Datazioni dirette di ossa fossili umane provenienti da siti archeologici dell’I talia Centro-Meridionale effettuate con il metodo della racemizzazione dell’acido aspartico

Direct aspartic-acid racemization dating of human fossil bones from archeological sites of Central-Southern Italy

Abstract

A technique has been recently developed by Jeffrey L. BADA & alii, which is based on racemization of amino acids contained in collagen, namely aspartic acid. This paper describes the first application of this new technique to date some specimens of human and big-mammal faunal bones from the following archeological sites of Central-Southern Italy: Palidoro, Grotta Maritza, Grotta La Punta, Grotta dell’Orso, Grotta dei Piccioni, Grotta Polesini, Grotta Paglicci and Riparo Vado all’Arancio. The method enabled to directly date some important fragments of human bone weighing a few grams (Homo Maritza, Homo Marsicanus, child from the Paglicci burial, etc.) which it would have been impossible to radiocarbon date owing to the considerable amount of bone material that the latter method requires. Ages obtained with this dating technique were generally in good agreement with carbon-14 ages, the greatest difference being 18 % and the average one 8%. The procedure for extracting acid from fossil bones as well as the conditions relative to the synthesis of diastereomeric dipeptides L-leucyl-D-aspartic acid and L-leucyl-L-aspartic acid, necessary to measure the D/L ratio, are described. The procedure followed to identify the bone specimens which have been exposed to elevated temperatures is also indicated. Finally, in some samples having a carbon-14 of less than 12,000 years, the influence of such environmental factors as pH, humidity and leaching on aspartic acid racemization rate was studied.