Process of Elimination

KARL CAMPBELL IS a craftsman bedeviled by bad tools. He’s a middle-aged, medium-size, muscular Australian with a five-day beard and an intense gaze who seems perpetually coiled, even angry, when at rest. He’s smiling and relaxed only when his body is in motion—preferably fixing something, building something, or killing something.

His craft—and his mission—is saving as many endangered species as he can, in what he reckons the most effective way. It’s a grueling job by which he creates life out of death, preventing the catastrophe of irreversible extinction with a tide of blood. He kills goats and rats and other human-­introduced animals that threaten rare island creatures, but his tools—traps, long-range rifles, and poisons—are brutal, deployable only on a small scale and wildly indiscriminate. To excise the rat, say, from an ecosystem requires a sledgehammer that falls on many species.

Ecology is complex, even on tiny islands, and things don’t always go according to plan. In 2012, for instance, Campbell, who works for an organization called Island Conservation, helped round up the 60 Galapagos hawks that lived on Pinzón Island, a steep volcanic nubbin in the Galapagos chain, so they wouldn’t eat the rats that Campbell was about to poison. But when the rare raptors were released back into the wild after a couple of weeks, they began dropping like flies. It turned out the poison was lurking in lava lizards—hawk prey.

Campbell is now preparing for an even riskier maneuver: using a fiercely potent poison for the complete obliteration of rats on a 70-square-mile Galapagos island called Floreana. The island was once home to a chocolate-brown bird with a perky tail called the Floreana mockingbird, but the rats eat its eggs and chicks, so the bird remains on only a couple of islets. Once the rats are gone, the mockingbird could be brought back to the place for which it was named. The rats’ destruction will be brought about by a carpet-­bombing of lethal pellets: Some 300 tons of poisoned cereal will be dumped from helicopters, enough to kill every rat on the island. The problem is that 150 people and their farm animals also live on Floreana.

On a cool and sunny Monday last August, Campbell and I hopped in a local farmer’s battered Toyota Land Cruiser and headed for the highlands of Floreana. Rats are no friends to farmers either, and Campbell pointed to some corn in Claudio Cruz’s fields that had been nibbled away by sharp rodent teeth. Cruz had stacked two bright-red shipping containers up on blocks—one a gift from Island Conservation, one he bought himself. They will be used to store uncontaminated animal feed when the poison comes, tentatively in 2020. Island Conservation will also build coops, sties, and stables for the island’s chickens, pigs, and horses. It will buy sentinel pigs that will live outside the sties and be slaughtered at intervals so their livers can be tested for poison. The other pigs won’t be able to emerge until the sentinel pigs’ livers are clear. This might take three years. Parents will have to keep close watch over small children lest they eat pellets off the ground. Scores of native animals—likely including finches and short-eared owls—will be captured and held in aviaries both on and off the island. Campbell expects it will take 10 years and $26 million to clear this small island of rats.

All this is why Campbell has begun pushing for research into a much more precise and effective tool—one you might not associate with nature-loving conservationists. Self-­perpetuating synthetic genetic machines called gene drives could someday alter not just one gene or one rat or even a population of rats but an entire species—of rats, mosquitoes, ticks, or any creature. And this biological technology promises to eliminate these destructive animals without shedding a drop of blood. So Campbell has spent the past few years dividing his time between old-fashioned killing and traveling the world to pitch the gene drive approach to ecologists, ethicists, and prospective donors. He’s not alone in his enthusiasm. Institutions from the US military’s research agency to the Gates Foundation to the government of New Zealand are looking to gene drives as possible solutions for big problems (malaria, Lyme disease, species extinction). But the methods also contain the threat of unleashing another problem: They could change species, populations, and ecosystems in unintended and unstoppable ways.

Karl Campbell is looking for a better method than poisons to eradicate island rats. JAKE STANGEL

WHEN LINDA CAYOT, project coordinator for a Galapagos-based restoration program called Project Isabela, picked Campbell for an internship with the organization back in the late 1990s, she recalls that one of his virtues was a “certain macho army roughness.” Campbell had learned to shoot firearms and repair vehicles in the Australian Army Reserve. He’d spent a few weeks volunteering to catch and arrest antelope poachers in Malawi. He was well suited to the demands of the work on the islands: Once he slashed open his thumb and had a friend stitch it up in the field; another time he came back from a visit to a remote volcano with most of the skin on his feet peeling off. He didn’t bother to mention it.

Perhaps because of his disdain for comfort, Campbell thrived in the harsh volcanic landscape of the Galapagos, with its strange and wonderful wildlife. Because humans, with their talent for destruction, found these volcanic islands so late in history, 95 percent of the original and unique species remain. There are giant tortoises, marine iguanas that shoot salt snot from their nostrils, and waved albatrosses that glide on 8-foot-wide wings, eyes like black tapioca balls.

