I would respectfully disagree with you here. Before agriculture became the norm-we were hunter gatherers. This meant a diet high in protein, along with foraged foods such as nuts berries and wild growing fruits/veggies.
In uncivilized tribes still today, hunting/gathering is the main source of food in remote village tribes. Very low obesity there and almost no carbs.
Until very recently, eskimos existed on almost exclusively whale meat and blubber, seal meat and fish since veggies/grains could not be grown in permafrost and ice. It was not until western style carbohydrates were introduced into their diets that obesity and heart disease entered their world.
I do agree that whole grain carbs are good for you due to the fiber content not affecting blood sugars negatively, but to say that carbs were the mainstay of most in human history is incorrect.
Yes, hunters and gatherers and some horticulture. This did not mean a diet that got a majority of calories from meat and fat. Modern hunter/gatherer and horticulturalist societies outside the arctic circle (where plant matter is rare) get the majority of their calories from non-meat sources that are usually lower in protein and fat and higher in carbohydrates.
Yes, Eskimos eat an almost all meat and fat diet. They are healthy with a traditional diet but have problems with a Western diet.
Similarly, people from India are primarily vegitarians. Why are they not all fat?
Biochemically we are set up to consume carbohydrates as our major energy source.