La geochimica isotopica applicata a reperti scheletrici fossili di mammiferi terrestri: considerazioni paleoclimatiche e paleoambientali

Stable isotope analyses of human or animal skeletal remains collected in archaeological sites represent an established method for determining past diets and for reconstructing environmental condition in the areas where the human lived. In skeletal remains it is possible to measure the isotopic composition of several elements, for example: carbon, nitrogen and oxygen from organic (collagen) and inorganic (apatite) fractions of human/animal bones and teeth. These parameters, directly or indirectly, are indicators of habitat conditions in term of temperature, humidity, rainfall amounts, etc.. Furthermore they allow us to reconstruct the palaeo-diet and subsistence economies which indirectly describe the environmental features in ancient contexts. Some of these parameters can be use to identify individuals mobility and migration in response to climate changes that affect the biosphere. Studied samples come from several sites in the Parma and Piacenza territories, from Arene Candide Cave (SV) and Masseria Candelaro (FG) sites, so they represent three different areas: the Po Valley, a coastal northern Italy site and a southern Italy site. From a chronological point of view they spanning the period from Neolithic (~ 7500 BP) to the Bronze Age (4200-3600 BP). δ13C and δ15N collagen values for these areas indicate a C3 vegetation which are indicative of temperate climate conditions. Particularly, Po Plain shows an increasing moisture between I and II VBQ phase, a change towards more arid environment is pointed out for the Bronze Age. Both Arene Candide and Masseria Candelaro show, during the Neolithic, environmental conditions more arid than Northern Italy. In addition, we also considered a series of sample from El Salha area (Central Sudan), which cover a period of time from pre-Mesolithic (> 9000 BP) to Meroitic (2100-1500 BP). δ18O values from pre-Mesolithic bones samples indicate a greater amount of rainfall, otherwise Neolithic and Meroitic samples show an increase of aridity conditions. δ13C values from carbonate-hydroxyapatite point out, for the pre-Mesolithic group, a diet consisting practically of C4 plants and, for more recent individuals, a mixed diet with higher percentages of C3 plants.