Early Cultivation of Cacao (Theobroma [Malvaceae]) in Ancient Arenal, Costa Rica

Abstract Ethnohistoric sources document cacao ( Theobroma cacao ) as one of the most valued plant commodities produced in the Isthmo-Colombian Region following the Spanish Conquest, but there has been minimal archaeological evidence for the plant in this region in Prehispanic times despite its historical legacy of cacao production. Recent excavations in the Arenal region of Northwestern Costa Rica have recovered numerous fragments of wood charcoal identified to the Theobroma genus within residential contexts ranging from the Tronadora (2,000–500 BCE ) to the Arenal (500 BCE –600 CE ) cultural periods. Numerous taxa documented ethnohistorically as being used by native inhabitants in conjunction with cacao to prepare frothy beverages accompany the Theobroma wood charcoal, also in a macrobotanical form of preservation. These include Bixa orellana , Bourreria , Ceiba , Curatella americana , Magnolia , Piper , Pouteria , Quararibea , and Zea mays . Additionally, wood charcoal from madre de cacao ( Gliricidia sepium ) was also recovered, suggesting a deep history of cultivation of this shade tree alongside cacao trees in the Arenal region for the past several millennia.