


Some 270 million years ago, the spot where I’m now sitting would have sat next to the tropical shoals of a warm, globe-spanning, shallow ocean, populated by massive invertebrates and amphibians, the oxygen-rich air giving flight to dragonflies with the wingspans of birds and arachnids of nightmarish proportions. I’m writing in the dining room of my family’s home in Pittsburgh, a yellow-and-green craftsman house that’s a century old, not far from the confluence of the Ohio River in the Allegheny Mountains.
