13.This bidirectional link between food production and population density explains the paradox that food production, while increasing the quantity of edible calories per acre, left the food producers less well nourished than the hunter-gatherers whom they succeeded.
粮食生产和人口密度之间的这种双向联系解释了这样一个悖论:粮食生产在增加每英亩可食用热量的同时,却使粮食生产者的营养状况不如
们所继承的狩猎采集者。机翻