Darwin's phrase "natural selection" usually calls up struggle: the strong survive and the weak vanish. Dave Bonta gives it a quieter meaning in eight short lines. Humans, the poem suggests, are among the things being selected against, or at least overshadowed, and the news arrives with no panic at all. The last thing we see is a pair of birds, pleased with the place they have found.
The poem is built from four couplets, with no rhyme, no punctuation and no capital letters. This gives it a hushed, unhurried voice, closer to something overheard than announced. Because nothing ends with a full stop, nothing feels finished. That suits a poem whose first word of substance is "turning."
It opens with an invitation: "see how much turning / all things do." The word order is slightly inverted, like an old proverb, and the line break leaves "turning" hanging at the end of the line, so the reader pauses on the very motion the line describes. The second couplet widens the view with a list: "whether door or water / stories or ages." Each pairing is a step up in scale. A door turns on its hinge and water turns in an eddy. A story has its twists and an age turns over into the next. The list moves from the household to the planetary, and from objects we make to forces we only live inside. With no comma between "water" and "stories," the items slide into one another and seem part of one motion.
The third couplet holds the poem's argument, and its one unsettling word. "For the world is laboring / to eclipse us." "For" works as an old-fashioned "because," so all that turning is explained: it is the world's work. "Laboring" is double-edged. It can mean toil, the world straining at a task, but it also means the effort of childbirth, which would make the eclipse a kind of delivery, something new being brought forth as we are covered over. "Eclipse" carries a similar double meaning. It suggests the astronomical event, which depends on bodies turning until one stands in front of another, so the poem's opening image returns as a threat. It also means to outshine or supersede. Nobody is destroyed here. We are simply moved out of the light.
Then the poem does something unexpected and ends on an image with no verb at all: "the dove and wren / pleased with our chimney." After the abstractions of the middle, the chimney is concrete and domestic. The dove, often a symbol of peace, and the small, ordinary wren seem to be gentle choices of creature. "Pleased" is the most surprising word in the poem, because it gives the birds a mood. They take quiet satisfaction in a home we built, and the poem hints that we may no longer be using it. That is my inference from the image: a chimney that birds can occupy is probably not carrying smoke. Our hearth becomes their shelter, and our structures outlast our presence and turn into habitat. This is what the title means by "natural selection": the world picks what suits it next, and it picks without cruelty or triumph.
The poem is significant because it takes a large, frightening idea, humanity displaced, and treats it with calm, even a little humor. It is easy to read "eclipse us" as a catastrophe, and the final couplet refuses that reading by putting cheerful small birds where a grim warning might have stood. The poem does not tell us to feel relief or grief, and it leaves the tone to the reader. What it does insist on is humility. We are one more thing in the turning, like the door, the water and the story, and the world's attention is not fixed on us.
The poem's economy matters too. It uses about thirty words, almost all short and plain, and it never explains its metaphors. A reader who stops at "labor" or "chimney" will find that the poem keeps opening up, and that is a good reason to read it twice.