While early man led a nomadic existence and foraged for food, as tribes grew larger, they needed more dependable sources of food. To this end, man began cultivating land and domesticating animals. Nomadic tribes grew in size and settled, forming towns and farms which marked a turning point in history. At first, farmers used animal by-product fertilizers and plows as well as canals and reservoirs to improve early farming. As farming techniques and technology improved, the process required fewer workers and less land. These advancements freed people to pursue cultural and scientific innovation.