some evolutionary biologists believe this is why morning sickness still persists in human pregnancies. Morning sickness, which can last the entire day (and, for some women, the entire pregnancy), makes a woman stick to a bland, boring diet—if she eats much at all. This avoidance strategy would have kept our maternal ancestors away from the natural toxins in exotic or spoiled foods in the wild, unregulated menu of the Pleistocene diet. The accompanying fatigue would keep women from engaging in physical activity risky enough to harm the baby.
