Last year, researchers and policy experts expressed concerns about a — then hypothetical — way to use cutting-edge genetic techniques to rapidly alter entire populations of plants or animals. Such a technique, called a gene drive, could lead to un­anticipated ecological consequences, they cautioned (K. A. Oye et al. Science 345, 626–628; 2014). The authors discussed safety guidelines, made general policy recommendations, and met with some criticism: why raise alarm over a technique that did not yet exist?

Less than a year later, it did exist. Two groups have now published examples of gene drives engineered using CRISPR, a versatile and relatively easy system that allows researchers to make changes to genomes with pinpoint precision (see page 16). Crucially, it enabled a designated mutation to copy itself from one chromosome in a pair to the other, ensuring that it was passed to offspring and allowing it to spread rapidly through a population (V. M. Gantz and E. Bier Science 348, 442–444 (2015) and J.E.DiCarloetal.Preprintat;2015).

Engineering a lab animal or agricultural crop is one thing. Wielding the power to alter an entire wild population is quite another. The process understandably raises concern. But it could hold great benefit: mosquitoes could be tweaked so that they cannot carry malaria, or an endangered species could be saved by wiping out an invasive competitor.

Last week, the debate gained momentum when the US National Academy of Sciences held its first meeting to evaluate the potential benefits and risks of gene drives. As is often the case by the time such controversies start to attract mainstream attention, specialist researchers have been thrashing out the issue for years. These discussions have already produced various sets of guidelines on the use of gene drives, and the academy and others should use this literature as a starting point.

What is new is the advent of CRISPR. This adds extra dimensions to the debate, because it makes gene drives much easier and could dramatically accelerate the timeline for a potential release — accidental or intentional. Researchers and funding agencies should take note, and efforts to understand the ecological consequences of a gene drive should be made an urgent priority. Regulators and the wider world need to keep pace with the rapid development of CRISPR technology, and there is little time to waste.