we agree that intelligence might possibly have somethng to do with diets. You say meat and I repeated the idea of mind expanding mushrooms (as they moved from the forested areas into the open grasslands in search of food sources). The mushroom idea for intelligence came from Terrance McKenna and his book "Food of the Gods" where he presented chapter after chapter of scientific and historical evidence.
Amazon Online Reader : Food of the Gods: The Search for the Original Tree of Knowledge A Radical History of Plants, Drugs, and Human Evolution
Ouote from book -
Terence McKenna Quotes - Literary Quotes About Terence McKenna and Practically Everything Else Terence McKenna - Wikipedia, the free encyclopedia
The meat eating explanation also sounds reasonable enough. A meat eating fox would have to be smarter then the bunny in order to out fox the bunny, but the bunny would not need much intelligence to out fox a blade of grass.
So that makes sense, but I do not think the meat made creatures smarter but rather the need to develope better hunting skills. Gathering plant food takes less thinking then tracking down and skillfully capturing some meat to eat, in many cases. Also we would need to ask "what kind of super meat did humans eat that the chimps did not eat?" in order to make us so much smarter? What is the difference between Chimp meat and human meat diets that would cause such a difference in our intelligence status from a evolutionary standpoint? Did the scientists really think this through to the end? As I could go on with some more (perhaps unanswered) questions about the meat eating survey.
When I mention the "birthing pain" problem in humans I was going by what Carl Sagan wrote on this topic (what what has become this topic). Not sure just what page in what book - but as I recall this one might be it
The Dragons of Eden - Wikipedia, the free encyclopedia
However the squating position in giving birth makes things easyer as you noted, it is used in older Native American cultures and they report it is much better then laying down. I would tend to agree. But Sagan's points are also well outlined and backed with collected data from nature. Not being a woman I cannot say for sure that it is painless or not when in a upright position. According to Sagan the hip parts of the woman are too small for the head size of the infant and that would indicate a lack of evolutionary conformity for the female role. Sagan is a bit of a radical scientist at times so not sure if he fits your expectations for "real science".
Your outline about the internal workings of evolution are correct but they might be only part of the whole story. A turtle shell would be for protection and that had to evolve as an effect of some environmental cause. We build houses but other animals came up with all kinds of ways to protect their self and according to some of the Darwin related concepts that had to do with evolution. A turtle shell, a sea shell, the hard casing around a nut, and so forth, are all simular to the human skull relative to self protection. Sort of like a horse growing longer legs to try to outrun the mountian lions,.