Although children with Tourette syndrome (TS) only rarely present with a profound failure to develop social relations, they frequently have problems with delayed or defective speech and characteristically show many ritualistic or compulsive behaviors. Autistic and TS patients may have the following symptoms in common (Commings, 1990a): attention deficits, babbling, echolalia, palialia, echopraxia, facial grimacing, hand flicking, hyperactivity, inappropriate anger, obsessive-compulsive behaviors, onset in childhood, panic at minor environmental change, perseveration, poor control of speech volume, sniffing and smelling of objects, stereotyped movements, improvement with haloperidol treatment (Campbell et al., 1982), excerbation with dopamine agonists (Leckman and Cohen, 1983), and an implication of defective control of serotonin and tryptophan levels (Boulin el al., 1982; Hanley el al., 1977; Ritvo et al., 1970, 1971; Schain and Freedman, 1961; Takahashi et al., 1976; McBride et al., 1989; Blum et al., 1990; Comings, 1990a, 1990b) (p. 180). (Comings, D. E. & Comings, B. G. (1991). Clinical and genetic relationships between autism-pervasive developmental disorder and Tourette syndrome: A study of 19 cases. American Journal of Medical Genetics, 39(2), 180-91.)
I focus on possible evolutionary origins of autism. Tourette syndrome often feels closely related. Consider that a major barrier to understanding the relationship between evolution, autism and TS is our focus on natural selection as being the exclusive cause of human evolution.
Geoffrey Miller hypothesizes that sexual selection created the human species. If ritualistic and compulsive behaviors are signs of human forebear traits, then what might propel those with autism and Tourette syndrome back to when those traits were ubiquitous?
What prevents contemporary clinitians from studying what causes slides backward to pick up forebear features, and why are theorists not related that to TS and autism?