The decision to use a new technology often involves a risks-benefits assessment.  In some situations the potential drawbacks are known, in others it is not unusual to discover the rarer problems as we go along.  New drugs are carefully evaluated in laboratory studies and clinical trials, but a great deal of information is gathered after large-scale use has been approved.  Collection and analysis of ‘adverse events’ reports is an important mechanism to reveal problematic issues that appear infrequently.  

Researchers do their best to anticipate difficulties, but with complex systems making accurate predictions is often challenging.  When we begin to envision using gene drives – self-transmissible, autonomous CRISPR editing devices able to re-write the genes of an entire species – to alter whole ecosystems we really have to consider how to recognize and manage unforeseen consequences.  Once a gene drive is unleashed into the wild it cannot be recalled.  Investigators have proposed that reversal drives or immunizing drives could be released to undo any undesirable effects of a gene drive.  However, both gene drives and remediation strategies are hypothetical entities; no one can be sure if either will work as hoped.  In addition, while it may be possible to destroy or inactivate rogue gene drives, the consequential damages they inflict on an ecosystem may be irreversible.  

It is clear that gene drives and CRISPR editing may provide immense benefits.  Proponents are justifiably enthusiastic and some plans to use gene drives are clearly overselling the promise and underplaying the potential risks.  The issues will require careful scrutiny to weigh the risks and public consent to proceed.  

Our environmental stewardship track record leaves much to be desired and it is not clear that humans have the knowledge and wisdom to use gene drives safely.  Ecosystems are only vaguely comprehended and we have not done a good job managing unforeseen events because it is impossible to take all factors into consideration during the planning and testing process.  Migratory Monarch butterflies in the American Midwest are now under severe threat due a combination of environmental and economic factors impacting agricultural and habitat conservation practices.  Corn and soybean yields may be record-breaking, but it is sad to consider that there may soon be no room in our new world for Monarch butterflies.