δ18O variability in guanaco bone bioapatite in Southern Patagonia: Implications for paleoecological and paleoenvironmental studies

Abstract

The guanaco (Lama guanicoe) is the largest and the most widely distributed ungulate in South America since the Pleistocene and constituted the main prey for hunter-gatherers in Southern Patagonia (Argentina) in the past. An isomorphic relationship has been suggested between the mobility of these animals and that of human groups that inhabited the region, which presents altitudinal differences. On the one hand, we seek to understand the spatial dynamics of guanaco populations and their interaction with hunter-gatherer societies. On the other hand, to evaluate the utility of archaeological herbivores’ values as paleoenvironmental proxies that allow addressing theenvironmental variations during the Holocene in the region. We present the results of the analysis of δ18O in bioapatite of Lama guanicoe bone specimens from the area located in the central-western area of the province of Santa Cruz, between 70 and 72 degrees west longitude. We analyzed 41 samples. 22 of them correspond to modern individuals, while the remaining 19 were recovered from Holocene archaeological sites. The carbonatephosphate and estimated water equations will be used to compare with pre-existing data of δ18O in the waters of the region. Results showed that the mean value of δ18O of the pooled samples was 6.5 ‰ ± 1 ‰. Even though some differences were detected, both, between archaeological vs. modern and between highlands vs. lowlands samples, no statistically significant differences were obtained in either case. In general terms, the data respond to what was expected regarding the complex nature of the water intake behaviors of these animals. The data presented in this paper constitutes a first approximation to the expected values of δ18O for guanacos in the region, its relationship with the hydrological cycle and human populations.