The Influence of Life In the early times when human beings hunted and gathered food, they were not in control of their environment. They could only interact with their surroundings as the other lower animals did. When they learned to make fire, however, they became capable of altering their environment. To provide themselves with fuel, they cut down trees. They also burned clearings in forests to increase the growth of grass and to provide a greater grazing area for the wild animals that human beings fed upon. This development led to farming and the domestication of animals. Fire provided the means for cooking plants which had previously been inedible. Only when the process of meeting the basic need for food reached a certain level was it possible for humans to follow other pursuits such as setting up families, forming societies and founding cities. Useful words and Expressions: interact with 与……组合 clearing 空旷地 grazing 放牧，牧草 domestication 驯养，驯服 previously 先前，以前 inedible 不能吃的，不适于食用的 pursuit 追击 set up 设立