Biology, Behavior, and Free Will: Interview with Robert Sapolsky

By Francesca Paris 

Behave: The Biology of Humans at Our Best and Worst by Robert Sapolsky (ΦBK, Harvard College) is the recipient of the 2018 Phi Beta Kappa Science Book Award.

This award, established by Phi Beta Kappa in 1959, is offered to honor outstanding scientific contributions and to encourage literate and scholarly interpretations of the physical and biological sciences and mathematics.

The John A. and Cynthia Fry Gunn Professor of Biological Sciences at Stanford University and Professor of Neurology and Neurosurgery in Stanford’s School of Medicine, Sapolsky is a celebrated neuroendocrinologist. His books include Stress, the Aging Brain and the Mechanisms of Neuron Death (1992), The Trouble with Testosterone (1997), and Why Zebras Don’t Get Ulcers: A Guide to Stress-Related Diseases and Coping (1995). Known for his popular appeal, he also writes for magazines like Discover and Scientific American.

Behave is a sweeping, cross-disciplinary examination of human behavior. Sapolsky takes the reader through the biology of behavior, from the neural impulse that sparks an action to the cascade of factors preceding any decision. The book weaves complex scientific terms and humorous anecdotes into a picture that stretches back through a person’s life and, further still, through generations of humanity. 

As Sapolsky explains, it is impossible to separate any part of the decision-making process. Evolutionary pressures combine with childhood development, genetic factors, the nervous system, and more to produce a single action. This web of influence offers the reader a more nuanced view of concepts like good and evil, altruism and selfishness, hope and brutality. Behave looks critically at the intersection of science and society, and how our biology shapes our present and our collective future.


In Behave, you stress that each decision humans make has to be considered from many angles. What are the forces that shape our behavior, and why are they so challenging to study? 


SAPOLSKY: The multiplicity of forces is the main theme of the book. Someone does something—wonderful, awful, in between—and we ask why that behavior occurred. And to answer that, you have to consider what went on in the person’s nervous system a second before. But you also need to know what environmental stimuli in the prior minutes influenced those neurons. And you also need to know how hormones in the previous hours to days influenced the sensitivity of the brain to those stimuli. And from there it’s back to months of neural plasticity, then adolescence, childhood, fetal life, genes, culture, evolution—because they all shape what went in to the milliseconds of deciding to do that behavior. What’s challenging is not only that so many disciplines are pertinent, and how they are all interrelated, but also how many of these forces are subterranean, where we typically haven’t a clue of their impact.

You’re a professor of biology, neurology, and neurosurgery at Stanford University, but you write extensively in the book about topics that may seem unrelated, like morality, empathy, and free will. Why is it useful to consider all of these concepts in relation to human biology? 


SAPOLSKY: Well, the reason why I study the brain is to understand how it produces behavior, and what behaviors could be more interesting than moral or empathic acts, when someone steps out of the crowd and does the right thing that’s the hard thing to do? And in terms of free will, as far as I’m concerned, if you study neuroscience, you’re implicitly studying whether there is such a thing as free will (and I happen to think there isn’t any—“free will” is what we call the biology that hasn’t been discovered yet).

You also write about harm and care, violence and cooperation, and how intertwined these concepts are. In the end you push the reader to consider the many reasons we have to hope. Are you an optimist? How do you think future generations will look back on our behavior today?


SAPOLSKY: A major theme that lurks in the pages of the book is that life really has improved for the average human over the last few centuries, and we understand some of the biology that’s behind it. I’m a total pessimist by nature, so this progress has often only been an intellectualization for me. I’m as capable as the next person of reading the news and feeling like the world is an unbearably brutal place. In terms of future generations, I assume they will look back and be horrified at the harm we’ve done to each other out of our ignorance as to where our behaviors come from. 

Were there points in the process of putting the book together where you found yourself surprised, either by something you learned or by how the all the separate parts fit together? What do you think will be one of the greatest revelations for your readers?


SAPOLSKY: I was ultimately surprised that I managed to finish the damn thing…but aside from that, I suppose my biggest surprises came in learning about how culture influences and is in turn influenced by biology. It was probably the area of the book where I was least informed, and I was surprised by the really fascinating, rich information there is out there. In terms of revelations for readers, what I’ve been able to tell so far is that a lot of people spend a lot of the book thinking, “Whoah, I had no idea that biology had to do with this or that behavior.” Which, when added up, has to make the concept of free will suspect.

You received your bachelor’s degree in biological anthropology from Harvard College, where you became a member of Phi Beta Kappa. Are there any words of wisdom/advice you would like to share with undergraduates in the liberal arts and sciences today? 

SAPOLSKY: Well, my upbeat advice is to pay careful attention to your previous sentence. Liberal arts “and” sciences, rather than “or.” There’s plenty of time to specialize. My less upbeat advice recognizes that readers are likely to be accomplished, driven, ambitious—as much as is possible, be very clear in your mind what you are willing to give up in the name of that ambition.

What was your reaction to winning Phi Beta Kappa’s Science Book Award, especially as a member? 

SAPOLSKY: Surprise, pleasure. I’m still surprised and pleased that I got into Phi Beta Kappa 40 years ago.

Francesca Paris (ΦBK, Williams College, 2018) recently completed her bachelor’s degree in statistics and Arabic studies and is currently interning at NPR. Williams College is home to the Gamma of Massachusetts Chapter of Phi Beta Kappa.