Thursday, April 01, 2021

Defining "life": a scientific and philosophical demarcation problem

What does it mean to be "alive"? Viruses in general make biologists struggle with that definition, and COVID-19 has brought that issue back to life, especially with having relatively few genes even for a virus.

In one of his latest "Elk" columns for the New York Times, Carl Zimmer weighs in heavily on the issue, not just for science, but to some degree, for philosophy of science, or per Massimo Pigliucci, more specifically, for philosophy of biology.

I think that, per his piece, and what I've read elsewhere, probably a slight majority of biologists would accept viruses as "alive," period ... maybe 55 percent? Another 15 percent might still say "nope." And, the remaining 30 percent would say something like "alive but..."

That said, the piece is worth a read otherwise, especially for the last one-third, talking about viruses and viral DNA entering the animal biome, and namely the human biome. Zimmer first notes that viruses as well as bacteria in our gut are important to our microbiome.

But, that's small potatoes.

The biggie is how, over aeons, viral DNA has entered animal DNA. For example, mammalian females' placenta development is dependent in part on old viral DNA inside mammalian genes. In this and other cases, mammals long ago not only, for the most part, neutralized threats from viral DNA but managed to repurpose it.

Zimmer discusses this issue, and his new book, even more at Quanta, with an excerpt from it.

He cites Wittgenstein, and he's barking up the right tree if we mean linguistic philosophy in general as well as some specific Wittgensteinian ideas. The issue of "family resemblance," per Witty's comment about defining "games," is one important issue.

"Cancer" book author Siddhartha Mukherjee has a review of the book. He notes that Zimmer also discusses modern new studies on things like brain organoids, as well as viruses, in wrestling with the demarcation issue. Spores also make the discussion list. So do multicellular creatures, like snakes in deep estivation.

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