Can we really "learn" from these stories?
Absolutely. And some of the lessons are surprisingly simple and obvious. For example, one thing that amazed me was the number of folks in Yosemite who have insisted—and still insist—on wading into rivers just above the park's gigantic, thousand-foot-plus waterfalls. The streambeds up there are incredibly slippery. You've basically got an invisible coating of snotlike algae covering a surface of highly polished granite that has water washing over it at 13 miles an hour. Which means that if you slip, you'll travel 40 feet in about two seconds, and then you're over the edge and gone. Yet people continue to wade out there—apparently they just can't make the computational reality switch from suburbia to the real world—with absolutely horrible results.

It was a financial gamble for you to publish these books. What made you think people would want to read this stuff?
Look, if I had written a book called, say, Death in the City that outlined all the ways you can die in a really bad neighborhood—getting shot, getting run over, and so on—almost no one would buy the thing. But three or four million years of evolution have programmed us to pay attention to big, scary things that can hurt you in the natural world—storms, avalanches, glaciers, rapids, nasty animals, whatever. Every one of us has at least one ancestor who was eaten by a bear. Those are the kinds of threats that twang an atavistic nerve. We're supposed to pay attention. That's how you wind up not being the guy who gets eaten by the bear.

And yet—the dining habits of bears aside—some of this is actually quite funny, isn't it?
You know, unfortunately, it is funny. There's a lot of stuff in these books that's just Darwin Award material, and it can be horribly entertaining to realize that "Oh, my God, I belong to a species with a huge range of intellect ... and that's the low end of the spectrum right over there." Some of these incidents are almost an embarrassment to Homo sapiens. At a certain point, you begin to realize that the average squirrel possesses more intellect than the average human being.

Really?
People do some of the dumbest things you could imagine, things that no other species would ever do. How about Shane Kinsella, a Yosemite tourist from Ireland? After drinking one hell of a lot of wine in August 2005, he poses for a photo in which he's pretending to fall into the river just above Upper Yosemite Falls, which is a 1,430-foot drop. The shot doesn't work out, so his friend—who's also been drinking a hell of a lot of wine—tells him to do it again. Shane obliges, only this time he loses his balance for real, falls in the river, shoots off the lip of the waterfall, spins into space, and, when he hits, explodes into pieces like a ripe melon. Only a human being—not even an amoeba—would make that mistake.

Do these stories ever bum you out?
Oh, yeah. It's just awful, doing the research and reading through hundreds and hundreds of accounts of terrible things that people have done to themselves. But the whole process is kind of double-edged. On the one hand, I'm depressed by all these fatalities. But then, if two or three people who happen to read one of the books end up not doing something that might otherwise have killed them, I've done a good thing and saved a life.

Has anybody ever been upset by what you've written?
I was expecting to get a lot of "how dare you!" letters from readers of Over the Edge, but we got zero. In fact, it was just the opposite: We got letters from many people, especially relatives of those who died, expressing gratitude for the way the book gave them closure. Often they would write to say, "I never understood what happened. Finally I do. Thank you for writing this." It was the last thing I was expecting. And it was really kind of amazing.