Bones, teeth and hair are often the only physical evidence of human or animal presence at an archaeological site; they are also the most widely used sources of samples for ancient DNA (aDNA) analysis. Unfortunately, the DNA extracted from ancient samples, already scarce and highly degraded, is widely susceptible to exogenous contaminations that can affect the reliability of aDNA studies. We evaluated the molecular effects of sample handling on five human skeletons freshly excavated from a cemetery dated between the 11 to the 14th century. We collected specimens from several skeletal areas (teeth, ribs, femurs and ulnas) from each individual burial. We then divided the samples into two different sets: one labeled as “virgin samples” (i.e. samples that were taken by archaeologists under contamination-controlled conditions and then immediately sent to the laboratory for genetic analyses), and the second called “lab samples”(i.e. samples that were handled without any particular precautions and subject to normal washing, handling and measuring procedures in the osteological lab). Our results show that genetic profiles from “lab samples” are incomplete or ambiguous in the different skeletal areas while a different outcome is observed in the “virgin samples” set. Generally, all specimens from different skeletal areas in the exception of teeth present incongruent results between “lab” and “virgin” samples. Therefore teeth are less prone to contamination than the other skeletal areas we analyzed and may be considered a material of choice for classical aDNA studies. In addition, we showed that bones can also be a good candidate for human aDNA analysis if they come directly from the excavation site and are accompanied by a clear taphonomic history.
The available mitochondrial DNA (mtDNA) data do not point to clear genetic relationships between current Tuscans and the Bronze-Age inhabitants of Tuscany, the Etruscans. To understand how and when such a genetic discontinuity may have arisen, we extracted and typed the mtDNAs of 27 medieval Tuscans from an initial sample of 61, spanning a period between the 10th and 15th century AD. We then tested by serial coalescent simulation various models describing the genealogical relationships among past and current inhabitants of Tuscany, the latter including three samples (from Murlo, Volterra, and Casentino) that were recently claimed to be of Etruscan descent. Etruscans and medieval Tuscans share three mitochondrial haplotypes but fall in distinct branches of the mitochondrial genealogy in the only model that proved compatible with the data. Under that model, contemporary people of Tuscany show clear genetic relationships with Medieval people, but not with the Etruscans, along the female lines. No evidence of excess mutation was found in the Etruscan DNAs by a Bayesian test, and so there is no reason to suspect that these results are biased by systematic contamination of the ancient sequences or laboratory artefacts. Extensive demographic changes before AD 1000 are thus the simplest explanation for the differences between the contemporary and the Bronze-Age mtDNAs of Tuscany. Accordingly, genealogical continuity between ancient and modern populations of the same area does not seem a safe general assumption, but rather a hypothesis that, when possible, should be tested using ancient DNA analysis.
Estimation of age at death is an unavoidable step in the process of human identification, both in forensic\ud practice and in the anthropological and palaeopathological study of skeletal remains. In several cases, in\ud which medical or demographic records are completely lacking, a reliable estimation of the age at death\ud becomes very important. Skeletal remains from archaeological contexts suffer from several biasing\ud factors such as post-mortem changes, taphonomy and various burial practices depending on age, sex and\ud social status of the deceased persons.\ud Currently, anthropological methods of age determination reveal several possibilities of inaccuracy. Of\ud all the body parts used in age estimation, teeth are the least affected by any taphonomic process.\ud Although there are many dental methods for age at death estimation, some of them are very complex\ud and/or destructive and they are not normally used in anthropology. However, study of the apposition of\ud secondary dentine by examining peri-apical X-rays of canines is beginning to supply very interesting\ud results.\ud The aim of this work was to test Cameriere’s method on a large sample of historical subjects from\ud several cemeteries in Spain and Italy. The Spanish sample belongs to the Medieval cemetery of La Torrecilla\ud (Arenas del Rey, Granada) and is housed in the Laboratory of Anthropology, Faculty of Medicine,\ud University of Granada. The Italian samples come from the Medieval cemeteries of Comacchio (Ferrara)\ud and Castel S. Pietro (Bologna).\ud In order to test the reliability of Cameriere’s method, age estimations of canines were compared with\ud the mean ranges of age of the most commonly applied anthropological methods such as tooth wear\ud changes in the pubic symphysis or the metamorphosis of the auricular surface of the ilium. Tests on these\ud Middle Ages cemeteries produced satisfactory results, indicating that Cameriere’s method is a reliable\ud tool in determining age at death in skeletal remains of archaeological context
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