by Hope Jahren
Now, in the lurching cabin of the power boat, Genz worried about whether Kelen knew what he was doing. Because Kelen was not a ri-meto, social mores forced him to insist that he was not navigating but kajjidede, or guessing. The sea was so rough tonight, Genz thought, that even for Joel, picking out a route would be like trying to hear a whisper in a gale. A voyage with this level of navigational difficulty had never been undertaken by anyone who was not a ri-meto or taking his test to become one. Genz steeled himself for the possibility that he might have to intervene for safety’s sake, even if this was the best chance that he and his colleagues might ever get to unravel the scientific mysteries of wave piloting—and Kelen’s best chance to rally support for preserving it. Organizing this trip had cost $72,000 in research grants, a fortune in the Marshalls.
The radio crackled. “Jebro, Jebro, this is Jitdam,” Kelen said. “Do you copy? Over.”
Genz swallowed. The cabin’s confines, together with the boat’s diesel odors, did nothing to allay his motion sickness. “Copy that,” he said. “Do you know where you are?”
Though mankind has managed to navigate itself across the globe and into outer space, it has done so in defiance of our innate way-finding capacities (not to mention survival instincts), which are still those of forest-dwelling homebodies. Other species use far more sophisticated cognitive methods to orient themselves. Dung beetles follow the Milky Way; the Cataglyphis desert ant dead-reckons by counting its paces; monarch butterflies, on their thousand-mile, multigenerational flight from Mexico to the Rocky Mountains, calculate due north using the position of the sun, which requires accounting for the time of day, the day of the year, and latitude; honeybees, newts, spiny lobsters, sea turtles, and many others read magnetic fields. Last year the fact of a “magnetic sense” was confirmed when Russian scientists put reed warblers in a cage that simulated different magnetic locations and found that the warblers always tried to fly “home” relative to whatever the programmed coordinates were. Precisely how the warblers detected these coordinates remains unclear. As does, for another example, the uncanny capacity of godwits to hatch from their eggs in Alaska and alone, without ever stopping, take off for French Polynesia. Clearly they and other long-distance migrants inherit a mental map and the ability to constantly recalibrate it. What it looks like in their mind’s eye, however, and how it is maintained day and night, across thousands of miles, is still a mystery.
Efforts to scientifically deduce the neurological underpinnings of navigational abilities in humans and other species arguably began in 1948. An American psychologist named Edward Tolman made the heretical assertion that rats, until then regarded as mere slaves to behavioral reinforcement or punishment, create “cognitive maps” of their habitat. Tolman let rats accustom themselves to a maze with food at the end; then, leaving the food in the same spot, he rearranged the walls to introduce shortcuts—which the rodents took to reach the reward. This suggested that their sampling of various routes had given them a picture of the maze as a whole. Tolman hypothesized that humans have cognitive maps too, and that they are not just spatial but social. “Broad cognitive maps,” he posited, lead to empathy, while narrow ones lead to “dangerous hates of outsiders,” ranging from “discrimination against minorities to world conflagrations.” Indeed, anthropologists today, especially those working in the Western Pacific, are increasingly aware of the potential ways in which people’s physical environment—and how they habitually move through it—may shape their social relationships and how those ties may in turn influence their orienteering.
The cognitive map is now understood to have its own physical location, as a collection of electrochemical firings in the brain. In 1971, John O’Keefe, a neuroscientist at University College London, and a colleague reported that it had been pinpointed in the limbic system, an evolutionarily primitive region largely responsible for our emotional lives—specifically, within the hippocampus, an area where memories form. When O’Keefe implanted electrodes in rats’ hippocampuses and measured their neural activity as they traveled through a maze, he detected “place cells” firing to mark their positions. In 1984, James B. Ranck Jr., a physiologist at the State University of New York, identified cells in an adjacent part of the brain that became active depending on the direction a rat’s head was pointing—here was a kind of compass. And in 2005, building on these discoveries, Edvard and May-Britt Moser, neuroscientists at the Kavli Institute for Systems Neuroscience in Norway, found that our brains overlay our surroundings with a pattern of triangles. Anytime we reach an apex of one, a “grid cell” in an area of the brain in constant dialogue with the hippocampus delineates our position relative to the rest of the matrix. In 2014, O’Keefe and the Mosers shared a Nobel Prize for their discoveries of this “inner GPS” that constantly and subconsciously computes location.
