Genetic evidence for prehistoric demographic changes in Europe

Objectives: Two main models have been proposed to explain the origins of the patterns of genetic variation in Europe, one emphasizing Paleolithic and the other Neolithic immigration from the Southeast. In this paper, I summarize how the models developed and how they can help address some open questions. Methods: The rationale of the methods traditionally supporting the Neolithic and the Paleolithic models is discussed, and the evidence supporting either of them is reviewed. Results: Ancient DNA evidence proves for good that the studies traditionally supporting the Paleolithic model had serious methodological flaws. This does not imply that the alternative model is right, but rather calls for further analyses explicitly testing the two models against the genomic information now available. Conclusions: Questions that need to be addressed include whether the two main models differ enough to be discriminated by analyses of modern DNA diversity, and to what extent inferences from ancient mitochondrial DNA can be trusted in the absence of sufficient datasets of ancient nuclear DNA. The time seems ripe for the construction of a more complex (and hence more realistic) model, incorporating the possibility of different processes affecting different geographic locations at different times

Reasoning has become a luxury

It is being talked about all over the world; an editorial in the Economist of 19 October 2013 entitled “How Science Goes Wrong” reports a dramatic decline in the quality of scientific publications. Research has changed the world, now it needs to change itself, the subheading reads. The detailed report is based on facts which are difficult to disprove; an example being a Harvard biologist, John Bohannon, who sent an invented article full of nonsense on how to combat cancer using lichens to 304 scientific journals. Of this number, 157 accepted it for publication. While these publications were second tier, the problem affects them all, even those of greater importance

Author Correction: An earlier revolution: genetic and genomic analyses reveal pre-existing cultural differences leading to Neolithization.

A correction to this article has been published and is linked from the HTML version of this paper. The error has not been fixed in the paper

Genomic Evidence for an African Expansion of Anatomically Modern Humans by a Southern Route

There is general agreement among scientists about a recent (less than 200,000 yrs ago) African origin of anatomically modern humans, whereas there is still uncertainty about whether, and to what extent, they admixed with archaic populations, which thus may have contributed to the modern populations’ gene pools. Data on cranial morphology have been interpreted as suggesting that, before the main expansion from Africa through the Near East, anatomically modern humans may also have taken a Southern route from the Horn of Africa through the Arabian peninsula to India, Melanesia and Australia, about 100,000 yrs ago. This view was recently supported by archaeological findings demonstrating human presence in Eastern Arabia 90,000 yrs ago. In this study we analyzed genetic variation at 111,197 nuclear SNPs in nine populations (Kurumba, Chenchu, Kamsali, Madiga, Mala, Irula, Dalit, Chinese, Japanese), chosen because their genealogical relationships are expected to differ under the alternative models of expansion (single vs. multiple dispersals). We calculated correlations between genomic distances, and geographic distances estimated under the alternative assumptions of a single dispersal, or multiple dispersals, and found a significantly stronger association for the multiple dispersal model. If confirmed, this result would cast doubts on the possibility that some non-African populations (i.e., those whose ancestors expanded through the Southern route) may have had any contacts with Neandertals

Genealogical Relationships between Early Medieval and Modern Inhabitants of Piedmont

