It is fitting that viruses and bacteria feature prominently in The Code Breaker, since contemporary gene-editing technologies are inspired by the battle between the two diminutive giants. The focus on viruses is doubly important in the age of pandemics, because the coronavirus and other vectors will continue to evolve and present new challenges. However, underlining these pertinent issues is Isaacson’s admiration for the complex workings such simple organisms can orchestrate. Viruses, for instance, are described as “tiny packets of genetic material” that “are essentially lifeless on their own” (32). Yet viruses can hijack a cell’s machinery to replicate themselves, wreaking havoc on their host, as seen with COVID-19. It is the very simplicity of a virus’s genetic material that makes it so easy to replicate. As Isaacson says, “In SARS-COv-2, the RNA is about 29,900 base pairs long, compared to more than three billion in human DNA” (394). The COVID-19 virus can code for a mere 29 proteins, one of which is the dreaded spike protein that can wriggle into cells lining human lungs, intestines, the liver, and more.

If viruses are ingenious, bacteria, who have fought viruses far longer than human beings, are equally wily opponents. They remember a virus’s code, adapt some of their genetic material to mimic it (as CRISPRs), and use a scissors-like enzyme to chop up the matching genetic code.