Have you ever noticed how those children born in India often have more arms or legs like the depictions of their gods? Have you ever wondered why there are conjoined twins? What is the bodies reasoning behind making a new born retarded or autistic? These questions may be new to you, as they are rather new to me, and, now is time to discuss them. I figure that with all the dreams of these angels and spirits, the mind will alter to form new arms and legs for the foetus? This would be down to 'the power of the imagination' being too potent and manifest for the egg cell. Maybe the autistic children are 'a new form of evolution?' Think, now, they learn slower, but do maths faster, this means they are no longer becoming more perceptive, but rather settling down into a pattern, like nomadic versus settled peoples. Of course, there is the problem of them not being fully aware, so, maybe the parent was working a lot with numbers - of course, another example of the mind altering the child to be born, yes? This is evidence of the mind being more powerful than the body.
Autism rates are significantly higher in Silicon Valley. Some have speculated it might be analogous to the phenomena of Sick Cell Anemia in Africa. Where certain genes can confer a certain advantage in one situation, but those same genes can also create a risk that the offspring of parents who both have the gene(s) will be born with a disabling condition.
There is no evidence that Autism is genetic. It is nothing like the enzyme deficiencies (such as Sickle Cell etc). Autism is as likely to be environmental (as in, parenting) as it is anything else. More so, really. But any genuinely concerned and committed parent of an autistic child will work from the point of view of assumed responsibility for the condition. Even if it does turn out to be genetic (which is unlikely), their improved parenting will stand the child in good stead. It does not serve the child to behave as though it's "not my fault". This potential cause was once well understood and accepted, but political correctness compromised research late last century. The people researching the disorder today are religiously avoiding any suggestion of parental 'fault', so the science as it stands is deeply flawed. It is no science at all, in fact.
Most autist don't reproduce, so clearly autist aren't a new form of human life. However, maybe that genes who cause autism cause enough advantages when they don't create autism to enable their spread.
Nature doesn't think, especially in mistakes or success, there is things that can be and things that can't be. Genetic sickness can be considered as a nature mistake. However, in Africa, many people have a blood genetic sickness who give resistance against paludism. I don't remember the case, but it can cause troubles in the late life, but give resistance against devasting sickness.
I think autism is caused by seizures, which are more common in individuals with lower verbal abilities. Seizure disorders, including epilepsy, occur in as many as 39 percent of those with autism and they are more common in people with autism and intellectual disability. Due to repeated seizures experienced in early childhood, autistic children develop speaking or learning difficulties as some parts of their brains related to speaking or learning are partially damaged by infantile spasms, thus making them very reluctant or unable to interact with others.
Perhaps the seeming increase in autism is a stage in human evolution. A group of people who seldom speak or speak not at all (autism) will be followed by a group that doesn’t need to speak because they are telepathic.
Autist who doesn't speak are a minority and they end to be able to speak. Non-speaking autistic people are extremly dependant and I doubt any of them had every spread their genes.