Here’s an interesting fact that you might want to swirl around in your head, along with a sip of the morning coffee: Scientists have now assembled and archived more than 12 million genome sequences of SARS-CoV-2, the virus that causes COVID-19.

    Each of those sequences is derived from a sample of saliva or other material drawn from an individual patient. Each consists of almost thirty thousand genomic letters in the alphabet of DNA (as translated, for stability during lab work, from the less stable alphabet of the virus’s RNA genome). Together they constitute data points reflecting the evolutionary history of SARS-CoV-2, from its earliest form as detected in Wuhan to its latest variants. Scientists have assembled those data points into a family tree, depicting the divergence and evolution of viral lineages as branches and limbs and twigs. (Actually, there are multiple versions of the tree, differing slightly from one another based on differences in the subset of data used and in the interpretation of ambiguities.) From the details of that family tree and its ongoing growth, disease experts and public health officials draw insights helpful to understanding and containing the spread of the virus. That field of science is called genomic epidemiology.

    Last week I published an Op Ed in The New York Times on this subject:
https://www.nytimes.com/2022/08/10/opinion/
coronavirus-evolution-vaccines.html

    The Op Ed took about eight days of work, writing and revising, then editing and correcting, with help from a fine editor and a crackerjack fact-checker at the Times. It drew also on my two years of effort toward a new book, Breathless: The Scientific Race to Defeat a Deadly Virus, which will be published by Simon & Schuster on October 4. (See the main post, left of this column.) And that book itself drew on—in addition to 95 interviews with scientists and other experts around the world, during early 2021—my twenty years of intermittently following and writing about the subject of emerging viruses.

    I never foresaw, back in the days when I was a young man writing fiction, or during the decades I worked as a journalist and author focused on ecology, evolutionary biology, and conservation, that I would spend so much of my elder years as an explainer of viruses. But it didn’t seem illogical, once I realized that a) all science writing needs to be storytelling, and b) the stories of emerging viruses are all tales of ecology and evolutionary biology.

    Darwin would have understood. But Darwin never had the gruesome satisfaction of pondering viral evolution, its strange turns and its awesome speed, because viruses weren’t known to exist in his era. Too small to see, too weird to imagine. Edward O. Wilson (who died last Christmas and is much missed) did understand, even though he didn’t study viruses himself. Ed recognized that viruses account for a vast portion of what he cared about most, the biological diversity of planet Earth. And he wrote an influential essay titled “The Little Things that Run the World.” He never mistook size for importance.

    Anyway, that’s what I did with my summer “vacation”: literary virology. So as not to sound like a drudge, I’ll add that there has also been time for a vast amount of dog-walking, a bit of cycling, a bit of gardening, and hours of diverse reading (including biographies of Khrushchev, Buster Keaton, and James Angleton) in the backyard. Plus, a continuing gambol across the green and unforgiving fields of golf. I hope your summer has been verdant and rich also.

    Did I say golf? Oh, yeah, sorry. It’s one of the things you do when you’re 74 years old and on your second pair of knees. Golf is healthy because it’s forever humbling, I’ve found, and you walk a lot. It’s interesting because it’s so hard. I suppose that’s the only thing it has in common with molecular evolutionary virology.