The Tell-Tale Brain: A Neuroscientist's Quest for What Makes Us Human

IS MAN AN APE OR AN ANGEL (AS BENJAMIN DISRAELI ASKED IN A famous debate about Darwin’s theory of evolution)? Are we merely chimps with a software upgrade? Or are we in some true sense special, a species that transcends the mindless fluxions of chemistry and instinct? Many scientists, beginning with Darwin himself, have argued the former: that human mental abilities are merely elaborations of faculties that are ultimately of the same kind we see in other apes. This was a radical and controversial proposal in the nineteenth century—some people are still not over it—but ever since Darwin published his world-shattering treatise on the theory of evolution, the case for man’s primate origins has been bolstered a thousandfold. Today it is impossible to seriously refute this point: We are anatomically, neurologically, genetically, physiologically apes. Anyone who has ever been struck by the uncanny near-humanness of the great apes at the zoo has felt the truth of this.

I find it odd how some people are so ardently drawn to either-or dichotomies. “Are apes self-aware or are they automata?” “Is life meaningful or is it meaningless?” “Are humans ‘just’ animals or are we exalted?” As a scientist I am perfectly comfortable with settling on categorical conclusions—when it makes sense. But with many of these supposedly urgent metaphysical dilemmas, I must admit I don’t see the conflict. For instance, why can’t we be a branch of the animal kingdom and a wholly unique and gloriously novel phenomenon in the universe?

I also find it odd how people so often slip words like “merely” and “nothing but” into statements about our origins. Humans are apes. So too we are mammals. We are vertebrates. We are pulpy, throbbing colonies of tens of trillions of cells. We are all of these things, but we are not “merely” these things. And we are, in addition to all these things, something unique, something unprecedented, something transcendent. We are something truly new under the sun, with uncharted and perhaps limitless potential. We are the first and only species whose fate has rested in its own hands, and not just in the hands of chemistry and instinct. On the great Darwinian stage we call Earth, I would argue there has not been an upheaval as big as us since the origin of life itself. When I think about what we are and what we may yet achieve, I can’t see any place for snide little “merelies.”

Any ape can reach for a banana, but only humans can reach for the stars. Apes live, contend, breed, and die in forests—end of story. Humans write, investigate, create, and quest. We splice genes, split atoms, launch rockets. We peer upward into the heart of the Big Bang and delve deeply into the digits of pi. Perhaps most remarkably of all, we gaze inward, piecing together the puzzle of our own unique and marvelous brain. It makes the mind reel. How can a three-pound mass of jelly that you can hold in your palm imagine angels, contemplate the meaning of infinity, and even question its own place in the cosmos? Especially awe inspiring is the fact that any single brain, including yours, is made up of atoms that were forged in the hearts of countless, far-flung stars billions of years ago. These particles drifted for eons and light-years until gravity and chance brought them together here, now. These atoms now form a conglomerate—your brain—that can not only ponder the very stars that gave it birth but can also think about its own ability to think and wonder about its own ability to wonder. With the arrival of humans, it has been said, the universe has suddenly become conscious of itself. This, truly, is the greatest mystery of all.

It is difficult to talk about the brain without waxing lyrical. But how does one go about actually studying it? There are many methods, ranging from single-neuron studies to high-tech brain scanning to cross-species comparison. The methods I favor are unapologetically old-school. I generally see patients who have suffered brain lesions due to stroke, tumor, or head injury and as a result are experiencing disturbances in their perception and consciousness. I also sometimes meet people who do not appear brain damaged or impaired, yet report having wildly unusual perceptual or mental experiences. In either case, the procedure is the same: I interview them, observe their behavior, administer some simple tests, take a peek at their brains (when possible), and then come up with a hypothesis that bridges psychology and neurology—in other words, a hypothesis that connects strange behavior to what has gone wrong in the intricate wiring of the brain.¹ A decent percentage of the time I am successful. And so, patient by patient, case by case, I gain a stream of fresh insights into how the human mind and brain work—and how they are inextricably linked. On the coattails of such discoveries I often get evolutionary insights as well, which bring us that much closer to understanding what makes our species unique.