The discovery that human orientation takes place in memory’s seat—researchers have long known that damage to the hippocampus can cause amnesia—has raised the tantalizing prospect of a link between the two. In the late 1990s, Eleanor Maguire, a neuroscientist at University College London, began studying London taxi drivers, who must memorize the city’s complex layout to obtain a license. Eventually she showed that when cabbies frequently access and revise their cognitive map, parts of their hippocampuses become larger; when they retire, those parts shrink. By contrast, following a sequence of directional instructions, as we do when using GPS, does not activate the hippocampus at all, according to work done by Veronique Bohbot, a cognitive neuroscientist at McGill University.
Bohbot and others are now trying to determine what effect, if any, the repeated bypassing of this region of the brain might be having on us. The hippocampus is one of the first areas disrupted by Alzheimer’s disease, an early symptom of which is disorientation; shrinkage in the hippocampus and neighboring regions appears to increase the risk of depression, schizophrenia, and post-traumatic stress disorder. On the other hand, the taxi drivers who exercised their hippocampuses so much that parts of them changed size were worse at other memory tasks—and their performance on those improved after they retired. Few of us spend all day every day navigating, however, as cabbies do, and Maguire doubts that our GPS use is extreme enough to transform our gray matter.
What seems clear is that our ability to navigate is inextricably tied not just to our ability to remember the past but also to learning, decision-making, imagining, and planning for the future. And though our sense of direction often feels innate, it may develop—and perhaps be modified—in a region of the brain called the retrosplenial cortex, next to the hippocampus, which becomes active when we investigate and judge the permanence of landmarks. In 2012, Maguire and coauthors published their finding that an accurate understanding of whether a landmark is likely to stay put separates good navigators from poor ones, who are as apt to take cues from an idling delivery truck as a church steeple. The retrosplenial cortex passes our decisions about the stability of objects to the hippocampus, where their influence on way-finding intersects with other basic cognitive skills that, like memory, are as crucial to identity as to survival.
Recently Maguire and colleagues proposed a new unified theory of the hippocampus, imagining it not as a repository for disparate memories and directions but as a constructor of scenes that incorporate both. (Try to recall a moment from your past or picture a future one without visualizing yourself in the physical space where that moment happens.) Edvard and May-Britt Moser have similarly hypothesized that our ability to time-travel mentally evolved directly from our ability to travel in the physical world, and that the mental processes that make navigation possible are also the ones that allow us to tell a story. “In the same way that an infinite number of paths can connect the origin and endpoint of a journey,” Edvard Moser and another coauthor wrote in a 2013 paper, “a recalled story can be told in many ways, connecting the beginning and the end through innumerable variations.”
Disorientation is always stressful, and before modern civilization
it was often a death sentence. Sometimes it still is. But recent studies have shown that people who use GPS, when given a pen and paper, draw less precise maps of the areas they travel through and remember fewer details about the landmarks they pass; paradoxically, this seems to be because they make fewer mistakes getting to where they’re going. Being lost—assuming, of course, that you are eventually found—has one obvious benefit: the chance to learn about the wider world and reframe your perspective. From that standpoint, the greatest threat posed by GPS might be that we never do not know exactly where we are.
Genz took his thumb off the radio receiver’s talk button and waited for Kelen’s reply. He could make out on deck John Huth, a Harvard physicist and member of the international team that discovered the Higgs boson particle, vomiting volubly off the port side. The last time Genz checked, Gerbrant van Vledder, an oceanographer at Delft University in the Netherlands, one of the world’s foremost institutions for wave modeling, was huddled miserably behind the abandoned galley, where a lone cabbage thudded against the walls of the sink. Compounding their digestive distress, a booby, ignoring the limitations of its webbed feet, had crash-landed on the deck, barring the men’s access to the head. Sometimes Genz felt that all his decade of research on wave piloting had taught him was that he could never hope to predict what might go wrong next.
