“You must make your heart hard,” the sailor says.

We are steaming to Arabia on a vessel the length of a soccer pitch.

The ship is packed with nearly 9,000 souls—8,000 sheep, 855 camels and 24 human beings. (The roster of the latter species: 20 crew, three veterinarians, one passenger.) The sailor seems unnerved, ashamed, embarrassed. He is worried about how his job is perceived. It is his ship’s humble merchandise: live animals that must endure the sweltering crossing of the Red Sea. Sheep bleat in metal pens on the upper decks. The lumbering camels mill far below, their necks swaying in the semidarkness of the ship’s hold like trees in a strange subterranean forest. We are an anti-ark. The animals are bound for slaughter in the Middle East. But the sensitive sailor protests too much. He is young. He doesn’t seem to understand that we hardened our hearts from the very start—long before our ancestors first crossed the Red Sea 60,000 years ago, abandoning Africa, eating their way across the world. What was eaten is gone. Today we haul our tamed food with us.

The Motor Vessel Abuyasser II: my gritty ticket out of Africa.

Photograph by Paul Salopek

Flagged to Freetown, Sierra Leone. Built in Italy in 1978. (The bridge’s engine controls still read like opera: Adagio, Mezza, Tutto, Finito.) Originally, a transporter of vehicles. Back in Djibouti, the stevedores had hazed livestock up the ship’s car ramp after midnight, under the flaming orange port lamps. (The silence of this operation, the complete noiseless pad of soft camel feet on corrugated steel, was like a hallucination.) Bound for Jeddah, Saudi Arabia, we will now rock at sea for three days. We are a floating barnyard. We trail bits of straw in our wake. The ship’s officers are Syrian. This only increases our cargo of pathos.

“Why kill the children?” Captain Abdulla Ali Nejem says. “Why kill the mans? Why kill the womans? Why? The fattoria? ‘Stroyed! The streets? ‘Stroyed! The hospital? ‘Stroyed! The school? ‘Stroyed! My country? ‘Stroyed! All ‘stroyed! Syria—finished! Finished!”

War has obliterated the brightly lit but dated images of a homeland inside Nejem’s mind, which is all the country that mariners own. He sits cross-legged like a swami on the bridge, an aging descendant of Phoenician traders, peeling small tart oranges with a pocketknife. He is a friendly and emphatic man. When he repeats himself in triplicate it is not an opinion rendered. No: it is a law of the universe expounded. Captain Abdullah repeats himself often because there are many such laws. (The universe is a complicated place.) This one is the false seductions of technology:

“Everything electronic! Everything electronic! Ev-very-thing electronic! By hand! Do by hand! Do by hand! Better! Better! Better!” 

Nejem shows me his old-fashioned sextant. It gleams like a gold nugget in a teakwood box lined with green baize. He once steered a freighter all the way to India and back using this beautiful mechanical instrument. But when I climb to the bridge later that night, I spot an iPhone glowing on the ship’s console. Nejem is using a GPS app to help him bump north through the waves. In the pale blue light of the phone, I glimpse his face, crumpled inward in sadness.

There is a lot of this—absentness, escapism—aboard the Abuyasser II. The chief engineer sits before his laptop for hours, chain-smoking, eyes closed, listening to birdsongs downloaded from the Internet. The first officer stands at the helm, sipping tea, gazing empty-eyed at the slate-blue horizons.

Photograph by Paul Salopek

This mood of wistfulness is infectious. I peer backward, watching Africa recede astern: a chalky line, a white disc seen on edge, a pale host that melts away on the tongue of the ocean. With every olive eaten at mess, we pull closer to Arabia. The porthole to my cabin looks back.  The tiny chamber is a surprise. An officer has surrendered it to me for the duration of the voyage. It is decorated with red Christmas tree bulbs. They dangle on strings from the ceiling. A large stuffed heart swings above the narrow bed. Love motel decor. Yet there is little love aboard a camel boat, except perhaps self-love.

Photograph by Paul Salopek

We chug past the Bab-el-Mandeb—the narrow Strait of Grief between Africa and Arabia. I watch straw fly in our wake. Another name for this bottleneck into the Red Sea is the Strait of Tears.

"The Red Sea"—Captain Abdullah declares—"is saltier than the Mediterranean."

Of course it is. Of course it is. Of course it is.

The sea is black. But the shore glows with orange light: a port on fire.

Yet it is not open flames. It is the cold radiance of the of sodium-vapor dock lamps, the glare of a ceaseless 24-hour exchange: of commerce, of global barter, of the tireless labor needed to move vast heaps of humanity’s goods across the oceans on massive ships made of steel—ships that are many city blocks long, as high as tall buildings, bursting with every product, necessity, luxury, tool, medicine, and weapon employed by humankind at the turn of the millennium. It is the fire our species’ mind and will. I stare at it, trying to imagine this African port—a minor entrepôt on the Red Sea—as it will look 10,000 years from now, after the next Ice Age: a lens of concrete, steel, and glass crushed between geological strata. A future archaeologist exploring Africa’s Rift Valley will stumble across a jackpot here; his core sample will reveal shards of all we once dreamed we owned.

