The takeaway of Robert Sapolsky’s Determined: A Science of Life Without Free Will is basically the same as that espoused by those Snickers commercials: You’re not you when you’re hungry. Except according to Sapolsky, there is no “you”—the hunger is what dictates your behavior, along with your stress level, whether or not you were born with fetal alcohol syndrome or grew up in a culture that valorizes individual freedoms versus one that prioritizes communal responsibility or in one that believes in an omniscient, omnipotent, vengeful deity.

Hormones, neurotransmitters, and how they are affected by your current and historical circumstances—these are the only things that determine how you will act and what decisions you will make at those inflection points when you’re called upon to make impactful choices. And all of them are things you did not choose and cannot control.

Sapolsky, a neurobiologist at Stanford University, is not averse to the notion of our having free will; it’s just that he can’t find it. And he’s looked everywhere. He has studied—intensely—not only neurobiology but also endocrinology, behavioral science, philosophy, primatology, criminology, psychiatry, sociology, anthropology, evolution, and history. Not a single one of these disciplines precludes free will, but all of them together do. All there is to us is biology and the way that biology is affected by our environment. That’s it. We are not, as Yoda suggested, luminous beings; we are only crude matter.

This is tough stuff for Americans, who are practically addicted to our meritocratic, rags-to-riches, pull-yourself-up-by-your-bootstraps mythology. So in chapter four, “The Myth of Grit,” Sapolsky deals with people who overcome their circumstances (along with their foils, those who “squander” their good fortune). The secret of their success (and failure) all comes down to their prefrontal cortex (PFC).

The PFC is famously the last part of the brain to mature; it’s not fully constructed in humans until we’re in our mid-20s. Not because it’s harder to build—it’s made of the same components as the rest of the brain, which has been largely functional for the past couple of decades. Rather, Sapolsky claims that it matures late specifically to enable it to become the brain region most influenced by the experiences we have in those first two decades—to learn from those experiences and have them shape us. Grit, pluck, willpower, stick-to-it-iveness, and self-restraint are controlled by the PFC and are shaped by the environment we grew up in. And that’s an environment we do not choose or control.

“What the PFC is most about is making tough decisions in the face of temptation—gratification postponement, long-term planning, impulse control, emotional regulation,” he writes. “The PFC is essential for getting you to do the right thing when it is the harder thing to do.”

Difficult decisions take a ton of mental energy. That’s not a metaphor; the PFC consumes an immense amount of cellular energy. So much so that if you’re hungry, tired, stressed, or lack resilience because you were born poor, which gave you chronically elevated glucocorticoid levels, your PFC simply does not have the juice to make good decisions when it matters. Sapolsky points out that “a substantial percentage of people incarcerated for violent crime have a history of concussive head trauma to the PFC.”

An ambitious goal

“This book has a goal,” Sapolsky writes. “To get people to think differently about moral responsibility, blame, and praise.” Although the world is wholly deterministic, we can, and have, learned to change our views and behaviors—both on the individual and the societal levels. We learn and we change when our environment modulates the same molecules, genes, and neuronal pathways that controlled our original views and behaviors. Incidentally, these are the same molecules, genes, and neuronal pathways modulated when a sea slug learns to avoid being shocked by a researcher—i.e., not free will.

Sapolsky’s stated goal of rethinking blame is exceedingly difficult, even for him. He refers to Bettelheim, the self-hating Jew who insisted that autism in kids is caused by their cold “refrigerator mothers” as “a sick, sadistic fuck.” He calls Anders Breivik, who carried out the largest terrorist attack in Norwegian history when he murdered 69 kids at summer camp in 2011, “a lump of narcissism and mediocrity” who “finally found his people among white supremacist troglodytes.”

Yet he thinks that punishing them is as unjust as punishing someone with diabetes. He promotes a public health-based approach to criminal justice: Criminals should be removed from society so they don’t further harm others, much like those with infectious diseases should be quarantined so they don’t harm others. (Because that worked out well.)