The Chimp and the River: How AIDS Emerged from an African Forest (12 page)

It was scarcely midafternoon of the Voyager’s first day in Ouesso and he had killed someone. What sort of hellish place was this?

His next shock came when he rolled the dead man over. It wasn’t a man’s face; it was a boy’s. Smooth skin, baby cheeks, long jaw, barely old enough for initiation. The Voyager had been fooled by height. He had killed a tall youngster, a gangly boy who had dared to stoop over his canoe. A boy from the town, with relatives who would miss him. This wasn’t good.

The Voyager stood for a moment, exhausted and pained, calculating his situation. Then again he moved quickly. He dragged the boy’s body to the river. Splashing into the shallows, stumbling, he pulled it offshore just enough to be sure of current, released it, and watched it drift away. The body floated low in the water but it floated. Back on the bank, he rifled down into his canoe and confirmed that the tusks were still there. They were. He gripped each individually at the tip, assuring himself: one, two. He peeled back the leaf wrap and looked. Yes, ivory, two tusks. He dragged his canoe to the water, climbed in, and began paddling downstream. Within fifty yards he caught up with the boy’s body and passed it by. He did not glance back toward Ouesso.

Now he was launched, untethered, no going back. For three weeks he journeyed downstream. Or maybe four weeks; he didn’t keep a tally of the days. He had his canoe and his tusks, his machete, his fishing line and hooks, little else. His immediate purpose was to stay alive, day by day. His driving goal was to recoup a life from the ivory. He resumed fishing as he went, trolling with his line, seldom stopping except for the night. He ate what he caught, saving the dried and smoked fish for contingency. He was on the water again every morning by full light. He passed another town, avoiding it along the far bank, and paddled through a stretch where the river meandered slowly amid swamplands. He could see it was taking him generally south. There were adventures and mishaps and some further narrow escapes along the way. Maybe you can imagine them as well as I can. There was the encounter with the men on the log raft, drifting downriver, to whom he sold fish and by whom he was warned about the Bobangi, an imperious people controlling trade and passage at the mouth of the Sangha. He didn’t know what that meant, the mouth of the Sangha; he pictured this river going on forever. There was the ambush by the crocodile, another hateful moment, but he had been lucky that morning. It was a nasty animal, not large, barely six feet, presumptuous and stupid to attack a human, and he’d had his revenge. He ate the belly meat and tail of the crocodile for six days afterward. He had never eaten chicken so to him it tasted like fish. He placed the crocodile’s severed head into a column of driver ants and they cleaned it of flesh within an afternoon. Now the sun-bleached skull rode atop the other cargo in his canoe, toothy and grinning, like a totem. He reached the mouth of the Sangha and tried to elude the Bobangi, running midriver at night and laying up by day. But he couldn’t stay with his treasures every moment. He left the boat unguarded once, for only a short time, to gather fruit beneath a
mobei
tree,
and so there was his standoff with the solitary Bobangi man whom he found, as he had found the Tall Boy, committing an outrage: looking into his canoe. Unlike the Tall Boy, this man heard him and turned around.

The man had gray hair at his temples and his left eye was milky blue. His right eye was normal. He was old but not too old to be dangerous; his body appeared still strong. He carried a small iron knife, but no machete, and a little packet in animal hide strung around his neck. He looked like a magus or a sorcerer. He had unwrapped the Voyager’s ivory. The Voyager knew that there were many other Bobangi on the river, maybe even some within earshot. The Voyager felt trapped. He remembered the sickening sound of his machete on the Tall Boy’s head. He decided, very quickly, upon a desperate compromise. He addressed the blue-eyed man in Lingala, not sure whether a Bobangi would understand.

I give you one tusk,
the Voyager said.

No sign of response.

I give you one tusk,
he repeated, speaking very clearly.
You deliver it to your chief. Or . . . you don’t.

He waited, letting the blue-eyed man ponder.

One tusk,
he said. He held up a finger.
Or I fight you and I kill you for two.

It seemed a long delay. The Voyager began wishing he had simply cracked the man’s skull, at least tried to, whatever the consequences. Then the blue-eyed man turned back to the Voyager’s canoe. He rummaged, shoved away leaves, and, with an effort that showed in his back muscles, lifted out one tusk. He stroked it, testing the smooth cool surface, and appeared satisfied. The Voyager watched him; willed him on his way.
All right. Take it. Go.
But then, no, the man stooped again. He picked up a single smoked fish. He gaped back at the Voyager with an expression
of shameless, bemused defiance. The blue eye twitched—or was that a wink? He took the tusk and the fish and he departed.

