Incognito: The Secret Lives of the Brain

by David Eagleman

And over the past century, neuroscience has shown that the conscious mind is not the one driving the boat. A mere four hundred years after our fall from the center of universe, we have experienced the fall from the center of ourselves.

In the first chapter we saw that conscious access to the machinery under the hood is slow, and often doesn’t happen at all. We then learned that the way we see the world is not necessarily what’s out there: vision is a construction of the brain, and its only job is to generate a useful narrative at our scales of interactions (say, with ripe fruits, bears, and mates). Visual illusions reveal a deeper concept: that our thoughts are generated by machinery to which we have no direct access. We saw that useful routines become burned down into the circuitry of the brain, and that once they are there, we no lon...

In the wake of all the scientific progress, a troubling question has surfaced in the minds of many: what is left for humans after all these dethronements?

Philosophers such as Heidegger, Jaspers, Shestov, Kierkegaard, and Husserl all scrambled to address the meaninglessness with which the dethronements seemed to have left us. In his 1942 book Le mythe de Sisyphe, Albert Camus introduced his philosophy of the absurd, in which man searches for meaning in a fundamentally meaningless world.

This improved understanding of human behavior can translate directly into improved social policy.

Our deeper understanding of the inner cosmos also gives us a clearer view of philosophical concepts. Take virtue. For millennia, philosophers have been asking what it is and what we can do to enhance it. The team-of-rivals framework gives new inroads here. We can often interpret the rivalrous elements in the brain as analogous to engine and brakes: some elements are driving you toward a behavior while others are trying to stop you. At first blush, one might think virtue consists of not wanting to do bad things. But in a more nuanced framework, a virtuous person can have strong lascivious drives as long as he also commands sufficient braking power to surmount them. (It is also the case that a virtuous actor can have minimal temptations and therefore no requirement for good brakes, but one could suggest that the more virtuous person is he who has fought a stronger battle to resist temptation rather than he who was never enticed.)

Like your enteric nervous system and your sense of attraction, almost the entirety of your inner universe is foreign to you. The ideas that strike you, your thoughts during a daydream, the bizarre content of your nightdreams—all these are served up to you from unseen intracranial caverns.

By the same token, to know oneself may require a change of definition of “to know.” Knowing yourself now requires the understanding that the conscious you occupies only a small room in the mansion of the brain, and that it has little control over the reality constructed for you. The invocation to know thyself needs to be considered in new ways.

All of this leads to a key question: do we possess a soul that is separate from our physical biology—or are we simply an enormously complex biological network that mechanically produces our hopes, aspirations, dreams, desires, humor, and passions?

“uptake inhibitor”:

neurotransmitters

Consider epilepsy. If an epileptic seizure is focused in a particular sweet spot in the temporal lobe, a person won’t have motor seizures, but instead something more subtle. The effect is something like a cognitive seizure, marked by changes of personality, hyperreligiosity (an obsession with religion and a feeling of religious certainty), hypergraphia (extensive writing on a subject, usually about religion), the false sense of an external presence, and, often, the hearing of voices that are attributed to a god.10 Some fraction of history’s prophets, martyrs, and leaders appear to have had temporal lobe epilepsy.

Consider Joan of Arc, the sixteen-year-old-girl who managed to turn the tide of the Hundred Years War because she believed (and convinced the French soldiers) that she was hearing voices from Saint Michael the archangel, Saint Catherine of Alexandria, Saint Margaret, and Saint Gabriel. As she described her experience, “When I was thirteen, I had a voice from God to help me to govern myself. The first time, I was terrified. The voice came to me about noon: it was summer, and I was in my father’s garden.” Later she reported, “Since God had commanded me to go, I must do it. And since God had commanded it, had I had a hundred fathers and a hundred mothers, and had I been a king’s daughter, I would have gone.” Although it’s impossible to retrospectively diagnose with certainty, her typical reports, increasing religiosity, and ongoing voices are certainly consistent with temporal lobe epilepsy. When brain activity is kindled in the right spot, people hear voices. If a physician prescribes an anti-epileptic medication, the seizures go away and the voices disappear. Our reality depends on what our biology is up to.

