Paleontologists too embrace the idea and even the term. Jablonski himself, in a 1991 paper published in Science, extrapolated from past mass extinctions to our current one and suggested that human activities are likely to take their heaviest toll on narrowly endemic species, while causing fewer extinctions among those species that are broadly adapted and broadly distributed. “In the face of ongoing habitat alteration and fragmentation,” he wrote, “this implies a biota increasingly enriched in widespread, weedy species—rats, ragweed, and cockroaches—relative to the larger number of species that are more vulnerable and potentially more useful to humans as food, medicine, and genetic resources.” Now, as we sit in his office, he repeats: “It’s just a question of how much the world becomes enriched in these weedy species.” Both in print and in talk he uses “enriched” somewhat caustically, knowing that the actual direction of the trend is toward impoverishment of variety.
Regarding impoverishment, let’s note another dark, interesting irony: that the two converse trends I’ve described—partitioning the world’s landscape by habitat fragmentation and unifying the world’s landscape by global transport of weedy species—produce not converse results but one redoubled result, the further loss of biological diversity. Immersing myself in the literature of extinctions and making dilettantish excursions across India, Madagascar, New Guinea, Indonesia, Brazil, Guam, Australia, New Zealand, Wyoming, the hills of Burbank, and other semiwild places over the past decade, I’ve seen those redoubling trends everywhere, portending a near-term future in which Earth’s landscape is threadbare, leached of diversity, heavy with humans, and “enriched” in weedy species. That’s an ugly vision, but I find it vivid. Wildlife will consist of the pigeons and the coyotes and the whitetails, the black rats (Rattus rattus) and the brown rats (Rattus norvegicus) and a few other species of worldly rodent, the crab-eating macaques and the cockroaches (though, as with the rats, not every species—some are narrowly endemic, like the giant Madagascar hissing cockroach) and the mongooses, the house sparrows and the house geckos and the houseflies and the barn cats and the skinny brown feral dogs and a short list of additional species that play by our rules. Forests will be tiny insular patches existing on bare sufferance, much of their biological diversity (the big predators, the migratory birds, the shy creatures that can’t tolerate edges, and many other species linked inextricably with those) long since decayed away. They will essentially be tall woody gardens, not forests in the richer sense. Elsewhere the landscape will have its strips and swatches of green, but except on much-poisoned lawns and golf courses, the foliage will be infested with cheatgrass and European buckthorn and spotted knapweed and Russian thistle and leafy spurge and salt-meadow cordgrass and Bruce Babbitt’s purple loosestrife. Having recently passed the great age of biogeography, we will have entered the age after biogeography, in that virtually everything will live virtually everywhere, though the list of species that constitute “everything” will be small. I see this world implicitly foretold in the UN population projections, the FAO reports on deforestation, the northward advance into Texas of Africanized honeybees, the rhesus monkeys that haunt the parapets of public buildings in New Delhi, and every fat gray squirrel on a bird feeder in England. Earth will be a different sort of place—soon, in just five or six human generations. My label for that place, that time, that apparently unavoidable prospect, is the Planet of Weeds. Its main consoling felicity, as far as I can imagine, is that there will be no shortage of crows.
Now we come to the question of human survival, a matter of some interest to many. We come to a certain fretful leap of logic that otherwise thoughtful observers seem willing, even eager, to make: that the ultimate consequence will be the extinction of us. By seizing such a huge share of Earth’s landscape, by imposing so wantonly on its providence and presuming so recklessly on its forgiveness, by killing off so many species, they say, we will doom our own species to extinction. This is a commonplace argument among the environmentally exercised. In earlier years, from a somewhat less informed perspective, I made the same argument myself. Since then, my thinking has changed. My objection to the idea now is that it seems ecologically improbable and too optimistic. But it bears examining, because it’s frequently offered as the ultimate argument against proceeding as we are.
Jablonski also has his doubts. Do you see Homo sapiens as a likely survivor, I ask him, or as a casualty? “Oh, we’ve got to be one of the most bomb-proof species on the planet,” he says. “We’re geographically widespread, we have a pretty remarkable reproductive rate, we’re incredibly good at co-opting and monopolizing resources. I think it would take a really serious, concerted effort to wipe out the human species.” The point he’s making is one that has probably already dawned on you: Homo sapiens itself is the consummate weed. Why shouldn’t we survive, then, on the Planet of Weeds? But there’s a wide range of possible circumstances, Jablonski reminds me, between the extinction of our species and the continued growth of human population, consumption, and comfort. “I think we’ll be one of the survivors,” he says, “sort of picking through the rubble.” Besides the loss of all the pharmaceutical and genetic resources that lay hidden within those extinguished species, and all the spiritual and aesthetic values they offered, he foresees unpredictable levels of loss in many physical and biochemical functions that ordinarily come as benefits from diverse, robust ecosystems—functions such as cleaning and recirculating air and water, mitigating droughts and floods, decomposing wastes, controlling erosion, creating new soil, pollinating crops, capturing and transporting nutrients, damping short-term temperature extremes and longer-term fluctuations of climate, restraining outbreaks of pestiferous species, and shielding Earth’s surface from the full brunt of ultraviolet radiation. Strip away the ecosystems that perform those services, Jablonski says, and you can expect grievous detriment to the reality we inhabit. “A lot of things are going to happen that will make this a crummier place to live—a more stressful place to live, a more difficult place to live, a less resilient place to live—before the human species is at any risk at all.” And maybe some of the new difficulties, he adds, will serve as incentive for major changes in the trajectory along which we pursue our aggregate self-interests. Maybe we’ll pull back before our current episode matches the Triassic extinction or the K-T event. Maybe it will turn out to be no worse than the Eocene extinction, with a 35 percent loss of species.