That night the Voyager passed onward through Bobangi territory, slipping by their big village near the mouth of the Sangha, where this river debouched into another, unimaginably huge: the Congo. He was astonished when daylight revealed the extent of its braiding channels, islands, and strong currents. It was like a bundle of rivers, not just one. He paddled harder than ever now, but also more carefully, learning wariness of the eddy lines that could knock a canoe sideways, the whirlpools that could suck it under. He kept a distance between himself and other canoes. When he saw men on a raft, he paddled within shouting distance, offered to sell fish, sought information. Once he encountered a steamboat, like a great house proceeding upriver under power, with a machine inside thumping stupidly, passengers and bundled cargo on the deck. It was a strange sight. But the Voyager had seen other strange sights—the spilled brains of a boy, the Ouesso market, a blue-eyed Bobangi thief—and by now felt almost inured to astonishment. The boatman on this noisy, belching vessel, he could see, was a white man. The Voyager hugged the opposite shore.

The river continued south. He entered the territory of the Tio, a more tractable people than the Bobangi—eager for trade but not demanding monopoly, according to what the Voyager heard. Maybe the Tio were humbler because the river was now so vast. No one could imagine himself owning such a river. No tribe, even. Here the Voyager saw dozens of other boats. It was a new universe. Many canoes, several more steamboats, people hollering and trading from one boat to another. The maze of channels and the traffic, plus the increasing distance from Ouesso, gave a sense of jumble and anonymity and security that allowed the Voyager to travel by daylight, which was fortunate in these formidable waters. He sold fresh
fish to Tio boatmen and swapped fish for manioc. He chatted.
Yes, I’ve come from the upper river, very far
. But he didn’t say which river. He didn’t mention ivory. He gathered intelligence without revealing much. He was tired.

He had an intermediate goal now, between the daily purpose of survival and the dream of due reward for his troubles. He had a destination: a place called Brazzaville. It was a large town, downriver, some days ahead. It sat on the right, beside a great pool. He would know it when he saw it—so he’d been told. Another big town sat on the left bank, across the pool, but that one was owned by the Belgians.
Who are the Belgians?
he asked.
Are they a tribe like the Bobangi?
Worse. Yes, he heard, Brazzaville was a good market for fish or whatever you had.

And so the Voyager arrived. He rounded a last bend, came to a great pool where the river seemed as wide as it was long, put a large island to his left as advised, and saw white buildings on the right bank, some of them twice as tall as a house, taller even than the circular market hall at Ouesso. He paddled toward the white buildings. Coming near, he held himself some distance out, drifting, observing, until he was well past the docks and the big boats and the bustle of workingmen, then beached his canoe in a quieter place. Several children gaped, as children do, but no one else noticed him. People were busy and no adults diverted their attention to the sight of a strong young Bakwele coming ashore in tattered clothes with a crocodile skull, a single fine tusk, and half a boatload of rotten fish.

He stepped out of the water and stood alone. No one greeted him.

No one knew what he had done. No one compared him to Lewis and Clark. No one hailed him as the Marco Polo of the upper Congo basin. No one knew that he was Huck Finn and Jim, John Wesley Powell on the Colorado, Teddy Roosevelt on
the River of Doubt, Frank Borman circling the moon in
Apollo 8
, and Dr. Richard Kimble at large. No one knew.

The Voyager walked into town and sold his tusk the first afternoon, receiving 120 brass rods, which was a good price, he thought, but also somehow anticlimactic and unsatisfactory. For his crocodile skull, at the benign whim of the ivory buyer, he received another ten brass rods. He bought some palm wine, got drunk, found that experience not to his liking, and never did it again. The rest of his money he saved, or rather set aside, spending it slowly and variously until it was gone. He had arrived.

He found lodging in Poto-Poto, a neighborhood east of the city center, full of others from the upper river, and got work on the waterfront. He made friends. He settled in. Urban life suited him. He became something of a colorful figure, confident, charming in his river-man way, with stories to tell. No one viewed him as the pariah son of a sorceress. No one guessed that he had ever been a surly young loner. No one knew his real name because he had invented another. And the other thing no one knew, not even he, was that he had brought a new element, a new circumstance, to Brazzaville. A virus, in his blood. More specifically: He had brought HIV-1 group M.

