(D.A. Peterson/For The Washington Post)

We’re interested in the preservation of the biodiversity on Earth — anything you can think of that’s alive and, in particular, those that are at risk of disappearing. Everything is interconnected. This is like a big, big watch: Some pieces are large, some pieces are small, but they are all important in keeping this planet going.

What I’ve been working on is bats and rats. Just looking at rats, you can understand continental drift and climate change. We’ve actually rediscovered rats that were thought to be extinct. Darwin was the last one to document them in the Galapagos. People had gone there for hundreds of years and not seen a one. In 1997, I went there with my mentor and another graduate student. It’s this bizarre thing. Everyone thought we were crazy. Why look for something that doesn’t exist? They wouldn’t even give us permits. Our plan was to stop on a beach for a day and then hike up to the top of an extinct volcano where very few people had been. We’re on this picturesque, isolated beach. We set out the traps just to see what we might find — maybe some introduced rats — not expecting anything, certainly not the rats. The next morning, I check my traps, and there was one — in the very first trap! I immediately ran back to my mentor. He thought I was crazy. But when he looked in the metal trap — I’ll never forget his face — it looked like he’d seen a ghost.

So why find a rat that was supposed to be extinct? For one, it proves that we know very little about the world around us. I certainly understand the argument: “Who cares about an extinct rat?” But you have no idea what role that rat plays in that functioning ecosystem. People can appreciate beauty, so that’s why people love pandas and want to keep them around. You never hear, “What good is a panda?” Ecologically, these rats are much more important to their ecosystem than those pandas — not that I don’t love pandas, but we have to look beyond the big and beautiful.

I teach conservation biology and evolution. In both, you have to appeal to “Why is this important to me?” Some scientists refuse to do that. That’s my entire approach. I’ll ask, “How many of you had a family member who was in a tornado, hurricane, major flood?” and almost every hand goes up. Now everyone is invested. They’re thinking about their grandmother in Missouri. Climate change is suddenly very personal, and now they want to hear what you’re saying. You’re not looking for sympathy for the rats but for a greater understanding of the system. You want them to see this as a big puzzle. You can’t just throw pieces of the puzzle away and expect the puzzle to stay together.