Autism and schizophrenia are opposites

Autism and schizophrenia are severe mental illnesses, but they can also be just a bunch of personality traits in high-IQ high-functioning people.

Psychiatrist Slate Star Codex writes:

There’s been a lot of discussion over whether schizophrenia is somehow the “opposite” of autism. Many of the genes that increase risk of autism decrease risk of schizophrenia, and vice versa. Autists have a smaller-than-normal corpus callosum; schizophrenics have a larger-than-normal one. Schizophrenics smoke so often that some researchers believe they have some kind of nicotine deficiency; autists have unusually low smoking rates. Schizophrenics are more susceptible to the rubber hand illusion and have weaker self-other boundaries in general; autists seem less susceptible and have stronger self-other boundaries. Autists can be pathologically rational but tend to be uncreative; schizophrenics can be pathologically creative but tend to be irrational. The list goes on.

We might finally get some hard science:

For the past two decades, scientists have been exploring the genetics of schizophrenia, autism and other brain disorders, looking for a path toward causation.

It may turn out that some positive brain traits can be credited to Neanderthal genes:

On Thursday, a team of scientists revealed that two pieces of Neanderthal DNA may have another effect: They may change the shape of our brains.

The study, published in the journal Current Biology, wasn’t designed to determine how Neanderthal genes influence thought — if they do so at all. Instead, the value of the research lies in its unprecedented glimpse into the genetic changes influencing the evolution of the human brain.

Someone commented:

Neanderthals were ethnically cleansed from Europe by the invaders from the South. Neanderthals had lower fertility rates than the invading Home Sapiens from Africa, thus were overwhelmed demographically. The peak population of Neanderthals was just 150,000, they had a low fertility rate and could not maintain their species when faced with an invasion of thousands of fertile Africans , who were set on raping all the neanderthal females and killing off the males. Some of the DNA from the few female neanderthals who mated with the invaders can still be found in the DNA of Europeans today.

The same process can be observed today in Europe. The aboriginal Europeans are declining in population, because they have a low fertility rate, they are being invaded from the south by more fertile ethnic clans and thus the aboriginal peoples of Europe will be extinct. It will take just another 200 years at the current rate..in 5,000 years the people living in Europe may well have traces of DNA from the caucasians who once populated Europe. Just as the people of Europe today have some trace DNA from the Neanderthals who once populated Europe.

It is commonly remarked that the African invaders had greater Darwinian fitness, but that just means that they reproduced more.