“Are you hopeful?” I ask.
Given that hope is a duty from which paleontologists are exempt, I’m surprised when he answers, “Yes, I am.”
I’m not. My own guess about the midterm future, excused by no exemption, is that our Planet of Weeds will indeed be a crummier place, a lonelier and uglier place, and a particularly wretched place for the 2 billion people composing Alan Durning’s absolute poor. What will increase most dramatically as time proceeds, I suspect, won’t be generalized misery or futuristic modes of consumption but the gulf between two global classes experiencing those extremes. Progressive failure of ecosystem functions? Yes, but human resourcefulness of the sort Julian Simon so admired will probably find stopgap technological remedies, to be available for a price. So the world’s privileged class—that’s your class and my class—will probably still manage to maintain themselves inside Homer-Dixon’s stretch limo, drinking bottled water and breathing bottled air and eating reasonably healthy food that has become incredibly precious, while the potholes in the road outside grow ever deeper. Eventually the limo will look more like a lunar rover. Ragtag mobs of desperate souls will cling to its bumpers, like groupies on Elvis’s final Cadillac. The absolute poor will suffer their lack of ecological privilege in the form of lowered life expectancy, bad health, absence of education, corrosive want, and anger. Maybe in time they’ll find ways to gather themselves in localized revolt against the affluent class, and just set to eating them, as Wells’s Morlocks ate the Eloi. Not likely, though, as long as affluence buys guns. In any case, well before that they will have burned the las
t stick of Bornean dipterocarp for firewood and roasted the last lemur, the last grizzly bear, the last elephant left unprotected outside a zoo.
Jablonski has a hundred things to do before leaving for Alaska, so after two hours I clear out. The heat on the sidewalk is fierce, though not nearly as fierce as this summer’s heat in New Delhi or Dallas, where people are dying. Since my flight doesn’t leave until early evening, I cab downtown and take refuge in a nouveau-Cajun restaurant near the river. Over a beer and jambalaya, I glance again at Jablonski’s 1991 Science paper, titled “Extinctions: A Paleontological Perspective.” I also play back the tape of our conversation, pressing my ear against the little recorder to hear it over the lunch-crowd noise.
Among the last questions I asked Jablonski was, What will happen after this mass extinction, assuming it proceeds to a worst-case scenario? If we destroy half or two thirds of all living species, how long will it take for evolution to fill the planet back up? “I don’t know the answer to that,” he said. “I’d rather not bottom out and see what happens next.” In the journal paper he had hazarded that, based on fossil evidence in rock laid down atop the K-T event and others, the time required for full recovery might be 5 or 10 million years. From a paleontological perspective, that’s fast. “Biotic recoveries after mass extinctions are geologically rapid but immensely prolonged on human time scales,” he wrote. There was also the proviso, cited from another expert, that recovery might not begin until after the extinction-causing circumstances have disappeared. But in this case, of course, the circumstances won’t likely disappear until we do.
Still, evolution never rests. It’s happening right now, in weed patches all over the planet. I’m not presuming to alert you to the end of the world, the end of evolution, or the end of nature. What I’ve tried to describe here is not an absolute end but a very deep dip, a repeat point within a long, violent cycle. Species die, species arise. The relative pace of those two processes is what matters. Even rats and cockroaches are capable—given the requisite conditions; namely, habitat diversity and time—of speciation. And speciation brings new diversity. So we might reasonably imagine an Earth upon which, 10 million years after the extinction (or, alternatively, the drastic transformation) of Homo sapiens, wondrous forests are again filled with wondrous beasts. That’s the good news.
The River Jumps Over the Mountain
LIFE IS SHORT and the Grand Canyon is long, especially when you paddle your way down it in a kayak. From the put-in at Lees Ferry, not far below Glen Canyon Dam, the Colorado River winds 226 miles between walls of primordial rock to a take-out at Diamond Creek, on the Hualapai Indian Reservation, dropping through dozens of major rapids along the way. Beyond that is slightly more river, more canyon, but the urgency, the majestic ferocity, and the sense of otherworldly containment dissipate down there, as the canyon walls tilt back into rubble slopes of Sonoran desert vegetation and the water’s awesome momentum dribbles out anticlimactically into flat, inert Lake Mead. The deep magic and adamantine power that make this particular canyon grander than all others on Earth lie in those upper 226 miles, between the launch point and Diamond Creek. My own little kayak, of stiff yellow plastic, is nine foot two.
Simple arithmetic tells me that I’ll need to travel 130,271 boat-lengths from start to finish. It’s a ratio conducive to humility.
