In Beaverland: How One Weird Rodent Made America (Twelve, Dec.), Philip explores the animals’ ecological and economic impact on the country.

How are beavers tied up in America’s past?

They’re an extraordinary lens into our history. Explorers came here to look for beaver fur, and the American empire began with the conversion of natural resources, starting with their fur. We almost wiped them out. But through luck, the beavers’ natural resilience, and then some really good environmental policy, they were restored to their landscape.

Did that restoration have ecological benefits?

Yes. In the early 20th century, they were brought back to Connecticut, and beavers began to show us the extent to which they could repair extremely damaged river systems. When we took the beavers out of the landscape, the wetland systems began to dry and degrade. Many of the environmental problems we face today have to do with water, with river systems that are so degraded that even when it rains, the water rushes right out into the ocean instead of seeping back into the ground, hydrating everything it needs to hydrate or filling the aquifer.

How intelligent are the creatures?

An individual beaver may not rank as all that intelligent, but working together, beavers can build extra- ordinary constructions. They know how to dam the water just at the point where the volume won’t wipe away the dam. And instead of making one big dam the way humans might, like the Hoover Dam, they’ll make a series of dams in a row, so they’re incredibly resilient to floods. Because if the top dam is breached, and the second dam catches that breach, then the water force is dispelled. How does an animal figure out this engineering feat? We don’t fully know.

You write in the book that beavers make you hopeful. Why?

They’re extraordinary problem-solvers. When they have a hole in a dam, they just repair it with whatever they have to hand—a rock, a stone, some fiber-optic cable. They’ll just stuff that in. Mike Callahan, who heads up the Beaver Institute, sent me a picture of a beaver dam built around a pickup truck, which I thought was one of the best examples of our moment. I lie awake at night, worrying about the environment and the future, and I think beavers are just an extraordinary story of hopefulness. Because this is nature’s resiliency, doing what it can do, if we either leave it alone or give it the opportunity. We are in a moment where I think we need to adapt. And beavers are incredible adapters.