“It’s never dark here,” my friend Saleh Mohamed Ali says. “It’s always bright as midday.”

We are bracing ourselves on the foredeck of a tugboat that bumps across the waves of Djibouti harbor.

Saleh is a ship insurer, a patient negotiator who must solve all the problems of the maritime world. We are chugging out to a Chinese-flagged cargo vessel that has called for help. They’re carrying unwelcome human cargo: African stowaways, three young men from Ghana. Maritime law prohibits captains from forcibly discharging such migrants on land against their wishes. So the ship has been shuttling the Ghanaians across the globe for eight months. No country—on a voyage stretching from the west coast of Africa to Brazil, through the Mediterranean, all way to the Philippines—will have them. But tonight, Djibouti will allow the Ghanaians to disembark. It will permit them to fly home. Saleh’s insurance company will pay for their air tickets.

“I get stowaways about once a month,” Saleh says, smiling the rueful smile of a man who has seen all. “I feel sorry for them, I pity them, but they cost my company a lot of money.”

He tells me the story of a stowaway who changed his mind at the airport. The man did not wish to be flown home to Somalia. He stripped himself naked on the jetway. He began to dance, to bark and wail. The alarmed flight crew refused to allow him on board. A stalemate. The man had no papers, no identity documents. Saleh hired him to be his gardener.  

Scaling a cargo ship’s 40-foot Jacob’s ladder at sea is all in a day’s work for ship insurers taking custody of stowaways. Photograph by Paul Salopek

The tugboat throttles back. We board the ship, the MV POS ISLAND, via a swaying, 40-foot-high rope ladder. This is all in a night’s work for middle-aged Saleh. The South Korean captain is eager to rid himself of his guests. He summons the stowaways to his fluorescent-lit quarters: three subdued men dressed in clothes that haven’t been washed in a very long time. They have spent months locked inside a cabin. They squat on their haunches against a bulkhead. One wears a single shoe. Do they want to go home? Saleh asks them gently, in a fatherly way. Yes, they reply glumly. They will abandon their hope of work in Europe. They will return to their steamy fishing village in Ghana. “Take me off this boat!” one cries.

I look into their tired, yellowed eyes. I am seeking out a connection. My journey, too, has been dry-docked. I have been stranded for weeks in Djibouti.

Two countries along my onward route—Eritrea and Sudan—have not replied to visa requests. Yemen is in turmoil. There are bombings in Sanaa, and the country’s beautiful Tehama coast is too dangerous to traverse on foot. Saudi Arabia has generously invited me to walk its western shoreline, north toward that ancient crossroad of human migration, the Middle East. But few vessels now risk taking passengers across the southern Red Sea. It is the fear of Somali pirates. The big steel ships, the moving warehouses of civilization, now steam in sealed convoys through the Bab el Mandeb, the Strait of Grief.

And so I wait: a stowaway marooned in Djibouti.

I pass hours in drowsy embassy foyers. I sit with Saleh in his small, glass-walled office. We sip tea, discussing ships, dhows, freighters, planning schemes, weighing possibilities. His phone rings constantly. All the world’s commerce pours into his ear. Complaints. Crises. Excuses. Pleas. Favors. He absorbs it all nodding, the mild wizard behind the curtain in this hard-bitten Oz. And then: the call to remove stowaways. He sighs. There must be hundreds, perhaps thousands of them, he says.

All the world is on the move.

The UN calculates that a record 215 million people now live outside their country of origin. An additional 700 million are adrift within the borders of their own nations. This represents a seventh of the global population. It is part of the greatest diaspora in human history, a hegira from country to country, from city to city, from empty belly to mouthful of bread. It is our species’ oldest trajectory. Only the colossal scale is new.

Africa swarms with these tattered ramblers, with the hand-to-mouth armies of the displaced, the unemployed. There are millions walking the desert trails, milling in slums, sleeping the sleep of the dead atop stained cardboard at the entrance to Djibouti port. If you believe their dire travels will not reach you, you are wrong. They already swarm around your oil pipelines. They scour the booming farms, toiling, at two dollars a day, picking your flowers and fruit. They scale the anchor chains of your hulking ships at night. They are coming to a street corner near you. In Africa, they help each other live. They share burdens out of all proportion to their means, because nobody else will. I have been the undeserved beneficiary of such grace: the crumb of bread held up in the desert, the bleak joke shared on the waterless path, the calloused hand pulling me to the safety of a border slum shack, to sleep beyond the reach of growling drunks. Beached in Djibouti, I am already missing this bruising solidarity of the road.

Two ship guards—a Welshman and an Australian hired to fend off pirates—march the three Ghanaians off the Chinese boat. 

“They gave me a bit of trouble at the airport,” Saleh tells me the next day. He smiles his melancholy smile.

Three Ghanian stowaways head home after their arrest in Djibouti. Photograph by Paul Salopek

The stowaways suddenly demanded new shoes, he says, new travel bags, toiletries, and $1,000 in pocket money. They knew they had Saleh cornered. Djibouti didn’t want them. Ghana was not lobbying for their return. In the end, Saleh gave them $150 each and belted them into the plane.

