Because it was incredibly dangerous to live back then. Even something like a broken limb could kill you. As well as that your life was at risk from wild animals, other tribes, bites, cuts, the weather. etc. Don't forget skeletons have been found of primitive men who were 90 years of age.
Which Africans are you talking about as it is a large continent made up of many different countries?
Type 1 diabetic for 25 years.
Low carb for 7 years, LC Primal for 2.5 of those.
Fruit and starch free.
Total weight loss- 3 stone/42 pounds. Current weight = 121 pounds. Height 5'5
I take Zymessence systemic enzymes.