One of the stories that inspired bestselling author Susan Casey’s new book on the intricate world of dolphins, Voices of the Earth, is almost too beautiful to be believed.

A biologist named Maddalena Bearzi was studying a group of dolphins off the coast of Los Angeles when she noticed something strange. The “pod” (group of dolphins) had just landed upon a herd of sardines. They were about to start feeding—something that usually transfixes the whole group—when one, unexpectedly, darted off.

In moments, the rest followed, swimming full speed out to sea. When she reached them, three miles offshore, the pod had a formed a circle—in the middle of it, a girl’s floating body. Very near death, the girl had a plastic bag with her identification and a suicide note wrapped around her neck. With the dolphins help, she was saved.

“I still think about and dream about that cold day,” Bearzi wrote of the sighting. “And that tiny, pale girl lost in the ocean and found again for some inexplicable reason, by us, by the dolphins.”

Our inexplicably intimate relationship and longtime fascination with dolphins provides a backdrop for Casey’s third book. From bizarre 1950s scientists to a community of dolphin worshippers, it’s an eye-opening look at the world below the sea.

You make it a point to clarify in the beginning that there are misconceptions about dolphins. Can you explain?

People think of dolphins and they don’t realize there are about 42 species of dolphin—and some of the dolphins are called whales. The word “whale” doesn’t mean that specific species or scientific definition, it just means large. Killer whales are the largest dolphin, so a dolphin is a toothed whale.

Also, the first dolphins lived on land?

Oh yeah. I’ve seen pictures of this and I struggle to know how to describe it. If you look it up the first dolphins you’ll just laugh out loud. It looks like this sort this feral, lupine rodent with hooves. It took them 25 million years to adapt to being in the water. When they first got into the water they were these big, almost dinosaur-like creatures with fangs, they were giant—they looked like those skeletons you see at the Natural Museum of History that look like sea monsters.

How did they adapt to live in the water?

Their bodies shrank and their teeth shrank and their brains got big—which is the opposite of what you’d think would happen. They did all kinds of shape-shifting evolutionarily. Their brains grew significantly—they weren’t always like that. It’s fascinating because scientists don’t know why. There’s one theory that it was to adapt to their echolocation, but most scientists’ main guess is that it was due to their changing social behavior.

So let’s talk about John Lily. He was a neuroscientist in the 1950s who pioneered a lot of the research on dolphins—but was also incredibly controversial. Why?

I think he always had good intentions but some of his experiments were pretty awful. Some of the ways he dealt with the dolphins in his lab, we would just balk at now—thank god. He wanted to poke wires into specific areas of the brain and in order to do it in the exact area he had to hammer these metal sleeves into their skulls. He couldn’t anesthetize them because they don’t breathe involuntarily. But he believed it wasn’t painful to them—he tried it on himself and said he could handle it. It was the noise of the hammer that freaked them out. I don’t think being a dolphin in Lily’s lab was a very happy fate.

Do you think he’s still important to the field?

He was the one who made it widely known through his book and appearances that dolphins had something going on upstairs and that they were creatures we should look closely at. He couldn’t prove most of his theories but he put them out there and in the 1970s he was largely the voice behind save the whales. I think he always had good intentions. He was an army-trained neuroscientist surgeon who had tremendous, rigorous academic training. But I think that era, you can’t underestimate it, it was a weird time—freewheeling pioneering but at the same time weirdly paranoid era. A lot of his funding was coming from the military and they wanted to figure out how to control people’s minds.

What were some of his crazier theories?

He had this thought that we were going to be speaking to them any day now, that it would be them speaking English, and they could tell us what was going on in the oceans and they could work for us and help us. He really, he had a voice.

One of his more bizarre experiments, the “flooded house” consisted of a woman cohabiting with a dolphin for 10 weeks—and eventually dealing with the dolphin’s sexual desires. What happened there?

That was a woman they recruited from the island. She was a local woman who was interested in dolphins and obviously very much a trooper. They lived together for 10 weeks. Dolphins are super, highly sexual creatures. Particularly a young male dolphin—a young male bottlenose dolphin, which are known to basically herd females and groups of males.

She chronicled the experience in writing, which you discuss in the book. I love the one quote you pulled out from her journal, which you wrote in italics and bold: “He won’t go away.”

Yeah, they’re not angels. It wasn’t surprising.

Are dolphins generally aggressive like that?

Dolphins can get riled up and in captivity there is a lot of injuries—I don't blame them. They have their breaking point just like we do. They’re remarkably tolerant given what we do to them.

Right. On the topic of that, there are thousands of dolphins held captive worldwide. Some argue that it exposes kids to new things and teaches them about sea life. What are your thoughts?

