I’m taking a college psychology course. In one class we heard the instructor say she thinks there is an actual drive among human beings to alter consciousness through use of substances. I hadn’t heard that before. Do you think it’s true?”

I first encountered that particular theory in Ronald Siegel‘s book Intoxication: The Universal Drive For Mind-Altering Substances. Dr. Siegel is both an eminent scientist and a gifted writer, so be sure to check it out.

In brief, Siegel posits a fourth ‘drive’, to go along with sex, food, and sleep, that he believes accounts for the persistence of drug use throughout history. Personally, I found that unconvincing. I could see no clear biological benefit to intoxication, of the sort associated with eating, sleeping, and reproduction. I think the continuing popularity of substance use through the ages is because in practical terms, substances work.

There are those that calm us, those that excite us, those that alter our perception in fascinating ways, at least for a while. And who doesn’t want that from time to time?

It happens because those substances are able to make use of pathways that already exist in the brain.

That’s why a simple preparation made from poppy juice can suppress pain so effectively that it plays a key role in medicine for 5,000 years. It closely resembles something in the body’s own natural pain suppression process. And therefore can make use of those same pathways.

And that’s an accident. At some point in history, human beings stumbled across it and began to experiment. They had no idea why it worked, but they could certainly see that it did.

Perhaps something similar happened with hallucinogens. You can see what happens to birds who devour the seeds of certain plants. Having visions has long been a way to impress others for fun and profit.

There are unintended consequences to all these substances. The euphoria associated with opium makes it a prime candidate for abuse, while a painful withdrawal syndrome makes it highly addictive. The human cost of both can be enormous. The enchanting perceptual distortions associated with hallucinogens carry some risks as well.