“It is hard.” Saleh waves his hands over his cluttered desk, over the ships’ manifests sprinkled with invisible human beings of no commercial value. “What can you do? Eh? You tell me. What can you do?”

Flash floods have marooned his vehicles in hip-deep pools of mud. Grazing wars between nomads have blocked access to promising fossil beds. And campfire visits by snakes and tarantulas are so routine they rank as minor nuisances.

Yet nothing has stymied White’s pursuit of knowledge—or thwarted his scientific ambitions—like the hard-eyed men in flip-flop sandals who, valuing doubloons above Darwin, set sail hundreds of miles away in skiffs stocked with machine guns and rope ladders: Somali pirates.

Read the full story on National Geographic News

Houssain Mohamed Houssian, the Afar guide, leads the way, singing as usual.

We cross our first pavement in eight days. It is the Yugoslav-built road from the capital, Djibouti city, to the remote desert outposts of the north—Sagallou, Tadjourah, Obock. A car flashes past. Pale faces, possibly French sailors on shore leave, glance back through dusty glass. We coax our two weary camels over the fiery tarmac, across a field of basalt cobbles, onto a shingle beach. The instant Houssain toes the surf, he falls silent. He stops singing. A sweltering day of walking still lies ahead of us. But I will never hear him chant a caravan song again.

This is no random coastline.

From sand to seawater.  Photograph by Paul Salopek

At least 60,000 year ago, somewhere along this scribbled line of flotsam that stretches north to the Bab-el-Mandeb—the pinched “strait of grief” dividing Africa and Arabia—hardy bands of anatomically modern humans first began to walk out of Africa in earnest. Sea levels were 200 feet lower then. Ghostly archipelagos that lurk under the salt waves today provided these early wanderers the necessary stepping-stones to abandon the mother continent. Scientists tell us they coasted north and east, scavenging seafood along the margins of present-day Yemen and Saudi Arabia, all the way into East Asia.

Some human wayfarers branched off northwest to the Middle East and Europe. Still others paddled, somehow, to distant Australia. And the most dogged, the hungriest, the bitter-enders, continued trudging north and east for a thousand generations more, spanning the course of 20,000 additional years, over vanished grasslands, advancing perhaps a mile a generation under the fluid rose and emerald sheets of the auroras, north into Beringia, into the New World.

. . . for a transitory enchanted moment man must have held his breath in the presence of this continent, compelled into an aesthetic contemplation he neither understood nor desired, face to face for the last time in history with something commensurate to his capacity for wonder.

This is F. Scott Fitzgerald imagining what currents must have stirred Dutch sailors’ hearts as they tacked their reeking ships up the waters of the Hudson for the very first time, just four centuries ago.

Unlacing my boots beside our kneeling camels, I squint out across the silver bar of the Red Sea toward invisible Arabia. I try to relive that moment when the entire planet beckoned to us from this spot, this ocean door, almost 3,000 lifetimes ago. We were fully human then. Our nearest prehuman ancestors, the Neanderthals, had stood on similar beaches for hundreds of thousands of years and had not ventured to cross open waters.

Tea by the Red Sea. Modaita, the yawning camel, is unimpressed. Photograph by Paul Salopek

“It’s only fully modern humans who start this thing of venturing out on the ocean where you don’t see land,” the geneticist Svante Päabo told The New Yorker. “Part of that is technology, of course; you have to have ships to do it. But there is also, I like to think or say, some madness there. You know? How many people must have sailed out and vanished on the Pacific before you found Easter Island? I mean, it’s ridiculous. And why do you do that? Is it for the glory? For immortality? For curiosity? And now we go to Mars. We never stop.”

It is the 43^rd day of walking up the Great Rift Valley from the Afar encampment of Herto Bouri, Ethiopia, the starting point of this journey. I have covered perhaps 400 miles. Seven years of walking still lie ahead.

Houssain fetches the thermos of tea from the saddlebags of Modaita, our big, randy bull camel. The shot glasses, sticky with sugar. A last, hoarded sack of dates. The cameleers, Ibrahim Hagaita and Mohamed Youssef, both reliable men, chew in silence. When we speak, it is in loud, hoarse tones, the way people do by the surf. I sit, cross-legged on a cushion of wet pebbles, rubbing my feet, my numb toes. And I watch the green waves spin their thread of foam at the flank of a continent I have called home, off and on, for more than 10 years. I am leaving Africa.

The sea is a loom of time, ceaselessly knitting past to future.

Its waves roll in like a weaver’s shuttle . . . pushing westward, toward inland memory, back to the apricot dawns of the Danakil, to the laughing old Afar woman who dippered her scarce and brackish well water for us to drink, to the light-headed days of hunger, the days of pure horizon-eyed freedom, to the mummified bodies of the migrant dead, to the campfires where Alema the caravan boss exclaimed, with something like joy, No gun! No rock! No torch! I must throw my American shoes at the hyenas!

And they pull away . . . eastward toward Yemen and the Tehama Coast, toward fields of rhododendrons in the valleys of the Himalaya, toward ice, toward sunrise, toward the hearts of unknown people.

There is no sleep—at least not for outsiders, not for dusty wayfarers like us. No refuge. No relaxation. No peace. No rest. It is the wind.

