Exploring size and shape variations in late Holocene projectile points from Northern and Southern coasts of Magellan Strait (South America)

CHARLIN, J.; BORRAZZO, K.; CARDILLO, M.

Florianopolis

Congreso; XVI World Congress UISPP; 2011

Sociedade de Arqueologia Brasileira y Union Internacionale de Sciences Prehistorique et Protohistoriques

The peopling of southern South America occurred around 10-12,000 yr BP. At that time, Tierra del Fuego Island was intermittently connected to the continent by a narrow land bridge. Early hunter-gatherer groups populating Fuego-Patagonia shared a projectile technology, known as Fishtail points. After 9,000 yr BP, the sea level definitively flooded the land connection forming the Magellan Strait and Tierra del Fuego Island. Then, terrestrial hunter-gatherer populations inhabiting the area were divided and isolated from each other by a permanent marine channel of 3.5 to 30 km width. Here we focus on the study of variations in artifact designs and/or use-life in order to explore the existence of divergence processes (Borrero 1989-1990) in projectile point technology on both the mainland and the island as was suggested by other lines of evidences (rock art, bioanthropological characters, Lama guanicoe body size, among others). Pursuing this aim we assess morphometric variation among late Holocene lithic projectile points recovered from northern (southern continental Patagonia) and southern (northern Tierra del Fuego Island) sides of Magellan Strait. Geometric morphometric techniques are used to compare size and shape changes of projectile points and to explore patterns of shape variation across space. Our study shows that despite the narrow width of the Strait and the short geographic distance between northern and southern samples, there are differences in the whole shape of projectile points. This morphological disparity (sensu Zelditch et al. 2007) is also observed at three different dimensions: the shape of blade and stem considered as independent modules, the covariation trends between them, as well as in the general allometry patterns among late Holocene projectile points recovered from northern Tierra del Fuego and southern continental Patagonia. Moreover, closer samples have similar shapes (spatial correlation), resulting in two main clusters (island and mainland). Finally, we inform about the differentiation of a third morphological group, identified in archaeological samples located near the coast in southern continental Patagonia which might be related to maritime environment exploitation.