“A six-year-old boy,” reported the Times of India, “has been returned to his parents after being in the company of wolves for four and a half years.” In the fall of 1957, shortly after this story appeared, a curious sociologist traced the story’s origins. There was a boy who had been found alone, who spoke few words and seemed “interested in people only as objects.” But there were no wolves. Scholars have argued that this boy, named Parasram, and many children before him belong to the pre-history of autism. And really, consider it: An unspeaking child is found untended in the wild, and we conclude that she or he was stolen by wolves or nursed by pumas. We interpret scars as evidence of a life among beasts. There is a deficit of humanity in these stories, but it doesn’t belong to the abandoned children or to the nurturing packs and prides. The deficit lies in our inability to recognize ourselves among the less-familiar forms of human experience.

In a new book, NeuroTribes: The Legacy of Autism and the Future of Neurodiversity, the author Steve Silberman documents society’s emergence from this pre-history. He describes people who, given a supportive environment, thrived in the days before autism had a name. There was Lord Henry Cavendish, an 18th-century physicist who isolated himself on his England estate. “The way to talk to Cavendish,” one colleague advised, “is never to look at him.” In 1797, Cavendish set an elaborate system of weights and rods swinging, and using this contraption accurately estimated the mass of the Earth. There was the protégé of Nikola Tesla who pioneered mail-order gadgetry and science-fiction publishing, and the visionary computer scientist who gave us the term “artificial intelligence,” as well many of the field’s tools. As Silberman collects these compelling figures, he makes a quiet argument that autism has always been among us, that its features define one of the many dimensions of human potential. His book is never far from a human face, from a personal story that reminds the reader how much is at stake.

Steve Silberman is an eclectic and big-hearted polymath: a respected writer on science and culture, a Deadhead, TED head, former restaurant critic, and assistant to poet Allen Ginsberg. His book is a wide-ranging and authoritative history of autism. That history echoes through the lives of the many people affected by autism, and it will resonate with anyone whose experience registers outside narrowing definitions of normal. Admittedly, I am one of those people. A few years ago I took a personality test favored by academic psychologists. I failed it. Apparently I’m more than a little ADD, someone autism advocates might call a “cousin,” our kinship defined by a shared strangeness. My mental wandering led me to work in two disciplines, social neuroscience and evolutionary biology, whose intersection reveals just how varied brains can be. I didn’t find much neurobiology in NeuroTribes, probably because researchers know so little about what makes a brain autistic. There is, however, a moving record of society’s awakening to diversity.

In the days before psychiatry’s Diagnostic and Statistical Manual, the DSM, diagnoses were done by ballot, with a group of doctors voting, for example, on whether a child was schizophrenic or simply “feebleminded.” When compared to the richness of human variety, their categories were few—as though sorting worlds of color into bins of blue and yellow—and doctors might not agree on how to label any particular hue of human experience. In the 1940s, Leo Kanner described autism as a distinct cluster of traits marked by an extreme isolation and adherence to routine. Thirty years later, a group of London researchers led by Lorna Wing, a brilliant physician and the parent of an autistic girl, would draw attention to the overlooked writing of the Austrian clinician Hans Asperger.

Wing and colleagues pushed for finer shades of diagnosis, broadening criteria until they could include the many children who had been misclassified or overlooked. As Silberman recounts with welcome clarity, these changes in diagnosis had consequences. In the late 1960s, the estimated prevalence of autism was roughly 1 in 2,000; in 2010, the Centers for Disease Control and Prevention published the most recent numbers: 1 in 68. This rapid rise was not an epidemic. It was a revision of what it meant to have autism, as new categories like Asperger’s syndrome and the euphonic “pervasive developmental disorder not otherwise specified” took hold.

The shifting boundaries of diagnosis bring NeuroTribes into one of the most contested territories of mental health: What defines a disease? As Silberman puts it, “The fact that [Asperger’s] syndrome shaded into subclinical eccentricity raised a question that cut to the core of the entire psychiatric enterprise: Was Asperger’s syndrome truly a mental disorder or a common personality type in its most extreme form?” A disease is easily mistaken for a physical fact, an enduring burden that can be spotted in an X-ray or on a chromosome. But diseases and disorders are ideas, medicine’s imperfect attempts to bring order to nature’s messy realities. Autism advocates coined the term “neurotypical” to label normalcy as a disorder of social obsession and chatty conformity; this playful inversion is a reminder that sometimes people suffer simply by the numerical accident of rarity. We imagine the healthy mind to be a geological feature whose contours we map to learn its landscape, so we can return if we get lost. Maybe it is more like a disputed land whose borders and flags need negotiation. For its part, the American Psychiatric Association recently stopped naming the varieties of autism. The DSM-5, published in 2013, now recognizes only varying degrees of Autism Spectrum Disorder.