Seven and eight and nine years later, near the end of his life, the Voyager would tell some of his stories to friends, acquaintances, and a few of the women with whom he had relationships, transient or longer: about the Dead Elephant, the Half-Portuguese Merchant, the Tall Boy, the Crocodile, and the Blue-Eyed Bobangi. In his telling, the Tall Boy became an adult and the Crocodile was very large, a leviathan. No one doubted his word. They knew he had come down the river and it must have been perilous. The crocodile skull wasn’t there to belie him. During those years he slept with thirteen women, all of whom were femmes libres to one degree or another. One of those, a young
Tio girl who had recently arrived in Brazzaville from upriver, and who found that she fancied him more than she did her freedom, became his wife. Eventually he infected her with the virus. He also infected one other, a rather more professional woman who lived in a small house in the Bacongo neighborhood, west of town, where he visited her on an intermittent basis when his wife was pregnant. The other eleven women had only fleeting sexual contacts with him and were luckier. They remained HIV-negative. The Voyager’s personal lifetime contribution to the basic reproduction rate was therefore precisely 2.0. People liked him and were sorry when he fell ill.

The Bacongo girlfriend was vivacious and pretty and ambitious for wider horizons, so she crossed the pool to Léopoldville, where she had a successful career, though not a long one.

18

I
f the virus reached Léopoldville in 1920 or so, that still leaves a gap of four decades to the time of ZR59 and DRC60, those earliest archival HIV sequences. What happened during the interim? We don’t know, but available evidence allows a rough sketch of the outlines of possibility.

The virus lurked in the city. It replicated within individuals. It passed from one person to another by sexual contact, and possibly also by the reuse of needles and syringes for treatment of well-known diseases such as trypanosomiasis. (More on that possibility, below.) Whatever its means of transmission, presumably HIV caused immunodeficiency, eventually death, among
most or all people infected—except those who died early from other causes. But it didn’t yet assert itself conspicuously enough to be recognized as a distinct new phenomenon.

It may also have proliferated slowly in Brazzaville, across the pool, helped along there too by changing sexual mores and programs of therapeutic injection. It may have lingered in villages of southeastern Cameroon or elsewhere in the upper Sangha basin. And wherever it was, but definitely in Léopoldville, it continued to mutate. The wide divergence between ZR59 and DRC60 tells us that. It continued to evolve.

Studying the evolutionary history of HIV-1 is (notwithstanding that ill-advised comment by the WHO’s David Heymann to Tom Curtis) more than an idle exercise. The point is to understand how one strain of the virus, group M, has made itself so deadly and widespread among humans. Such understanding, in turn, may lead toward better measures to control the devastation of AIDS, possibly by way of a vaccine, more likely by way of improved treatments. That’s why scientists such as Beatrice Hahn, Michael Worobey, and their colleagues explore the molecular phylogenetics of HIV-1, HIV-2, and the various SIVs. One issue they address is whether the virus became virulent before, or only after, its spillover from
Pan troglodytes
. To state the question more plainly: Does SIV
_cpz
kill chimps, or is it only an innocuous passenger? Answering that one could reveal something important about how human bodies respond to HIV-1.

For a while after the discovery of SIV
_cpz
, the prevailing impression was that it’s harmless in chimpanzees, an ancient infection that may once have caused symptoms but no longer does. This impression was bolstered by the fact that, in the earlier years of AIDS research, more than a hundred captive chimpanzees had been experimentally infected with HIV-1 and none had shown immune system failure. When a single lab chimpanzee did progress to AIDS (ten
years after experimental infection with three different strains of HIV-1), its case was remarkable enough to merit a six-page paper in the
Journal of Virology
. The researchers implied that this was good news, finally offering hope that chimpanzees do represent a relevant experimental model (that is, a sufficiently analogous test subject) for studying human AIDS. There was even a report, based on genetic analysis of captive animals in the Netherlands, suggesting that chimpanzees had “survived their own AIDS-like pandemic” more than 2 million years ago. They had emerged from the experience, according to this line of thought, with genetic adaptations that render them resistant to the effects of the virus. They still carry it but apparently don’t get sick. That notion, to repeat, was founded on captive chimpanzees. As for SIV-positive chimps in the wild: No one knew whether they suffer immunodeficiency. It was a difficult question to research.