I don’t think you’re learning a whole lot about a dolphin by watching it in a swimming pool. I mean, yes, the kid gets to see the dolphin but what is he learning? As far as I know, there are no marine parks in the world with captive dolphin shows—where they are jumping through hoops—that also have a very rigorous science program.

How different is the environment, in captivity, than in the wild?

I mean, these are animals that swim 70 miles a day and they’re really all about sociology. Their pods are their lives so if you take them out of their pod you’re just preempting their lives and adding the schamu soundtrack. Once you start finding out the science behind dolphins it becomes increasingly apparent that it’s very rough life for a dolphin socially and psychology because they are adapted to swim long distances and being together.

Beyond captivity, you mention other ways that we are endangering them?

There are tremendous problems in their habitat: overfishing is a huge one, pollution—we’ve outlawed some really bad chemicals but they don’t vanish like poof they’re gone, they bind to fat. Dolphins are filled with mercury heavy metals, insecticides, and flame retardants, all of which weaken their immune system and make them more susceptible to viruses. There’s also a lot of industrial noise from ships and Navy sonar. The sonar is so loud we couldn’t tolerate it—not even close. Some of the dolphins freak out when they hear it and swim to the surface, then hemorrhage and die.

Wow. I’m surprised that they’re not meaner to us.

Me too. Or that they want anything to do with us!

Are you angry with humans?

We’re sort of bright light dark shadow, you know. I would like to see humans become more conscious of other creatures. I don’t think we’re going to do very well ourselves against the rest of living beings on this earth. We’re not separate. We harm nature at our own peril and our expense. I think we could do with a big dose of humility. It does not make sense to wreck the environment that sustains us, the life that sustains us, yet we’re doing it.

The dolphins that saved the girl from committing suicide is incredible. How did you find it?

You hear all these stories about dolphins rescuing humans—not to say that every human is going to be rescued by a dolphin. Some scientists make a point of saying don’t count on that. I looked for stories that were verifiable. That was one of my favorites because it was a scientist observing it and writing about it—them forming a circle like: “here, here!”

How did the dolphin know the girl was there?

That’s the big questions. They don’t rely on vision, I mean, their eyes work just as well in air as in water, but their dominant sense is their hearing, their bio sonar. They work with sound frequency and vibration because in the ocean where there is not always light. I suspect it had something to do with frequency and vibration but of course that’s a guess. We don’t know.

What do you think makes them react like this?

There’s a chapter about solitary friendly dolphins. They tend to treat us the way they would treat other dolphins. By themselves, they’re vulnerable—to sharks, getting lost, all these things. So when you see dolphins together there is constant touching. They know how to help each other.

You discuss how they are one of the few animals with a recognized sense of self. Is it something you were able to connect with?

I’ve looked into the eyes of white sharks and you see this incredible creature that’s adapted for 400 million years that’s adapted into its niche, but you don’t see someone looking back at you necessarily. With dolphins, there’s someone looking back at you. That’s the shocking thing.

One of the most colorful parts of the book is your visit to a new-age dolphin community in Kona, Hawaii called Dolphinville. Many people have been critical of this community as cult-ish. What do you think?

I think Joan [Ocean, who started the group] is a wonderful woman. People think she’s super wacky, but I am very fond of her. I don’t think she’s doing anything to harm the dolphins. They don’t actually live with dolphins, they live along the coastline in Kona they have a large population of spinner dolphins who come in near the shore to rest in the afternoon. It’s a very predictable pattern, which is very unusual in the wild. If you want to swim with wild dolphins that probably the best place in the world to go. Scientists are starting to get a little worried that dolphin’s resting is being disturbed by people but I’ve found that it’s generally the dolphins choice if they want to come over to you. I’m respectful of the viewpoint that people may cause the dolphin’s problems, so they can’t feel like they can really rest while swimming, but it’s hard to bother them if you’re just swimming.

What do you think dolphins think of us?

I think they’re individuals. I don’t think necessarily that every dolphin thinks “Hey, a human! I wanna go play with them,”—but some do. When you’re with a group of wild dolphins you can see that some are more curious than others. There are actually shy dolphins, that’s been proven. There’s a great paper out by this scientist Stan Kuzak, he proved that they have stable and distinct personalities. Some dolphins are really curious about us and some avoid us—probably a lot like we would be in their position. .

You begin the book by discussing your first swim with dolphins—something you say everyone should experience. What was it like, did they acknowledge you?

In any group you encounter there are a couple dolphins that are like the “scouts” who will check you out, that definitely happened. There was one that kept studying me. After that they made the choice to stay with me it was quite clear because I was just there in the water and they just kept going around me. They stayed with me—they didn’t have to. So I think it was they had decided they were going to do it, maybe because they were curious, I don’t know. You can never know it’s certainly made a difference on my outlook on life. It’s hypnotic. It’s like you’re in an ether of blue.