The World Without Us

Below the moor, a 1,000-foot band of bamboo circles the Aberdares Mountains, sanctuary to the nearly extinct bongo, another of Africa’s striped camouflagees. In bamboo so dense it discourages hyenas and even pythons, the spiral-horned bongo’s only predator is unique to the Aberdares: the seldom-seen melanistic, or black, leopard. The brooding Aberdares rain forest is also home to a black serval and a black race of the African golden cat.

It’s one of the wildest places left in Kenya, with camphor, cedar, and croton trees so thick with lianas and orchids that 12,000-pound elephants easily hide here. So does the most imperiled of all African species: the black rhino. About 400 remain in Kenya, down from 20,000 in 1970, the rest poached for horns that bring $25,000 each in the Orient for alleged medicinal properties, and in Yemen for use as ceremonial dagger handles. The estimated 70 Aberdares black rhinos are the only ones in their original wild habitat.

Humans once hid here, too. During colonial times, the well-watered, volcanic Aberdares slopes belonged to British tea and coffee growers who alternated their plantations with sheep and cattle ranches. The agricultural Kikuyu were reduced to sharecropping plots called shambas on their now-conquered land. In 1953, under the cover of the Aberdares forest, they organized. Surviving on wild figs and the brown speckled trout stocked by the British in Aberdares streams, Kikuyu guerrillas terrorized white landowners in what became known as the Mau Mau Rebellion. The Crown brought divisions from England and bombed the Aberdares and Mount Kenya. Thousands of Kenyans were killed or hung. Barely 100 British died, but by 1963 a negotiated truce had inexorably led to majority rule, which became known in Kenya as uhuru— independence.

Today, the Aberdares is an example of that wobbly kind of pact that we humans have struck with the rest of nature known as a national park. It is haven to rare giant forest hogs and the smallest antelopes—jackrabbit-sized suni—and to golden-winged sunbirds, silvery-cheeked hornbills, and incredible scarlet-and-beyond-blue Hartlaub’s turacos. The black-and-white colobus monkey, whose bearded visage surely shares genes with Buddhist monks, dwells in this primal forest, which sweeps in all directions down the slopes of the Aberdares…

…until it stops at an electric fence. Two hundred kilometers of galvanized wire, pulsing 6,000 volts, now encircle Kenya’s greatest water catchment. Electrified mesh rises seven feet above ground and is buried three feet beneath it, its posts hot-wired to keep baboons, vervet monkeys, and ringed-tailed civets off them. Where it crosses a road, electrified arches allow vehicles to pass, but dangling live wires deter vehicle-sized elephants from doing the same.

It is a fence to protect animals and people from each other. On either side lies some of the best soil in Africa, planted in forest above and in corn, beans, leeks, cabbage, tobacco, and tea below. For years, incursions went in both directions. Elephants, rhinos, and monkeys invaded and uprooted fields by night. Burgeoning Kikuyu populations snuck farther up the mountain, felling 300-year-old cedars and podo conifers as they advanced. By 2000, nearly one-third of the Aberdares was cleared. Something had to be done to keep trees locked in place, to keep enough water transpiring through leaves and raining back into Aberdares rivers, to keep them flowing to thirsty cities like Nairobi, and to keep hydroelectric turbines spinning and Rift lakes from disappearing.

Hence, the world’s longest electric barricade. By then, however, the Aberdares had other water problems. In the 1990s, a deep new drain had opened at its skirts, cloaked innocently in roses and carnations, as Kenya passed Israel to become Europe’s biggest provider of cut flowers, which now exceed coffee as its main source of export income. This fragrant turn of fortune, however, incurs a debt that may keep compounding long after flower lovers are no longer around.

A flower, like a human, is two-thirds water. The amount of water a typical floral exporter therefore ships to Europe each year equals the annual needs of a town of 20,000 people. During droughts, flower factories with production quotas stick siphons into Lake Naivasha, a papyrus-lined, freshwater bird and hippo sanctuary just downstream from the Aberdares. Along with water, they suck up entire generations of fish eggs. What trickles back whiffs of the chemical trade-off that keeps the bloom on a rose flawless all the way to Paris.

