CONICET | Buscador de Institutos y Recursos Humanos

Central-easternNorth Patagonia is characterized by a severe environmentalfragmentation due to the scarce and heterogeneous distribution offresh water. The main local wet zones, the Negro and Colorado rivervalleys in the North and the Somuncura Foothills in the South areseparated by a large and harsh dry land, the travesía.In this paper, we assess the effects of this environmentalfragmentation in the mobility of the Late Holocene hunter-gatherersthrough the analysis of the stable isotopes of oxygen in both enameland water sources. We analyzed the δ18Oof the enamel carbonate of 64 human teeth from 42 individuals fromthe Negro River valley (n=30) and the Somuncura Foothills (n=12) and transformed them into drinking water values (δ18Odw)to be compared with an oxygen water baseline built from the mostimportant surface water sources of the area. Our results showvariable mobility, but they also highlight two trends regarding thedirection of the movement. First, people buried at the Negro Rivervalley seem to have consumed more regularly water from the ColoradoRiver in the North than from other water sources located farthersouth (e.g. Somuncura Foothills). Second, the δ18Odwvaluesfrom the Somuncura sample show east-to-west prevalent mobility alongthe foothills, far from the northern water sources (e.g. ColoradoRiver). This weak connectivity between the northern and the southernparts of the study area (Negro and Colorado river valleys andSomuncura Foothills) is probably related to the harsh environmentalconstraints imposed by the travesía.Our isotopic results in conjunction with the available archaeologicaland ethnohistorical data indicate that this large dry land acted as amarginal space in terms of human exploitation and that it certainlyinfluenced human mobility.

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