Decades ago, few paediatricians had heard of autism. In 1975, 1 in 5,000 kids was estimated to have it. Today, 1 in 68 is on the autism spectrum. What caused this steep rise? Steve Silberman points to "a perfect storm of autism awareness" - a pair of psychologists with an accepting view, an unexpected pop culture moment and a new clinical test. But to really understand, we have to go back further to an Austrian doctor by the name of Hans Asperger, who published a pioneering paper in 1944. Because it was buried in time, autism has been shrouded in misunderstanding ever since.