If you're a neuroscientist, one of your heroes is almost certainly the 2nd century Roman physician Galen. In his time, the prevailing wisdom was that the "mind" -- language, memory, emotions -- was centered in the heart, while the brain was some sort of useless packing material inside the skull. Galen's experience as team physician for the gladiators led him to conclude otherwise.
Galen noted that when someone came in with a brain injury -- like, say, a trident embedded in his head -- other things often didn't work right. Depending on which part of the brain was damaged, the man might have a paralyzed limb or he might have lost sensation or the power of speech. His memory might be impaired or his personality altered. From studying these unfortunate warriors, Galen drew a shocking conclusion: The mind resides in the brain.
From that insight came others, including one that we're still grappling with today: the notion that behavior is a brain function and that abnormal behavior comes from an abnormal brain.
In the centuries since Galen, understanding of the brain has grown tremendously. In recent years, it's gotten a huge boost from increasingly fancy tools: functional brain imaging, neurogenetics, manipulation of neural stem cells, brain/computer interfaces. And all the information that has come from these new measurement tools and approaches keeps underlining Galen's key point -- that the full range of behavior is anchored in the functioning of the brain.
This knowledge has helped us understand the brain, but it has also required us to think in new and inflammatory ways about free will and how much of it we really have. And that in turn has raised questions about everything from our own everyday foibles to terrible criminal acts.
Consider the case of Jerry Sandusky and his nightmarish behavior.
In the aftermath of his conviction came a brave, important opinion piece on CNN. Writing under the provocative heading of "Do pedophiles deserve sympathy?," James Cantor of the Department of Psychiatry at the University of Toronto explained how there tend to be neurobiological differences between pedophiles and everyone else. The disorder, he noted, runs in families at a higher than chance level, raising the specter of the involvement of genes that influence brain function.
Moreover, pedophiles have higher-than-expected rates of brain injuries during early childhood. And particularly complex findings suggest that many pedophiles experienced in-utero abnormalities in hormones that help regulate the development of the brain.
Does this raise the possibility that the neurobiological die is cast -- possibly even before birth -- and that some people are destined to be pedophiles? Precisely. As Dr. Cantor concludes: "One cannot choose to not be a pedophile."
Uh oh. Does this mean that a child molester may not be able to control his behavior? Is Sandusky-as-monster actually Sandusky-as-broken-nervous-system?
Dr. Cantor denies Mr. Sandusky that biological out: "One cannot choose to not be a pedophile, but one can choose to not be a child molester." In other words, even if one has neurobiologically based abnormal urges, it is a criminal act to give in to them.
So, how does that work? In Dr. Cantor's view, a pedophile has sexual urges that are "biological" and cannot be changed. But there are also things he can control, character traits such as self-discipline, motivation and virtue. And those things can be mustered to resist the urge to act on his pedophilic desires.
That reasoning can be carried over to all sorts of things. A person might have a family predisposition toward alcoholism but makes a decision whether to take that first drink. A person might have a nice face but makes a decision about whether to get that massive, hideous nose ring.
But this kind of thinking presupposes a weird dichotomy. We can't help our individual swirls of biological yuck and squishy brain parts filled with genes and hormones and neurotransmitters. But somewhere within each of us, perhaps in some secluded corner of the brain, a command center exists that is independent of biology. And this completely separate part of us enables us to resist abnormal urges that have arisen from an abnormal brain.
A lovely thought, but that's not how it works. Self-discipline, impulse control, gratification postponement and emotional regulation are all just as much products of biology as anything else that emanates from the brain. The same types of evidence that allowed us to understand the role for biology in such things as abnormal sexual urges have also demonstrated a role for biology in giving in to those urges.
Consider these examples: There's a part of the cortex that, when damaged, produces someone who knows the difference between right and wrong yet still can't control his behavior -- even murderous behavior. There's a gene that influences risk-taking and sensation-seeking behaviors. There's a microscopic parasite that can burrow into the brain and form cysts that cause people to become more impulsive. There's a class of stress hormones that cause neurons to atrophy in a part of the brain that is central to executive function and long-term planning; by early elementary school, children raised in poverty tend to lag behind in the maturation of this brain region.
Findings like these present a huge challenge in reconciling the criminal justice system with what brain science is teaching us. I sure don't know how to do it.
We can't lock up people preventively because their brain chemistry suggests they are predisposed to criminal acts, nor can we exonerate people who've committed crimes simply because of their brain chemistry. But the more we understand about these things, the clearer it is that we can't just ignore them.
I, for one, am glad that increasing numbers of legal scholars, theologians and neuroscientists are working collectively to consider these questions. But the issue even transcends such a large and consequential topic, challenging each of us to reconsider how we think about our triumphs and failures, our own peaks of self-discipline and troughs of self-indulgence. Ultimately, findings like these force us to touch something that you wouldn't want to touch with a 10-foot pole, that big ol' philosophical elephant in the room -- the issue of free will.
It cannot be that our thoughts, emotions, urges and itches are the exclusive province of biology, while what we do with them is entirely in the biology-free province of good and evil. If we are going to incorporate biology into thinking about human behavior -- as logic demands we do -- then we have to consider how it applies to all our domains of behavior. There are no separate categories.opinion_commentary
Robert M. Sapolsky is a professor of neuroscience at Stanford University and the author of "A Primate's Memoir," among other books. Copyright (C) 2012, Los Angeles Times.