Methodological strategies to assess the degree of bone preservation for ancient DNA studies.

BACKGROUND: Archaeological bones contain only small amounts of DNA due to post-mortem DNA degradation and the changes endogenous DNA is subjected to during diagenesis. An important step before undertaking such time-consuming and costly analyses as ancient DNA investigation is to predict the presence of DNA in ancient samples. To date, the leading screening method has been amino acid racemization; however, other analytical techniques can also be used to assess the degree of bone preservation. AIM: The aim of the present study was to relate the presence of DNA with bone preservation in order to select samples potentially suitable for ancient DNA analysis. SUBJECTS AND METHODS: Bones collected from several archaeological sites, different locations (cave, rockshelter or sub divo) and diachronic periods were selected for analytical and spectroscopic analysis in order to correlate bone tissue preservation with the presence of DNA. Different techniques were combined to assess the degree of preservation of organic and inorganic components. RESULTS: As determined by different analytical methods, preservation of the inorganic component was best associated with the presence of DNA. CONCLUSION: Evaluation of the bone preservation state may be an efficient step to predict the presence of DNA in ancient samples prior to aDNA analysis.

Stable isotopic evidence for diet at the Imperial Roman coastal site of Velia (1st and 2nd centuries AD) in Southern Italy.

Here we report on a stable isotope palaeodietary study of a Imperial Roman population interred near the port of Velia in Southern Italy during the 1st and 2nd centuries AD. Carbon and nitrogen stable isotope analyses were performed on collagen extracted from 117 adult humans as well as a range of fauna to reconstruct individual dietary histories. For the majority of individuals, we found that stable isotope data were consistent with a diet high in cereals, with relatively modest contributions of meat and only minor contributions of marine fish. However, substantial isotopic variation was found within the population, indicating that diets were not uniform. We suggest that a number of individuals, mainly but not exclusively males, had greater access to marine resources, especially high trophic level fish. However, the observed dietary variation did not correlate with burial type, number of grave goods, nor age at death. Also, individuals buried at the necropolis at Velia ate much less fish overall compared with the contemporaneous population from the necropolis of Portus at Isola Sacra, located on the coast close to Rome. Marine and riverine transport and commerce dominated the economy of Portus, and its people were in a position to supplement their own stocks of fish with imported goods in transit to Rome, whereas at Velia marine exploitation existed side-by-side with land-based economic activities.