The heavy oceanic air gushes ceaselessly inland from the Red Sea—we can smell the salt!—sucked westward into the heart of the desert, into Africa, by the hot, dry bowl of Lac Assal, the lowest point on the continent. A trick of physics has turned this mountain pass into a perfect wind tunnel. It makes the lapels on my shirt whir like helicopter blades. And the tottering village of Leita—erected here of rusty scraps of corrugated metal, of odds and ends pried from an abandoned salt works—sounds as if it is rolling sideways across the land. Every tied-down, wired-together, rock-weighted shack rattles, bangs, squeaks, gongs, pings, taps, clangs, and scrapes. Constantly. A nerve-wracking rumpus. A 24-hour din.

No need for mothers and fathers to mask their intimate nights in Leita. Even in the tiniest hut packed with children, the incessant cymbals of wind and metal will drown the loudest cry of passion. The offspring of these noisy couplings must grow up half deaf. They must learn from birth to read lips. If the wind ever stopped in Leita, the 3,000 inhabitants of this poor, forgotten, cacophonous outpost—a village of windward-leaning, unemployed salt miners—will face a crisis. They will run about in amazed circles, wide-eyed, clapping the sides of their heads.

For the first time in their lives, they will hear their own voices clearly.

They will listen to the beating of their own hearts.

Silence will terrify them.

It does not look like any brewery I have ever seen before: a small oasis of doum palms, crawling with Afar men—lanky young boys, doddering grandfathers—who wander about, hacking at the trees with knives. An oasis of mad butchers.

The source of the brew–doum palms. Photograph by Paul Salopek

Many of the young trees are decapitated, hacked down to nubs, to stumps. Beneath the open gashes hang cups made of old plastic water bottles. These catch the palms’ nectar, which oozes out slowly, melancholically, in a frothy drool. This viscous sap will be fermented for one week with the fruit of the palm itself. The end product looks like lemonade. It tastes sweet, fizzy. Each tree will surrender perhaps five gallons.

The cut that quenches thirst–slicing doum palms to make palm wine. Photograph by Paul Salopek

Hidden in this howling wilderness: a brewery of palm wine.

“It is very nutritious, even for children,” explains my camel guide Houssain Mohamed Houssain, who buys a large bottle or six for us. “You can put it in their sorghum cereal. It’s full of vitamins. That way, they don’t get malaria. The mosquitos bite them, but they don’t get the disease!”

Cameleer Ibrahim Hagaita brings survival rations of palm wine along for the trail. Photograph by Paul Salopek

An elixir Humphrey Bogart would approve of.

By nine a.m., the thermometer pegs 90 degrees Fahrenheit (32 degrees Celsius). I begin to stew in my sweat. The Afar guides, meanwhile, shiver under shirts, sweaters, scarves. Mohamed Youssef, a cameleer, zips himself inside a “Tom Tailor” brand parka from China. The only uncomplaining one is Madoita, the lead camel. He is both warmed and shaded by a $600 blanket of photovoltaic silicon cells. He is a belching, furry, ambulatory wall plug for my satellite phone. We take turns cleaning the dust from these cells with a cloth. A new chore on an ancient caravan trail: Wiping down your solar camel.

Mohamed Youssef wards off the chilly 90-degree evenings with a parka. Photograph by Paul Salopek

It is the Djiboutian gendarmes.  They smile from their roadside guard post. They hold up their hands in a sympathetic gesture.

One of their patrols has detained us, confiscated my passport and impounded the camels A’urta and Suma’atuli. They have marched us here, to the official frontier checkpoint, for an explanation. Because we have staggered down a mountain trail, lost. Because we have blundered into the blurry no-man’s-land between Ethiopia and Djibouti. Because no battery-powered gimcrack, no alien gewgaw, no child’s toy called a GPS, was going to tell my proud Ethiopian cameleers where they stood on the face of the Earth: that we had crossed, unwittingly, into Djibouti.

But all is now smoothed over. Cleared up. Illuminated. Justified. The Djiboutians instruct us—apologetically—to return to a distant Ethiopian guard post. I must have my exit visa stamped. How far away is it? It’s at least four miles back. I will ping pong, in this way, between nations whose edges are drawn on the sand, on the wind. I slog for miles along a melting, truck-clogged road, across a phantom divide that parses nothing from nothing.

The new caravans: a mile of trucks at the Galafi border crossing to Djibouti. Photograph by Paul Salopek

Or so it seems. For borders do rule the most powerful topography on the planet: the corrugations of the human mind.

Ethiopia: ancient, sprawling, crowded, buzzing with purpose, with nationalist slogans, the top dog in the Horn of Africa. Djibouti: only 36 years old as a country, a miniscule former French colony, fewer than a million people, a sleepy afterthought on the Red Sea.

Ethiopia: The ear prickles with a babel of Amharic, Oromo, English—and 87 other minority languages. Djibouti: only French, Afar and Somali.

Ethiopia: Police stand at attention in camouflage battle fatigues, signaling a martial government forever on war footing with its nemesis, Eritrea. Djibouti: Here the uniforms, often disheveled, are gaudy blue and green with white patent-leather belts, like bandstand musicians, as befits a statelet with no enemies.

