Songbird Underwater
Eight months ago, an experienced birder observed a family of Kirtland’s warblers on a small lake in northern Michigan. The mother was teaching the chicks how to dive. The birder was taken aback: this was strange behavior for a songbird, especially one that nests exclusively in jack pine forests. More sightings of the aberrant birds followed, and soon scientists were moving in to study their behavior.
After catching and testing (and releasing) some of the warblers, they discovered something incredible in the birds’ feathers: compounds almost identical in structure to PFAS, one of the so-called toxic forever chemicals. Because of the persistence of their chemical bonds, PFAS are often used in cleaning products, nonstick cookware, and water-resistant fabrics. Why not feathers too?
To learn more, I met up with Dr. Holger Anghel at Avery Lake, located in Michigan’s lower peninsula, the only site where the warblers have been observed so far. Anghel is an evolutionary biologist, ecologist, and professor at The University of Michigan. His latest book, The Roach in the Drawer, looks at the relationship between human material culture and the evolution of insects.
KYLE E. MILLER: Can you tell us how this happened?
HOLGER ANGHEL: We spend a lot of time trying to piece together the narratives of evolution, but we’re not always perfect at reading nature. Simply put: PFAS are abundant in our environment now. Soil, water. They’re already in the body. A mutation in the warbler’s genome allowed it to appropriate PFAS into its development, which made its feathers waterproof. Probably an advantage.
All birds have water resistant feathers, but unless you’re a cormorant or something, you have to dry them, oil them, clean them—and you can still get waterlogged. Most birds just aren’t adapted to being semi- or fully aquatic. Definitely not songbirds.
That changed for Kirtland’s warbler, at least here. There are probably two species now.
KM: Let’s back up for a second. You said the waterproofing was “probably” an advantage. Wouldn’t it have to be beneficial in order to be passed on?
HA: Technically, the PFAS-friendly warblers simply had to reproduce successfully for x generations, which could happen in the absence of an advantage. It could be that the change is neutral, so to speak, in the calculus of survival. “The survival of the fittest” is a little misleading. It’s more like the survival of those who survive.
A common advantage bestowed by mutations, even indirectly, is access to a new food source. Most of my colleagues believe that to be the case here.
KM: I’ve heard people say things like, “the warblers used PFAS to become better swimmers.” Granting intention or agency to the birds rather than the genes. Do you think this is accurate?
HA: We’ve been taught, by people like Richard Dawkins for example, that the organism is a kind of vehicle for the genome, but this is semantic terrorism. [Laughs.] As a metaphor, it may have its uses, but it’s unsound on a number of levels. The genome wouldn’t exist without the organism. Ultimately, I don’t really care. I think in some ways it’s only a semantic problem.
It’s also important to remember that the mutation had to occur, and the warbler had to discover it. It was probably an accident. Imagine, the bird takes a bath as usual, but notices that its feathers require less attention afterward. Maybe it saw something in the water that looked yummy and found that it could recover from water more easily than usual. This could all happen below the level of consciousness.
KM: Do you think they’ll continue to evolve toward an aquatic species?
HA: That’s the question. I kind of doubt it. It could even revert, disappear. The population is pretty small at this point. But you could imagine them changing the shapes of their feet, their nesting habits, their beaks.
KM: And what about the PFAS? If it isn’t harming the birds, in fact seems to be helping them, do we have to worry about it? Is it still PFAS?
HA: The molecule is actually broken down by the warblers’ mechanism. I don’t know all the details off the top of my head, and some of it’s still being researched. It’s not that the birds are making PFAS on their own, but rather that they’ve found some way to use it. Like iron in the human body. Our genome can’t create iron, it’s an inorganic element and can’t be built by our bodies, but structures that use it can be. PFAS is a common element in the warblers’ environment. It’s probably passed down through the egg and reappropriated during development as well as replenished through food and water. During that process, it breaks down.
KM: The PFAS is broken down.
HA: Yes.
KM:[Pauses.] Isn’t that a good thing? Like, very obviously a great thing, and it must be unprecedented right?
HA: Many of my colleagues are excited about it too and hope to figure out exactly how it works, even though it may not be reproducible.
KM: But the implications are huge, aren’t they? The PFAS is being recycled by the Earth.
HA: That’s one way to put it, yes.
KM: You seem resistant.
HA: To what?
KM: I don’t know. To making too much of it. Deriving moral meaning from nature.
HA: Nature isn’t an infinite Aesop’s Fables, regardless of how insecure the foundations of civilization become. It’s fine for the poets, but I think we have to be careful of this... ecological appropriation. We stare at nature and see another mirror. I think it tends to lead us back inward. Psychoanalysis is a deeply limited medicine. To change, if that’s what we want, we have to look outward and open ourselves to things that may have no use to us.
KM: Which in itself sounds moralistic, doesn’t it?
HA: It’s not a moral judgment, although it may be a value statement. The problem is chronic instrumentality. A lot of this comes out of criticism. I think the whole project of academic criticism is outdated, outmoded. It’s changed in order to keep up with the times, but it’s become toxic to the surrounding disciplines. Bruno Latour wrote about this, I can’t remember the name of the essay, but it’s wonderful. He had it exactly right.
KM: I feel like you’re still moving toward a message, or a meaning. Maybe that’s just how human language works.
HA: Maybe, maybe. The inevitability of meaning? Like with writing. It’s almost impossible not to derive something even from nonsense. But I wouldn’t say so much about it. Maybe that’s my point. These things are happening out here--what do they mean? I don’t know, but I’m going to try to describe them as best as I can. Are they good, bad? I can’t say.
KM: Scientific objectivity?
HA: Not quite. Taking the self out of it.
KM: To bring us back, considering what’s happened here, it feels like there’s a direction to evolution. Like there’s progress.
HA: It would be a mistake, I think, although I understand what you mean. Popularly, the word “evolution” has come to imply progress, but we can’t even agree on what that means for society. I will say that what’s happened with the warblers does show us that we don’t know what’s going to happen next. The future of any species is dark.
KM: An ecological critique of knowledge.
HA: [Nods.]
KM: Do you think it’s a good thing, that we don’t know what’s going to happen?
HA: I wouldn’t say. It’s a fact. Will it make you humble, pessimistic, optimistic, afraid? If you were in Paradise and didn’t know what was going to happen next, you’d probably be afraid, because any change would be bad, but if you were in Hell...
KM: Not that we should start excusing ourselves for using forever chemicals, but I think it makes me optimistic.
HA: I wouldn’t blame you. The repercussions of course are completely unknown.
KM: Yeah, that’s true. It could be bad in the long term. And evolution is just building, right, statistically, on what came before? It’s kind of “dumb” in that way? Like a generative AI. Evolution hopes the next “word” makes sense, but sometimes it doesn’t.
HA: But nature is not a model. Generative AI models writing, but doesn’t understand it. Nature, evolution, ecology, whatever you call the whole, is not a model of anything. It is the thing. It has the benefit not only of the past, but also a thousand dialectics within itself, elements that constantly test and question each other. ChatGPT has a limited ability to react to what it’s already written, and it doesn’t have anyone guiding it with questions. Nature is different. The soil questions the worm. The worm questions the soil. This is why evolution will never be totally random.
KM: So, the future is still a guess, but it’s an intelligent guess?
HA: Sort of. The future of the system contains itself. It can’t collapse totally, or it wouldn’t uphold reality and we wouldn’t be here talking.
Hopefully, Avery Lake and its surroundings will continue to yield answers to nature’s secrets. Dr. Anghel seemed to think so. We saw only loons on the water that day. I imagined all the warblers were underwater.