But now more than 1 million species are at risk of extinction, and millions more are in decline. This biodiversity crisis is our fault, driven by the combined tragedies of overfishing, deforestation, pollution and the climate emergency. And the irony is that, if we hope to go on thriving, we may need to intervene even more dramatically. Indeed, our survival — and that of the world that sustains us — may depend on our willingness to make nature a lot less natural.
Today, the functionally extinct American chestnut tree, once the backbone of eastern North American forests, is on the precipice of a comeback. That’s because scientists added a wheat-derived gene to the tree’s genome that neutralizes the fatal acid produced by the fungus targeting the trees. It’s a feat that will probably make some recoil, accustomed as we are to the idea that genetically modified organisms are suspect or even dangerous. But it’s gained support from other scientists and from the American Chestnut Foundation. People have started asking for seedlings to plant in their yards, and the Eastern Band of Cherokee Indians in North Carolina has signed on to plant fungus-resistant American chestnuts on tribal land.
This transformative work is a product of synthetic biology, a suite of technologies that allow us to engineer organisms’ genomes directly. Combining computer science with genomic analysis and gene editing, this emerging field involves deciphering which genes have some beneficial effect in one organism — such as the acid resistance that could save the American chestnut — and inserting those genes into another. As our knowledge of genetics grows, these technologies will make it possible for us to help species adapt to a world that might otherwise become unlivable for them. Synthetic biology may be our most powerful tool in creating a future that is both biodiverse and filled with people.
Older forms of genetic modification through conventional breeding were relatively scattershot, making it more likely that even a beneficial change would come with dubious trade-offs. In selecting for, say, more delicious apples, you might inadvertently introduce a mutation that made your fruit tree more attractive to pests. Those traditional approaches are also slow, which makes it difficult to respond quickly to urgent crises like those caused by ocean acidification or protracted wildfire seasons.
With synthetic biology, by contrast, we can work with far greater precision, directly targeting genes that result in beneficial characteristics, meaning we can often introduce a single, specific change without compromising the other DNA that has allowed an organism to thrive. Synthetic biology also operates more quickly than traditional approaches to conservation, since our growing libraries of genes make it much easier to predict what might work best under a given set of circumstances or in response to a particular need. Traditional approaches such as manually culling invasive species often taking generations before they make a real difference. Synthetic biology, by contrast, can alter species at a pace that matches the urgency of today’s crises. We might, for example, use “gene drive” technology to effectively sterilize malarial mosquitoes or tortoise-killing invasive rodents, solving a pressing problem without risking harm to the rest of an ecosystem.
To date, conservation-minded synthetic biology has had the most success in agriculture. The papaya industry in Hawaii, for example, was saved from devastation by introducing a short stretch of virus DNA into plants that makes them resistant to infection. Soybean and wheat varieties have been made drought-tolerant with the addition of genes that evolved in sunflower. Golden rice provides nutritional vitamin A thanks to the addition of two genes — one from daffodil and another from a bacterium — to the rice genome. These and other approved-as-safe agricultural products improve yield and nutrition, often in less-than-ideal growing conditions.
There is work underway that could help animal species, as well. A program led by the nonprofit Revive & Restore intends to engineer resistance to sylvatic plague into the genomes of endangered black-footed ferrets by adding genes that evolved in domestic ferrets. A first and pivotal step in this project was the birth last year of a healthy black-footed ferret kit, Elizabeth Ann, a genetic clone of a ferret that died more than 30 years ago. The introduction of her DNA into the black-footed ferret gene pool — which had grown dangerously shallow as populations shrunk — will provide a dose of diversity that will help the ferrets avoid excessive inbreeding and increase their ability to fight off infectious disease.
Synthetic biology also allows us to tackle a given problem — the collapse of oceanic ecosystems, for example — from multiple angles at once. Thus, while some synthetic biologists are developing approaches to help corals and fish survive in warmer water, other groups are working to create microbes that break down the plastics polluting our oceans, or to engineer plants that produce healthy oils like omega-3 and thereby reduce our reliance on oceanic fish for these substances. Together, these engineered organisms promise to maintain and even improve the quality of our planet’s habitats, benefiting us and the other species that share these spaces.
Synthetic biology gives us greater power to alter species than our ancestors had, and some will find that troubling. But the fact remains that we are already changing the natural world in ways that far outstrip its ability to respond. As we look to the future, we can choose to use synthetic biology to make even more with less, to protect wild species and wild spaces, and to do so in a sustainable way. Or we can reject our new biotechnologies and risk losing everything that we claim to protect.