IN AMERICA in 1970 one child in 14,000 was reckoned to be autistic. The current estimate is one in 68—or one in 42 among boys. Similarly high numbers can be found in other rich countries: a study in South Korea found that one in 38 children was affected. Autism is a brain condition associated with poor social skills. It has a wide spectrum of symptoms, from obsessive behaviour to hypersensitivity to sound, light or other sensory stimulation, the severity of which ranges from mild to life-blighting. The range of consequences is also wide. At one end, the autism of a computer scientist may be barely noticeable; at the other, a quarter of autistic children do not speak.