We continue from COVID Resurgent: Of Hares and Foxes; Primer for Policy Makers, Part 3., which poses a list of questions. With our Houston Astrodome experiment, we explored the natural balance between the predator (virus) and the prey (host, you.) We saw that in the extreme, mutual extinction could occur. While this may have happened unobserved, the closest known example is a transmissible cancer that affects the Tasmanian Devil, an Australian marsupial.
The first question of our list is:
- How can a virus appear to have an intelligent strategy, when it isn’t even alive? Does Darwin’s theory of natural selection play a role?
If you think the mind has a monopoly on thinking, try to put this notion aside temporarily. When you think about a problem, you try to imagine all the ways it could turn out. At the level of atoms, molecules, viruses, and heredity, Nature tries combinations at incredible speed. The result appears thoughtful. Maybe it is.
So Nature rolls the dice constantly. The processes by which a virus or cell or any form of life reproduces has the chance of error. We call this error mutation. The result of constantly occurring mutation is genetic diversity.
Genetic diversity is key to the survival of a species. Without it, the human species would already be extinct, killed off by something like COVID. This diversity prevents a virus from knowing its prey too well. It’s the difference between a burglar who has cased the joint, and one who hasn’t.
Genetic diversity saves us from one outcome of the Astrodome experiment. If the foxes are super-efficient at hunting rabbits, they kill off their food supply. Both go extinct. But rabbits are wily and evasive. The foxes can’t catch all of them.
Genetic diversity is responsible for an axiom of infectious disease: No disease is 100% fatal. Rabies was thought to be. A few years ago, a young woman walked into a Texas hospital with rabies. With no specific treatment, she walked out three weeks later.
Likewise, if a virus did not mutate, the prey would develop universal immunity, so the virus would go extinct. Mutation comes easily to RNA viruses like COVID, because RNA is fragile. DNA is so tough you could make golf club shafts out of it. Yet mutation is so important, even DNA viruses roll the dice. (Science Daily) How poxviruses such as smallpox evolve rapidly, despite low mutation rates.
The viral mutations we see are the ones that enable one strain of COVID-19 to out-compete other strains; this is Darwin’s natural selection. Selection works on humans too, but we want to prevent it with medicine and public health policy.
We have addressed the first question of our list: Even though they cannot think, viruses and immune systems have strategies that appear thoughtful.
The human race will survive COVID. But we want to prevent a Darwinian outcome. And you’ve got some personal skin in the game.
Our next question: What drives virulence, and what holds it back?