On February 3, 2009, evidence of 1000 year old chocolate was found in Pueblo Bonito, and was reported in Tuesday‘s issue of Proceedings of the Nation academy of Sciences by Patricia Crown of University of New Mexico and W. Jeffery Hurst of the Hershey Center for Health and Nutrition. The location of the chocolate indicates trade between the Chaco Canyon and the cacao growers in Central America. The people in Central America drank chocolate in rituals, but the full purpose of this is unknown. This chocolate that they drank was unsweetened and very bitter. Crown found pieces of ceramic from jars in Central America, so she decided to check if there was evidence of chocolate being stored in them. There was indeed evidence of this, theobromine, a bitter alkaloid of the cacao plant. "This illustrates the importance of collections in archaeology," Crown said, "that we can return to material with new techniques and find out new things. Every artifact has a story to tell." It is also believed that chocolate was used as a currency by the Aztec.