Diet at Herculaneum in AD 79. A high resolution approach through Compound Specific Stable Isotope Analysis of Amino Acids (CSIA-AA).

By the 1st century AD, the Roman Empire had almost reached its greatest expansion and the estimated population density was unprecedented in human history. To supply such a vast territory, the state relied on an elaborate system of production and distribution, in which the Bay of Naples had a central role until the AD 79 eruption of Mount Vesuvius. This thesis applies the carbon and nitrogen isotope analysis of amino acids (CSIA-AA) to the bone collagen of the individuals who tragically perished at Herculaneum in AD 79. Indeed, this exceptional assemblage represents a unique opportunity to investigate the life of an ancient community who lived and died together in one of the central economic hubs of the Roman Empire. Carbon and nitrogen stable isotope analysis (SIA) of the bulk bone collagen has been extensively applied in archaeology allowing us to gain meaningful insights into ancient human dietary practices. However, several studies have now exposed the important limitations of SIA regarding how carbon and nitrogen from different food sources and macronutrients are registered in collagen, potentially resulting in misleading interpretations. On the contrary, CSIA-AA allows to distinguish between single signals -the amino acids- whose fractionation mechanisms are better understood. In this thesis, the results obtained by CSIA-AA were investigated using two innovative Bayesian models that incorporate knowledge of amino acid synthesis. Thanks to the joint application of CSIA-AA and Bayesian statistics, it was possible to observe that men at Herculaneum had easier access to C3 cereals and marine fish, while women were obtaining the majority of their proteins and calories from terrestrial animal products. The high-resolution gained thanks to this approach permitted to compare the estimates obtained with those from modern Mediterranean populations, showing a similar contribution of terrestrial animal products and a three times higher contribution of protein from marine fish at Herculaneum in AD 79.