Sorry I didn't read through the whole thread, but I like the OP and had something to say, or more accurately a question to ask
1 is there some minimal brain size needed?
2 are there certain brain areas needed?
3 is there a method of measuring intellegence based simply on brain size?
I have no clue the answers to these questions. But this question:
4 is there any evidence to show that intellegence has increased over time?
I will answer with another question.
I recently saw a special on national geographic channel about the discovery of a "wolfe boy" A boy raised by wolves. I don't remember all the specifics, but a scientist, or a psychologists took him to try and raise him, and teach him to be accepted in society. It was tough, and the boy did not respond very well. Having been raised by wolves, he did not appear intelligent at all. He was no smarter than a wolfe. Funny millions of years of evolution gone in the blink of an eye.
So my question is if we get smarter over time, and evolution, then why was this boy so "dumb"?
Is that evidence against "intelligence increasing over time"
I will add, that from watching that, I see our intelligence is based directly on what the person before has discovered, and how well it has been taught to us, which forms our "neural networks?" which allows us to take that thinking to the next level?
Our species has the ability to communicate better than any other species, which allows us to be "smarter". Is that ability the only thing, or main thing that allows us to become smarter?