Ethiopia: The Afar nomads bestow traditional names on their camels—“Branded on the Ear,” “Traded for a Cow.” Djibouti: When I ask my new Afar camel guides, Houssain and Musa, the names of our two cargo beasts, Houssain says, “Houssain.” And Musa replies, “Musa.” Then they laugh.

My chapeau gets a long overdue washing by Houssain Mohamed Houssain–in boiling sulfur water. Delousing was included. Photograph by Paul Salopek

The Djiboutian cameleers wear knockoff Ray-Ban sunglasses and cargo pants. They are better equipped than I. They pack a stainless steel pasta strainer. The chief of the caravan, a debonair man named Houssain Mohamed Houssain, offended by my grubby hat, snatches it off my head and scrubs it in a hot spring. He carries a large black wireless telephone, like some prop from an ancient James Bond film, through the searing desert. As we walk, he shouts into it constantly. What is he talking about? “I am running for parliament,” he tells me. “I am managing my campaign.”

Guides Houssain Mohamed Houssain (Bond) and Musa Lubak (Moneypenny) share a multimedia moment in the Gagade desert. Photograph by Paul Salopek

That afternoon, nine glary miles into Djibouti, huddled under the watery blue shade of a doum palm, we break for lunch: haricots verts in mustard sauce, rice pilaf, curry sauce, boiled eggs and baguettes, coffee, and tea. For the past week I have been walking on biscuits. On noodles and water. I set aside a fork. (A fork!) Reverently, I photograph my plate. Vive la francophonie.

Photograph by Paul Salopek

Why is impatience signaled by the tapping of a toe: a gesture that telegraphs walking away— hoofing it, laying tracks, leaving, shoving off lickety-split? Why is movement the default solution of our species? What’s wrong with standing still? Why even ask such questions? Because we are restless. Because we always ask.

Berhane Asfaw, the distinguished Ethiopian paleoanthropologist, was walking in the desert of his sepia-toned country, in the Rift Valley of Africa, near the steamy banks of the Awash River. He was surveying the site of one his team’s most famous discoveries: the fossil remains of Herto man, considered by some scientists to be the oldest fully recognizable human being ever found. A thick-wristed ancestor. A maker of moderately improved stone axes. A tireless eater of hippo meat. About 160,000 years old.

“These people didn’t move around much,” Asfaw reminded me. “It was greener here back then, kind of swampy, with open woodland. They had plenty of resources, plenty of food.”

Asfaw and his two colleagues, Tim White and Giday WoldeGabriel, had invited me to this anthropologically famous spot to begin walking across the world. I was setting out that very afternoon, in fact, on a long foot journey—seven years—whose object is to recreate, step by step, the transcontinental voyage of the first modern humans who dispersed successfully out of Africa. Ancient diasporas. Human migration. Exploration. Wanderlust. Exile. These were my themes. But Herto man had predated all such woolly notions by scores of millennia. Asfaw’s point: We were African homebodies for a long while, indeed, before hitting the global trail.

Even so, faint traces of our species’ trademark antsiness glimmered at dusty Herto Bouri.

The Herto specimens—identical to us in every respect but for some minor skeletal details—were found with their skulls severed from their bodies. They had been scalped. Moreover, one cranium belonging to a child of six or seven had been polished smooth by prolonged handling. This was, to say the least, a mystery. A puzzle. Clearly, these primordial elders had been asking a few uneasy questions of their own.

“It might have been some ritual,” Asfaw said, dabbing his sweaty brow with a folded bandanna. “Maybe mortuary practices. Who knows?”

It was a boiling January afternoon in the African cradle. The sun was toxic. In the middle distance, more scientists were swimming in squiggling heat waves. They were walking across the desert in erratic circles.

All were members of the Middle Awash Project, an international group of archaeologists, geologists, and paleontologists that Asfaw helps lead. They shuffled across the barren landscape in silence, as if in a trance, their heads bowed like an austere order of mendicants, forever looking down. They planted droopy little plastic flags in the dust: blue for stone tools, yellow for bones. Some carried ice axes designed for scaling alpine peaks. Occasionally, they swung these alien implements at the scorching earth: tink . . . tink . . . tink. One man directed the walkers here and there with shouts, with bellowed instructions, like a caller at a barn dance. A dance of sleepwalkers. Of dreamers. Of the blind, rummaging about for something lost, some totem of importance that had been misplaced, forgotten, a thing of value.

Little changes on the banks of the Awash River.

THE AGELESS QUEST

The man booming commands across the moonscape of the Ethiopian desert—the choreographer of the Middle Awash Project—was Tim White.

White was most definitely restless.

