2. How did the human brain develop?
The idea of the co-evolution of mind or culture and brain, or the common and mutually stimulating development of mind/culture and brain always reminds me of Baron K. F. H. von Münchhausen. In his A Wonderful Journey on Water and on Land, he tells the story of how he and his horse pull themselves out of the swamp into which they had gotten.
The narrative contradicts the elementary laws of physics (the Archimedean point is missing). However, this did not bother the narrator or his readers. Since Darwin, the idea of co-evolution has been that after the regrettable loss of the Christian creator-God, the human spirit takes over his role, grabs the spiritual head and pulls itself and the human brain out of the swamp of animal spiritlessness.
Or, to put it another way: The human mind and/or culture are said to have deterministically supervised the evolution of the monkey brain to the human brain. Since no other solution was available, Darwin himself and his successors overlooked the fact that with this solution they contradicted Darwin’s theory of evolution.