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

I started by outlining an evolutionary and anatomical framework for understanding many strange neuropsychiatric syndromes. I suggested that these disorders could be regarded as disturbances of consciousness and self-awareness, which are quintessentially human attributes. (It’s hard to imagine an ape suffering from Cotard syndrome or God delusions.) Some of the disorders arise from the brain’s attempts to deal with intolerable discrepancies among the outputs of different brain modules (as in Capgras syndrome and apotemnophilia) or inconsistencies between internal emotional states and a cognitive appraisal of the external circumstances (as in panic attacks). Other disorders arise from derangement of the normally harmonious interplay of self-awareness and other-awareness that partly involves mirror neurons and their regulation by the frontal lobes.

I began this book with Disraeli’s rhetorical question, “Is man an ape or angel?” I discussed the clash between two Victorian scientists, Huxley and Owen, who argued over this issue for three decades. The former emphasized continuity between the brains of apes and humans, and the latter emphasized human uniqueness. With our increasing knowledge of the brain, we need not take sides on this issue anymore. In a sense they were both right, depending on how you ask the question. Aesthetics exists in birds, bees, and butterflies, but the word “art” (with all its cultural connotations) is best applied to humans—even though, as we have seen, art taps into much of the same circuitry in us as in other animals. Humor is exclusively human but laughter isn’t. No one would ascribe humor to a hyena or even to an ape that “laughs” when tickled. Rudimentary imitation (such as opening a lock) can be also accomplished by orangutans, but imitation of more demanding skills such as spearing an antelope or hafting a hand axe—and in the wake of such imitation the rapid assimilation and spread of sophisticated culture—is seen only in humans. The kind of imitation humans do may have required, among other things, a more complexly evolved mirror-neuron system than what exists in lower primates. A monkey can learn new things, of course, and retain memory. But a monkey cannot engage in conscious recollection of specific events from its past in order to construct an autobiography, imparting a sense of narrative and meaning to its life.

Morality—and its necessary antecedent “free will,” in the sense of envisioning consequences and choosing among them—requires frontal lobe structures that embody values on the basis of which choices are made via the anterior cingulate. This trait is seen only in humans, although simpler forms of empathy are surely present in the great apes.

Complex language, symbol juggling, abstract thought, metaphor, and self-awareness are all almost certainly unique to humans. I have offered some speculation on their evolutionary origins, and suggested also that these functions are mediated partly by specialized structures, such as the angular gyrus and Wernicke’s area. The manufacture and deployment of multicomponent tools intended for future use probably requires yet another uniquely human brain structure, the supramarginal gyrus, which branched off from its ancestor (the inferior parietal lobule) in apes. Self-awareness (and the interchangeably used word “consciousnesses”) has proved to be an especially elusive quarry, but we have seen how it can be approached through studying the inner mental life of neurological and psychiatric patients. Self-awareness is a trait that not only makes us human but also paradoxically makes us want to be more than merely human. As I said in my BBC Reith Lectures, “Science tells us we are merely beasts, but we don’t feel like that. We feel like angels trapped inside the bodies of beasts, forever craving transcendence.” That’s the essential human predicament in a nutshell.

We have seen that the self consists of many strands, each of which can be unraveled and studied by doing experiments. The stage is now set for understanding how these strands harmonize in our normal day-to-day consciousness. Moreover, treating at least some forms of mental illness as disorders of self might enrich our understanding of them and help us devise new therapies to complement traditional ones.