A rangy, bespectacled professor in the Department of Integrative Biology at the University of California at Berkeley, he is a superstar in the ultracompetitive field of human origins research. Famously prickly, no sufferer of fools, his technical brilliance—his sheer bloody-mindedness—is acknowledged even by his bitterest rivals. He was involved in the excavation of the famous Laetoli fossil footprints in Tanzania in the 1970s. On the opposite end of the evolutionary timescale from relatively young bonanzas such as Herto man, he and his colleagues have pushed back the hominid lineage nearly 6 million years, to Ardipithecus, an ancient, four-foot-tall creature that apparently divided its time between the ground and the trees. White’s team spent 15 painstaking years analyzing a single fabulous “Ardi” skeleton before they felt prepared to publish their results. To say the man is intense is like declaring the temperature of a molten Rift Valley afternoon a wee bit toasty. He steered his Toyota Landcruiser in tight, irritated circles whenever the expedition’s convoy of vehicles, bogged behind in the desert, dared slow him down. He urged his fellow fossil hunters onward with into-the-breach exhortations like, “Go, hominid!”

He roared: “Okay, guys, report back—now!”

“Alemayu! Come Here! Go around this hill! Below the soldiers! Go! Fifteen minutes! Go!”

“We’re done! We’re finished here! That’s the verdict of Idi Amin Dada, president for life!”

The soldiers in question were 38 Ethiopian National Police toting Kalashnikov rifles. This year, they accompanied the Middle Awash Project’s team of sun-struck scientists (from Ethiopia, France, Chad, America) into the desert to protect them against the primordial warfare between local Issa and Afar nomads. That Tim White would deem an armed platoon a normal part of a day’s research goes a long way toward explaining why his crew emerged from the Rift this collecting season with a trove of more than 2,000 fossils—including the bones of five primate species (one a giant baboon), wild pigs, monitor lizards, hippo, antelopes, an extinct bovid called Pelorovis with a six-foot horn spread and, the grail of grails, hundreds of precious fragments from more than 30 hominid individuals. They found thousands upon thousands of stone tools, mostly ancient hand axes, shaped like petrified teardrops. They avidly trailed a yard-wide stratum of 300,000-year-old artifacts across the vast, tectonically rumpled landscape, the thinnest of pages from one of the blankest chapters of human evolution, from the first biological inklings of who we were eventually to become, Homo sapiens.

“There is no other place like this in the world,” White said of the boneyard of the Middle Awash, where hominids are scattered atop each other in at least 15 geological layers. “There are six million years of prehistory out here. It covers everything, back to our common ancestry with apes.”

White was sitting at his expedition’s tented camp, poring over a large color satellite map of his survey area. He’d already crisscrossed much of the surrounding desert on foot since he first came to Ethiopia in 1981. He peered at the bronze Rift walls, the pleated badlands, the Awash River’s thorny floodplains in a way virtually nobody else could, in four dimensions, through time. It was almost shamanic. He saw ghostly ecosystems jutting from the side of crumbly, anonymous scarps. He saw ancient volcanoes belching ash within pale, sugary horizons of tuff. He’d bend down to pick up a nondescript fossil, off-handedly mutter, “Proximal radius of a monkey,” and walk on, leaving troupes of spectral apes and flocks of archaic birds to bloom and chitter and fade in a long vanished woodland behind him.

The ferocity of White’s intellect, the mortal seriousness of his intent, his devotion to the question at hand—“The fact that these tools are Acheulean is the most boring thing about them. Who the hell cares? It’s what these tool assemblages tell us about what these people were doing and why, now that’s what’s interesting”—was a privilege to behold. It was like watching a virtuoso paint or a diva sing. In an age of junk information, awash in Googled laziness, his adulation of a bombproof fact gave you hope in the survival of the Enlightenment.

“That skeleton. Looked like it went through a blender. Afar kids were using pieces of it to throw at goats. We found a fragment of its distal humerus 150 meters away.”

This was a typical Tim White anecdote.

There seemed little doubt, as he popped a potato chip into his mouth one day in the miserly shade of an acacia, that in another 15 years he’d have those bones reassembled. Around him, meanwhile, the bone hunters sprawled on the ground, hats over faces, trying to doze through another suffocating lunch break. A few were making tuna-fish-and-peanut-butter sandwiches at a folding camp table. I never could figure out if they actually enjoyed eating such grotesqueries, or if it was some perverse exercise in esprit de corps, the way Shackleton’s men had shaved their heads in solidarity in the Antarctic.

“Your timing is good,” White told me at one point, wistfully, because he loved walking, because he was thinking of joining me awhile as I plodded out of Africa. “You’re going through the Middle Awash before it changes forever. Roads. Dams. Towns. I’ve never seen anything like it. This’ll all be gone in five years.”

But there are no golden ages, of course. Just golden memories.

When the Middle Awash Project finally struck its desert base camp—a nylon outpost of nomad scholars, replete with solar-heated shower bladders and a portable kitchen that turned out crepes–I remember spotting the great Tim White, whose work is ranked in the top one percent of his field by the academic database Essential Science Indicators, toiling alone out under the sun. He was lost in his work, concentrating with usual vehemence, breaking down the latrine barehanded, apparently a job he delegated to nobody. I liked him immensely.

THE REMEMBERED JOURNEY

Memory unlocked the doors of the world.

When anatomically modern Homo sapiens walked out of Africa to become masters of the planet between 60,000 and 90,000 years ago, they likely were pushed, so the current thinking goes, by the effects of apocalyptic famines.

