L’Archaïque récent au Costa Rica, contribution des sites Piedra Viva et Linda Vista à l’histoire culturelle

The following paper is based on the analysis of two archaeological sites located in the Turrialba valley in Costa Rica, that where excavated for the present master’s thesis: the Piedra Viva (C-306 PV) and Linda Vista (C- 230 LV) sites. The Piedra Viva site has revealed lithic artefacts associated with an archaeological context C14 dated at 6,820 ± 30 rcyBP, (cal AA 7,690 - 7,610), constituting the third site in the country presenting an occupation dated to the Late Archaic via radiocarbon. Our study aims to situate chronologically and culturally the various lithic assemblages studied and to understand the correspondence with the available information in Panama. We have therefore carried out a techno morphological analysis of the lithic assemblages of these sites. On the basis of the comparison with the Piedra Viva collection, our assemblages would correspond to the same unifacial lithic industry, dating to the Late Archaic period (7,000 to 3,600 rcyBP), different from the lithic industries already occurring in Costa Rica. From a technological standpoint, the groups that occupied our sites seem to have abandoned the bifacial knapping technique and preferred local lithic materials for the elaboration of various unifacial lithic tools. Despite the absence of organic remains on the sites, we have tried to understand the subsistence of the occupants of the Piedra Viva site, through a study of the paleobotanical remains obtained from the surface of some of the tools. We have therefore proceeded to the extraction of phytoliths and starch grains on a grinding stone and on a chipped stone knife from the Piedra Viva site. The paleobotanical analysis demonstrated that these tools where used around 14C at 6,820 ± 30 rcyBP in the processing of cultigens such as maize (Zea mays) and cassava (Manihot esculenta) in addition to squash (Cucurbita sp.) and possibly starch-rich tubers such as arrowroot (Maranta arundinacea), as well as achira (Canna sp.) and "wild" resources such as palms.  The sites examined seem to subscribe to the model recognized for the Late Archaic in Panama, both in terms of the types chipped stone tools and ground stone tools (grinding stone) in use, as well as the settlement and subsistence pattern which are similar. Our archaeobotanical data also support the view for the time being, that the first traces of maize south of Mesoamerica seem to appear around relatively the same period near ± 7000 rcyBP (± 7 900 cal. A.A). Moreover, the traces of manioc on Piedra Viva’s grinding stone of would be almost contemporary with the oldest known traces found in Panama dating around 6 910 ± 60 rcyBP. These data suggest that the occupants of our sites also constituted actors of the domestication and of the initial diffusion of these cultigens. These transformations in lithic technology and subsistence pattern perceptible on our sites would be characteristic of a surge of changes of greater amplitude at the Late Archaic, at the scale of the Isthmo-Colombian and Caribbean regions and beyond, in the settlement pattern and the quantity and density of occupations. The advent cultigens of capital importance such as corn and cassava were certainly one of the driving forces behind this cultural transformation.

Keyphrases: Costa Rica, Phytolithes, Early and Late Archaic, Lithic technology, Subsistence, Archaeobotany, Paleobotany, Prehistoric horticulture, Phytoliths, Starch grains, Cultigens