So we see that the invisibly small molecules we call narcotics, neurotransmitters, hormones, viruses, and genes can place their little hands on the steering wheel of our behavior. As soon as your drink is spiked, your sandwich is sneezed upon, or your genome picks up a mutation, your ship moves in a different direction. Try as you might to make it otherwise, the changes in your machinery lead to changes in you. Given these facts on the ground, it is far from clear that we hold the option of “choosing” who we would like to be. As the neuroethicist Martha Farah puts it, if an antidepressant pill “can help us take everyday problems in stride, and if a stimulant can help us meet our deadlines and keep our commitments at work, then must not unflabbable temperaments and conscientious characters also be features of people’s bodies? And if so, is there anything about people that is not a feature of their bodies?”16

These examples demonstrate that it is neither biology alone nor environment alone that determines the final product of a personality.26 When it comes to the nature versus nurture question, the answer almost always includes both.

Without a doubt, minds and biology are connected—but not in a manner that we’ll have any hope of understanding with a purely reductionist approach.

Reductionism is misleading for two reasons. First, as we have just seen, the unfathomable complexity of gene–environment interactions puts us a long way from understanding how any individual—with her lifetime of experiences, conversations, abuses, joys, ingested foods, recreational drugs, prescribed medications, pesticides, educational experience, and so on—will develop. It’s simply too complex and will presumably remain so. Second, even while it’s true that we are tied to our molecules and proteins and neurons—as strokes and hormones and drugs and microorganisms indisputably tell us—it does not logically follow that humans are best described only as pieces and parts. The extreme reductionist idea that we are no more than the cells of which we are composed is a nonstarter for anyone trying to understand human behavior. Just because a system is made of pieces and parts, and just because those pieces and parts are critical to the working of the system, that does not mean that the pieces and parts are the correct level of description.

And this forces a reconsideration of how to build a scientific account of the brain. If we were to work out a complete physics of neurons and their chemicals, would that elucidate the mind?

A meaningful theory of human biology cannot be reduced to chemistry and physics, but instead must be understood in its own vocabulary of evolution, competition, reward, desire, reputation, avarice, friendship, trust, hunger, and so on—in the same way that traffic flow will be understood not in the vocabulary of screws and spark plugs, but instead in terms of speed limits, rush hours, road rage, and people wanting to get home to their families as soon as possible when their workday is over.

There’s another reason why the neural pieces and parts won’t be sufficient for a full understanding of human experience: your brain is not the only biological player in the game of determining who you are. The brain is tied in constant two-way communication with the endocrine and immune systems, which can be thought of as the “greater nervous system.” The greater nervous system is, in turn, inseparable from the chemical environments that influence its development—including nutrition, lead paint, air pollutants, and so on. And you are part of a complex social network that changes your biology with every interaction, and which your actions can change in return. This makes the borders interesting to contemplate: how should we define you? Where do you begin and where do you end? The only solution is to think about the brain as the densest concentration of youness. It’s the peak of the mountain, but not the whole mountain. When we talk about “the brain” and behavior, this is a shorthand label for something that includes contributions from a much broader sociobiological system.** The brain is not so much the seat of the mind as the hub of the mind.

So let’s summarize where we are. Following a one-way street in the direction of the very small is the mistake that reductionists make, and it is the trap we want to avoid. Whenever you see a shorthand statement such as “you are your brain,” don’t understand it to mean that neuroscience will understand brains only as massive constellations of atoms or as vast jungles of neurons. Instead, the future of understanding the mind lies in deciphering the patterns of activity that live on top of the wetware, patterns that are directed both by internal machinations and by interactions from the surrounding world. Laboratories all o...

If our brains were simple enough to be understood, we wouldn’t be smart enough to understand them.