> But without the corpus callosum the hemispheres have virtually no means of exchanging information They can communicate physically though. Each half of the brain can access the eyes and control various parts of the body, they could make the body do things that they could see/hear in order to act as a basic messaging channel. The conscious part of the brain could be completely oblivious to these subtle physical chann…
Not sure what would be the evolutionary purpose of that. I doubt that many of our ancestors survived brain split and managed to reproduce in order to pass the genes, so having that feature would probably mean it's necessary for something else... sounds like a long shot for me though.
It's also well known that when one part of the brain dies, other parts will step up to assume its responsibilities. So it's not inconceivable that there is some flexibility there.