Early Woodland people, known as the Adena, incorporated and intensified several significant lifestyle changes, including the introduction of pottery, the cultivation of plants as a primary source of food, and increasing trade for exotic raw materials like copper and marine shells. The treatment of the dead dramatically changed with the construction of the first burial mounds. Mounds from this time are vertical cemeteries that were built to recognize high social status and to serve as links between the living and the dead.