the emergence of a pure, ethereal soul from the Earth’s muddy materials.
Forty Jains were sitting on the floor in neat rows, their legs crossed in the lotus position. The women wore fresh saris they’d carried up the mountain for the occasion. The men were dressed in all white. I wedged into a spot in the back.
We faced a dark, tunnel-like space lined by two sets of columns. At the far end, candlelight illuminated a black marble statue of a seated male figure. Its barrel chest was inlaid with gemstones, as were its eyes, which appeared to float, serenely, in the dark space, inducing a hypnotic effect, broken only when the man sitting next to me tugged my shirt. “Neminath,” he said, nodding toward the statue.
It was here on this mountain that Neminath is said to have achieved a state of total, unimpeded consciousness, with perceptual access to the entire universe, including every kind of animal mind. Jains believe that humans are special because, in our natural state, we are nearest to this experience of enlightenment. Among Earth’s creatures, no other finds it so easy to see into the consciousness of a fellow being.