It couldn’t be easier to make sweeping edits on a computer document. If I were so inclined, I could find every instance of the word “genome” in this article and replace it with the word “cake”.

Now, a team of scientists from Yale and Harvard Medical School have done a similar trick for DNA. Geneticists have long been able to edit individual genes, but this group has developed a way of rewriting DNA en masse. And they’ve used it to recode the entire cake genome of a bacterium.

Their success was possible because the same genetic code underlies all life. It’s written in the four letters (nucleotides) that chain together to form DNA: A, C, G and T. Every set of three