Genz met Alson Kelen and Korent Joel in Majuro in 2005, when Genz was 28. A soft-spoken, freckled Wisconsinite and former Peace Corps volunteer who grew up sailing with his father, Genz was then studying for a doctorate in anthropology at the University of Hawaii. His adviser there, Ben Finney, was an anthropologist who helped lead the voyage of Hokulea, a replica Polynesian sailing canoe, from Hawaii to Tahiti and back in 1976; the success of the trip, which involved no modern instrumentation and was meant to prove the efficacy of indigenous ships and navigational methods, stirred a resurgence of native Hawaiian language, music, hula, and crafts. Joel and Kelen dreamed of a similar revival for Marshallese sailing—the only way, they figured, for wave piloting to endure—and contacted Finney for guidance. But Finney was nearing retirement, so he suggested that Genz go in his stead. With their chief’s blessing, Joel and Kelen offered Genz rare access, with one provision: he would not learn wave piloting himself; he would simply document Kelen’s training.
Joel immediately asked Genz to bring scientists to the Marshalls who could help Joel understand the mechanics of the waves he knew only by feel—especially one called di lep, or backbone, the foundation of wave piloting, which (in ri-meto lore) ran between atolls like a road. Joel’s grandfather had taught him to feel the di lep at the Rongelap reef: he would lie on his back in a canoe, blindfolded, while the old man dragged him around the coral, letting him experience how it changed the movement of the waves.
But when Joel took Genz out in the Pacific on borrowed yachts and told him they were encountering the di lep, he couldn’t feel it. Kelen said he couldn’t either. When oceanographers from the University of Hawaii came to look for it, their equipment failed to detect it. The idea of a wave-road between islands, they told Genz, made no sense.
Privately Genz began to fear that the di lep was imaginary, that wave piloting was already extinct. On one research trip in 2006, when Korent Joel went below deck to take a nap, Genz changed the yacht’s course. When Joel awoke, Genz kept him away from the GPS device, and to the relief of them both, Joel directed the boat toward land. Later he also passed his ri-meto test, judged by his chief, with Genz and Kelen crewing.
Worlds away, Huth, a worrier by nature, had become convinced that preserving mankind’s ability to way-find without technology was not just an abstract mental exercise but also a matter of life and death. In 2003, while kayaking alone in Nantucket Sound, fog descended, and Huth—spring-loaded and boyish, with a near-photographic memory—found his way home using local landmarks, the wind, and the direction of the swells. Later he learned that two young undergraduates, out paddling in the same fog, had become disoriented and drowned. This prompted him to begin teaching a class on primitive navigation techniques. When Huth met Genz at an academic conference in 2012 and described the methodology of his search for the Higgs boson and dark energy—subtracting dominant wave signals from a field until a much subtler signal appears underneath—Genz told him about the di lep, and it captured Huth’s imagination. If it was real, and if it really ran back and forth between islands, its behavior was unknown to physics and would require a supercomputer to model. That a person might be able to sense it bodily amid the cacophony generated by other ocean phenomena was astonishing.
Huth began creating possible di lep simulations in his free time and recruited van Vledder’s help. Initially the most puzzling detail of Genz’s translation of Joel’s description was his claim that the di lep connected each atoll and island to all 33 others. That would yield 561 paths, far too many for even the most adept wave pilot to memorize. Most of what we know about ocean waves and currents—including what will happen to coastlines as climate change leads to higher sea levels (of special concern to the low-lying Netherlands and Marshall Islands)—comes from models that use global wind and bathymetry data to simulate what wave patterns probably look like at a given place and time. Our understanding of wave mechanics, on which those models are based, is wildly incomplete. To improve them, experts must constantly check their assumptions with measurements and observations. Perhaps, Huth and van Vledder thought, there were di leps in every ocean, invisible roads that no one was seeing because they didn’t know to look.
