In response to warming climates at the end of the last Ice Age, from about 10,000 years ago, some groups adapted to the environment in new ways, while others remained hunter-foragers. Settled agriculture appeared in several different parts of the world. The switch to agriculture created a more reliable, but not necessarily more diversified, food supply. Agriculturalists also had a massive impact on the environment through intensive cultivation of selected plants to the exclusion of others, through the construction of irrigation systems, and through the use of domesticated animals for food and for labor. Populations increased; family groups gave way to village life and, later, to urban life with all its complexity. Patriarchy and forced labor systems developed, giving elite men concentrated power over most of the other people in their societies. Pastoralism emerged in arts of Africa and Eurasia. Pastoral peoples domesticated animals and led their herds around grazing ranges. Like agriculturalists, pastoralists tended to be more socially stratified than hunter-foragers. Because pastoralists were mobile, they rarely accumulated large amounts of material possessions, which would have been a hindrance when they changed grazing areas. The pastoralists’ mobility allowed them to become an important conduit for technological change as they interacted with settled populations.