When humans did establish permanent residency on the islands, starting in 1805, they brought beasts of burden, animals for meat, and the clever and voracious rat, hidden in the holds of their ships. The animals of the Galapagos, like island species everywhere, had let down their defenses over evolutionary time and simply could not cope with these bulldozing newcomers. Some had lost their ability to fly away; some had taken up nesting on the ground, with their eggs out in the open; perhaps most dangerously, they had lost their fear. Even when invaders didn’t eat the native fauna, they did damage in other ways. On the Galapagos, goats ate so many plants that one estimate claimed that 60 percent of the Galapagos’ 194 endemic plants were threatened with extinction—not to mention the islands’ giant tortoises, which were starving to death with no plants to eat.

For Project Isabela, Campbell shot goats with semiautomatic rifles, mostly from helicopters, occasionally on foot with dogs. But he quickly recognized the imperfection of these methods. He came up with a strategy for inducing sexual receptivity in females in order to lure other goats out of hiding, round them up, and shoot them. The resulting “Mata Hari” goats were a big success and propelled Campbell to a kind of fame, but he dismisses the technique as a mere “incremental innovation.” He was looking for a “transformative innovation.”

In 2006 Campbell went to work for Island Conservation, taking his skills beyond the Galapagos. He has helped rid San Nicolas Island, in California, of feral cats; Choros Island, Chile, of rabbits; and Desecheo Island, Puerto Rico, of rhesus macaques. But every eradication is a grind, and Campbell is vexed by the scale of the problem: There are 465,000 islands on Earth, home to 41 percent of endangered land vertebrates, and most of the islands with endangered species also have introduced species on them. “We are barely scratching the surface,” Campbell says.

Then, in 2011, Campbell stumbled upon an idea that smelled like the transformative innovation he had been looking for.

An entomologist at North Carolina State University named Fred Gould had written a paper positing that genetic engineering techniques that had been used with insects were ripe for deployment in other troublesome species like rodents. (Along with driving island species extinct, rats and mice eat enough rice each year to feed 180 million people, and they transmit Lyme disease and hantavirus.) Scientists could use genetic engineering to favor certain traits, Gould pointed out, and push them through wild populations. Normally, for any given gene that comes in different types, an offspring has a 50 percent chance of inheriting the mother’s version and a 50 percent chance of inheriting the father’s version. But some genes have naturally evolved a way to cheat this system—if one parent has the gene an offspring has a virtually 100 percent chance of inheriting that version. That mysterious cheat code is called a gene drive, and if scientists could engineer a synthetic gene drive, they could spread a desired trait through a population and down through generations. To eradicate rats on an island, you might push a gene for infertility that would cause a population to crash once it reached a certain prevalence—no poisons necessary. The rodents would simply fade away, like heirless lords.

Campbell invited himself for a visit to Gould’s lab in Raleigh. As you do, Gould turned to the internet to figure out who Campbell was. “I was just shocked,” Gould says. “If you look at the Island Conservation website it is all woodsy-greensy.” A lot of passionate environmentalists are opposed to genetic engineering. Gould asked Campbell, “Do you know what you are getting into?”

Campbell did. But he didn’t care that other conservationists considered genetic engineering too risky to attempt and too unnatural to countenance. He wanted to stop extinctions. Gould liked the man’s pragmatism.

Gould’s ideas were theoretical. But in 2012 the prospect of making the theoretical real suddenly got a lot better with the discovery of the Crispr technique, a new way to edit genes quickly, cheaply, and precisely. With Crispr, any DNA sequence could be precisely cut and pasted into any location in any genome.

Kevin Esvelt invented the synthetic gene drive—and then got worried about its potential power. GUIDO VITTI

About two years later, Kevin Esvelt, a geneticist then at Harvard University, put gene drives and Crispr together. Instead of poking a big fat glass needle loaded up with synthetic DNA into every organism that you want to change, you do it once, with a gene drive that encodes not only the gene you want (or the deactivation of the gene you don’t want) but also instructions to do that same manipulation with the Crispr technique in another genome. So when your altered organism mates, its chromosome gets to work, engineering the chromosome inherited from the mate too. This guarantees that the offspring has the desired change, plus the instructions to make the desired change.

When the offspring reaches maturity and mates, the process repeats. In a perfect “global” gene drive, 100 percent of offspring have the gene drive carrying the desired trait.

The possibility was a tantalizing one for conservation. You could start thinking way bigger than Floreana: the Galapagos island of Santa Cruz, with its 12,000 people. Or, hell, Australia—Campbell’s home country, a massive island with dozens of species endangered largely because of introduced cats and foxes. You could fix every island in the world.

The idea of using gene drives to save species began to hum. Campbell helped organize people from Island Conservation and researchers in the United States, Australia, and New Zealand, as well as the United States Department of Agriculture, to research the approach. The group formalized as the Genetic Biocontrol of Invasive Rodents program, or GBIRd. In June 2016, Paul Thomas, a mouse geneticist from the University of Adelaide, Australia, visited Gould in North Carolina and got fired up. Thomas felt that his lab could be the place to figure out how to make a synthetic gene drive work in rodents. If he could succeed in lab mice, he could succeed with the wild mice and rats that eat the eggs and young of rare species on islands. Thomas joined GBIRd.

 

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