The late anthropologist Colin Turnbull once described an interesting experience he had driving a tribal man through an open park. This man had never left the dense jungle before. Several miles below the road they were traveling on, a herd of buffalo grazed. "What insects are those?" the man asked. He laughed at first at the answer, but as the car approached, he grew silent as the "insects" increased in size.
"His only comment," Turnbull wrote, "was that they were not real buffalo, and he was not going to get out of the car again until we left the park." In the thick of the forest, the anthropologist realized, the range of vision was so limited that the man had never fully developed his capacity to sense depth. He never had to.
If vision is so adaptive, could the way people perceive things be more dependent on what we experience as individuals than on how we've evolved as a species? Does the brain even have a "natural" language?
Oliver Sacks's new book, The Mind's Eye, explores these essential questions with anecdotes like Turnbull's and case studies of people affected by challenging neurological conditions. We meet a concert pianist who is losing her capacity to recognize objects, a novelist who suddenly can't read but can nevertheless still write, and a neurobiologist who begins to see in three dimensions for the first time in her fifties. Sacks explores prosopagnosia or "face blindness," an underreported condition affecting an astonishing 6 million Americans that makes it difficult to recognize faces, as well as its opposite, a rare capacity that shows up in "super-recognizers," who from a distance can place people they've spoken to only once years ago.
Reached in New York by phone, Sacks, professor of neurology and psychiatry at Columbia University, described the nature of such neurological challenges as ambiguous. "I try to present human lives as they have been altered by neurological or perceptive mishap," he said, "although I use the word 'mishap' cautiously." That's because, he told me, some people look at what happens somewhat positively, like the theologian John Hull, who called his blindness a "dark paradoxical gift" for how it heightened his other senses. "Paradox is built in to a number of these experiences," Sacks said. "People lose something on the one hand, but they may gain on another."
“I wanted to bring [prosopagnosia] to public, and for that matter, medical attention,” Sacks said, “because I think it is quite common, millions have it, and it’s hardly recognized.”
The Mind's Eye probes each individual case with Sacks' characteristic combination of scientific detachment and compassion. The doctor also turns his clinical gaze inward. Delving into the day-to-day lives of those who may struggle to maintain their dignity in the face of diverse neurological trials, Sacks also details his recent eye cancer and loss of vision in one eye, as well as own lifelong affliction with prosopagnosia.
"I wanted to bring [prosopagnosia] to public, and for that matter, medical attention," Sacks said, "because I think it is quite common, millions have it, and it's hardly recognized." After publishing an article in The New Yorker in August detailing the condition—a version of the piece, "Face-Blind," appears in the book—Sacks received an outpouring of responses. "I get letters every day," he told me, from people who now feel "partly liberated because I've sort of brought the term out."
Also of particular interest in this, his 11th book, is what Sacks dubs the "Wallace problem," after Alfred Russel Wallace. Wallace was puzzled that the human capacity for speech evolved over hundreds of thousands of years, but as Sacks writes, "this cannot be maintained in regard to reading, for writing emerged little more than 5,000 years ago." If the natural and social environments of pre-literate societies could not have selected for reading or calculus, Wallace wondered, why do modern humans have such undeniable aptitude for them?
As Sacks notes, if the capacity for such skills could not have evolved expressly for exercising those skills, it must be that the brain has an astounding ability to re-direct pre-existing neural capacities toward new ends. In the case of writing, Sacks writes, such "a redeployment of neurons is facilitated by the fact that all (natural) writing systems seem to share certain topological features with the environment, features which our brains evolved to decode." Letters, in short, have evolved by cultural selection to mimic shapes our brains have evolved to recognize easily in nature.
Sacks is now 77, and the string of accolades attached to his work speaks for itself. His book Awakenings inspired the Oscar-nominated film. W.H. Auden dedicated a poem to him. The New York Times called him "the poet laureate of medicine." It is little wonder, then, that The Mind's Eye is both intellectually compelling and at times poetic. The pianist Sacks profiles, her capacity to recognize objects deteriorating, mutters "all is forgiven" after playing a beautiful quartet. A mother who can no longer speak remains grateful for every day. The novelist who can't read uses dictation to continue to write books.
As to what degree the brain has a natural language, there are more questions and answers. In our conversation, Sacks described his book as is a kind of "letter to anyone who might be interested." His exploration of the paradoxical gifts that sometimes accompany perceptual mishaps is a profound reflection on the anomalies of human experience. Most arrestingly, he also reveals the grace that can miraculously inhabit affliction.
Jamie Holmes is a program associate at the New America Foundation. His writing has appeared in Foreign Policy, the Christian Science Monitor, the Philadelphia Inquirer, and The Huffington Post.