The Chimp and the River: How AIDS Emerged from an African Forest

by David Quammen

  Most of the poachers, Dongmo added, are Kakos, a tribe from the north with a strong affinity for bushmeat. Many of them have drifted down here to the southeast, drawn by marital connections or opportunity in the bush. The local Baka Pygmies, on the other hand, have traditional strictures against eating apes, which are deemed too close to human. In fact, Dongmo reckoned, there was probably less eating of apes down here than in some other sectors of the country—apart from the totemic consumption of ape parts by Bakwele people in connection with a certain initiation ceremony for adolescent boys. And that offhanded comment from Zacharie Dongmo was the first I’d heard of a Bakwele ritual known as beka.

  We lingered in Yokadouma for two nights and a day, long enough for me to walk the dirt streets, admire the concrete statue of an elephant gracing the town’s central roundabout, photograph a piteous pangolin about to be butchered for meat, and encounter a fellow who told me more about beka. This man, whose name I omit, had written a small report on the subject, which his organization declined to publish. He gave me a copy. Yes, he said, the Bakwele people here in the southeast use chimp and gorilla meat in their beka ceremony. They especially favor the arms. As a result, he said, “chimps are becoming more and more scarce.” So scarce that gorilla arms are now often used as a substitute.

  His report described a typical beka initiation, complete with slaughtered sheep and chickens, the neck of a tortoise (because it resembles a penis), and “virgin lasses” in attendance through a long prelude that culminates at four in the morning. The boy to be initiated is dressed in leaves and given drugs to keep him awake. Drums beat through the night until, before dawn, the boy is led into a special area of forest, where he’s obliged to confront two chimpanzees. Some of what follows seems to be symbolic enactment, some of it blood-real. “A gong is sounded,” according to a Bakwele chief who informed my source, “a voice calls out from the forest, and two chimpanzees respond. The male chimpanzee comes out first and touches the boy’s head. The female chimpanzee emerges minutes after and the boy is expected to kill it.” At dawn the boy bathes, then stays awake until late afternoon, pacing and expectant, at which point the circumciser comes at him with a homemade knife. “I nursed my wound for 45 days after,” one initiate said. But now he was a man, no longer a boy. The unpublished report added:

  Until recently, the Bakweles have been using chimps for this ritual. They claim two chimps could be used for circumcision of as many as 36 people. They amputate the arms of the chimps. This part of the animal is eaten by elders of the village. Of late, however, due to the scarcity of chimps, Bakweles go for gorillas.

  Eight gorilla arms had recently been seized from a poacher who fled when confronted by game rangers, leaving the meat behind in a bag. The arms were intended for an impending beka. “We cannot do without these animals,” the Bakwele chief complained, “if we must perform this important traditional rite.”

  It’s no condescension against Bakwele culture to note that butchering chimpanzees to eat their arms as part of an ancient and bloody ritual could be a very good way to acquire SIVcpz. Then again, in a landscape as lean and severe as southeastern Cameroon in 1908, beka might have been superfluous. Sheer hunger could account for the original spillover just as well.

  14

  Thirty miles farther south, at a crossroads known as Mambele Junction, with a central roundabout defined by three truck tires piled up like coins, we dined by kerosene lantern at a small cantina, eating smoked fish (at least, I hoped it was smoked fish) in peanut sauce and drinking warm Muntzig beer. This happened to be the place where Karl Ammann saw chimpanzee arms stashed under the hood of a log truck. It was also one of the locations featured in Brandon Keele’s paper on the chimpanzee origins of HIV-1. Chimp fecal samples from hereabouts had shown high prevalence of the virus in its most fateful form. Somewhere very nearby was Ground Zero of the AIDS pandemic.

  After dinner, my compadres and I stepped back outside and admired the sky. Although this was Saturday night, the lights of Mambele Junction didn’t amount to much and despite their dim glow we could see not just the Big Dipper, Orion’s Belt, and the Southern Cross but even the Milky Way, arcing overhead like a great smear of glitter. You know you’re in the boonies when the galaxy itself is visible downtown.

  Two days later, at a modest building nearby that served as headquarters for Lobeke National Park, I met with the park’s conservateur, its director, a handsomely bald man named Albert Munga, dressed in a floral shirt and (unmatched) floral pants. He sat aloof at his desk for several minutes, shuffling papers, before deigning to notice me, and then for a while longer he seemed cool to my questions about chimpanzees. The office was heavily air-conditioned; everything about it was cool. But after half an hour Mr. Munga warmed, loosened, and began to share some of his data and his concerns. The park’s population of great apes (chimps and gorillas combined) had fallen abruptly since 2002, he told me: from about sixty-three hundred animals to about twenty-seven hundred. Commercial poachers were the problem, and by his account they came mainly across the eastern boundary of the park, the Sangha River, which happens also to be the southeastern border of Cameroon. Beyond the Sangha lie the Central African Republic and, slightly farther south, the Republic of the Congo, two countries that have known insurgency and war in the last couple decades. Those political conflicts have brought military weapons (especially Kalashnikov rifles) into the region, vastly increasing the difficulty of protecting animals. Bands of well-armed poachers come across the river, mow down elephants and anything else they see, whack out the ivory and the elephant meat, lop off the heads and limbs of the apes, take the smaller creatures whole, and escape back across the water. Or else they move their booty downriver by boat. “There is a huge bushmeat traffic on the Sangha,” Munga told me, “and the destination is Ouesso.” The town of Ouesso, a river port of some twenty-eight thousand people, just over the border in Congo, is a major trading nexus on the upper Sangha. By no coincidence, it was my destination too.

