Human illnesses can be understood as damage to those adaptations that we took on at various stages in our evolution from pre-life molecules to modern Homo sapiens. Preventing these illnesses entails avoiding what causes the damage-- which too frequently are the everyday hazards of twenty-first-century life, as the chart below shows: Level of Evolution Cause of adaptive failure resulting disease or problem Pre-life Environmental poisons Certain birth defects Single cell (bacteria and amoeba-like) Viral infection Colds/flu/HIV Morula (sponge-like) Cellular stress Cancer Chordate Physical stress Back pain Fish Excess dietary salt Hypertension/heart disease Amphibian Tobacco smoke Lung cancer/emphysema Lower primate Excess dietary sugar Diabetes mellitus Higher primate Vitamin C deficiency Scurvy Ape Excess dietary protein Gout Homo sapiens Reduced dietary variety Nutritionaldiseases/food allergies