2-3分钟英文演讲 介绍 食物

What is food? Looked at in biological terms, it would appear that food is merely a source of the energy and nutrients essential for life. However, viewed from an anthropological perspective, it becomes evident that food has played a central role in human history. While the everyday quest for food shaped the life of prehistoric man, the onset of the production of a reliable and sufficient supply of food is likely to have led to the rise of civilizations, and to human population expansion. Furthermore, the ability of man to colonize almost every part of the world is at least in part due to his adaptability with regard to food. Not only are humans omnivorous, they have also shown remarkable ingenuity in identifying and preparing nutritious foods out of unpromising materials. For example, bitter cassava (Manihot esculenta), a root crop that contains toxic levels of cyanide-producing compounds, comprises, after thorough processing, the major food item in the diet of millions of people wo