Droughts had parched the African savannas of our species’ infancy. Starvation wiped out more than 90 percent of humankind. It was a near extinction event. A classic bottleneck. Survivors burst out of the continent when the climate shifted again and greened the Middle East, allowing people to migrate into a lush haven of savannas and lakes located in what are today the gravel wastes of central Arabia. From there, the continents fell to us like dominoes.

Another sort of weather may have contributed as well to our rapid dominance of the Earth—in this case, a change in the electrical storms inside our skulls. Something odd happened to our brains about this time. Neural lightning struck. We suddenly exhibited fully modern behaviors such innovative tool making, a compulsion to make art, and facility for advanced language and symbolic thinking. Until recently, convention held that this “Neolithic revolution” only happened once we left Africa. (Hence Lascaux Cave in France.) But growing evidence from Africa shows this not to be the case; 100,000-year-old artifacts that display abstract consciousness have been unearthed in South Africa.

Rick Potts at the Smithsonian Institute gave an explanation for humanity’s global dominances that seems obvious once it’s shared: There were simply enough of us alive at the same time. When we stepped out of Africa, we had rebuilt our populations to a point where collective experience, ideas, knowledge, at last could be transmitted to successive generations. We didn’t have to reinvent the wheel over and over again, as we had when we kept dying out. We remembered each other’s memories. We could marshal the words to remember them by.

THE WAITING SEA

One day, the Great Rift Valley will drown.

Arabia is drifting away from Africa at the rate of 16 millimeters—or 5/8 of an inch—every year. Massive stress cracks gape in Ethiopia’s Rift, in the otherworldly volcanic badlands of the Danakil Depression. The Earth here bulges and buckles. Valleys erode, sag, deepen, their bottoms yanking apart like taffy, forming grabens, slips—gargantuan concavities that yawn thousands of miles southward to Mozambique. Within ten million years—or by lunchtime tomorrow; it all depends on the size of the next earthquake—saltwater will come frothing in a muddy wall down from the Red Sea. The sole plugs at the moment are the low coastal hills of Djibouti and Eritrea. This embryonic new inlet might be called the Eritrean Sea. Its birth will be messy. It would be something to see.

“The surface will be way up there,” Giday WoldeGabriel said. He pointed at the dust-white Ethiopian sky. “Five hundred feet up, maybe.”

We both looked up from the Rift’s slumping floor.

And I could imagine it: The dark, weedy hulls of ships passing in silhouette, slicing the waves high above us: oil tankers, barnacled dhows, fishermen’s skiffs—an armada of the future that would drag its attenuated shadows, like wavering blue planarians, across the barren tan hills of the western Rift. There would be a ferry between the brand new shoreline of Africa and the gigantic island of Somalia. Such millenarian visions came easily in the Middle Awash. Occasionally, the stacked weight of the years pressed on your chest, taking your breath away. Ardi and Herto man, the famous australopithecine called Lucy and many other undiscovered, nickname-able ancestors—all these roots, junctures and branches of our family tree will be underwater, submerged. An irreplaceable book of time, a priceless genealogy, will become a coral reef.

WoldeGabriel shrugged. Being the timekeeper of the Middle Awash Project had made him philosophical.

A friendly, athletic man from the Los Alamos National Laboratory in New Mexico, he was the team’s chief geologist: a connoisseur of the stacked volcanic tuffs that the bone prospectors employed to date their finds. He scrambled like a goat up and down steep slopes in the puckered badlands, digging out cupfuls of ash and depositing them into plastic baggies. His much younger French colleague, a geochemist named Anne Lebatard, struggled to keep up. WoldeGabriel never seemed to sweat.

I asked him why, geologically speaking, this improbably discrete patch of the Rift was the Klondike of the fossil hominid world. It turned out to be complicated. A combination of biochemistry (just the right minerals in soil to replace bone’s calcium) and tectonics (just enough uplift to expose fossiliferous layers). But WoldeGabriel circled back to the common ingredient in both life and death.

“Water covered these remains, preserving them when this desert was a swamp,” he said. “Water will take them away. Nature mines itself. It’s a very interconnected process, never ending.”

THE TRAIL AHEAD

The human conquest of the Earth was a zigzag affair.

It progressed over the course of at least 40,000 years in fits and starts, discursively, with advances and retreats, backflows and strides ahead, much like the blind dance of the paleontologists—like the trajectory of s single life. And how could it be anything different? We’re restless. We’ve always been grasping for something beyond our reach. The journey itself makes us human.

A surprising amount of wildlife still survived around the Middle Awash. Given the prevalence of firearms—the Afar and Issa nomads carry assault rifles—this struck me as little short of miraculous.

When I finally walked away from the work of the scientists, animals began to appear. Ostriches and jackals were common. Once, in the distance, I saw an oryx. But the most abundant creatures by far were gazelles. There were hundreds, possibly thousands of them. They sprang across the trail not 20 yards away, unafraid. I could never take this as a matter of course. It brought to mind the American poet William Stafford, who noted how “you can pass an antelope and not know / and look back, and then—even before you see— / there is something wrong about the grass.” Stafford’s was a poem about walking, perhaps even about picking up a bone, about the mysterious and lingering power of the past:

Tell everyone just to remember
their names, and remind others, later, when we
find each other. Tell the little ones
to cry and then go to sleep, curled up
where they can. And if any of us get lost,
if any of us cannot come all the way—
remember: there will come a time when
all we have said and all we have hoped
will be all right.

