dragonwriter is right in general sense. We can evaluate it, though, from our own perspective. It's a step forward in terms of intelligence and stability in world. It's a giant leap backward in terms of success or happiness in a world of non-autistic people. Evolution would also consider it a negative in that autistics get laid and reproduce less than non-autistics. They also are more likely to loose in competition in corporations, battlefields, and jungles. So, it's a net loss overall for evolution's main function but autistics persist for one reason or another.