Lake Naivasha, however, doesn’t look quite so alluring. Phosphates and nitrates leached from flower greenhouses have spread mats of oxygen-choking water hyacinth across its surface. As the lake level drops, water hyacinth—a South American perennial that invaded Africa as a potted plant—crawls ashore, beating back the papyrus. The rotting tissues of hippo carcasses reveal the secret to perfect bouquets: DDT and, 40 times more toxic, Dieldrin—pesticides banned in countries whose markets have made Kenya the world’s number-one rose exporter. Long after humans and even animals or roses go, Dieldrin, an ingeniously stable, manufactured molecule, may still be around.

No fence, not even one packing 6,000 volts, can ultimately contain the animals of the Aberdares. Their populations will either burst the barriers or wither as their gene pools shrink, until a single virus snuffs an entire species. If humans are snuffed first, however, the fence will stop dispensing jolts. Baboons and elephants will make an afternoon fete of the grains and vegetables in the surrounding Kiyuku shambas. Only coffee stands a chance to survive; wildlife don’t crave caffeine very much, and the arabica strains brought long ago from Ethiopia liked central Kenya’s volcanic soils so much they’ve gone native.

Wind will shred the polyethylene greenhouse covers, their polymers embrittled by equatorial ultraviolet rays whose potency is abetted by the flower industry’s favorite fumigant, methyl bromide, the most potent ozone destroyer of all. The roses and carnations, addicted to chemicals, will starve, although water hyacinth may outlast everything. The Aberdares forest will pour through the deactivated fence, repossessing shambas and overrunning an old colonial relic below, the Aberdares Country Club, its fairways currently kept trimmed by resident warthogs. Only one thing stands in the forest’s way from reconnecting the wildlife corridors up to Mount Kenya and down to the Samburo desert: a ghost of the British Empire, in the form of eucalyptus groves.

Among the myriad species loosed on the world by humans that have surged beyond control, eucalyptus joins ailanthus and kudzu as encroachers that will bedevil the land long after we’ve departed. To power steam locomotives, the British often replaced slow-maturing tropical hardwood forests with fast-growing eucalyptus from their Australian Crown colonies. The aromatic eucalyptus oils that we use to make cough medicine and to disinfect household surfaces kill germs because in larger doses they’re toxins, meant to chase off competitive plants. Few insects will live around eucalyptus, and with little to eat, few birds nest among them.

Lusty drinkers, eucalypti go wherever there’s water, such as along shamba irrigation ditches, where they’ve formed tall hedgerows. Without people, they’ll aim to colonize deserted fields, and they’ll have a head start on the native seeds blowing down the mountain. In the end, it may take a great natural African lumberjack, the elephant, to blaze a trail back to Mount Kenya and expel the last British spirits from the land for good.

2. Africa After Us

In an Africa without humans, as elephants push above the equator through Samburo and then beyond the Sahel, they may find a Sahara Desert in northward retreat, as desertification’s advance troops—goats—become lunch for lions. Or, they may collide with it, as temperatures rising on a wave of a human legacy, elevated atmospheric carbon, quicken its march. That the Sahara has lately advanced so rapidly and alarmingly—in places, two to three miles per year—owes to unfortunate timing.

Only 6,000 years ago, what is now the world’s largest nonpolar desert was green savanna. Crocodiles and hippos wallowed in plentiful Sahara streams. Then Earth’s orbit underwent one of its periodic readjustments. Our tilted axis straightened not even half a degree, but enough to nudge rain clouds around. That alone was not sufficient to turn grasslands to sand dunes. But the coincidence of human progress tipped what was becoming an arid shrubland over a climatic edge. During two previous millennia, in North Africa, Homo sapiens had gone from hunting with spears to growing Middle Eastern grains and raising livestock. They mounted their belongings, and themselves, on newly tamed descendants of an American ungulate that luckily emigrated before its cousins back home perished in a megafaunal holocaust: the camel.