A ringside seat we could have done without
We are watching viral evolution in real time, and it's not a pretty sight
Four years have passed since SARS-CoV-2, the virus that causes COVID-19, first emerged in humans, and we are so far into the current pandemic that even “pandemic fatigue” is a thing of the past. In a first for public health policy, governments worldwide are allowing a newly emergent virus to spread untrammeled. The complete abandonment of mitigation measures has been sold to the public as a sign that the crisis is over.
But if humans have moved on from the pandemic, the virus certainly hasn’t. As predicted years ago, mass infection has led to runaway viral evolution, undermining the biomedical interventions that are our last line of defense at this point. We are living through an uncontrolled — in both senses of the word — experiment. May you live in interesting times, as the Chinese never said.
Every new wave of SARS-CoV-2 reminds us that evolution is real- the subject has leapt off the pages of high school biology textbooks and into our daily lives. There are practical consequences, and the details matter now. At the same time though, Darwinian evolution can be unintuitive.
It’s not a stretch to say that the ongoing COVID-19 pandemic is the most intensely studied example of evolution in the history of the subject. The virus is evolving at a breakneck pace, and the abundance of sequencing data provides a detailed and dynamic view of the process at a scale never before seen.
Like a mural that is at once enormous and highly detailed though, it can be hard to process, and insights about the bigger picture have repeatedly gotten lost in the details. In the early pandemic, this forest-for-the-trees problem led to assessments about SARS-CoV-2 evolution that were way off. The problem persists, as dubious statements about viral evolution continue to find their way into public discourse.
Evolution in real time
As the geneticist Theodosius Dobzhansky famously remarked 50 years ago, “Nothing in biology makes sense except in the light of evolution”. Evolution is the fundamental unifying theory of the life sciences, but in terms of day-to-day life it may seem rather abstract. Sure, examples of real-world significance such as the evolution of antibiotic resistance may grab attention, but for many, evolution is something that happened in the past over eons and is a topic best left to paleontologists, geneticists, and other academics to contemplate. The ongoing COVID-19 pandemic has revealed just how important a proper understanding of the causes and consequences of evolution is for human health. Viral evolution has leapt off the pages of textbooks, ambushing us at every turn as we try to return to “normal”.
If you think you understand evolution…
…you don’t know nearly enough about it. So wrote Michael LePage in New Scientist. He went on to note:
“Most of us are happy to admit that we do not understand, say, string theory in physics, yet we are all convinced we understand evolution. In fact, as biologists are discovering, its consequences can be stranger than we ever imagined. Evolution must be the best-known yet worst-understood of all scientific theories.”
Study after study has revealed that even Darwin’s mechanism of natural selection is poorly understood and subject to widespread misconceptions. This is not helped by the fact that much evolution education is superficial and most depictions of evolutionary ideas in popular culture are very misleading. Natural selection, it must be noted, is only one mechanism of evolutionary change, and the others (mutation, genetic drift, and gene flow) are not any better grasped. Major patterns of evolution are likewise widely misinterpreted. A simple Google image search for “evolution” turns up page after page of linear “evolutionary line-up” figures, which is a fundamentally inaccurate illustration of how evolution actually occurs.
Real world evolution is caused by a mixture of chance and deterministic processes, happens at multiple levels and scales, and may or may not lead consistent directions of change (and much change is not adaptive). In other words, evolution is messy.
Viral evolution is not our friend
Evolution creates surprises. It can lead to things getting better or worse. Or just being different. So at one level, it’s unpredictable. In the context of the current pandemic, though, over the longer term, unrestrained viral evolution poses a number of serious risks. By analogy, each new viral variant can be thought of as being potentially bad for our health in the same way as driving drunk. The vast majority of people who down three beers and drive home immediately after do so with no consequence. On average, it takes a drunk driver two hundred drunk drives before the averages catch up with them. In the same way, while any individual viral variant may or may not pose a threat, a public health ‘strategy’ of permitting endless new waves of variants is not sustainable. During the early pandemic, one of us (A.C.) published extensively on the potential downside risks of unrestrained viral evolution. Many of those potential risks are now reality, unfortunately. At this point, new risks have opened up, and ongoing viral evolution poses an open-ended threat. Being aware of potential risks is the first step in behaving rationally to mitigate them.
The pandemic doesn’t end until we rein in viral evolution
If we let SARS-CoV-2 spread uncontrollably, any single measure that we take to try to rein it in will be pounded against by the process of evolution. Every infection generates trillions of viral particles, all slightly different from each other. Under the current ‘let it rip’ policy, we will see hundreds of millions of infections every year, if not more. That’s quadrillions of monkeys banging away ceaselessly on their typewriters, looking for ways to defeat anything we throw at them. All the tools we have at our disposal are vulnerable to viral resistance, in one form or other.
We turn our back on viral evolution at our own peril. Endemicity- the state of stable disease levels and a steady maintenance of immunity to the disease- will be nothing more than a buzzword for as long as the virus continues to spread wildly and evolve rapidly.
What can you expect from this blog
Think of this blog as Viral Evolution 101- the class you never dreamed you’d need in college. Here we will dive into the subject, blending theory and practice together to explain the ways in which viral evolution does (and doesn’t) do its thing. We will touch on how SARS-CoV-2 viral evolution impacts our daily lives, and what this means for us in a day-to-day context. A clear understanding of viral evolution is a practical life skill these days.
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