Why the ‘molecular scissors’ metaphor for understanding CRISPR is misleading

Last week I read an article about CRISPR, the latest tool scientists are using to edit DNA. It was a great piece – well researched, beautifully written, factually accurate. It covered some of the amazing projects scientist are working on using CRISPR, like bringing animals back from extinction and curing diseases. It also gave me the heebies, but not for the reason you might expect.

My unease was the echo of a feeling I’d had during the early days of my PhD, when some fellow malaria researchers made a discovery that was reported on the news. I was thrilled for them, but I understood the incremental nature of the work they were doing. I knew that in a real-world, drugs-in-the-clinic sense, we were no closer to a breakthrough than we’d been the day before. I thought the reporters had communicated that clearly. Five minutes later my Dad called to ask if I was out of a job, and what I was going to do now that malaria was cured.

I don’t pretend to understand all the myriad reasons for the...