Theodicy: bad bacteria seen differently (Introduction)

by David Turell @, Saturday, July 10, 2021, 19:40 (403 days ago) @ David Turell

It says we are accidental targets:

"When microbes aren’t killing us, we are largely oblivious to them. So, we construct narratives of hosts and pathogens, heroes and villains, us and them. Those that cause disease exist to reproduce at our expense, and we need new ways of resisting them. And so we study how they evolve to outfox our immune system or to spread more easily from one person to another. We identify genes that allow them to cause disease and we label those genes as ‘virulence factors’. We place ourselves at the centre of their world. We make it all about us.

"But a growing number of studies show that our anthropocentric view is sometimes unjustified. The adaptations that allow bacteria, fungi and other pathogens to cause us harm can easily evolve outside the context of human disease. They are part of a microbial narrative that affects us, and can even kill us, but that isn’t about us. This concept is known as the coincidental evolution hypothesis or, as the Emory University microbiologist Bruce Levin described it in 2008, the ‘shit happens’ hypothesis.


"The coincidental evolution hypothesis helps to resolve these paradoxes. It tells us that at least some human diseases have nothing to do with us at all.

"The coincidental evolution hypothesis explains a number of other recent discoveries about microbes. Scientists have found antibiotic resistance genes in bacteria that have been frozen for 30,000 years, or isolated in million-year-old caves. We might think of antibiotics as modern inventions, but they’re actually weapons that bacteria have been using against each other for aeons, or at least well before Alexander Fleming noticed a funky mould in a Petri dish in 1928. Antibiotic resistance genes evolved as part of this ancient war, but they also help today’s microbes to deal with the medicines that we mass-produce.

"Likewise, many of the ‘virulence genes’ that help pathogens to cause disease have counterparts in marine microbes with no track record of infecting humans. And some supposedly pathogenic bacteria were often common parts of the environment. ‘These organisms become accidental pathogens,’ says the microbiologist Arturo Casadevall from Yeshiva University in New York. ‘They’ll still be there even if you remove all the animals from the planet. And yet, evolution selected for just the right combination of traits to cause disease in humans.’


"Many of the pathogens we fear most are mere tourists on the human body. Their real homes are oceans, caves, or soils. To understand them, we need to understand them within their natural ecology...We fear lions and tigers and bears; bacteria have to contend with phage viruses, nematode worms, and predatory amoebas.


"Casadevall likes to say that each microbe holds a different hand of cards – adaptations that allow it to cope with its environment. Most of these combinations are meaningless to us. A bacterium might be able to resist being digested by other cells, but it might not be able to grow at 37 degrees Celsius. It might grow at the right temperature, but it might not be able to tolerate our slightly alkaline pH levels. But that doesn’t matter. There are so many microbes out there that some of them will end up with a hand that lets them muscle their way into our game. ‘If you take all the microbial species in the world and imagine that they have these traits randomly, you can find pathogenic microbes for practically anything,’ says Casadevall.


"There is something unsatisfying, almost nihilistic, about this idea. It deprives us of answers. As Casadevall wrote in a review, it says that virulence can arise by chance, ‘in a process that has no explanation, except for that it happened’. According to this outlook, we’re not central actors in the dramas that affect our lives. We’re not even bit players. We are just passers-by, walking outside the theatre and getting hit by flying props.

"The most important parts of a microbe’s world are, after all, other microbes. They’ve been dealing with each other for billions of years before we came along. When we step into the crossfire of this ancient war, we risk becoming collateral damage."

Comment: when everyone has to eat something there is constant warfare. This essay says we are mainly innocent bystanders in the war between bacteria and themselves and other tiny organisms. The article is filled with examples of the battles. Read to be fascinated. My view is a wise God knew this, gave us immune systems an the brains to help ourselves. The 'bad' are not purposeful against us. God wouldn't do that.

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