The hyper-systemizing theory of autism proposes that the systemizing mechanism is set too high in people with autism. As a result, they can only cope with highly lawful systems, and cannot cope with systems of high variance or change (such as the social world of other minds). They appear 'change-resistant'. This proposal extends the extreme male brain theory of autism. Finally, evidence is reviewed for autism being the genetic result of assortative mating of two high systemizers.