Elizabeth Marshall Thomas, whose book “The Hidden Life of Dogs” was on the bestseller list for 10 months in the ’90s, has just released a memoir. “A Million Years With You” (Houghton Mifflin Harcourt, $25) is about a lifetime of watching the natural world. She spoke from her home in Peterborough, N.H.

You write about the way you’ve found meaning in life by keeping your eyes open. Why do you think more people don’t do this?

They’re busy doing other things, or they’re preoccupied. They’re talking on their cellphone or they’re playing a video game. But the world has so much to teach us if we pay attention to it. You learn. Kids used to play outside. We used to go in the woods by ourselves, and you can’t help noticing the world then, especially animals. People used to know a lot about the natural world, especially in the country. It’s kind of one big suburb now.

You learned to live what you call “the Old Way” from years interacting with the Bushmen in South-West Africa, now Namibia. What relevance does that have for people in Peterborough or Washington?

If you don’t have manufactured items or anything we think of as “civilization,” then you’re living according to your species. The Bushmen knew everything in their environment. To me, it’s a picture of what the natural world is all about. Most people now are so remote from that. Archaeologists found encampment sites next to seasonal lakes which had been occupied continuously for 35,000 years. The tools and things found at the sites were pretty much what people were still using. That means it was one of the most successful human cultures ever. The site was older than that; people had been there 100,000 years. We won’t be matching that again.

Why have animals — as readers will know from your book — been so important in your life?

Cats and dogs are a very good window into the natural world: a chance to see how another species lives and deals with its problems, what they like and what they don’t like. Especially cats. Dogs tend to be more accommodating to people, but cats tend to do what’s in their minds, not what’s in your mind. One year, we had a very hard winter. The deer were starving, so I fed them. I learned what deer did. I learned how they organize their time. One day there was a coyote in the field, lying low behind a rock and trying to be inconspicuous. The doe saw him, and she went over and threatened him. And he left the area in the way the Bushman told us to leave the area if we came upon a predator, like a lion. You’re supposed to walk away in an oblique angle, don’t run, just seem calm and indifferent to the predator. That’s how the coyote acted. It was the old way. I saw a lot of things like that. Every day something interesting happened.

You’re 81, and you write in your memoir that you don’t like growing old.

I don’t mind aging — I’m glad to be aging. I’ll never die young. I can do everything; I can’t do it as fast, and I don’t remember things as well as I did. I’m blessed with good health. But it’s got surprises. You get marginalized a lot. Senior citizen — you’re not a regular citizen. People are surprised to hear, if you can walk around and look okay, that you’re 80. ‘What, you’re 80?’ Well, this is what 80 looks like.

Burns, editor of “Off the Page: Writers Talk About Beginnings, Endings, and Everything in Between,” teaches creative writing at Cardiff Metropolitan University. in Wales.