Among those two peoples, diet was not the only thing that explorers and missionaries brought them. Lifestyle, certainly plays a role. One could also argue heredity playing a very important role. Keep in mind also that if man had not learned to cultivate the soil and produce large amounts of the starchy grains and legumes like potatoes, which are the major source of our caloric intake, most of us would not be here. Prehistoric man was a hunter gatherer, and was able to eat only what he could catch or find growing wild. Yes he ate wild grains when meat was scarce, but it did not exist in large amounts in any one place and was not refined in any way. (refined grains have the roughage removed and metabolize into sugars more easily). Fruits were his main source of sugars, but were only seasonal and again not concentrated in any one area. Large populations of people did not exist due to limitation of food sources, and starvation came when those sources dried up. Only when we learned to grow our own animals and grains did we settle down and expand our numbers. For those who are really interested, I suggest two books:
"Good Calories, Bad Calories" by Gary Taubes. It is a long but complete evaluation that was an attempt to find out why we get fat, but which revealed far more than that in regard to the current myths of cholesterol, heart disease and cancer. Very well written, and readable, but over 500 pages with full bibliography. If you read it in full, you will be enlightened.
"Fat and Cholesterol are Good for You!" by Uffe Ravnskov MD. PhD. Written for everyone. He debunks the cholesterol myth with some very compelling arguments. Easy read with some humor included. He is the leading researcher in debunking the cholesterol myth, and the hazards of statin drugs.
Both books are on Amazon Books.
My apology above was directed to the reply of pmillen who just recovered from a heart attack and two stents. I can understand why you would be confused about my "radical" statements. However, because of the interest that followed, I will not cancel this thread. I had a surprise double bypass in Dec. 2015 at age 79, so I can feel your concerns about my comments. Best wishes for a full recovery.