Antonella Casoli

Evidence for a genetic discontinuity between Neandertals and 24,000-year-old anatomically modern Europeans.

During the late Pleistocene, early anatomically modern humans coexisted in Europe with the anatomically archaic Neandertals for some thousand years. Under the recent variants of the multiregional model of human evolution, modern and archaic forms were different but related populations within a single evolving species, and both have contributed to the gene pool of current humans. Conversely, the Out-of-Africa model considers the transition between Neandertals and anatomically modern humans as the result of a demographic replacement, and hence it predicts a genetic discontinuity between them. Following the most stringent current standards for validation of ancient DNA sequences, we typed the mtDNA hypervariable region I of two anatomically modern Homo sapiens sapiens individuals of the Cro-Magnon type dated at about 23 and 25 thousand years ago. Here we show that the mtDNAs of these individuals fall well within the range of variation of todays humans, but differ sharply from the available sequences of the chronologically closer Neandertals. This discontinuity is difficult to reconcile with the hypothesis that both Neandertals and early anatomically modern humans contributed to the current European gene pool.

A highly divergent mtDNA sequence in a Neandertal individual from Italy

Neandertals are documented in Europe and Western Asia from about 230,000 to 29,000 years ago. Analyses of mitochondrial DNA (mtDNA) from Neandertal samples [1,2] and other analyses [3–5] appear incompatible with the hypothesis that Neandertals are direct ancestors of modern Europeans [6,7]. However, there are broad geographic gaps in the sampling of Neandertal DNA diversity. Here, we describe the sequence of the first mitochondrial hypervariable region (HVR1) in a new specimen from Monti Lessini (MLS) in Northern Italy.

A 28,000 years old Cro-Magnon mtDNA sequence differs from all potentially contaminating modern sequences.

Background DNA sequences from ancient speciments may in fact result from undetected contamination of the ancient specimens by modern DNA, and the problem is particularly challenging in studies of human fossils. Doubts on the authenticity of the available sequences have so far hampered genetic comparisons between anatomically archaic (Neandertal) and early modern (Cro-Magnoid) Europeans. Methodology/Principal Findings We typed the mitochondrial DNA (mtDNA) hypervariable region I in a 28,000 years old Cro-Magnoid individual from the Paglicci cave, in Italy (Paglicci 23) and in all the people who had contact with the sample since its discovery in 2003. The Paglicci 23 sequence, determined through the analysis of 152 clones, is the Cambridge reference sequence, and cannot possibly reflect contamination because it differs from all potentially contaminating modern sequences. Conclusions/Significance: The Paglicci 23 individual carried a mtDNA sequence that is still common in Europe, and which radically differs from those of the almost contemporary Neandertals, demonstrating a genealogical continuity across 28,000 years, from Cro-Magnoid to modern Europeans. Because all potential sources of modern DNA contamination are known, the Paglicci 23 sample will offer a unique opportunity to get insight for the first time into the nuclear genes of early modern Europeans.

Green pigments of the Pompeian artists’ palette

Green colored samples on wall paintings and green powder from a pigment pot found in Pompeii area are investigated by micro-Raman, FT-IR and, for one sample, SEM-EDX. To obtain the green color, green earths and malachite were used, together with mixture of Egyptian blue and yellow ochre. The mineralogical identification of the green earths has been attempted through the comparison of the vibrational features, discriminating between celadonite and glauconite spectra. Traces of a modern synthetic pigment containing copper phthalocyanine were found in a fresco fragment.

Gas chromatographic-mass spectrometric approach to the problem of characterizing binding media in paintings

Abstract A GC-MS method is proposed for the characterization of binding media in paint works of art. The basic methodology relied on the determination of amino acids and fatty acids after hydrolysis with HC1 and derivatization with 2-propanol and trifluoroacetic anhydride, and on the comparison with reference materials. The use of fused-silica capillary columns coated with methylphenylsilicone phases allowed to separate amino acid and fatty acid derivatives in a single analytical run. The method was applied to identify binding media used in ground and paint layers of polychrome sculptures of the eighteenth century.

