The Biology of Desire

Marc Lewis


I’m a neuroscientist and a professor. It’s my job to teach students whatever I know about the brain. I’ve taught and done research on emotional development and the brain for most of my career. But after my first decade of lecturing, I began to sound stodgy and dull, even to myself. What was I missing? The brain is the foundation of our needs, our desires, our joy and suffering, our darkest moments and our capacity to overcome them. Why was it coming across as an anatomical jigsaw puzzle, a blueprint for a circuit board, a thicket of labels, boxes, and arrows? How could I convey the gut-­wrenching reality of the brain as a motivational furnace? Even in graduate courses, students met my efforts with glassy stares and furious note taking. Look up! I wanted to shout. Look up from your notes and feel what your brain is doing. You can get this directly. Not from your notes. Just introspect a bit and you’ll discover that your brain is busily extending and revising a landscape of flitting thoughts, shocking associations, and childish impulses. It’s not just an organ of rationality, as you’ve no doubt been taught; it’s also the biological engine of our striking irrationality — it has a dark side. How does that work?

And how do I get it across?

About six or seven years ago I began to talk more candidly about my own messy emotions. I culled examples from my past, exposing the dark side of my own brain. That got their attention. Especially when I revealed that I’d been a drug addict through most of my twenties — something I’d locked away from public scrutiny for nearly thirty years. Professors aren’t supposed to be drug addicts, past, present, or future. This was interesting. At around the same time, I began riffling through the journals I’d kept from my late teens to mid-thirties. I relived hundreds of traumatic, horrific, and often baffling experiences of getting high and getting lost. I began to read and think about the brain processes underlying addiction, and I began the book I hoped would put it all together: my previous book, Memoirs of an Addicted Brain.

I stopped taking illegal drugs and taking drugs illegally at the age of thirty. Now, as a neuroscientist and a teacher, I needed to figure out what had happened to me all those years ago. How had my brain become so addled for such a long time? How did I finally quit? As I waded through a sea of papers on the neuroscience of addiction, I learned how circuits devoted to goal seeking become captivated by the appeal of a single goal. A drug, a drink, gambling, porn — whatever it is that satisfies a powerful desire, at least partially, while simultaneously increasing its own appeal. I started to understand the dark side of the brain as a scientist as well as an “end user” — and I began to convey what I was learning to my students, with passion, precision, and, I hope, insight.

This book is my current attempt to be that teacher. While I have a message to get across, an argument to make about addiction, my most daunting task is to move back and forth between two perspectives: life as we experience it — including its pinnacles and perils — and the concrete workings of the brain that make that experience possible. If we are to understand anything so complex and troubling as addiction, we need to gaze directly at the point where experience and biology meet. Because that’s the bottleneck, the linchpin, where human affairs are cast and crystallized. That’s where the brain shapes our lives and our lives shape the brain.

The Biology of Desire Marc Lewis