I think this is a fascinating subject, and a brilliant observation. Let me first say that I am in no way an expert on this, nor have I researched it as much as you have, so things I'm going to say are going to be pure speculation and me throwing thoughts around. There are a few people in my family that have Autism, so I have been around it a few times, as most people have these days, and I'm sort of torn in terms of what you're proposing. I don't think autism, as most of us think about it, could be an evolutionary process, because evolution is supposed to fix more problems than it creates, I think. However, I think one of two possibilities could be at play when it comes to an evolutionary step. First, everyone's brain is different and there are plenty of disorders that seem harmless and to have little to no effect in a person who isn't a part of the possible evolutionary step, but when they're born with said disorder and they're born into the next step in evolution, as it may be, the two things collide and conflict and cause the social and psychological problems of autism, while people who are born into the next evolutionary step, but without the disorder are simply the people we usually call geniuses, or have certain functions of their brain that work better than pre-evolutionary step humans, aka most people. Another idea is that what we call autism is simply a sort of... half-step, or mistake, as it were, where it's evolution trying to take its course, but it's genetically messed up in some way, forming a middle ground, where people who have extreme social and psychological issues but are incredibly smart can be found. Then that forms the middle of the spectrum where people can be on the low end, having not been effected by the evolutionary step are, or the high end, where people who didn't get messed up by something and are considered geniuses are. All just thoughts, of course.
