The Best American Science and Nature Writing 2014 (3 page)

You'll see choice and consequence echoing too in Amy Harmon's tale of a Florida orange grower's desperate quest to save his orchards from a tree-crippling bacterial disease. The disease, called citrus greening, has relentlessly crept from continent to continent. Scientists have not found a single citrus species that is resistant to infection. The grower profiled by Harmon realizes that the only answer may be in genetic modification. As he pursues that goal, to save his trees, he finds himself increasingly entangled in the angry political debate that currently swirls around the issue of genetic engineering. Harmon balances the fraught politics with the science in the most rational way, debunking some of the common myths about genetic modification and letting the reader consider the choice that must eventually be made—and its consequences.

In that same regard, I want to mention Nicholas Carr's “The Great Forgetting.” Carr explores the way that our reliance on such helpful technologies as GPS mapping makes us less reliant on our own abilities and knowledge. As we depend on the device rather than ourselves, that dependence changes us as well. I've long wondered about the consequences of GPS mapping because I use it every time I visit my son in Chicago and am required to drive the city's tangle of streets. Although I've made numerous visits, and driven many miles there, I still have no sense of the city's geography, and without looking at a real map can't tell you exactly where my son's neighborhood is. I might argue that I don't need to, since I use GPS, but sometimes I am uneasily aware that I used to be able to visualize the cities I traveled. Carr's point, though, is far more urgent than mine. He investigates airplane crashes in which the pilot's overdependence on autopilot contributes to fatal errors. “We're forgetting how to fly,” one veteran pilot says. Carr also tells us how some traditional cultures, such as the ice-hunting Inuit of Canada, have become so reliant on GPS that they've lost the ability to find their way on their own. They are starting to lose, as one observer puts it, their feel for the land.

Sometimes it seems that we're always slightly behind in this game of choice and consequence. We move forward with all the excited cheer of a new technology or biological insight, and then we realize that we've made our move without fully considering nature's countermove. Perhaps nothing illustrates that better than our overuse of antibiotics and the resulting tide of antibiotic resistance, told in chilling though beautiful detail in Maryn McKenna's look toward a “post-antibiotic” future. The best of popular science writing does many things well—illuminating complicated research, forgotten corners of the earth, the worlds that lie beyond our own—in ways that make the universe itself more real to us. But I've come to believe that it's the ability to see a discovery as a decision, to follow it from start to sometimes troubling, sometimes triumphant finish, that is one of the most important things we science writers bring to the story of science.

It is, of course, that very story of choice and consequence that eddies in my memory of radioactive dust, stirred into the air on that long-ago summer day.

 

So I'll return you now to that afternoon, finally allowing the science writer, her photographer, and their Nevada test-site guide to leave that drift of bomb-town dust behind. Aside from wishing to be elsewhere, of course, there was nothing to do but wait for the wind to give it up. We brushed ourselves off—no doubt making sure that the dust was all over our hands—and continued the tour.

The day was sunny, our guide was reassuringly nonchalant, and we headed down a strip of narrow roadway to our next destination, which turned out to be the test site's nuclear waste storage area. Metal barrels stamped with radiation symbols were stacked around us. I still have a slightly crackly photograph that my photographer insisted on taking. It shows a woman in her early thirties, wearing a baseball hat, T-shirt, and blue jeans, holding a traditional reporter's notebook in one hand, looking into the camera with a slight smile. Behind her is nothing but a wall of radioactive waste barrels, piled so high that there's no sky visible in the image.

“What were you thinking?” I say to her sometimes. But I know the answer. She was thinking what an incredible place this was, what a reminder of our atomic legacy. We've never really known what to do with the radioactive wastes of nuclear bombs except box them up and hide them away. Fifteen years ago the government created the Waste Isolation Pilot Plant and placed such nuclear detritus from its test facilities in a deep salt mine near Carlsbad, New Mexico. In late February of this year, a leak was reported there; thirteen workers tested positive for radiation exposure. The exposure was low, but it's a reminder that no problem ever remains fully buried. The lesson I took away from the Nevada site, or one of them, is that sometimes the most important thing the writer does is just tell the story, bring the choice and the consequence out of hiding, so that it's not invisible, so that we, as a society, don't forget.