One strength of NeuroTribes is the respect Silberman shows to those with firsthand knowledge of what it means to be autistic, a perspective that sometimes surprises. In scientific circles, for example, autistic people are often said to lack empathy, to be “mind-blind.” The idea is now an old one. Researchers can calculate an “empathy quotient” by asking questions like, “I prefer animals to humans,” and “I find it difficult to judge if something is rude.” Other data come from experiments on how people make sense of faces. Autistic people tend to avoid looking at eyes and, presented with isolated images of eyes, have trouble imagining what the depicted person might be feeling. This perspective-taking is referred to as cognitive empathy, or theory of mind, and is distinct from the ability to feel what another feels. In a passage about autism-activist Jim Sinclair, Silberman offers a subtle, humane challenge to the conventional wisdom of researchers. Sinclair is hurt by the description of autism he reads in a pamphlet. “I didn’t consider myself to be someone who didn’t have empathy,” Sinclair says. He wasn’t someone who “lacked the ability to form emotional bonds, and wasn’t interested in relating to others.” As Sinclair describes watching a documentary about another man with autism, there is a jarring incongruity between the scientists’ interpretation of the man’s behavior and Sinclair’s nuanced insights. Where a researcher claims the subject is oblivious, Sinclair sees a familiar struggle to communicate.

If empathy is the ability to inhabit another’s mind, Sinclair’s anecdote suggests that estimates of empathy should be calibrated for just how far one must travel to do so. NeuroTribes amasses a disturbing number of statements by autism researchers who seem unable to make the trip themselves. One clinician describes autism as a terminal illness and autistic children as dead souls. Others consider them “shells” or “husks.” The most unnerving revelation occurs when Silberman profiles Ivar Lovaas, the developer of a common therapy known as Applied Behavior Analysis. In a 1974 interview, Lovaas says that autistic children “are not people in the psychological sense.” He combats an autistic child’s self-injurious behavior by striking her, and his therapy rooms deliver corrective shocks through gridded floors. Spoons of sherbet serve as rewards—a method that seems less sweet when Lovaas reports that “it is a pleasure to work with a child who is on mild food deprivation.” Today’s behavioral therapies tend toward Lovaas-lite, an exacting but benign regimen of small treats, but just last year the Food and Drug Administration held a panel to discuss the use of electrical shock to modify self-injuring and aggressive behavior among autistic patients. Although representatives of a Massachusetts clinic argued it was a necessary treatment of last resort, the panel recommended banning the apparatus used in the procedure.

In the face of ignorance and indifference, parents became the advocates their children needed. As Silberman documents, these parents include Lorna Wing, who led efforts to recognize autism as a spectrum of traits; Bernard Rimland, a psychologist who wrote one of the first broad summaries of autism research and co-founded, together with Ruth Sullivan, the first autism-advocacy organization. Sullivan would go on to champion the 1990 Individuals with Disabilities Education Act, which lays out the educational rights of disabled children. As autistic children grew into autistic adults, however, they were not always pleased with parents who sought to speak on their behalf. Rimland said that he “envisioned autism as a powerful monster that had seized my child.” Parents at autism conferences sometimes shared their grief and disappointment. At a 1993 conference, Jim Sinclair delivered an address entitled, “Don’t mourn for us.” Silberman quotes him at length:

This is what we hear when you mourn over our existence. This is what we hear when you pray for a cure … that your greatest wish is that one day we will cease to be, and strangers you can love will move in behind our faces.

Sinclair was one of several adults with autism who had been diagnosed as “low-functioning” as a child, but went on to found the Autism Network International, a group that organized the first retreats for autistic adults. From the comfort of community came the idea of the “neurotypical,” and the first forays into self-advocacy. NeuroTribes describes how in 2007, when NYU’s Child Study Center began an ambitious fundraising campaign featuring ransom notes “signed by” autism—notes which read, “We have your son. We will make sure he will not be able to care for himself or interact socially as long as he lives,”—a new generation of advocates took action, mobilizing allies and overwhelming the Center with demands to withdraw the ads. They succeeded. This marked the debut of the Autism Self-Advocacy Network, their aim neatly summarized in a motto, “Nothing about us, without us!” Today activists raise alarms when treatments seem inhumane, when policy impedes employment, or when language promotes stigma. They argue that myths of lost kids, of children stolen by wolves or disease, are a kind of blindness. They show that sometimes the easiest way to relieve suffering is by offering services and accommodation. And in making space for themselves, autism self-advocates make space for anyone who feels not quite normal. That is progress.