Cows on a pasture, who, among other mammals, could experience immense suffering from the New World screwworm.
Combining CRISPR genome editing with the natural phenomenon of gene drive allows us to rewrite the genomes of wild organisms. The benefits of saving children from malaria by editing mosquitoes are obvious and much discussed, but humans aren't the only creatures who suffer. If we gain the power to intervene in a natural world "red in tooth and claw," yet decline to use it, are we morally responsible for the animal suffering that we could have prevented?
Given the power to alter the workings of the natural world, are we morally obligated to use it?
The scenario that may redefine our relationship with the natural world begins with fine clothing. You're dressed to the nines for a formal event, but you arrived early, and it's such a beautiful day that you decided to take a stroll by the nearby lake. Suddenly, you hear the sound of splashing and screams. A child is drowning! Will you dive in to save them? Or let them die, and preserve your expensive outfit?
The philosopher Peter Singer posited this scenario to show that we are all terrible human beings. Just about everyone would save the child and ruin the outfit... leading Singer to question why so few of us give equivalent amounts of money to save children on the other side of the world. The Against Malaria Foundation averages one life saved for every $7000.
But despite having a local bias, our moral compasses aren't completely broken. You never even considered letting the child drown because the situation wasn't your fault. That's because the cause of the problem simply isn't relevant: as the one who could intervene, the consequences are on your head. We are morally responsible for intervening in situations we did not create.
There is a critical difference between Singer's original scenario and the one above: in his version, it was a muddy pond. Any adult can rescue a child from a muddy pond, but a lake is different; you can only save the child if you know how to swim. We only become morally responsible when we acquire the power to intervene.
Few would disagree with either of these moral statements, but when they are combined with increasingly powerful technologies, the implications are deeply unsettling. Given the power to alter the workings of the natural world, are we morally obligated to use it? Recent developments suggest we had best determine the answer soon because, technologically, we are learning to swim. What choices will we make?
Gene drive is a natural phenomenon that occurs when a genetic element reliably spreads through a population even though it reduces the reproductive fitness of individual organisms. Nature has evolved many different mechanisms that result in gene drive, so many that it's nearly impossible to find an organism that doesn't have at least one driving element somewhere in its genome. More than half of our own DNA comprises the broken remnants of gene drives, plus a few active copies.
Scientists have long dreamed of harnessing gene drive to block mosquito-borne disease, with little success. Then came CRISPR genome editing, which works by cutting target genes and replacing them with a new sequence. What happens if you replace the original sequence with the edited version and an encoded copy of the CRISPR system? Gene drive.
CRISPR is a molecular scalpel that we can use to cut, and therefore replace, just about any DNA sequence in any cell. Encode the instructions for the CRISPR system adjacent to the new sequence, and genome editing will occur in the reproductive cells of subsequent generations of heterozygotes, always converting the original wild-type version to the new edited version. By ensuring that offspring will all be born of one sex, or by arranging for organisms that inherit two copies of the gene drive to be sterile, it's theoretically possible to cause a population crash.
(Credit: Esvelt)
When my colleagues and I first described this technology in 2014, we initially focused on the imperative for early transparency. Gene drive research is more like civic governance than traditional technology development: you can decline a treatment recommended by your doctor, but you can’t opt out when people change the shared environment. Applying the traditional closeted model of science to gene drive actively denies people a voice in decisions intended to affect them - and reforming scientific incentives for gene drive could be the first step to making all of science faster and safer.
But open gene drive research is clearly aligned with virtually all of our values. It's when technology places our deepest moral beliefs in conflict that we struggle, and learn who we truly are.
Two of our strongest moral beliefs include our reverence for the natural world and our abhorrence of suffering. Yet some natural species inherently cause tremendous suffering. Are we morally obligated to alter or even eradicate them?
To anyone who doubts that the natural world can inflict unimaginable suffering, consider the New World screwworm.
Judging by history, the answer depends on who is doing the suffering. We view the eradication of smallpox as one of our greatest triumphs, clearly demonstrating that we value human lives over the existence of disease-causing microorganisms. The same principle holds today for malaria: few would argue against using gene drive to crash populations of malarial mosquitoes to help eradicate the disease. There are more than 3500 species of mosquitoes, only three of which would be affected, and once malaria is gone, the mosquitoes could be allowed to recover. It would be extremely surprising if African nations decided not to eradicate malaria.
The more interesting question concerns our moral obligations to animals in the state of nature.
To anyone who doubts that the natural world can inflict unimaginable suffering, consider the New World screwworm, Cochyliomyia hominivorax. Female screwworm flies lay their eggs in open wounds, generating maggots that devour healthy tissue, gluttonously burrowing into the flesh of their host until they drop, engorged and sated, to metamorphose. Yet before they fall, the maggots in a wound emit a pheromone attracting new females, thereby acting as both conductors and performers in a macabre parade that consumes the host alive. The pain is utterly excruciating, so much so that infested people often require morphine before doctors can even examine the wound. Worst of all, the New World screwworm specializes in devouring complex mammals.
