Introduction

The American chestnut tree had significant ecological, economic, and cultural value to the forests and residents of the eastern United States until it was decimated by disease in the early twentieth century and became all but extinct. There are several current initiatives to make the American chestnut disease-resistant in hopes of reintroducing it to eastern forests. Chestnut de-extinction initiatives highlight a number of issues relevant to agricultural ethics, including the value of biodiversity, ethical arguments concerning genetically modified organisms (GMOs), and the concept of genomic integrity. In addition, the ethical arguments related to chestnut restoration highlight the tensions and commonalities between agricultural and environmental ethics. Ethical concerns regarding chestnut restoration pivot on questions related to whether the value placed on agricultural species is equivalent to or less than the value placed on wild species and whether there is or should be a clear distinction between wild and domesticated species.

Chestnut Blight and Recovery Efforts

Until the early decades of the twentieth century, the American chestnut tree (Castanea dentata) was one of the most abundant forest trees in eastern North America. Its range extended from Maine to Georgia, and it was especially prevalent through the Appalachian Mountains. Chestnuts were valued as a nut crop and as a timber source. The nuts were a reliable food source for people and wildlife, and collecting and roasting chestnuts was a shared cultural event in the region. Chestnut timber was valued because it was strong, straight-grained, easy to work, and rot-resistant. While other woods were considered to be either stronger or more beautiful, wood from chestnuts balanced these qualities, making it suitable for a wide variety of applications, from utility poles and railroad ties to furniture and paneling. Chestnut is also the fastest-growing hardwood in eastern forests, and its economic value through the eighteenth and nineteenth centuries was significant (Freinkel 2007).

In 1904, the chestnut blight fungus (Cryphonectria parasitica) was identified as causing the rapid decline and death of trees in the New York Zoological Park. The blight had been imported to several sites along the eastern seaboard in infected Japanese chestnuts (Castanea crenata), and in spite of costly attempts at control, by the middle of the century it had spread throughout the American chestnut’s range, killing billions of trees. Though not yet fully extinct, the American chestnut is functionally extinct. Very few reproductively mature trees exist. Sprouting roots continue to be fairly common throughout eastern forests, but the sprouts rarely survive to reproduce. With reproduction negligible, there is little hope for the natural evolution of disease resistance. The American chestnut is not expected to recover on its own (Freinkel 2007).

There are several current plans for assisting chestnut recovery. Through most of the twentieth century, attempts to create a disease-resistant hybrid had little success. Although the Chinese chestnut (Castanea mollissima) has enough resistance to allow it to coexist with the fungus, a twentieth-century USDA breeding program produced only a few plants that seemed to be disease-resistant, and these hybrids lost some of the unique characteristics of the American chestnut. In 1983, a group of plant geneticists founded a nonprofit organization, The American Chestnut Foundation (TACF), dedicated to developing disease resistance in American chestnuts and reintroducing them into eastern US forests. Using the technique of backcross breeding, TACF has developed a hybrid that is 15/16 American chestnut and 1/16 Chinese chestnut. The specimens in each generation were selected for traits that included resistance to chestnut blight along with aesthetic similarities to American chestnut, including its larger stature and smaller and sweeter nut. These trees are in a field-testing stage, with plans underway for reintroduction to begin in the near future while further backcrossing takes place (Smith 2012).

Another recovery program, carried out by researchers at the SUNY College of Environmental Science and Forestry, is working to genetically engineer disease-resistant American chestnuts using transgenic methods. Researchers have inserted a small number of genes from Chinese chestnut species, as well as genes from wheat, grapes, and peppers into the genome of American chestnut trees. Trees in field tests have so far shown resistance to chestnut blight that exceeds that of Chinese chestnut species (Powell 2014).

The American Chestnut Foundation is also supporting research to identify surviving disease-resistant American chestnut trees and to cross them with each other. This strategy is a long shot, will take longer to produce a viable genetic line if it does succeed, and carries higher risks of reduced genetic diversity. However, it has the advantage of avoiding most of the political controversies and ethical issues raised by the other two.

Agricultural Ethics and Environmental Ethics

These efforts to restore American chestnuts to the forests of the eastern United States highlight the fuzziness of several accepted boundaries: between environmental ethics and agricultural ethics, between wild and domesticated species, and between conceptions of land managed to be wild and land managed to produce for human needs. After a quick glance at the story of the chestnut’s demise and potential recovery, one might classify the case together with other contemporary recovery and restoration efforts, such as the successful return of wolves to Yellowstone Park and the contemporary effort to revive the passenger pigeon. However, while the rhetoric of those efforts revolves around wilderness and natural value, the rhetoric around the restoration of the chestnut also draws on cultural values, the provision of ecosystem services, and the trees’ economic value.

