How did Agriculture Change Lives? Topic sentence: Agriculture changed lives because people could do other jobs, build cities, and invent new things. Main idea #1: With the invention of agriculture, people could focus on other things, not just food. Support #1: For example, they developed a government system. Main idea #2: Farmers used irrigation and canals to control the river’s flow. Support # 2: Irrigation is a way of supplying water to an area of land using man-made waterways. Main idea #3: Lastly, settlements grew in size and cities developed. Support #3: These cities became power bases and were political, religious, and economic centers of civilization. Concluding Sentence: These are some of the ways agriculture changed lives.