Every second of every day, hundreds of millions of animals suffer the excruciating agony of being eaten alive. It has been so throughout North and South America for millions of years. Until 2001, when humanity eradicated the last screwworm fly north of Panama using the “sterile insect technique�. This was not done to protect wild animals or even people, but for economic reasons: the cost of the program was small relative to the immense damage wrought by the screwworm on North American cattle, sheep, and goats. There were no obvious ecological effects. Despite being almost completely unknown even among animal rights activists, the screwworm elimination campaign may well have been one of the greatest triumphs of animal well-being.
Unfortunately, sterile insect technique isn't powerful enough to eradicate the screwworm from South America, where it is more entrenched and protected by the rougher terrain. But gene drive is.
Contrary to news hype, gene drive alone can't cause extinction, but if combined with conventional measures it might be possible to remove targeted species from the wild. For certain species that cause immense suffering, we may be morally obligated to do just that.
(Credit: Esvelt)
South Americans may well decide to eradicate screwworm for the same economic reasons that it was eradicated from North America: the fly inflicts $4 billion in annual damages on struggling rural communities that can least afford it. It need not go extinct, of course; the existence of the sterile insect facility in Panama proves that we can maintain the screwworm indefinitely in captivity on already dead meat.
Yet if for some reason humanity chooses to leave the screwworm as it is - even for upstanding moral reasons, whatever those may be - the knowledge of our responsibility should haunt us.
Tennyson wrote,
Are God and Nature then at strife,
That Nature lends such evil dreams?
So careful of the type she seems,
So careless of the single life.
Evolution by natural selection cares nothing for the single life, nor suffering, nor euphoria, save for their utility in replication. Theoretically, we do. But how much?
[Editor's Note: This story was originally published in May 2018. We are resurfacing archive hits while our staff is on vacation.]
Declining numbers of insects, coupled with climate change, can have devastating effects for people in more ways than one. But clever use of technologies like AI could keep them buzzing.
And because many insects serve as food for other species—bats, birds and freshwater fish—they’re an integral part of the ecosystem’s food chain. “If you like to eat good food, you should thank an insect,” says Scott Hoffman Black, an ecologist and executive director of the Xerces Society for Invertebrate Conservation in Portland, Oregon. “And if you like birds in your trees and fish in your streams, you should be concerned with insect conservation.”
Deforestation, urbanization, and agricultural spread have eaten away at large swaths of insect habitat. The increasingly poorly controlled use of insecticides, which harms unintended species, and the proliferation of invasive insect species that disrupt native ecosystems compound the problem.
“There is not a single reason why insects are in decline,” says Jessica L. Ware, associate curator in the Division of Invertebrate Zoology at the American Museum of Natural History in New York, and president of the Entomological Society of America. “There are over one million described insect species, occupying different niches and responding to environmental stressors in different ways.”
Jessica Ware, an entomologist at the American Museum of Natural History, is using DNA methods to monitor insects.
Credit:D.Finnin/AMNH
In addition to habitat loss fueling the decline in insect populations, the other “major drivers” Ware identified are invasive species, climate change, pollution, and fluctuating levels of nitrogen, which play a major role in the lifecycle of plants, some of which serve as insect habitants and others as their food. “The causes of world insect population declines are, unfortunately, very easy to link to human activities,” Lehmann says.
Climate change will undoubtedly make the problem worse. “As temperatures start to rise, it can essentially make it too hot for some insects to survive,” says Emily McDermott, an assistant professor in the Department of Entomology and Plant Pathology at the University of Arkansas. “Conversely in other areas, it could potentially also allow other insects to expand their ranges.”
Without Pollinators Humans Will Starve
We may not think much of our planet’s getting warmer by only one degree Celsius, but it can spell catastrophe for many insects, plants, and animals, because it’s often accompanied by less rainfall. “Changes in precipitation patterns will have cascading consequences across the tree of life,” says David Wagner, a professor of ecology and evolutionary biology at the University of Connecticut. Insects, in particular, are “very vulnerable” because “they’re small and susceptible to drying.”
For instance, droughts have put the monarch butterfly at risk of being unable to find nectar to “recharge its engine” as it migrates from Canada and New England to Mexico for winter, where it enters a hibernation state until it journeys back in the spring. “The monarch is an iconic and a much-loved insect,” whose migration “is imperiled by climate change,” Wagner says.
Warming and drying trends in the Western United States are perhaps having an even more severe impact on insects than in the eastern region. As a result, “we are seeing fewer individual butterflies per year,” says Matt Forister, a professor of insect ecology at the University of Nevada, Reno.
There are hundreds of butterfly species in the United States and thousands in the world. They are pollinators and can serve as good indicators of other species’ health. “Although butterflies are only one group among many important pollinators, in general we assume that what’s bad for butterflies is probably bad for other insects,” says Forister, whose research focuses on butterflies. Climate change and habitat destruction are wreaking havoc on butterflies as well as plants, leading to a further indirect effect on caterpillars and butterflies.