Vai, Stefania et al.In the period between 400 to 800 AD, also known as the period of the Barbarian invasions, intense migration is documented in the historical record of Europe. However, little is known about the demographic impact of these historical movements, potentially ranging from negligible to substantial. As a pilot study in a broader project on Medieval Europe, we sampled 102 specimens from 5 burial sites in Northwestern Italy, archaeologically classified as belonging to Lombards or Longobards, a Germanic people ruling over a vast section of the Italian peninsula from 568 to 774. We successfully amplified and typed the mitochondrial hypervariable region I (HVR-I) of 28 individuals. Comparisons of genetic diversity with other ancient populations and haplotype networks did not suggest that these samples are heterogeneous, and hence allowed us to jointly compare them with three isolated contemporary populations, and with a modern sample of a large city, representing a control for the effects of recent immigration. We then generated by serial coalescent simulations 16 millions of genealogies, contrasting a model of genealogical continuity with one in which the contemporary samples are genealogically independent from the medieval sample. Analyses by Approximate Bayesian Computation showed that the latter model fits the data in most cases, with one exception, Trino Vercellese, in which the evidence was compatible with persistence up to the present time of genetic features observed among this early medieval population. We conclude that it is possible, in general, to detect evidence of genealogical ties between medieval and specific modern populations. However, only seldom did mitochondrial DNA data allow us to reject with confidence either model tested, which indicates that broader analyses, based on larger assemblages of samples and genetic markers, are needed to understand in detail the effects of medieval migration.This work was supported by the Italian Ministry for Universities and Research (MIUR), PRIN 2012 funds to DC, AA, AT and GB, FIRB funds “Futuro in Ricerca” 2008 (RBFR08U07M) and 2012 (RBFR126B8I) to AA, AO and ER; Compagnia di San Paolo, Turin to DC; the Anneliese Maier Research Award of the Alexander von Humboldt Foundation and the German Federal Ministry for Education and Research to PG; FEDER and Spanish Government grant BFU2012-34157 to CLF; European Research Council (ERC Advanced Grant No. 295733 “LanGeLin”) to GB.Peer reviewe

More rule than exception: parallel evidence of ancient migrations in grammars and genomes of Finno-Ugric speakers

To reconstruct aspects of human demographic history, linguistics and genetics complement each other, reciprocally suggesting testable hypotheses on population relationships and interactions. Relying on a linguistic comparative method based on syntactic data, here we focus on the non-straightforward relation of genes and languages among Finno-Ugric (FU) speakers, in comparison to their Indo-European (IE) and Altaic (AL) neighbors. Syntactic analysis, in agreement with the indications of more traditional linguistic levels, supports at least three distinct clusters, corresponding to these three Eurasian families; yet, the outliers of the FU group show linguistic convergence with their geographical neighbors. By analyzing genome-wide data in both ancient and contemporary populations, we uncovered remarkably matching patterns, with north-western FU speakers linguistically and genetically closer in parallel degrees to their IE-speaking neighbors, and eastern FU speakers to AL speakers. Therefore, our analysis indicates that plausible cross-family linguistic interference effects were accompanied, and possibly caused, by recognizable demographic processes. In particular, based on the comparison of modern and ancient genomes, our study identified the Pontic-Caspian steppes as the possible origin of the demographic processes that led to the expansion of FU languages into Europe

Formal linguistics as a cue to demographic history

Beyond its theoretical success, the development of molecular genetics has brought about the possibility of extraordinary progress in the study of classification and in the inference of the evolutionary history of many species and populations. A major step forward was represented by the availability of extremely large sets of molecular data suited to quantitative and computational treatments. In this paper, we argue that even in cognitive sciences, purely theoretical progress in a discipline such as linguistics may have analogous impact. Thus, exactly on the model of molecular biology, we propose to unify two traditionally unrelated lines of linguistic investigation: 1) the formal study of syntactic variation (parameter theory) in the biolinguistic program 2) the reconstruction of relatedness among languages (phylogenetic taxonomy) The results of our linguistic analysis have thus been plotted against data from population genetics and the correlations have turned out to be largely significant: given a non-trivial set of languages/populations, the description of their variation provided by the comparison of systematic parametric analysis and molecular anthropology informatively recapitulates their history and relationships. As a result, we can claim that the reality of some parametric model of the language faculty and language acquisition/transmission (more broadly of generative grammar) receives strong and original support from its historical heuristic power. Then, on these grounds, we can begin testing Darwin's prediction that, when properly generated, the trees of human populations and of their languages should eventually turn out to be significantly parallel

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 earl