By Karla Renschler
Is evolution about to get even more controversial? In an article in Science Express, the journal Science's forum for rapid publication of timely articles, a team of researchers makes a forceful argument for the use of "applied evolutionary biology"-the conscious manipulation and guidance of evolutionary processes in plants and animals -- in order to mitigate the negative impacts of human activity on the environment.
With a growing population of over 7 billion, it is widely understood that human beings are significantly altering the global environment. Some scientists believe we've entered a new geological era -- the Anthropocene -- in which Earth is now dominated by human impacts. One of the most important and dangerous of these impacts is how human influences drive rapid evolutionary changes, in species ranging from bacteria and pathogens to plants, insects, and other animals. These changes are giving rise to enormous challenges in the fields of health, agriculture, natural resource management, and conservation, which in turn threaten us humans.
In the Science review article, a team of researchers, including UCLA's Thomas B. Smith, explores numerous examples of what Smith and colleagues have called "prescriptive evolution" in another paper published in the Annual Review of Ecology, Evolution and Systematics. They analyze the enormous potential of such strategies to meet some of the most difficult environmental challenges facing the planet and people today and in the future.
According to the scientists, humans affect the evolution of plant and animal species in two main ways. First, the widespread use of drugs and pesticides meant to control populations of undesirable species, such as bacteria, weeds, and insects, also breeds resistance and thus contributes to the rise of unmanageable and destructive "super" diseases, weeds, and bugs. Second, the rapid environmental change caused by human activities is outpacing the ability of natural populations to adapt, leading to the loss of species and biodiversity. Both of these challenges are characterized by the evolutionary mismatch of species' natural adaptations to the new human-influenced environments that they are exposed to.
Rather than allow this unconstrained evolution to occur haphazardly, the researchers explain that prescriptive evolution offers scientists a tool to guide the direction of evolutionary change in ways more beneficial to humankind. Such evolutionary approaches include both those that are already well tried and those that technological advances have only recently made possible.
Well-tested methods of applied evolutionary biology have already been important in responding to the rise of antibiotic and pesticide resistance in diseases and pests. These approaches include planting crops that are susceptible to bugs as well as using combination drugs to target resistant diseases.
Scientists have also tried more controversial evolutionary strategies to help species adapt to their swiftly changing environments. Genetic modification and selection for crops that are pest-resistant and tolerant to changes in climate have improved food security for expanding human populations. Strategically selected plants and animals used in environmental restoration help recovering populations withstand future climate stressors and pressures.
But because some of these approaches are still experimental, they may raise the risk of unintended negative consequences. And the scientists stress the need for extensive monitoring of these evolutionary approaches in order to maintain control of changes that are happening, especially if such methods are implemented on a widespread scale.
Despite the great potential of prescriptive evolution, some have also raised objections to the manipulation of evolution on an ethical basis, criticizing it for influencing the "natural course" of evolution. The authors of the paper address this concern by reminding readers that humans are already dramatically affecting the environment in ways that are neither intentional nor strategic. Thus, it may be smarter to harness the power of evolutionary approaches rather than let human impact wreck havoc on existing natural populations.
Another concern about prescriptive evolution is that many of its approaches require short-term private sacrifices in order to secure long-term public goods. For example, farmers who grow crops susceptible to pests, in order to ensure that their populations don't become resistant to pesticides, will lose some of their immediate harvest so that resistance to insecticides does not build up in the long-term. In order to mitigate this predicament, the researchers suggest using public policy to ease some of the costs to private individuals.
Although prescriptive evolution is an emerging field that raises a number of difficult questions, the researchers argue that these approaches could provide a robust toolbox for securing a sustainable future not just for human populations but also for the rest of the planet's inhabitants.
Click here for an interview with Tom Smith on "prescriptive evolution."
Photo by Ruth Ellison of Melbourne Museum display on Charles Darwin's On the Origin of Species.