The number of autism diagnoses has risen steadily in recent years and currently stands at one in 45 American children diagnosed each year. There’s been concern that the increase is being fueled by environmental causes, but a new history of autism research says the condition has always been common and is widely misunderstood. In NeuroTribes: The Legacy of Autism and the Future of Neurodiversity, Steve Silberman walks us through the history of autism research, including the work of Hans Asperger