There will be that form in the grass.

Breaking camp near Dubti after a night of walking in circles in the sugarcane fields. Photograph by Paul Salopek

We camp on the flank of Asa Fatma mountain, a basalt sentinel overlooking the caravan trails that braid eastward to the old Sultanate of Tadjourah, a distant port where ivory, salt, and slaves were once shipped by dhow to Arabia. The tiny Republic of Djibouti sprawls below us: a waterless plain, hotter and drier than the Ethiopian desert, sere lake beds of blinding white salt, scarps of gunmetal grey, and, doubtless, huddled somewhere in the shade of a doum palm, more Afar nomads—herders cleaved from their Ethiopian brethren by a colonial border, speaking in halting French.

This is where I begin to say goodbye to my walking companions, the Afar camel men from Herto Bouri.

The Ethiopians declare themselves ready to push on. They are ready, they insist, to walk with me to the beaches of the Red Sea. But this is impossible. My two cameleers, Kader Yarri and Mohamed Aidahis, possess no documents, no scraps of paper attesting to their physical existence, no passport. (“This is all Afar land!” they say.) And Ahmed Alema Hessan, my guide and camel-driving mentor, has relapsed beneath his mosquito net into a mysterious illness. He issues his camel-loading orders lying down, from under his shire, his sarong, which he drapes like a sheet over his head. In a few hours, we will part ways in the grim border town of Howle.

What is it like to walk through the world?

It is mornings like these: Opening your eyes to nothing but seamless sky for day after day; a pale, numinous void that for one fleeting instant when you first awake, seems to suck you upward, out of yourself, out of your body. It is the clean hollowness of hunger, a lightness that seems blown through by the wind, the way an empty pipe is blown, to make it whistle. (We trekked 18 miles yesterday on short rations, on a single bowl of noodles and a handful of biscuits each. My wedding ring, once tight, jiggles loosely along my finger.) It is learning to interrogate landscapes with your eyes for camel fodder, for wind direction (dust), for wood, and of course for water—an antique power resides in this. And it is watching the vastness of Africa slip by at a walking pace, and coming to realize dimly that, even at three miles per hour, you are still moving too fast. It is the journey shared.

Mohamed Aidahis crosses the tamed Awash. Photograph by Paul Salopek

Mohamed Aidahis:

A powerful, ant-stomping gait—he plants his feet with force, with vigor, as if to correct the path of the Earth along its orbit. We call him the Third Camel. His appetite is bottomless. One night he gorged himself on bread intended for all. While I fumed, the others laughed. He laughed, too. This is the Afar way: to live (and eat) in the moment. We must disarm him in the towns—his jile dagger is long and sharp—before the police do. At dawn we hear his blade’s tok-tok-tok as he prepares the camels’ thorny breakfasts, chopping branches high up in an acacia tree.

Kader Yarri, the quiet one. Photograph by Paul Salopek

Kader Yarri:

The marionette looseness of a skinny man’s step, light, tireless, eternal, the continent-spanning gait of the ancestors. He is the quiet one, and thus listened to. Early on, I mistook his silences for aloofness: to the pastoralist, to the nomad, sedentary people who own no livestock are inferior beings. But this man’s silence is generous. A watchful steadiness. Without comment he always shoulders more than his share of work. “What will the camels eat?” he asked one day, worried about the cauterized deserts near the Djibouti border. I shrugged: I had no idea. I picked up a stone, held it out. It was the only time I saw him laugh.

Paul Salopek and his Ethiopian guide, Ahmed Alema, arrive in Haramfaf village to a welcoming song. Photograph by John Stanmeyer-VII

Ahmed Alema Hessan, balabat, or leader, of the Bouri Modaitu clan (and, only incidentally, my guide):

Bandy-legged, energetic, with a spring-loaded step. In another place—in the tumbleweed towns of West Texas, say—Alema might have made a fine square dancer. He is the “road boss” of our shambolic little caravan: a human knot, complex, tough, a nexus of murky connections who plays all the angles, as one must on a lean desert margin. At first, his bawdy locker-room English made me doubt his seriousness: He seemed to consider the walk a cosmic joke, a windfall by which to add an executive wing to the shack of his third and youngest wife in the truck stop town of Mile. But Alema is beyond serious. In truth, he has taken possession of this journey, located himself fully within it. He rallies us when we are tired. He presses on. The walk now belongs to him. (“I don’t care about the money, man. It’s the history.”)

On our best days, we four ramblers recognize our good luck. We ricochet down raw mountain trails, almost running, with the whole shining desert of Ethiopia at our feet. We bounce our voices off the walls of black-rock canyons in whooping contests. Then we catch each other’s eye, three Afars and a man from the opposite longitude of the Earth, and grin like children. The cameleers catch the spark, and sing.

What is it like to walk through the world?

It is like this. It is like serious play. I will miss these men.

End of the trail in Ethiopia: the descent into boiling Djibouti. Photograph by Paul Salopek