Population dynamic of the extinct European aurochs: genetic evidence of a north-south differentiation pattern and no evidence of post-glacial expansion

BackgroundThe aurochs (Bos primigenius) was a large bovine that ranged over almost the entirety of the Eurasian continent and North Africa. It is the wild ancestor of the modern cattle (Bos taurus), and went extinct in 1627 probably as a consequence of human hunting and the progressive reduction of its habitat. To investigate in detail the genetic history of this species and to compare the population dynamics in different European areas, we analysed Bos primigenius remains from various sites across Italy.ResultsFourteen samples provided ancient DNA fragments from the mitochondrial hypervariable region. Our data, jointly analysed with previously published sequences, support the view that Italian aurochsen were genetically similar to modern bovine breeds, but very different from northern/central European aurochsen. Bayesian analyses and coalescent simulations indicate that the genetic variation pattern in both Italian and northern/central European aurochsen is compatible with demographic stability after the last glaciation. We provide evidence that signatures of population expansion can erroneously arise in stable aurochsen populations when the different ages of the samples are not taken into account.ConclusionsDistinct groups of aurochsen probably inhabited Italy and northern/central Europe after the last glaciation, respectively. On the contrary, Italian and Fertile Crescent aurochsen likely shared several mtDNA sequences, now common in modern breeds. We argue that a certain level of genetic homogeneity characterized aurochs populations in Southern Europe and the Middle East, and also that post-glacial recolonization of northern and central Europe advanced, without major demographic expansions, from eastern, and not southern, refugia.

Raman microspectrometric investigation of wall paintings in S. Giovanni Evangelista Abbey in Parma: a comparison between two artists of the 16th century.

Micro-Raman spectroscopy, combined with gas chromatography and ultra-violet fluorescence photography, was used to study some wall paintings in the S. Giovanni Evangelista Abbey in Parma, Italy. The restoration of some painted chapels enabled a comparison between two painters of the 16th century: Parmigianino (Girolamo Francesco Maria Mazzola, 1503-1540) and Michelangelo Anselmi (1492?-1556?). Micro-Raman spectroscopy determined the palette used by the artists, leading to the identification of different white, yellow, red, brown, green, blue and black pigments. Some pigments are evidence of later restorations. Gas chromatography combined with mass spectroscopy revealed the presence of organic binding media and enabled to distinguish between fresco and secco paintings.

SPECTROCHEMICAL AND STRUCTURAL STUDIES ON A ROMAN SAMPLE OF EGYPTIAN BLUE

Abstract A ball of Egyptian blue excavated on the archaeological site of Augusta Praetoria (Aosta, Italy) has been investigated by several techniques. Optical microscopy and X-ray diffraction gave proof of the identity of the pigment, while indicating that silica phases had also been formed because of sand excess in the reaction mixture. No evidence was found of the presence of tin compounds, thus excluding the use of bronze scraps in the preparation of the pigment. The crystal structure of the pigment was refined using single-crystal X-ray diffraction data; Fourier transform infrared spectroscopy, UV-vis-NIR reflectance spectroscopy and electron paramagnetic resonance spectroscopy were used to characterize further the pigment. Scanning electron microscopy, coupled with energy dispersive detection of emitted X-rays, was finally used to investigate morphology and determine the composition of representative areas of both pigment and impurities.

Genealogical discontinuities among Etruscan, Medieval and contemporary Tuscans

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.

Application of multivariate chemometric techniques to the study of Roman pottery (terra sigillata)

Abstract Supervised and unsupervised pattern recognition techniques were used to classify 48 sherds of Roman pottery (terra sigillata), analysed by inductively coupled plasma atomic emission spectrometry and atomic absorption spectrometry for seven major and minor elements (Al, Fe, Ca, Mg, K, Ti and Mn). Hierarchical agglomerative clustering and principal component analysis were used to classify the studied material into compositional groups which could account for different centres of production; soft independent modelling of class analogy (SIMCA) was used to solve questions regarding doubtful assignments. The results indicate that, in the case study, a throughout statistical treatment can allow one to discriminate wares produced in different geographical areas on the basis of the seven elements accounted for.