Over many thousands of years, human beings became increasingly dependent on cultivated crops and less and less dependent on wild varieties. The earliest agriculturists practiced subsistence level farming, which provides food only for the farmer’s family. Because each farmer could provide for only a few people, the first villages and their populations were small. Subsistence-level farming gave way to a more advanced form of agriculture with the development of the plough and other metal tools and as time went by, people began to do business with neighboring villages. The human populations began to grow more interconnected with improvements in agricultural technology and trade; the villages grew into cities and became major trade centers. As the agricultural societies began to lay emphasis on trade, the link with the natural environment, so visible in hunting-gathering societies, was weakened. But he agriculturist’s attitude towards nature was much like those of hunter-gatherers. Population’ need was fulfilled without disturbing the natural environment.