And as you can tell, I haven't forgotten that windblown day. I haven't forgotten because when we went through the radiation detectors on our way out, the alarms started clanging like a fire truck as my photographer passed through. I could feel my eyes go wide, and I know his were as he looked back at me. They sent him through again, and this time the alarms were silent. “Just a little glitch,” the guards manning the exit assured us, and this time I could feel my eyes narrowing. But “Just a glitch,” I repeated to the photographer as we sped back toward the casino-hotel in Las Vegas where we were staying. The desert whipped by the windows in a blur of russet and gray-green. I had my foot down on the gas because, well, I was in a hurry to get back.

“You know,” I said casually as I hopped out of the car, “I think I'll just go take a shower.” As I recall, I said it to his back because he was already on his way. When we met for dinner, we were both shiny from soap and water. Over the chicken, though, he decided that he was still so stressed out he might just try relaxing in the glitter of the casino. That night, playing blackjack, he lost every dollar we'd brought to cover our expenses.

But that, as they say, is another story.

D
EBORAH
B
LUM

FROM
Audubon

 

“I
LOVE GETTING
huge boxes of blood,” says the genetic ornithologist Rachel Vallender as she pulls open a drawer full of small plastic vials in her laboratory at the Canadian Museum of Nature in Ottawa, where she's a visiting scientist. Each tube, carefully labeled and organized, holds a blood sample from a single warbler. Whether the bird is actually a hybrid is the question Vallender seeks to answer.

Hybrids of golden-winged and blue-winged warblers are increasingly popping up across the Northeast and into Canada. The physical differences between the mixed progeny and their pure counterparts can be subtle. A bird might, for instance, have the distinctive yellow patches on its wings, the golden head, and the jet-black collar of a golden-winged warbler but with the yellowish belly of a blue-winged warbler. So individual scientists and conservation groups, including Audubon North Carolina and Bird Studies Canada, are gathering samples from across eastern North America and sending them to Vallender, who analyzes mitochondrial DNA in the blood to determine the birds' genetic history. She examines the shipments she receives in free moments—on nights, weekends, and vacation days from her full-time job with Environment Canada, a government agency. The research is revealing how prevalent this intermingling of genes is and helping bring to light some of the potential dangers it poses.

Records of blue-wingeds spreading into golden-winged territory, hybridizing with them, and gradually replacing them extend back to the early twentieth century. Such mixing isn't unusual in the avian world: nearly 10 percent of all bird species are known to occasionally interbreed. But the genetic work of Vallender, who has been studying warbler hybridization for more than a decade, backs up the observations of birders and scientists who, during the same time period, have reported growing numbers of hybrids while conducting population surveys. She's found that in many places across the United States and Canada, hybrids now make up as much as 30 percent of golden-winged warbler populations. “This isn't just some sporadic event anymore,” she says.

This shift, says Vallender, correlates with the onslaught of climate change. Biologists have long known that habitat loss is a major factor driving blue-winged warblers to expand their range. The bird's preferred scrubland habitat is disappearing as abandoned farmland reverts to forest. Warming temperatures might be adding additional pressures, causing blue-wingeds to move north in search of cooler climes and into habitat already occupied by golden-wingeds.

For reasons unknown, the golden-winged warblers seem to suffer more from the interaction. While blue-winged populations are experiencing declines, golden-winged populations are plummeting, and scientists are wary of the species' chances for long-term survival. “If [this decline] continues at the rate it has been going, we could see drastic reductions in their populations or, worst-case scenario, extinctions,” says Vallender. “We need to do this research now.”

 

What's happening to the two warblers isn't unique. Polar bears and grizzly bears are mating, as are different species of everything from butterflies to sharks.

