Originally published in Trends (the electronic newsletter of the Section of Environment, Energy, and Resources of the American Bar Association)
Genetically modifying wild populations may be able to help conserve biodiversity, and new “gene drives” could eradicate dangerous disease vectors. But even if we can, should we?
Threatened coral reefs
Individually, corals are unimpressive: small squishy marine invertebrates that form colonies of polyps. They grow fixed exoskeletons, which accumulate into massive reefs that offer habitats for numerous other species.
But corals are being squeezed by climate change. On one side, warmer water causes them to eject their symbiotic internal algae that provide nutrition. The corals then lose color and die. On the other side, atmospheric carbon dioxide—the most important greenhouse gas—dissolves into ocean water. The resulting acidic water dissolves corals’ calcium carbonate exoskeleton. Together, warmer ocean water and its acidification may constitute the greatest current threat to the natural world: loss of irreplaceable, diverse ecosystems.
What is to be done? We are trying to cut greenhouse gases emissions and develop technologies to remove them from the air, but progress has been slow and disappointing. Even solar geoengineering—the proposal to counter climate change by making the planet more reflective—would not prevent ocean acidification.
Biotechnology may offer a remedy. Scientists are investigating whether they could genetically modify corals to withstand warmer, more acidic waters. If such biotech corals were introduced, they would outcompete the vulnerable, natural ones. Proponents call this “assisted evolution,” because if the environmental changes were slower, then natural selection would produce a similar result. If technically possible—and it seems to be—then we could assume the management of corals and other vital, valued ecosystems.
Of course, “could” indicates neither “should” nor “would.” Perhaps we should not or would not genetically modify corals because of the risks of the engineered genes flowing to other species or being accidentally released. Or because such modification might undermine efforts to reduce greenhouse gas emissions or would be hubristically controlling nature. These scientific and ethical questions aside, who, if anyone, has the legitimate authority to decide to genetically modify a wild species?
Malaria and mosquitoes
Allow me to further complicate and amplify the stakes. Some mosquitos transmit malaria, which was once rife in the southern United States but was eradicated there and throughout industrialized countries by the draining of wetlands and the use of pesticides. However, malaria remains a leading cause of death, particularly of young children, in sub-Saharan Africa, even topping the list in some countries. Although the disease’s impact has generally been slowly declining in Africa through similar techniques used here a century ago, more than half of a million people still succumb annually. And for each death, about 500 times as many who contract malaria will suffer and survive.
Could we eradicate malaria-carrying mosquitos through biotechnology? The challenge here is that those individuals with a genetic modification designed to inhibit reproduction would have few or no offspring and thus fail to pass on the trait, while the “natural” ones would reproduce normally. As a result, the genetic modification would quickly disappear from the wild.
Enter gene drives—genetic engineering on overdrive. These genetic elements cause all offspring of a genetically modified parent to inherit the modifications, in contrast to the typical half of offspring that would receive such a gene. Through this mechanism, a genetic alteration could be “driven” through a population, despite the constraint described above. The gene drives could cause all offspring to be male, make members of one sex infertile, or propagate a recessive gene for infertility. With any of these modifications, the local population would sharply decline and perhaps disappear entirely. Of the roughly 3,500 mosquito species, only a few transmit most malaria, and ecologists are not particularly concerned about the negative consequences of their absence. Gene drives have been successfully developed in a few species, including malaria-carrying mosquitos, in the lab. Field tests may occur in the near future.
Gene drive technology poses similar ethical and governance challenges as genetically modifying corals and other threatened species, but now in sharper relief. The risk-risk tradeoff is no longer within nature—should coral reefs face climate change or our genetic tinkering?—but instead between nature and humans—should we extinguish a species to reduce our disease burden? Such questions are complicated, or perhaps simplified, by the fact that most of the ethical hand-wringing takes place in wealthy, malaria-free countries while relatively poor sub-Saharan Africans do the suffering.
Biocentrism and anthropocentrism
Debates about how humans should relate to the natural world are challenging and persist. One might turn to law for guidance, but it has plural, sometimes competing, objectives. The mission of the U.S. Environmental Protection Agency is “to protect human health and the environment.” International agreements are no clearer, with the Convention on Biological Diversity aiming for both “the conservation of biological diversity [and] the sustainable use of its components.” Legal discussions of specific proposals to genetically modify wild species remain uncommon. For example, the U.S. Department of Agriculture is considering approving a genetically modified chestnut tree that could withstand a fungal blight that eradicated the tree in the wild a century ago.
Outside of the law, science writer Elizabeth Kolbert explores these debates in her new book, Under a White Sky (Crown 2021), and Charles Mann traces their postwar history in his The Wizard and the Prophet (Vintage 2019). Earlier, at the dawn of the 20th century, John Muir called for nature’s ecocentric preservation while Gifford Pinchot for its anthropocentric conservation (Lukas Keel,Frenemies John Muir and Gifford Pinchot, 41 Human. (Winter 2020)). Even the book of Genesis addresses this. Should humankind “rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground” (Genesis 1:26 (New International))? Should we “take care of” (Genesis 2:15 (New International)) the garden that we have inherited so that we may thrive in it? Or would intentionally altering or eradicating wild species be the technological equivalent of eating the fruit of the tree of the knowledge, posing the risk that humanity loses its natural Eden? Such questions are each year becoming less theoretical, and more real.