The dominant model in research on autism is that of a hard-wired "theory of mind" that operates in neurotypical folks but that doesn't operate (maybe the wires get crossed in some more-or-less literal sense) in those developing children who end up "on the spectrum." Whereas the neurotypicals come to understand without reflexion that there is another person behind the various human faces they encounter, this never comes easily to those with the crossed wires. On this theory, (call it the meta-theory of mind) many if not all of the characteristic symptoms of the disorder derive from that point.
It is a neat (meta-) theory, but it is worth mentioning now and then that it isn't established fact.
Indeed, the more neurologists get to work trying to home in on this wired-in theory of mind, the more evasive it seems. And (assuming the paradigm) there are theory-of-mind deficits that one would not call autistic.
OTOH, I'm sure there is something to it.
Further, primate research has uncovered something intriguing. The May 19, 2017 issue of SCIENCE carries a report with the title "A dedicated network for social interactional processing in the primate brain."
The authors had monkeys watch movies, specifically videos of other monkeys engaged in social interactions. The video viewing monkeys were at this time brain-scanned for neuronal activity.
The researchers found that a subset of the brain of the spectator monkey was active exclusively during monkey-monkey screen interactions, NOT when the "actor monkeys" were dealing with objects. Further, the network activated in monkeys by seeing other monkeys interacting "shares some of its components ... with a possible homolog of the human network involved in the theory of mind."
Note that the language is cautious. One network shares "some" components with a "possible homology" etc. Still, this is welcome. Parallax is the phenomenon that allows us three-dimensional sight, and parallax involves a second eye. Neurologists working on this problem may learn to use monkeys as a second eye to understand broad primate neurological development.
For those interested in further reading, here's a URL: http://science.sciencemag.org/content/356/6339/745