Nutrition - fats, carbohydrates, proteins, minerals vitamins - provides energy structure function to the body. Different ecosystems provide different nutrition and The people adjust itself to it. Required 800 600 kilo calories per day.
High metabolic rate in in in better diet Nations
Frequent famines create tolerance among people thrifty genotype. Nielsen.
lactose intolerance. Difficulty in digesting milk. 80% American Indians are lactose intolerant. Michael de vrese 2001. 75% world is lactose intolerant.
Small body size.
light skin helps absorb solar radiation and produce vitamin D which is required for calcium.
Pig feast in African tribes to adjust protein diet. Dani tribe.