听力原文： Botany, the study of plants, occupies a peculiar position in the history of human knowledge. For many thousands of years it was the one field of awareness about which humans bad anything more than the vaguest of insights. It is impossible to know today just what our Stone Age ancestors knew about plants, but from what we can observe of pre-industrial societies that still exist, a detailed learning of plants and their properties must be extremely ancient. This is logical. Plants are the basis of the food pyramid for all living things, even for other plants. They have always been enormously important to the welfare of people, not only for food, but also for clothing, weapons, tools, dyes, medicines, shelter, and a great many other purposes. Tribes living today in the jungles of the Amazon recognize literally hundreds of plants and know many properties of each. To them, botany, as such, has no name and is probably not even recognized as a special branch of 'knowledge' at all. Unfortunately, the more industrialized we become, the farther away we move from direct contact with plants, and the less distinct our knowledge of botany grows. Yet everyone unconsciously has an amazing amount of botanical knowledge, and few people will fail to recognize a rose, an apple, or an orchid. Our Neolithic ancestors, living in the Middle East about 10,000 years ago, discovered that certain grasses could be harvested and their seeds planted for richer yields the next season. That was the first great step in a new association between plants and animals. Grains wore discovered and from them flowed the marvel of agriculture: cultivated crops. (30)