The World Without Us

One of the unfathomables is why bonobos, smaller and more slender than chimps but equally related to us, don’t seem very aggressive at all. Although they defend territory, no intergroup killing has ever been observed. Their peaceful nature, predilection for playful sex with multiple partners, and apparent matriarchal social organization with all the attendant nurturing have practically become mythologized among those who insistently hope that the meek might yet inherit the Earth.

In a world without humans, however, if they had to fight it out with chimpanzees, they would be outnumbered: only 10,000 or fewer bonobos remain, compared to 150,000 chimpanzees. Since their combined population a century ago was approximately 20 times greater, with each passing year chances weaken for either species to be around to take over.

Michael Wilson, hiking in the rain forest, hears drumbeats that he knows are chimpanzees pounding on buttress roots, signaling each other. He runs after them, up and down Gombe’s 13 stream valleys, hurdling morning glory vines and lianas strung across baboon trails, following chimp hoots until, two hours later, he finally catches them at the top of the Rift. Five of them are in a tree at the edge of the woodland, eating the mangoes they love, a fruit that came along with wheat from Arabia.

A mile below, Lake Tanganyika flashes in the afternoon sunlight, so vast it holds 20 percent of the world’s freshwater and so many endemic fish species that it’s known among aquatic biologists as the Galápagos of lakes. Beyond it, to the west, are the hazy hills of the Congo, where chimpanzees are still taken for bush meat. In the opposite direction, past Gombe’s boundaries, are farmers who also have rifles, and who are tired of chimps who snatch their oil palm nuts.

Other than humans and each other, the chimpanzees have no real predators here. The very presence of these five in a tree surrounded by grass testifies to the fact that they’ve also inherited the gene of adaptability, and are far more able than gorillas, which have highly specialized forest diets, to live on a variety of foods and in a variety of environments. If humans were gone, however, they might not need to. Because, says Wilson, the forest would come back. Fast.

“There’d be miombo moving through the area, recovering the cassava fields. Probably the baboons would take first advantage, radiating out, carrying seeds in their poop, which they’d plant. Soon you’d have trees sprouting wherever there’s suitable habitat. Eventually, the chimps would follow.”

With plenty of game returning, lions would find their way back, then the big animals: cape buffalo and elephant, coming from Tanzania’s and Uganda’s reserves. “Eventually,” Wilson says, sighing, “I can see a continuous stretch of chimpanzee populations, all the way down to Malawi, all the way up to Burundi, and over into Congo.”

All that forest back again, ripe with chimpanzees’ favorite fruits and a prospering population of red colobus to catch. In tiny Gombe—a protected shred of Africa’s past that is also a taste of such a posthuman future—no enticement is readily evident for another primate to leave all that lushness and follow in our futile footsteps.

Until, of course, the ice returns.

CHAPTER 5 The Lost Menagerie

IN A DREAM, you walk outside to find your familiar landscape swarming with fantastic beings. Depending on where you live, there might be deer with antlers thick as tree boughs, or something resembling a live armored tank. There’s a herd of what look like camels—except they have trunks. Furry rhinoceroses, big hairy elephants, and even bigger sloths—sloths?? Wild horses of all sizes and stripe. Panthers with seven-inch fangs and alarmingly tall cheetahs. Wolves, bears, and lions so huge, this must be a nightmare.

A dream, or a congenital memory? This was precisely the world that Homo sapiens stepped into as we spread beyond Africa, all the way to America. Had we never appeared, would those now-missing mammals still be here? If we go, will they be back?

AMONG THE VARIOUS slurs hurled at sitting presidents throughout the history of the United States, the epithet with which Thomas Jefferson’s foes smeared him in 1808 was unique: “Mr. Mammoth.” An embargo that Jefferson slapped on all foreign trade, intended to punish Britain and France for monopolizing shipping lanes, had backfired. While the U.S. economy was collapsing, his opponents sneered, President Jefferson could be found in the East Room of the White House, playing with his fossil collection.