I saw such an invention at Imperial College London. A student led me through a steel door, under a powerful gust of air, and into a humid room heated to 83 °F. Behind glass, mosquitoes clung to the sides of small cages covered in white netting. A warning sign read, “THIS CUBICLE HOUSES GENE DRIVE GM MOSQUITOES.” It went on to caution that the insects’ DNA contains a genetic element that has “a capacity to spread” at a “disproportionately high” rate.

A gene drive is an artificial “selfish” gene capable of forcing itself into 99 percent of an organism’s offspring instead of the usual half. And because this particular gene causes female mosquitoes to become sterile, within about 11 generations—or in about one year—its spread would doom any population of mosquitoes. If released into the field, the technology could bring about the extinction of malaria mosquitoes and, possibly, cease transmission of the disease.

Anopheles gambiae mosquitoes. The species spreads malaria in Africa.

The mosquitoes I saw were created as part of Target Malaria, a project led by Imperial College that has quietly expanded to involve 16 institutions and includes teams in Italy and three African countries, Mali, Burkina Faso, and Uganda, where secure mosquito facilities are currently being outfitted. Its work is funded by the health foundation of Microsoft billionaire Bill Gates, in Seattle. An official there said the foundation now considers gene drives “necessary” to end malaria and projects that the technology will be ready years before an effective vaccine. According to a business plan developed for the Gates Foundation, the self-annihilating mosquitoes could be unleashed in 2029.

The plan is to disperse Anopheles gambiae mosquitoes harboring selfish genes across sub-Saharan Africa. The gene drive could spread across a huge swath of territory, causing mosquitoes to disappear and blocking transmission of the parasite that causes malaria. “Malaria is a problem of poverty, of instability and lack of political will,” says Andrea Crisanti, the Italian parasitologist and genetic engineer who developed the insects at Imperial College. “We are asking the drive to do what we can’t do politically or economically.”

Beyond helping with malaria, conservationists think gene-drive technology could save Hawaii’s disappearing native birds (from avian malaria) or maybe rid Australia of invasive, destructive toads that have been hopping westward across the continent. Why not also eliminate Aedes aegypti, the mosquito spreading dengue fever and Zika in the Americas?

Does any country, agency, or individual have the right to change nature in ways that could affect everyone?

The technology creates risks that society has never before had to consider. Would removing mosquitoes upset ecosystems? Are we risking a genetic epidemic if the selfish DNA should jump the species barrier to affect other insects? Most perplexing: what country, agency, or individual has the right to change nature in ways that could affect the entire globe? “This is why I hate the malaria problem,” says Kevin Esvelt, an MIT biologist who has been warning about the unprecedented dilemmas gene drives will create. “It makes the technology so tempting to use.”

These questions need answers soon. Only 12 months ago, gene-drive technology was still a promising theory. Not anymore. Rapid-fire technical advances are occurring thanks to CRISPR, a new gene-editing technique. At Imperial’s lab I peered through a microscope at an immature mosquito, called a pupa, a grisly creature that looks like a holiday ham with a lobster tail attached. Inside its body I could see fiery fluorescent spots where an artificial selfish gene was busy copying itself. The potentially ecosystem-altering transformations had been carried out mostly by a 27-year-old student named Andrew Hammond during a few months of late nights in the lab. “There are so many cool ways to build these,” Hammond exulted. “There are so many easy things to do.”

And that’s just the problem. Officials in the United States and elsewhere worry that it might be a little too easy. The FBI is looking into whether gene drives could be misused, say, to create a designer plague. And this May, the U.S. National Academy of Sciences is expected to publish recommendations for “reducing ecological and other risks” ahead of any field test. Twenty-seven researchers wrote to Science with warnings against the accidental release of gene-drive organisms, something they fear would devastate public trust. Others have said the research ought to be classified, though it’s too late for that.

Despised species

Of the 3,500 species of mosquitoes, about 30 spread malaria, although three nearly indistinguishable subtypes of Anopheles gambiae do the most damage in Africa. The female mosquito’s bite spreads the plasmodium parasite, which gives people fever and chills by exploding red blood cells. These three mosquitoes are the ones targeted by Imperial for elimination, Crisanti says, swinging his glasses by a tip and jumping up from his chair.

Crisanti acknowledges that gene-drive technology is generating tension. Pressure will mount to use the technique, given the health and social benefits that ending malaria could bring. On the other hand, there are as yet no agreed-upon regulations or procedures for developing a technology able to spread itself among wild organisms. “The gene drive is controversial for the potential to wipe out a species,” he says. “So there should be a clear benefit.”

At the Italian outpost of Target Malaria, female Anopheles mosquitoes take a blood meal. Three days later they will lay eggs.

A gene drive wouldn’t necessarily doom these mosquito species to extinction. Pockets of mosquitoes might remain, or they could be maintained in a lab, should anyone want to bring them back. But eradication is a possible outcome, Crisanti says, in particular if release of the gene drive coincided with conditions like a dry spell or a cold snap. Species go extinct continually, of course, but I wondered: is it ethical to eliminate any part of nature on purpose? “Are you asking in a Darwinian way or a theological way?” Crisanti responded. “I think it’s a species competition between us and the mosquito. And I don’t think a species has the right to exist or not to exist.” He says what species do have is “fitness”—they have adapted to flourish in their environmental niche. For species we hope to save, we might use gene drives to add beneficial genes, like ones for disease resistance. For species we despise, we can add ones that make them unfit for survival.

Selfish genes

Target Malaria is led by Austin Burt, an evolutionary theorist at Imperial College whose specialty is selfish genetic elements. These are parasitic genes, found in many species, that make extra copies of themselves. (One, called the P element, even managed to hitchhike its way into the genome of every fruit fly on Earth during the 20th century.) Burt was interested in a particular kind of selfish gene present in slime molds, called an endonuclease. These slash open DNA at very precise spots they recognize and then, by offering themselves as a repair template, can trick a cell into copying them. Burt concluded that the simplicity of this process left it “open to human artifice,” and in a 2003 paper he described how it could be turned into an extinction device.

The paradox Burt had to solve is how something very bad for mosquitoes could also be spread by them. One answer, he saw, was a selfish gene that is harmless if one copy is present but causes sterility if two copies are. (Like humans, mosquitoes have two sets of chromosomes, one from each parent.) Starting with a male mosquito with one copy, the selfish gene will ensure that it ends up in every one of his sperm, rather than just half. That way any offspring with a wild mosquito will also be carriers, as will all their offspring’s offspring. As a result, the gene will rocket through the population.

Eventually, it becomes likely that any mating pair of mosquitoes will both be carriers—and their offspring, with two copies, will be infertile. Quickly, the population will crash, reeling from the genetic poison. On my dog-eared copy of Burt’s paper, I underlined its concluding sentences: “Clearly, the technology described here is not to be used lightly. Given the suffering caused by some species, neither is it obviously one to be ignored.”

Burt is a retiring Canadian whom I located in an office that was largely empty, except for a computer. He served tea that no one drank and answered several of my most provocative formulations about the massive power of biotechnology by saying, “Um, yeah.” He did confide that he’d tried to patent his idea. But it was rejected because he had little experimental evidence at the time to prove it could work. “I wanted to believe I had invented something,” he says.

At the time, Crisanti’s lab had just determined how to genetically engineer Anopheles mosquitoes—a prerequisite for Burt’s ideas to work. They applied to the Gates Foundation for funding, and since then Gates has spent $44 million on the project, easily the largest sum spent to date on gene-drive research.