Early last year Genz and Kelen, grants in hand, saw a chance to show Huth and van Vledder the di lep. Kelen is the director of Waan Aelõñ in Majel, or Canoes of the Marshall Islands, a nonprofit organization that teaches students to build canoes using traditional methods and modern materials. If the students hurried, the first sailing canoe to be built in the Marshalls in decades—the Jitdam Kapeel, which can be roughly translated as “the sharing of knowledge”—could be ready by summer’s sailing season. Kelen’s goal is for his students to build, staff, and maintain a fleet that will transport goods and passengers between atolls and islets without using fossil fuels. Despite the expectation that the Marshalls will be one of the first countries to disappear beneath rising seas, Kelen envisions a renaissance of sailing: a means for his students to reclaim their heritage while creating jobs that don’t contribute to their own destruction.
Huth and van Vledder bought plane tickets to Majuro while Genz and Kelen made arrangements for the journey. At the last minute Joel’s leg became infected, and Kelen offered to pilot in his place. The scientists embraced this new plan: talking with Joel before and after, they figured, would be almost as useful as having him onboard.
Soon after arriving they visited him at home, where he was confined to bed, and eagerly showed him their maps and simulations while posing detailed queries about various properties of the di lep. Although this was the scientific investigation Joel had been pushing for, he seemed reluctant to respond. He asked Huth and van Vledder if they believed in the di lep; they still weren’t sure, they replied. Holding a rudimentary map that Huth had made of wave frequencies between Majuro and Aur, the captain traced a shaded region with his finger. “Di lep here,” he said.
The next afternoon Kelen and his five-man crew set out for Aur. A breeze rattled the palms, blowing the Jitdam past a fleet of slumbering cargo ships anchored in the lagoon. The power boat Jebro puttered in pursuit. At the mouth of the opening between islets into the Pacific, the setting sun threw a flickering train on the water. “Now we get the truth,” Huth cried, thrusting a sextant toward the sky. “The moment of reckoning!”
Twelve hours later Huth was seasick, bent over the deck rail, to which he had bound himself with a harness and tether. “If anyone said the di lep was subtle, they were wrong,” he said, wiping his mouth. Nevertheless, he was doggedly recording on the hour the boat’s GPS coordinates, the wind speed and direction, and his observations of the waves in a waterproof notebook. Th
is data would allow him to map the journey with wind and wave details at each coordinate; van Vledder could later add wind data collected by satellite and local bathymetry, using programs written at Delft, to create a computer model of the seas they were currently in.
In the cabin Genz heard Kelen’s voice on the radio again. Kelen could see the lights of the Jebro behind him, he said, and he thought they were about 10 miles east of Aur. Because they were approaching its reef too fast, his plan was to overshoot it, then look for it to his west after sunrise. Genz glanced at the boat’s GPS device and realized that Kelen, over the last decade, might have learned more than he had ever let on. He wanted to shout congratulations.
“Copy that,” he said instead.
The sky grew lighter, revealing more sky, a flock of seabirds fishing, and finally, far ahead, the canoe, battered but intact, struggling to head downwind. After getting a brief tow from the Jebro, it reached Aur under its own power. An empty beach came into view, then children running on it. “This is feeling like an adventurer,” van Vledder said. “Coming to a new place, and people out to welcome you.”
The entire village was waiting in a palm-frond-thatched pavilion, having been alerted by ham radio. A woman put leis around the necks of the sailors and scientists as they entered. The community had piled a long table with lobster, fish, breadfruit, plantains, and rice balls with coconut. The acting chief of the island made a speech. He said the local children had never seen a sailing canoe before. The islanders wanted to learn to build them again; they had only one motorboat, and gasoline there cost more per gallon than most of them made in a month of selling fish and handicrafts in Majuro.
