I think it was some type of psychoactive that separated us from other animals because just eating fat and protein isn't going to give your knowledge on how to do things different. This is the main thing that separates us from other animals, the knowledge we have.
When I hear people state protein is what made us smarter you have to ask why aren't we getting smarter now since we have access to more food high in protein than any other time that we know of. Only a few people are changing things but their are billions of people who eat a lot of protein yet no major change. I doubt it was protein that moved us but some type of psychoactive that brought more blood to the brain and allowed the food we did eat to be used to make the connections in the brain more efficient because what makes you intelligent is the blood flow to the brain, nutrients, and how strong your connections are to connect your experiences and allow you to see them in different ways and cannabis and mushrooms do all three of these things.
we are getting smarter now. Our brain is still evolving, as well as our bodies. for instance the pinky finger is disappearing and the thumb is growing larger.
The reason protein did this is because it grew our brains. It is known in basic biology that humans have the largest brain to body size ratio of any mammal. They have also proven that brains are like engines. The larger they are the more potential for power they have, which also results in a need for greater fuel intake. aka protein fats carbs. Now an engine produces power from fire, our brain is more like a pc. An engine that produces electricity and enzymes.
The larger brain being more powerful, results in a much higher form of thought and logic. It can more efficiently and easily produce everything your body needs to have these thoughts.
I have had just as profound discoveries from books as I have had from mushrooms. In fact all mushrooms do is make you more cave man like, not actually smarter. it makes your brain react to poison and not work as efficiently. what happens is your thought breaks everything down to it's simplest form and removes all pollution around a concept leading you to think you have had new discoveries, but really you knew it the whole time. you just had to look at it from a different perspective to realize the importance of that idea that you would not see with out the mushrooms.