Different insect species have different levels of sensitivity to environmental changes. For example, one-half of the bumblebee species in the United States are showing declines, whereas the other half are not, says Christina Grozinger, a professor of entomology at the Pennsylvania State University. Some species of bumble bees are even increasing in their range, seemingly resilient to environmental changes. But other pollinators are dwindling to the point that farmers have to buy from the rearing facilities, which is the case for the California almond industry. “This is a massive cost to the farmer, which could be provided for free, in case the local habitats supported these pollinators,” Lehmann says.
For bees and other insects, climate change can harm the plants they depend on for survival or have a negative impact on the insects directly. Overly rainy and hot conditions may limit flowering in plants or reduce the ability of a pollinator to forage and feed, which then decreases their reproductive success, resulting in dwindling populations, Grozinger explains.
“Nutritional deprivation can also make pollinators more sensitive to viruses and parasites and therefore cause disease spread,” she says. “There are many ways that climate change can reduce our pollinator populations and make it more difficult to grow the many fruit, vegetable and nut crops that depend on pollinators.”
Disease-Causing Insects Can Bring More Outbreaks
While some much-needed insects are declining, certain disease-causing species may be spreading and proliferating, which is another reason for human concern. Many mosquito types spread malaria, Zika virus, West Nile virus, and a brain infection called equine encephalitis, along with other diseases as well as heartworms in dogs, says Michael Sabourin, president of the Vermont Entomological Society. An animal health specialist for the state, Sabourin conducts vector surveys that identify ticks and mosquitoes.
Scientists refer to disease-carrying insects as vector species and, while there’s a limited number of them, many of these infections can be deadly. Fleas were a well-known vector for the bubonic plague, while kissing bugs are a vector for Chagas disease, a potentially life-threatening parasitic illness in humans, dogs, and other mammals, Sabourin says.
As the planet heats up, some of the creepy crawlers are able to survive milder winters or move up north. Warmer temperatures and a shorter snow season have spawned an increasing abundance of ticks in Maine, including the blacklegged tick (Ixodes scapularis), known to transmit Lyme disease, says Sean Birkel, an assistant professor in the Climate Change Institute and Cooperative Extension at the University of Maine.
Coupled with more frequent and heavier precipitation, rising temperatures bring a longer warm season that can also lead to a longer period of mosquito activity. “While other factors may be at play, climate change affects important underlying conditions that can, in turn, facilitate the spread of vector-borne disease,” Birkel says.
For example, if mosquitoes are finding fewer of their preferred food sources, they may bite humans more. Both male and female mosquitoes feed on sugar as part of their normal behavior, but if they aren’t eating their fill, they may become more bloodthirsty. One recent paper found that sugar-deprived Anopheles gambiae females go for larger blood meals to stay in good health and lay eggs. “More blood meals equals more chances to pick up and transmit a pathogen,” McDermott says, He adds that climate change could reduce the number of available plants to feed on. And while most mosquitoes are “generalist sugar-feeders” meaning that they will likely find alternatives, losing their favorite plants can make them hungrier for blood
Similar to the effect of losing plants, mosquitoes may get turned onto people if they lose their favorite animal species. For example, some studies found that Culex pipiens mosquitoes that transmit the West Nile virus feed primarily on birds in summer. But that changes in the fall, at least in some places. Because there are fewer birds around, C. pipiens switch to mammals, including humans. And if some disease-carrying insect species proliferate or increase their ranges, that increases chances for human infection, says McDermott. “A larger concern is that climate change could increase vector population sizes, making it more likely that people or animals would be bitten by an infected insect.”
Science Can Help Bring Back the Buzz
To help friendly insects thrive and keep the foes in check, scientists need better ways of trapping, counting, and monitoring insects. It’s not an easy job, but artificial intelligence and molecular methods can help. Ware’s lab uses various environmental DNA methods to monitor freshwater habitats. Molecular technologies hold much promise. The so-called DNA barcodes, in which species are identified using a short string of their genes, can now be used to identify birds, bees, moths and other creatures, and should be used on a larger scale, says Wagner, the University of Connecticut professor. “One day, something akin to Star Trek’s tricorder will soon be on sale down at the local science store.”
Scientists are also deploying artificial intelligence, or AI, to identify insects in agricultural systems and north latitudes where there are fewer bugs, Wagner says. For instance, some automated traps already use the wingbeat frequencies of mosquitoes to distinguish the harmless ones from the disease-carriers. But new technology and software are needed to further expand detection based on vision, sound, and odors.
“Because of their ubiquity, enormity of numbers, and seemingly boundless diversity, we desperately need to develop molecular and AI technologies that will allow us to automate sampling and identification,” says Wagner. “That would accelerate our ability to track insect populations, alert us to the presence of new disease vectors, exotic pest introductions, and unexpected declines.”