ice age, likely would have been much larger than now, allowing the common ancestor of chimpanzees and bonobos to circumvent the entire river system and cross over to the other side. But during the glacial maximum, the forest shrank, and survived only in the wettest pockets. Gorillas, who are vegetarians and sustain themselves on protein-rich shoots and buds, would have seen their food sources become scarce and their habitat dramatically reduced. They likely would have withdrawn to wet climates near mountains or died off, especially to the south of the river, where there was no mountainous terrain. The versatile chimpanzee-bonobo ancestor would have occupied more space and might, in certain areas, have lived largely in savannahs.
During the following interglacial, as ice caps melted and humidity returned to the equator, abundant rain carved new tributaries and enlarged existing rivers. Wrangham and Peterson explain that though the food sources optimal for gorillas would have reappeared in abundance throughout the basin, the gorillas would have struggled to return to all areas. Rivers would have hampered their travel, and despite the humid interglacial, the forests might not have returned to their previous size, no longer offering a clear path around the Congo’s elaborate river system.
Judging by the gorillas’ present habitat, it appears that they expanded only into the sections of the Congo rainforest currently inhabited by chimpanzees. The chimp-bonobo ancestors who lived in the same areas as gorillas faced limited resources and might have benefited by becoming significantly more competitive with one another for food, evolving toward chimpanzees. However, the chimp-bonobo ancestor across the river to the south, living without gorillas, had an easier time, benefiting from the diets of both chimpanzees and gorillas, as bonobos do today. With so many resources, it might have evolved to have increasingly less competition between individuals. Even now, chimps, just to the north of the river, rely much more on hunting. Of course, owing to the lack of fossil evidence, we can’t easily judge whether the chimp-bonobo ancestor more closely resembled chimpanzees or bonobos, or had a unique disposition from which its descendents dramatically diverged.
Is a lesson in 65.5 million years of global history necessary to understand the planet’s few remaining rainforests and the ways that apes now occupy them? If humans are the bookend, the driving force in a new mass extinction, it is clearly important to understand exactly what may be ending, and all that would be lost. The long, largely continuous evolution and expansion of species since the demise of dinosaurs appears, at least from our limited perspective, to be at a crucial juncture, with habitats being rapidly destroyed by humans. Given the exponential increase of human populations and industry, we must act quickly if we are to preserve remaining ecosystems at a time when few of us even understand their significance.
The story of this evolution changes how I see the forest—not as a natural resource or a feature of the landscape, but as a central factor in the story of our evolution. As it vanished, apes evolved and our ancestor separated from theirs. The only surviving members of their group took refuge in the equatorial forests that have existed in some form for millions of years, and they teach us more about the past and ourselves than fossils ever could. Sally Jewell Coxe often describes bonobos and chimpanzees as exemplifying the yin and yang of human nature, and their models shed light not only on how we can interact with each other, but on the ways an environment can cause us to change.
The plane banked and began to lose altitude, and I wondered how I would feel standing in virgin rainforest and seeing bonobos. As the last great ape that Westerners became aware of, they made us realize all that we didn’t know about ourselves and the forest itself. Increasingly, though, as BCI’s logo of a bonobo standing in a circle suggested, they represented the importance of coalitions to save that very forest. Today, Africa’s rainforests are barely absorbing the carbon emissions of its cities, and the lesson in planetary history also serves to remind us of how carbon dioxide can transform the earth, and how the forests that we’re cutting down are essential for sequestering it.
For years, studies of ice cores from glaciers have revealed that the current level of carbon dioxide is the highest the planet has known in the last eight hundred thousand years. New research, however, suggests that the last time the atmosphere held this much carbon dioxide was fifteen million years ago, when, according to the scientist Aradhna Tripati, a professor at the University of California, Los Angeles, “global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland.” Historically, global temperatures largely correlate to atmospheric carbon levels, and though temperatures are at their highest level in four thousand years, they are expected to rise at an unusually rapid rate over the next century, one too fast to allow most creatures to adapt. Some scientists have suggested that we are crossing into unknown territory, over a tipping point, where carbon emissions will create a domino effect, transforming the planet at an exponential rate. And yet our impact is increasing, a day in Kinshasa enough to make me understand the urgency of human need and hunger. The DRC’s population—already the fourth largest in Africa after those of Nigeria, Egypt, and Ethiopia—is set to double to 140 million within twenty years. A glance from the airplane window sufficed to remind me of how isolated and unknown our few remaining rainforests are, how they can disappear without our knowing, and how much of a challenge it will be for humanity to work together to save them.
Ten minutes before landing, we crossed over the wide river again. Dozens of long forested islands split it into as many as five channels, yellow and brown sandbars visible beneath the water, carved by the current into shapes reminiscent of dunes. The jet coasted low, dropped its landing gear as my ears popped, and a minute later it banged down on the runway, all of us clutching armrests and gritting teeth.
We were let out into a sunny afternoon and crossed the tarmac to the yellow terminal, the main chamber of which contained two rows of wooden benches that looked like church pews. When I heard people say Mbandaka, I listened closely. The stress was on the first syllable, the m largely silent to my ear, at most a slight holding of the lips together before the plosive b sound.
Aimée Nsongo, a short, sturdy woman who was BCI’s Mbandaka office manager, stood waiting for us. She commanded a group of young men who gathered the dozen large duffel bags, each weighing sixty or seventy pounds. We followed them outside the airport to where six Chinese motorcycles were parked. A single white pickup, rented by BCI, was in the gravel lot. The young men loaded the bags into the back while Aimée went inside to speak with agents of the Direction Générale de Migration (DGM) regarding the legal formalities of our travel in Équateur Province.
At least a dozen people sat in blue plastic chairs, drinking large bottles of Primus beer. We joined them as shoeshine boys gathered, along with vendors selling pineapples and bowls of large squirming mpose grubs, the larvae that rhinoceros beetles lay in rotting wood.
“Mmm—mpose!” Michael said as a young man held out a metal tub of what looked like thumb-size writhing maggots with pincers on their heads. He explained that both Congolese and bonobos eat them, and I would later read that they contain more protein than chicken and beef. He paid a cook to fry them in garlic, and they were delicious, with a texture and flavor like buttered lobster, the heads crunching lightly. We would spend the following weeks asking if anyone had mpose. They were our first meal in Mbandaka and would be our last one, a month later, again at the airport, before we returned to Kinshasa.
When Aimée finished with the DGM, we drove into the city along a paved road that, aside from a few humps, potholes, and fissures, was sound. Dozens of men passed the other way on bicycles, working the pedals with the laborious swaying of their bodies. Asphalt gave way to the wide red avenues of the city, multicolored umbrellas stuck in the roadside, vendors squatting beneath. Everything seemed tinged with the russet dust, concrete walls and buildings, people’s clothes and skin.
Founded in 1883,
