The Beaker phenomenon and the genomic transformation of northwest Europe

From around 2750 to 2500 bc, Bell Beaker pottery became widespread across western and central Europe, before it disappeared between 2200 and 1800 bc. The forces that propelled its expansion are a matter of long-standing debate, and there is support for both cultural diffusion and migration having a role in this process. Here we present genome-wide data from 400 Neolithic, Copper Age and Bronze Age Europeans, including 226 individuals associated with Beaker-complex artefacts. We detected limited genetic affinity between Beaker-complex-associated individuals from Iberia and central Europe, and thus exclude migration as an important mechanism of spread between these two regions. However, migration had a key role in the further dissemination of the Beaker complex. We document this phenomenon most clearly in Britain, where the spread of the Beaker complex introduced high levels of steppe-related ancestry and was associated with the replacement of approximately 90% of Britain’s gene pool within a few hundred years, continuing the east-to-west expansion that had brought steppe-related ancestry into central and northern Europe over the previous centuries

Don't throw the baby teeth out with the bathwater: Estimating subadult age using tooth wear in commingled archaeological assemblages

Commingled assemblages of fragmentary human skeletal remains are a common feature of many archaeological sites and pose significant analytical problems for bioarchaeologists. Such deposits often contain a high volume of the teeth of subadults from which it is challenging to estimate age, including developing permanent teeth with damaged roots, articulated teeth with roots obscured by alveolar bone, and deciduous teeth with completed root apices. Here, we present a new method for more precisely estimating age for such developmentally-ambiguous teeth of subadults from archaeological contexts. We used a sample of articulated subadult dentition from the Copper Age site of Marroquíes in Jaén, Spain, to build linear models of the relationship between dental age and tooth wear for deciduous and permanent molars. We tested three different strategies for identifying and removing outliers to build a linear model with the strongest relationship between age and wear. The Adjusted Residual (AR) strategy, which used diagnostic plots of linear regression residuals in the statistical package R to identify and remove outliers, was found to produce the strongest linear model. The linear model developed using the AR strategy was then used to provide estimated mid-point ages and upper and lower age bounds based on the wear scores from the sample of developmentally-ambiguous teeth. This study demonstrates that it is possible to estimate the age of developmentally-ambiguous deciduous and permanent molars with reference to an adequate sample of subadult dentition with estimated ages from the same population. This new method is valuable as it extracts information from developmentally-ambiguous teeth that would otherwise be inaccessible, allows for rapid data collection, employs standard macroscopic dental scoring methods, and can be used for sites from other regions and periods. We conclude by discussing the applications of this new method within bioarchaeology and identify directions for future research on subadult dental wear.This work was supported by a National Science Foundation Doctoral Dissertation Improvement Grant (BCS-1440017), the Ministerio de Economía y Competitividad de España (HAR2013-47776-R), the Consejo Superior de Investigaciones Científicas (CSIC) (2010RU0086), a Marie Skłodowska-Curie European Fellowship (746216), and the University of Michigan

Forum : Vol. 35, No. 02 (Summer : 2011)

https://digitalcommons.usf.edu/forum_magazine/1054/thumbnail.jp

The maternal genetic make-up of the Iberian Peninsula between the Neolithic and the Early Bronze Age

Agriculture first reached the Iberian Peninsula around 5700 BCE. However, little is known about the genetic structure and changes of prehistoric populations in different geographic areas of Iberia. In our study, we focus on the maternal genetic makeup of the Neolithic (~ 5500–3000 BCE), Chalcolithic (~ 3000–2200 BCE) and Early Bronze Age (~ 2200–1500 BCE). We report ancient mitochondrial DNA results of 213 individuals (151 HVS-I sequences) from the northeast, central, southeast and southwest regions and thus on the largest archaeogenetic dataset from the Peninsula to date. Similar to other parts of Europe, we observe a discontinuity between hunter-gatherers and the first farmers of the Neolithic. During the subsequent periods, we detect regional continuity of Early Neolithic lineages across Iberia, however the genetic contribution of hunter-gatherers is generally higher than in other parts of Europe and varies regionally. In contrast to ancient DNA findings from Central Europe, we do not observe a major turnover in the mtDNA record of the Iberian Late Chalcolithic and Early Bronze Age, suggesting that the population history of the Iberian Peninsula is distinct in character.Concerning research in the Alto Ribatejo, authors wish to thank Fundação para a Ciência e Tecnologia the support of research on the dawn of farming in the Tagus valley (project “Moving Tasks Accross Shapes” – PTDC/EPH-ARQ/4356/2014), as well as the Geosciences Centre of Coimbra University (strategic project UID/Multi/00073/2013). This study was funded by the German Research Foundation (Grant no. Al 287/14–1)