Just down the road from me, along Brattle Street on the way into Harvard Square, stands the Dexter Pratt House. Its minor claim to lasting fame is that old Dexter Pratt was the local blacksmith, and one fine day in 1840 as he labored under a nearby chestnut tree, who should walk by but Henry Wadsworth Longfellow. Inspiration smote the poet, and he set down these words.
Under the spreading chestnut tree
The village smithy stands…
The words remain, and so does the house. But the chestnut is gone. In fact, all the American chestnuts, almost without exception, are gone, having been wiped out by a devastating chestnut blight in the first have of the last century. My father, growing up in Crozet, Virginia, remembers watching the line of dying chestnuts march across the mountains. At the time of the blight, chestnuts made up as much as a third of the great forests of the east. Imagine seeing them all struck down in the span of a few years. By a freakin’ fungus.
The American chestnut isn’t quite extinct, but it’s on the doorstep. Other related chestnut species, notably the Chinese chestnut, don’t have the same blight susceptibility, and for years specialists have interbred the species trying to create an American chestnut with blight resistance. They have succeeded in making resistant hybrids, but none of these has anything like the majestic size of the old American breed.
Carl Zimmer, writing on the National Geographic website, has a good summary of more recent work done to save the tree: Resurrecting A Forest
Rather than using heavy-handed hybrid breeding, new genetic tools make it possible to move genes one at a time from species to species. This is allowing biologists to make a chestnut that is almost entirely native chestnut but with with just enough secret sauce to ward off the fungus. The odds are getting better and better that we (or our children) will see mighty chestnuts once again. But what story will we tell ourselves about it? Zimmer does a good job of capturing this puzzle.
If, a century from now, Powell’s chestnuts tower once again over the eastern United States, how will we think of those forests? Will we think of them as nature restored to its former glory, ecosystems thriving once more? Or will we think of them as unnatural, the product of human tinkering? Or both? Given the past century of struggle to save the chestnut, the choice here is not natural versus unnatural. It’s chestnuts versus no chestnuts. “It’s not going to fix itself,” says Powell.
As Longfellow might have written:
Under the genetically modified chestnut hybrid
The village cyborg stands…