On water like this, each boat-length of headway involves two paddle strokes and, through the more serious rapids, maybe a quick tactical brace to prevent being flipped upside down. The lovely thing about a whitewater kayak is that, far beyond any other sort of water craft, it offers maneuverability in exchange for vulnerability, a tradeoff that intensifies the boater’s sense of intimate interaction with a river. Climbing into a snugly fitted kayak, wedging your butt between the hip pads, arching your knees up into the thigh braces, is more like buckling on skis than like boarding a vessel. This is a sporting tool, not just a mode of conveyance. Stability is achieved, not given. A whitewater kayak even differs drastically from a sea kayak—roughly to the degree, say, that riding a unicycle in the circus differs from pedaling a ten-speed across Nebraska. Offering so little inherent equilibrium, so many dimensions of surprise, it’s therefore the perfect boat in which to explore the chaotic border zones between equilibria and disequilibria of a personal nature—which is what, for me anyway, this trip is about. I’ve recently been set wobbling by the end of what I’d thought was a very good, very permanent marriage. A descent of the Grand Canyon by kayak should be more robust and less piteous, I figure, than a midlife crisis.
We launch on a Tuesday in early September, with the days growing shorter but the sun still high enough at midafternoon to make the deepest canyon rocks radiate, into evening, like oven-fresh bread. There are sixteen of us, seven in kayaks, the rest as oarsmen or passengers on inflatable rafts, a motley assemblage of old friends and new acquaintances all centered on the trip’s organizational leaders, Cyndi and Bob Crayton of Bozeman, Montana.
Bob Crayton ran the Grand Canyon twenty years ago, as a young oil-field roughneck with a full head of hair, in a clumsy old fiber-glass kayak that he paddled without undue concern about what lurked around the next bend, either on the river or in life. It was a larkish, bachelor getaway with a gang of male pals, yet he was so lingeringly affected by the experience that when he met Cyndi she took it to be something worth sharing. After the birth of their second child, she applied for a Grand Canyon permit herself. The responsible officials at Grand Canyon National Park allow only eight private-party launches per week, and the waiting list is lengthy. Eleven years later, Cyndi’s name has come up, and her family—now including a lanky, handsome sixteen-year-old son, Chase, and a vivaciously feisty twelve-year-old daughter, Kinsey—forms the nucleus of our expeditionary party. Because the Park Service paperwork designates the permitee as “Trip Leader,” and because she has borne so much of the organizational burden, we have all stopped calling Cyndi by her name and switched to the honorific title TL. Where are we camping tonight? Ask TL. Which box, on which raft, has the Pringles? Ask TL. Hey, TL, thanks for the margaritas! Rising to this burdensome challenge, Cyndi will eventually take to wearing a rhinestone tiara (belonging to Kinsey, who packed it for Mom as a surprise) on select occasions, when asserting her authority.
By terms of the permit, we have eighteen days to cover our 226 miles. Life is short and eighteen days still shorter—even if you’re living out of boats, sleeping on the ground among scorpions and rattlesnakes, defecating into metal boxes, and bathing in a cold, silty river or not at all—but for an exercise in detachment from doleful confusions and mortal regrets, which is what I want, it should be sufficient.
An hour after launching, four miles downstream, we pass under Navajo Bridge, far above, and get our last glimpse for weeks of a vehicle that travels on wheels.
The river is slatey green and cold, having just emerged through dam gates from the bottom of Lake Powell. We paddle the flatwater stretches and bob through several warmup riffles, ogling the stone, elated that we’re finally under way. The current slides along at about four miles per hour, and if we rode it passively, we could make a good day’s distance between late morning and midafternoon, with no shortage of scenic amusements. Several bends downstream, we fall silent at the sight of several bighorn ewes grazing placidly on a sand flat along river right. They ignore us. A great blue heron roosts, with the cold dignity of a pterodactyl, on a high cliff. A belted kingfisher flies along one bank, making those trapeze-artist kingfisher swoops. The rock layers continue rising, revealing themselves as distinct strata and groups of strata by their differing colors and textures, and I’ve done just enough homework to try to identify them.
Let’s see, from the top: That must be the Kaibab formation, then the Toroweap, then the Coconino sandstone just below. I can recite the cardinal sequence thanks to a mnemonic offered by a scientist friend before I left Montana: Kissing Takes Concentration, However, Sex Requires More Breath And Tongue. It codes for Kaibab, Toroweap, Coconi
no, Hermit shale, Supai group, Redwall limestone, Muav limestone, Bright Angel shale, and finally Tapeats sandstone. After a few dozen miles, I notice what seems to be a distinct formation—crumbly, rounded off, as red as dried blood—just emerging at river level. Rick Alexander, one of my kayaker pals, with a half-dozen previous Grand Canyon trips on his résumé and an appreciation for the place that goes beyond whitewater hydrology, confirms that we’re now seeing the Hermit shale. I’m mesmerized by geologic spectacle, it’s better than watching a lava lamp—but then Kayaking Takes Concentration too, and we climb out of our boats to scout Badger rapid.
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