  Just outside Mr. Munga’s office, I paused in the corridor to look at a wall poster with lurid illustrations and a warning in French: LA DIARRHEA ROUGE TUE! Red diarrhea kills. At first glance I thought that referred to Ebola virus disease, another gruesome affliction faced by Central African villagers; but no. “Grands Singes et VIH/SIDA,” read the finer print. VIH is the French equivalent of HIV, and SIDA likewise is AIDS. The cartoonish but unfunny drawings depicted a stark parable about the connection between simian bushmeat and death. I lingered long enough for the oddness to strike me. Throughout the rest of the world you see AIDS-education materials crying out: Practice safe sex! Wear a condom! Don’t share needles! Here the message was: Don’t eat apes!

  We drove onward, along a dirt track between walls of green, still farther into Cameroon’s southeastern wedge. The country’s southern border out here is formed by the Ngoko River, a tributary flowing east to its junction with the Sangha. The Ngoko, according to local lore, is one of the deepest rivers in Africa, but if so there must be a steep wrinkle of rock underneath, because it’s only about eighty yards wide. We reached it around midday at a town called Moloundou, a scruffy place spread over small hills above the river. From any good point of vantage in Moloundou, the Republic of the Congo was easily visible across the water—close enough that, in the quiet of evening, we could hear the chainsaws of illegal loggers at work in the darkness over there. These log poachers would fell trees directly into the water and tangle them into rafts, I was told, then float the rafts down to Ouesso, where a mill operator would pay cash, no questions asked. Ouesso again: the outlaw entrepôt. There was no government presence, no law, no timber concessionaires defending their interests, on that side—so said scuttlebutt on this side, anyway. We had reached the frontier zone, which was still a bit wild and woolly.

  Early next morning we walked up to the market and watched sellers setting out their goods in neat piles and rows: local peanuts and pumpkinseeds and red palm nuts, garlic and onions, manioc tubers,
plantains, giant snails and smoke-blackened fish, hocks of meat. I hung back discreetly from the meat counters, leaving Neville and Max to investigate what was available. Mostly it was smoked duiker, a form of small forest antelope that served as a staple wild food; no sign of ape meat being sold aboveboard; and even pangolin, a seller told Neville, was out of season. I hadn’t expected different. Anything so valuable as a chimpanzee carcass would change hands in private, probably by prior arrangement, and not be slabbed out at a public market.

  Downstream from Moloundou, the last Cameroonian outpost on the Ngoko River is Kika, a logging town with a big mill that provides jobs and lodging for hundreds of men and their families, plus a dirt airstrip for the convenience of its managerial elite. There was no direct riverside road (why would there be? the river is a road) so we circled back inland to get there. Arriving in Kika, we reported promptly to the police station, a small shack near the river that served also as immigration post, where an officer named Ekeme Justin roused himself, pulled on his yellow T-shirt, and performed the necessary formalities for Max and me: stamping our passports sortie de Cameroon. We would exit the country here. Officer Justin, upon receipt of a fee for his stamp work, became our great friend and host, offering us tent space there beside the police post and help in finding a boat. He went off to town with Neville, the all-purpose fixer, and by sunset they had arranged charter of a thirty-foot wooden pirogue, with an outboard, capable of getting Max and me across the river border and down to Ouesso.

  I was up at 5:10 the next morning, packing my tent, eager to turn the corner on this big loop and head back into Congo. Then we waited through a heavy morning rain. Finally came our boatman, a languid young man named Sylvain in a green tracksuit and flip-flops, to mount his outboard and bail the pirogue. We loaded, covered our gear with a tarp against the lingering drizzle, and after warm good-byes to the faithful Neville and Moïse, also Officer Justin, we launched, catching a strong current on the Ngoko. We pointed ourselves downriver. For me, of course, this journey was all about the cut-hunter hypothesis. I wanted to see the route HIV-1 had traveled from its source and imagine the nature of its passage.

  15

  Let’s give him due stature: not just a cut hunter but the Cut Hunter. Assuming he lived hereabouts in the first decade of the twentieth century, he probably captured his chimpanzee with a snare made from a forest vine, or in some other form of trap, and then killed the animal with a spear. He may have been a Baka Pygmy man, living independently with his extended family in the forest or functioning as a sort of serf under the “protection” of a Bantu village chief. But probably he wasn’t, given what I had heard of Baka scruples about eating ape. More likely he was Bantu, possibly of the Mpiemu or the Kako or one of the other ethnic groups inhabiting the upper Sangha River basin. Or he may have been a Bakwele, involved in the practice of beka. There’s no way of establishing his identity, nor even his ethnicity, but this remote southeastern corner of what was then Germany’s Kamerun colony offered plenty of candidates. I imagine the man being thrilled and a bit terrified when he found a chimpanzee caught in his snare. He had proved himself a successful hunter, a provider, a proficient member of his little community—and he wasn’t yet cut.

