The topic of consensus has come up recently and it is interesting to look at the flip side of scientific consensus and look at broad rules of thumb that exist in wider society. With diseases caused by viruses, bacteria and parasites etc there is a reasonable (but flawed) assumption that over time a specific disease will become less deadly. The assumption rests on a rough sketch of how evolution works. An infected person needs to be alive for the virus to grow and spread and so, killing the infected person is of less advantage to a virus than leaving the person alive and walking about. It’s a reasonable idea because we are all hosts to a wide range of viruses that cause common colds that usually just make us snotty and miserable rather than dead.
But it is no more than a rule of thumb and the reasonableness of the idea hides a whole pile of complexity. Also, there’s an underlying cognitive error we all fall into when considering how natural selection works that makes us pretend that there’s some sort of agency behind how these changes happen. A virus doesn’t want to kill people, it has no wants or any capacity for anything like wants or a direction nor does evolution strive for perfection. An additional reasoning error is a more subtle version of the old anti-evolutionary argument “if humans evolved from apes, how come there are still apes?” Evolution spawns new varieties of reproducing things rather than just replacing old ones with shiny upgraded versions.
A moment’s thought about examples of long term diseases that humans have faced shows that many diseases remain very deadly despite long histories. Evidence of smallpox is present throughout most of recorded history and its deadliness was reduced not by the virus becoming less virulent by itself. Obviously, there are related viruses to smallpox that are less deadly but humanity had to live with those as well as smallpox. Improved care reduced the deadliness, inoculation as practice (intentional infection of people with matter from a smallpox-infected person possibly first used in China) reduced the impact of the disease and eventually, vaccination led to the disease being wiped out.
Influenza keeps working its own happy way through the evolutionary gambling tables each year, throwing up variations that are more or less injurious. Every living (or not quite living) thing is a glitchy, cobbled-together trade-off of adaptations. “Less deadly” is one direction but there’s not a simple genetic switch or “deadliness” parameter a virus can turn up or down without affecting other features of the virus.
Now I’m not a virologist or even a biologist. I don’t know what the odds of new variants of covid being more deadly are. The rule of thumb isn’t utter nonsense, all other things being equal, I can see why it makes sense that maybe a more infectious & less dangerous version of the virus might become more dominant and maybe (if we were very lucky) also give people sufficient immunity that the nastier versions would fade away. I wouldn’t bet money on it though. Again, appealing to what we can see, covid currently is relatively slow to kill people and there’s plenty of time for an infectious person to spread the virus before they feel so sick that they aren’t out and about spreading the disease. Also, many infected people are asymptomatic, so the deadliness is not much of a disadvantage to the disease.
But we really can only get so far trying to think these things through with general knowledge and a critical eye. Expertise matters and literally whatthehelldoIknow. Expertise matters much more, particularly when evaluating multiple competing factors. Here’s an article by experts in microbial evolution and mathematical biology explaining some of the issues far better than I can: https://theconversation.com/will-coronavirus-really-evolve-to-become-less-deadly-153817
That article also links to an academic paper looking at the potential evolution of the SARS-CoV-2 virus. That paper looks at multiple ways the virus may evolve into new strains. On this specific topic it notes:
“A crucial question is how virulence will evolve [28]. As discussed above, direct selection on virulence is weak (Figure 3D,H). Thus, virulence evolution will be driven largely by the indirect effects of pleiotropy. In Figure 4, we consider two potential examples. First, consider mutations that couple a higher transmission rate, the βs, with higher mortality, ɑ (positive pleiotropy, Figure 4A,C), as might occur if mutations increase viral replication rates. In this case, evolution will lead to higher mortality (see inset bars), as an indirect consequence of selection for increased transmission (see Supplemental Information and also [12,29]). Alternatively, consider a mutation that alters tissue tropism such that the disease tends to preferentially infect cells of the upper respiratory tract, rather than the lower respiratory tract. Such infections could lead to a higher transmission rate but be less virulent (negative pleiotropy) [30]. This would generate indirect selection for lower mortality rates (Figure 4B,D).”
On the evolutionary epidemiology of SARS-CoV-2, Troy Day, Sylvain Gandon, Sébastien Lion, and Sarah P. Otto Current Biology 30, R841–R870, August 3, 2020 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7287426/pdf/main.pdf
[Word of the day: pleiotropy – when a gene impacts two or more unrelated traits https://en.wikipedia.org/wiki/Pleiotropy]
So there you go, right? I’ve got experts and an academic citation from a paper with maths in it AND GRAPHS! Case closed, right?
Not really. I like the argument I just wrote but it is far from immune from being BS. I’m smart, STEM-educated and I can find academic papers and quote from them (and thank the Humanities for those skills). Yet, I’ve no real idea whether the academics I quoted are actually good at their jobs. I don’t know whether the two essays I’ve quoted are actually making well-known errors in the field of evolutionary virology or pushing some heterodox minority position. For all I know, the field of evolutionary virology is currently engaged in raging flame wars on this very issue and there’s a really, really strong argument that (aside from a few exceptions) viruses nearly always get substantially less deadly for reasons other than better treatment or vaccines. It’s not just that I’m not an expert on these topics but also I don’t know anything about the community of people who ARE experts.
Now, given the currency and high profile nature of this issue, I’m fairly confident that I’m not making an ass of myself and quoting a paper that virologists are scorning. Yet, this takes me back to the real topic of this post: consensus and truth not just in science but in any body of knowledge/field of expertise.
A body of knowledge is not a set of textbooks but a community of expertise in which opinions and experience matter. Those communities are flawed. They will have biases. They will be slow to adopt new ideas that are actually more true than old ideas. They will be vulnerable to professional and commercial pressures. These things are true because science is done by humans and communities of humans have these issues. That means we should not unthinkingly accept what any given community of experts say as the unimpeachable truth. However, the odds are that a community of expertise that adopts methods of self-correction and reasoning is far more likely to be a source of truth than our naive intuition about complex issues.
Do I have one more rhetorical trick up my sleeve to convince you that covid won’t necessarily get less deadly? I have lots but as this is a portmanteau essay on many things, including the art of rhetoric then I shall use a failed student of the art to convince you that covid can get worse:
“These utterly ignorant idiots don’t understand that it is the flawed vaccines that are causing the next variant to be worse, not the unvaccinated. If it had been left to progress naturally through the population, the virus would have become more infectious and less harmful, like every other virus in history. It’s already doing that, which is why the Delta variant is estimated to be 10x less lethal than the original one.”
Vox Day, https://web.archive.org/web/20210726205857/http://voxday.blogspot.com/2021/07/when-vaxxing-makes-it-worse.html
I call the move I’m making here the anti-appeal to a lack of expertise 😀
