Thoughts on quintessence, mutation, and evolution

This blog's name captures my longstanding interest in human nature: humans are apes, and animals, and yet somehow able to create music and gods, and sometimes plays like Hamlet. But what's that strange word at the beginning, 'quintessence'? Here's the context from Hamlet:

What a piece of work is a man, how noble in reason, how infinite in faculties, in form and moving how express and admirable, in action how like an angel, in apprehension how like a god: the beauty of the world, the paragon of animals — and yet, to me, what is this quintessence of dust?

—Hamlet, Act II, Scene II (Arden Shakespeare)

The word's history suggests that Shakespeare was (as usual) playing games with words and his audience (all quotes from the OED):

a quintessence can be a pure or perfect example of something and/or "The most essential part or feature of some non-material thing" as in "This seems to us the very quintessence of penny wisdom and pound folly in management"

and quintessence used to refer to a "In classical and medieval philosophy: a fifth essence existing in addition to the four elements, supposed to be the substance of which the celestial bodies were composed and to be latent in all things."

So, it seems Hamlet is saying that a human is a pure example of a blob of dust, but perhaps stardust. Either way (or both), he is commenting on what a human is at their core. Not just essence, but quintessence.

I don't know if this is a Western thing (I suspect it is), but essentialism like Hamlet's, in which we assume that a thing (a person, a gender, a gene, a protein, a species) has a definable essence, is a big hindrance to thinking about evolution.

Such essences are usually immutable, sometimes by definition.

Now look at that word: immutable. It's about mutation, which is simply change. But that word (mutation) is caught up in ideas and feelings like 'normal' and 'good'. We often (and sometimes explicitly) define a mutation as a harmful change, but even when we're not doing that, we are prone to thinking of mutation as a departure from normal, from "wild type," from a status quo or standard.

I think that makes it harder for us to think about mutation, and it famously hinders thought about evolution. To a person who thinks that a species (or genus or whatever, it doesn't matter) is a thing, with an essence—the kind of thing about which the ancients wrote "each according to its kind"—evolution is a freakish departure from the way things should work.

What is the "essence" of a barn owl? Can it change? What is the "essence" of Nerve Growth Factor? Can it change? Just asking these questions is, to me, flirting with madness. Or at least confusion.

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Image credit: "Illustration for Hamlet: Hamlet and Guildenstern (III,2)," Cooper Hewitt, Smithsonian Design Museum, public domain