  The chimp too, tethered by a foot or a hand, would have been terrified as the man approached, but also angry and strong and dangerous. Maybe the man killed it without getting hurt; if so, he was lucky. Maybe there was an ugly fight; he might even have been pummeled by the chimp, or badly bitten. But he won. Then he would have butchered his prey, probably on the spot (discarding the entrails but not the organs, such as heart and liver, which were much valued) and probably with a machete or an iron knife. At some point during the process, perhaps as he struggled to hack through the chimp’s sternum or disarticulate an arm from its socket, the man injured himself.

  I imagine him opening a long, sudden slice across the back of his left hand, into the muscular web between thumb and forefinger, his flesh smiling out pink and raw almost before he saw the damage or felt it, because his blade was so sharp. And then immediately his wound bled. By a lag of some seconds, it also hurt. The Cut Hunter kept working. He’d been cut before and it was an annoyance that barely dimmed his excitement over the prize. His blood flowed out and mingled with the chimp’s, the chimp’s flowed in and mingled with his, so that he couldn’t quite tell which was which. He was up to his elbows in gore. He wiped his hand. Blood leaked again into his cut, dribbled again into it from the chimp, and again he wiped. He had no way of knowing—no language of words or thoughts by which to conceive—that this animal was SIV-positive. The idea didn’t exist in 1908.

  The chimpanzee’s virus entered his bloodstream. He got a sizable dose. The virus, finding his blood to be not such a different environment from the blood of a chimp, took hold. Okay, I can live here. It did what a retrovirus does: penetrated cells, converted its RNA genome into double-stranded DNA, then penetrated further, into the cells’ nuclei, and inserted itself as DNA in the DNA genome of those host cells. Its primary targets were T cells of the immune system. A certain protein receptor (CD4) on the surface of those cells, in the Cut Hunter, was not very different from the equivalent receptor (another CD4) on the T cells of the butchered chimpanzee. The virus attached, entered the human cells, and made itself at home. Once integrated into the cellular genome, it was there for good. It was part of the program. It could proliferate in two ways: by cell replication (each time an infected T cell copied itself, the retroviral genome was copied also) and by activating its little subgenome to print off new virus particles, which then escaped from the T cell and floated off to attack other cells. The Cut Hunter was now infected, though apart from a slash on the hand he felt fine.

  Forget about Gaëtan Dugas. This man was Patient Zero.

  Maybe he carried the chimp carcass, or parts of it, back to his village in triumph. Maybe, if he was Baka, he delivered the whole thing to his Bantu overlord. He didn’t want to eat it anyway. If he was Bantu himself, his family and friends feasted. Or maybe the chimp was a windfall from which he could afford to take special profit. If the season had been bounteous, with some duikers or monkeys killed, some forest fruits and tubers to eat, a good crop of manioc, so that his family wasn’t starving, he may have lugged his chimpanzee to a market, like the one in Moloundou, and traded for cash or some valuable item, such as a better machete. In that case, the meat would have been parceled out retail and many people may have eaten bits of it, either roasted or smoked or dried. But because of how the virus generally achieves transmission (blood-to-blood or sexually) and how it doesn’t (through the gastrointestinal tract), quite possibly none of those people received an infectious dose of virus, unless by contact of raw meat with an open cut on the hand or a sore in the mouth. A person might swallow plenty of HIV particles but, if those virions are greeted by stomach acids and not blood, they would likely fail to establish themselves and replicate. (The greatest danger, left unspecified in that “Don’t eat apes” poster I saw, is not in the swallowing but in the killing, handling, and butchering of the animal.) Let’s suppose that fifteen different consumers partook of the chimp meat, and that they all remained fine. HIV-negative. Lucky folks. Let’s suppose that only the Cut Hunter became infected directly from the chimp.

  Time passed. The virus abided and replicated within him. His infectiousness rose high during the first six months, as virions in multitude bloomed in his blood; then the viremia declined some as his body mounted an early immune response, while it still could, and leveled off, for a period of time. He noticed no effects. He passed the virus to his wife, eventually also to one of the four other women with whom he had sex. He suffered no immunodeficiency—not yet. He was a robust, active fellow who continued to hunt in the forest. He fathered a child. He drank palm wine and laughed with his friends. And then a year later, let’s say, he died violently in the course of an elephant hunt, an activity even more perilous than butchering chimpanzees. He was one of seven men, all armed with spea
rs, and the wounded elephant chose him. He took a tusk through the stomach, momentarily pinning him to the ground. You could see the tusk hole in the dirt afterward, as though a bloody stake had been driven in and pulled. Of the men who scooped him up, the women who prepared him for burial, none had an open cut and so they were spared infection. His son was born HIV-negative.