So, while on the one hand the Chinese chestnut was domesticated as an orchard species, the American chestnut is a wild forest species. But, on the other hand, wild groves of American chestnuts were long managed and harvested, first by native Americans and then by European settlers (Freinkel 2007). Many of the eastern US forests that are most eligible for chestnut restoration are managed for hardwood timber production. A major contributor to restoration efforts is an energy company that invests in this effort because the species’ relatively quick growth is a promising method of restoring mined landscapes and of sequestering carbon. Most of the regulatory oversight and field support for the restoration projects is handled by the US Forest Service.

The restoration effort pragmatically positions the chestnut as straddling the border between nature and agriculture. While philosophers debate whether environmental values are properly human-centered or not, promoters of chestnut restoration mobilize both anthropocentric (human-centered) and nonanthropocentric sentiments. The chestnut de-extinction effort is closely identified with other de-extinction and rewilding programs. The restoration effort also evokes a sense of nostalgia and cultural value, emphasizing the many ways that the chestnut contributed to the rural Appalachian economy, how its dependable mast production was a reliable food source in hard times, and promoting chestnuts as a wild food that might, like wild-harvested mushrooms, again become a desirable commodity.

Ethical Issues Surrounding GM Chestnut Research

The chestnut recovery program pursued at SUNY-ESF aims to provide resistance against chestnut blight by inserting genes that improve the chestnut’s ability to repair damage caused by the fungus (Powell 2014). The appearance of saplings from genetically modified lines is similar to that of the American chestnut in height, crown shape, bur size, and the sweet taste of the nut.

Several characteristics of this species distinguish it from other GMOs. First, as a tree, it is slow to grow and reproduce compared to most crops. Second, it is intended for wild release. Third, all of its wild relatives are functionally extinct. Fourth, its primary use for humans is as timber, though it is expected that people would also gather chestnuts for consumption, and regulatory requirements account for its likely use as food. Each of these unusual characteristics may have an effect on assessment of the ethics of genetic manipulation in this case. Generally, the arguments against GMOs revolve around the existence of unknown health risks, unjustified ecological risks, or undesired social impacts. Specific features of the American chestnut, including its ecological and economic context, are such that the ethical arguments for and against GMOs ought to be reexamined to take these features into account.

Leaving aside the contentious question of whether GM foods present unrecognized risks to human health, the most significant ecological risk from GMOs arises out of concern that the modified organism will mate with wild relatives or with crop landraces, thus creating gene flow that could modify wild species or traditional varieties of crops to unknown effect (Thompson 2007). In the case of the chestnut, however, the American species and its native relatives have all become functionally extinct. There are so few surviving individuals that wild reproduction is rare or nonexistent. Therefore, the promoters of GM chestnut argue, if the GM research project can meet or exceed the level of disease resistance attained by traditional breeding techniques, genetic modification provides the American chestnut with its best chance to avoid extinction entirely without presenting the risk of unintended gene flow to wild populations. Proponents of using GM techniques for de-extinction purposes generally take a pragmatic view: if the desired outcome of ecological, economic, and cultural benefits can be attained at a reasonable cost and level of risk, then concerns about authenticity, historical continuity, and species integrity are beside the point.

Another ecological concern for some GMOs is that they have direct or indirect negative effects on other wild species. For instance, opponents of GMOs were concerned that pollen from Bt corn would poison monarch butterfly larvae. That concern was not substantiated by later studies, but it is likely the case that the increased use of roundup pesticide enabled by genetically modified Bt corn has eliminated butterfly habitat by eliminating the milkweed that monarchs depend on. Again, though, this concern is rather less justified in the case of American chestnut, as the goal is to restore a common forest species to its prior range. Food webs can be expected to alter in response to chestnut reintroduction, but the speed of change is limited by the rate of restoration and the trees’ own growth rate. Promoters for GM chestnut argue that the possible risks of reintroduction should be weighed against the known ecological, economic, and cultural costs of extinction (Powell 2014).

Arguments against the development of genetically modified crops also consider the possibility of negative social impacts, such as the creation of reliance on a single producer of GM seed and the control of seed sources as intellectual property. These anti-GMO arguments are weaker in the case of GM chestnut development than they are in the case of organisms like RoundupReady cotton or soy because the development of the seed source has so far been through a not-for-profit organization and university research programs which claim they do not intend to profit from the seeds. The goal of the programs is to release the seed into the wild for the sake of self-sufficient reproduction. One concern about social impact which is perhaps unique to this case is the charge that the research project has accepted funds from an energy company that causes ecological damage. As noted earlier, the energy company is funding chestnut research because of their potential forest carbon sequestration and to quickly reclaim coal-mining sites. At stake are ethical concerns about relying on tainted money – much the same concern driving the call for divesting from corporations that cause environmental damage (Jones 2014).

