In today’s Boston Globetoday’s Boston Globe, Anthony Doerr praises Microcosm: E. coli and the New Science of Life as “quietly revolutionary.”

As scientists study the genes of more and more strains of E. coli, they’re finding that foreign DNA has been steadily pouring into the genome. Not only is E. coli mutating within itself, it’s also claiming new genes from elsewhere.

A major source of this input is viruses. As Zimmer notes, “Viruses are quickly losing their reputation as insignificant parasites.” Viruses, we now know, pick up genes from one host and plug them like cassette tapes into the genome of a new host. This sort of gene-leapfrogging is called horizontal gene transfer, and it’s not limited to bacteria