In some instances, it's clear that climate change is playing a role. More than 1,700 animal species across the globe have shifted their ranges northward and upward in elevation, searching for colder temperatures and following as the plants and other animals they rely on shift as well. Ice sheets and other physical barriers that once kept species apart are disappearing. All of these changes are expected to accelerate as we spew ever more greenhouse gases into the atmosphere, driving up the earth's temperature.

Climate-driven intermixing is raising challenging conservation issues. Should hybrid offspring be protected if one parent species is threatened or endangered? Ecologically, does it matter if the world loses purebred species to hybridization? Is it best to get involved or to let nature take its human-altered course, creating new species and eliminating others? These are the questions experts are just beginning to ponder, even as the planet continues to warm.

 

In 2006 an American big-game hunter from Idaho shot and killed the first documented wild polar–grizzly bear hybrid, a mostly white male covered in patches of brown fur, with long grizzly-like claws, a humped back, and eyes ringed by black skin. Four years later a second-generation “pizzly” or “grolar” was shot. After hearing reports of the bears, Brendan Kelly, then an Alaska-based biologist with the National Oceanic and Atmospheric Administration, started to wonder which other species might be interbreeding as a result of a changing Arctic landscape.

Snow and sea ice hit record lows in 2012, and the Arctic has warmed more than 3.6 degrees Fahrenheit since the mid-1960s, more than twice the global average.

To gauge what kinds of effects these shifts were having on Arctic animals, Kelly teamed up with the biologist David Tallmon at the University of Alaska and the conservation geneticist Andrew Whiteley at the University of Massachusetts Amherst. The trio coauthored a seminal report for the journal
Nature
in 2010 that chronicled the hybridization that wildlife managers and First Nations communities had been seeing in the Arctic, including the mixing of beluga whales and narwhals, bowhead and right whales, Dall's and harbor porpoises, hooded and harp seals, spotted and harbor seals, and North Atlantic minke and North Pacific minke whales, in addition to polar and grizzly bears. They also outlined the devastating effects the new genetic exchanges could have on biodiversity, such as parent species being driven to extinction or creating hybrids unable to survive in the environments they are born into.

The scientific community at large quickly recognized that the genetic mixing wasn't limited to animals in the rapidly changing Arctic. Today they're finding it all over the place, in owls, petrels, squirrels, big cats, and wild canines.

Between 2007 and 2009, researchers from several Australian universities caught fifty-seven hybrid blacktip sharks while doing routine marine surveys off the northeast coast of Australia. Genetic tests confirmed that they were crossbreeds of Australian and common blacktips. The result of several generations of interbreeding, they were found south of the tropical areas where Australian blacktips typically live.

Elsewhere, scientists are discovering that hybridizing species are exchanging behavioral and physiological traits, not just physical ones. Mark Scriber is an entomologist and professor emeritus at Michigan State University who studies swallowtail butterflies. In 1999 he began noticing hybrids in northern ranges that could and were eating plants previously tolerated only by southern swallowtail species. He also discovered hybrids in the north whose emergence had been delayed by four or five weeks, so that they arrived too late to mate with the previous generation of butterflies and too early to mate with the next. They could mate only with each other, essentially creating a new species.

 

These sorts of interactions are, in their purest form, a kind of evolution, points out Kelly. For millennia, wildlife was forced together and pushed apart as climate, ecosystems, and landscapes changed. During these periods of upheaval, genes flowed between animals, creating new species and driving others to extinction. But genetic mixing that frequently takes centuries now takes only decades or even years, because modern climate change is altering the earth so quickly and drastically.

Regardless of the cause, Jim Mallet, an evolutionary biologist at Harvard University who has studied hybridization in European and South American butterflies, argues that we should let nature take its course. And while he isn't completely alone in his thinking, most other scientists interviewed for this story were divided over whether to take action or let the interactions play out unimpeded. “My feeling is that hybridization is natural,” Mallet says. “It is the result of a mating decision by an individual, and different individuals have different desires and interests. You don't want to label a mating decision as unnatural when it's found in the wild.”