One further argument given against the genetic modification project is that its practical long-term success depends on the amount of genetic variation that can be introduced into the modified lineages. If there is insufficient genetic variation to ensure a stable future population of American chestnuts, then the resources required for widespread restoration might achieve similar ends through other forest restoration measures.

Ethical Issues Surrounding Breeding Programs

While there is widespread opposition to biotechnology among the US public, this skepticism does not typically extend to the use of traditional breeding techniques to improve crops or to domesticate wild species. In this context, however, advocates of the GM project emphasize that biotechnology might be less problematic than traditional breeding, and not only on the grounds that, with some luck, genetic modification techniques may yield greater disease resistance. The central matter that is raised when comparing the traditional breeding program with the GM program is what it means to protect the integrity of the genome.

One of the arguments raised against the breeding program tracks the distinction between wild and domesticated species. The Chinese chestnut has been bred as an orchard tree, while the American chestnut, even when it received some cultivation, was not an object of selective breeding and is considered a wild species. This distinctive history can be seen in the different traits of the two species: the American chestnut is much taller, the burs are more difficult to handle, and the nuts are smaller. Some of the inserted genes come from non-chestnut species, but compared to traditional breeding techniques, a much smaller number of genes is required to confer disease resistance. The GMO program argues that an advantage of their technique is that this precision protects the integrity of the American chestnut genome (Powell 2014). Ironically, the charge of violating the integrity of a species is generally leveled at biotechnology rather than being used to defend biotechnology’s benefits relative to traditional breeding techniques (de Vries 2006).

The concept of genomic integrity is intuitively compelling but not well defined. It generally depends on some type of essentialism. Typically it treats species or genomes as static natural kinds. What is problematic about the concept of genetic integrity is that closely related plant species such as Chinese and American chestnuts are capable of reproducing in nature, even if they rarely do, and they share a large percentage of their genes. Thus, it is difficult or impossible to identify a simple criterion which separates one species from another. Moreover, artificial breeding of domesticated species and breeds routinely violates species and genomic integrity in order to improve characteristics which are of particular interest to humans. Whereas the genetically modified chestnut line includes only a small number of new genes, the backcrossed line carries about 6 % or 2000 genes from the Chinese species. However, because these species are closely related, a large percentage of their genes are likely identical or very similar (Freinkel 2007; Powell 2014).

The GM project uses the thesis that genetic modification is different in kind from traditional breeding to highlight the advantage of biotechnology’s precision. This thesis is usually used to paint biotechnology as unproven and untrustworthy. However, in this context it is used to garner support for biotechnology by coupling the thesis that it is different in kind from other breeding techniques with the value distinction between the wild and domesticated. This argument allies biotechnology with a value judgment that the less intervention there is in a genome, the more genomic integrity is preserved. This argument also sidesteps the usual association between biotechnology and agribusiness by implying that even if genetic engineering has harmful social and environmental consequences in agricultural environments, in the context of de-extinction it can be used to manage wildness without domesticating it. While the breeding programs blur the distinction between wild forest and managed resource, the GM program makes use of rhetoric that maintains conceptual distance between agriculture and nature while promoting a role for technological intervention in managing nature (Biermann 2014).

De-extinction Ethics

The goal of bringing back species from extinction has raised ethical questions which can be separated from issues raised by the particular techniques that might be used to achieve that goal. Even if a critic of de-extinction is not opposed to sophisticated genetic manipulation, there are still potential reasons for exercising ethical caution. When a species goes extinct, extinction is the result of a complicated nexus of natural and anthropogenic causes. If technology is able to circumvent those causes to reverse the extinction, critics argue, this technological rescue takes several risks. It risks replacing the power of nature with the power of technology, it risks ignoring natural history, and it risks accomplishing a deficient fix that neglects larger causes (Minteer 2014). The role that chestnut plays in this debate is to blur the distinction between restoration and de-extinction. Unlike most other candidates for de-extinction, the American chestnut is not fully extinct, its extinction was not caused by habitat loss, and its role in the ecosystem where it would be replaced is not distant history. And once again, its status as a species of agricultural and cultural value deflects some of the charge that there is an ethical penalty for exercising technological control, since agricultural species are routinely and unproblematically subjects of selective breeding and of intensive cultivation. In the de-extinction debate, as in the debate about the ethics of GM crops, the case of American chestnut restoration tests the principles at stake.

Summary

Because it blurs the distinction between wild and agricultural species, the case of chestnut breeding and GM programs presents a new test of standard criticisms of GMOs. At the same time it blurs the distinction between agricultural and environmental ethics. Because some of the newest conservation concerns and methods—such as novel ecosystems, the widespread development of ecosystem services throughout our wild and built landscapes, and the integration of wildlife habitat with agricultural lands—also soften this distinction, we can expect these questions to become ever more pressing.

Cross-References