Mic: Tell us about your research on the likely causes of drug addiction and why popular attitudes toward it are misguided.

Johann Hari: If you asked me four years ago, "What causes heroin addiction?" I would have looked at you as if you were simple-minded. I would have said, "Well, heroin causes heroin addiction." It's obvious. We've been told this story about addiction for a century now that's so deeply ingrained in our consciousness it seems like common sense.

We think that if you and me and the next 20 people to walk past this cafe all used heroin together, on day 21 we'd all be heroin addicts, because there are chemical hooks in heroin and our body would physically need those chemical hooks by the end of it, and that's what addiction is. It turns out that's not really the case.

A doctor in Vancouver explained it to me like this: If you and I step out into the street and you get hit by a car and break your hip, when you're taken to a hospital, it's very likely you'll be given a lot of diamorphine. Diamorphine is heroin. It's much better heroin than you'll ever score on the streets — it's medically pure. They've been giving it for quite a long period of time; it's happening in every hospital all over America.

If what we believe about addiction is right, what should happen? Those people should leave the hospital as addicts, right? That virtually never happens. That alerted me to the fact that something is not right about the story we've been told, but I couldn't quite figure it out — until I met an incredible professor named Bruce Alexander. He explained to me that our idea of addiction comes from a series of experiments conducted early in the 20th century.

They were really simple experiments. A rat would be placed in a cage and given two water bottles: one containing only water and one containing water that was laced with heroin or cocaine. The rat almost always preferred the drug water and almost always killed itself within a few hours. So there you go — that's our theory of addiction.

Bruce came along in the 1970s and said, Hang on a minute, we're putting the rat in an empty cage. He's got nothing to do, except use the drug water. Let's do this differently.

So Bruce built Rat Park. Rat Park was heaven for rats. Anything a rat could want, it got in Rat Park. It had lovely food, colored walls, tunnels to scamper down, other rats to have sex with. And they had access to both water bottles — the drug water and the normal water.

What's fascinating is that in Rat Park, they didn't like the drug water. They hardly ever used it. They only used it in low doses, none of them ever overdose and none used it in a way that looked compulsive or addictive.

What Bruce says is that this shows us that both the right-wing and left-wing theories of addiction are wrong. The right-wing theory of addiction is that it's a moral failing and hedonist. The left-wing theory is that you get taken over, your brain is hijacked. Bruce says, It's not your morality, it's not your brain — it's your cage. Addiction is an adaptation to your environment. Human beings need to connect, and when we can't connect with each other, because we're traumatized or beaten down or cut off, we will connect with something that will give us some sense of relief or pleasure. If you can't bond with people, you will obsessively bond with something that gives you some sense of purpose.

Mic: What are the implications of the Rat Park experiment for addiction and the war on drugs?

JH: The war on drugs is built on the idea that the chemicals are the problem. Once you realize that disconnection and isolation are the drivers of addiction, you suddenly realize that what we do actually makes addiction worse. We take addicts who are addicted because they're isolated and suffering, isolate them in prison cells and make it impossible for them to get jobs when they leave, and inflict more pain and suffering on them. As the doctor from Vancouver said to me, if you wanted to create a system that would make addiction worse, you would create the system that we have.

I went in Arizona to a prison called Tent City, where I went out with women who were forced to go out on a chain gang wearing t-shirts saying "I was a drug addict." When I went to the isolation unit where they're kept, they're literally put in a cell that that makes you think, "This the closest you could get to a human reenactment of the rat cage that guaranteed addiction — the one in the first set of experiments."

Mic: Many Americans think of the war on drugs as something that began under the Nixon administration and escalated under Reagan, whose presidency marked the beginning of a massive expansion of the prison population. But your book describes how that war began far earlier.

JH: Two global wars begin in 1914. One lasted four years, and one is still going. The one that's still going is obviously the drug war. Drugs were banned in the U.S. in 1914, which means they were transferred from being controlled by doctors and pharmacists, which worked pretty well, to being controlled by armed criminal gangs, a model that isn't working out so well.

If you ask, "Why were drugs banned?" I would guess that most people would say that they were banned for the same reasons we give them for banning them now. We don't want people to become addicted, we don't want kids to use them. That kind of thing.

But those barely come up if you study the time period. Drugs were banned in the United States in the middle of a race panic. There was a belief — which was obviously wrong — that African-Americans and Chinese-Americans were taking drugs, forgetting their place and attacking white people.

The way I tell this in the book primarily is through the story of Billie Holiday, and how she was stalked and killed by the man who launched the war on drugs. In 1939, not that far from where we are right now, Billie Holiday climbed onstage and sang the song "Strange Fruit," a song against lynching. It was incredibly shocking at the time.

That night, she was told by the Federal Bureau of Narcotics to stop singing that song. The bureau was run by a crazed racist named Harry Anslinger, a man who was regarded as a crazed racist even by other crazed racists of the 1930s. He used the N-word so often that his own senator said in an official memo that he should have to resign.

Holiday grew up in segregated Baltimore, and she promised herself that she would never bow her head to any white man. She effectively said, Screw you, I'm going to carry on singing my song. And that's when Anslinger decides to have agents stalk her. He has her sent in prison in 1947, and when she gets out, he makes it almost impossible for her to sing anywhere, because she needs a license to perform anywhere alcohol was served, and that was denied to her.