Jeremy Draghi and C. Brandon Ogbunu write:

In early March, the Chinese Academy of Sciences’ National Science Review published a peer-reviewed study titled “On the Origin and Continuing Evolution of SARS-CoV-2.” The authors argued that the various strains of SARS-CoV-2, the coronavirus that causes Covid-19, could be grouped into two clusters: An “L” type, which was predominant during the early weeks of the outbreak in Wuhan, and an “S” type, which could be distinguished from the L type by only two genetic changes. The researchers speculated that the L type was “more aggressive” and more contagious than the S-type strains that had become more common outside of China. The implication was that Covid-19 might not spread as quickly throughout the rest of the world as it had in Wuhan.

Although this analysis was based only on changes in mutation frequency in around 100 sequenced genomes, it caught on in the media. While some press outlets contextualized the study alongside its many criticisms, others extrapolated from it to predict that SARS-CoV-2 was evolving to become more benign, a dangerous oversimplification of a long-studied idea that many pathogens may evolve reduced severity after initial outbreaks.

These types of narratives — a Covid-19 brand of pseudoscience — have cropped up often in recent months. Just last week, media outlets swarmed to a non-peer-reviewed report of a mutation that was billed as an indication that SARS-CoV-2 populations are becoming more transmissible, and too diverse for any one vaccine to work against.

For the most part, respected evolutionary biologists have chosen to avoid weighing in on these controversies, opting instead to remain above the fray. This is surprising considering that evolutionary biologists are accustomed to debating creationists, and to the art of public discourse around contentious ideas. Their relative silence leaves a gap that less restrained commenters have rushed to fill: Seemingly every mutation in the novel coronavirus has been spun as a sign that the virus is either adapting to better reproduce and spread in its environment or becoming less harmful.

While genomic differences between different strains of the novel coronavirus are stark facts, our interpretation of those differences can be a wellspring of controversy. And right now, the media coverage of SARS-CoV-2 suggests that the American public fundamentally misunderstands how evolution works — and how to distinguish between two of its key driving forces, adaptation and genetic drift. The latter represents a gradual accumulation of chance events that have no true consequences for how a virus behaves. And when a particular genetic strain appears to make great leaps in its ability to thrive and proliferate, it’s often genetic drift, not adaptation, that’s at play. [Continue reading…]