This kind of diet required no tools or fire, and would have left little archaeological evidence of its existence. In tropical climates, vegetables, fruits, and seeds are the foods easiest to obtain. Tropical people would have favored them. Vegetables and fruits are rich in minerals, vitamins, enzymes and fiber, but low in fats. Their seeds contain ample fats.
Plains grow grasses and grains, and plains people became gatherers and later, farmers.
Plains also provided lean, low-fat animals such as buffalo, antelope, gnu, and other wild cattle. So, on early plains, we find hunters who followed the animals, herders who tamed these grazing animals and lived on meats, blood and milk, and farmers who grew food plants. Winters were long and cold, and vegetation was sparse. People along coasts, lakes and rivers included fish in their food supply. In each area, man adapted himself to the foods available, and learned the skills required to live.