Bell Beaker pottery spread across western and central Europe beginning around 2750 BCE before disappearing between 2200–1800 BCE. The mechanism of its expansion is a topic of long-standing debate, with support for both cultural diffusion and human migration. We present new genome-wide ancient DNA data from 170 Neolithic, Copper Age and Bronze Age Europeans, including 100 Beaker-associated individuals. In contrast to the Corded Ware Complex, which has previously been identified as arriving in central Europe following migration from the east, we observe limited genetic affinity between Iberian and central European Beaker Complex-associated individuals, and thus exclude migration as a significant mechanism of spread between these two regions. However, human migration did have an important role in the further dissemination of the Beaker Complex, which we document most clearly in Britain using data from 80 newly reported individuals dating to 3900–1200 BCE. British Neolithic farmers were genetically similar to contemporary populations in continental Europe and in particular to Neolithic Iberians, suggesting that a portion of the farmer ancestry in Britain came from the Mediterranean rather than the Danubian route of farming expansion. Beginning with the Beaker period, and continuing through the Bronze Age, all British individuals harboured high proportions of Steppe ancestry and were genetically closely related to Beaker-associated individuals from the Lower Rhine area. We use these observations to show that the spread of the Beaker Complex to Britain was mediated by migration from the continent that replaced >90% of Britain’s Neolithic gene pool within a few hundred years, continuing the process that brought Steppe ancestry into central and northern Europe 400 years earlier.

ABSTRACT. Bone is one of the most widely used materials for dating archaeological activity. It is also relatively difficult to pretreat effectively and new methods are an area of active research. The purpose of the chemical pretreatment of bone is to remove contaminants present from burial and to do so in a way which does not add any additional laboratory contaminant. To some extent, these two aims must be balanced since, on the whole, the more complex the procedure and the more steps included, the greater the chance for contamination. At the Oxford Radiocarbon Accelerator Unit (ORAU), the method used is a continuous-flow or manual acid/base/acid (ABA) treatment followed by gelatinization and ultrafiltration (based on Brown et al. [1988]; documented in Bronk Ramsey et al. [2000]). We find this overall method is very effective at removing more recent contamination in old bones. However, two aspects of the method have recently been improved and are reported here: the redesign of ORAU's continuous flow pretreatment and a new protocol in our pretreatment ultrafiltration stage.

Farming was first introduced to southeastern Europe in the mid-7th millennium BCE – brought by migrants from Anatolia who settled in the region before spreading throughout Europe. To clarify the dynamics of the interaction between the first farmers and indigenous hunter-gatherers where they first met, we analyze genome-wide ancient DNA data from 223 individuals who lived in southeastern Europe and surrounding regions between 12,000 and 500 BCE. We document previously uncharacterized genetic structure, showing a West-East cline of ancestry in hunter-gatherers, and show that some Aegean farmers had ancestry from a different lineage than the northwestern Anatolian lineage that formed the overwhelming ancestry of other European farmers. We show that the first farmers of northern and western Europe passed through southeastern Europe with limited admixture with local hunter-gatherers, but that some groups mixed extensively, with relatively sex-balanced admixture compared to the male-biased hunter-gatherer admixture that prevailed later in the North and West. Southeastern Europe continued to be a nexus between East and West after farming arrived, with intermittent genetic contact from the Steppe up to 2,000 years before the migration that replaced much of northern Europe’s population.

ABSTRACT. Precision and accuracy in accelerator mass spectrometry (AMS) dating relies on the systematic reduction of errors at all stages of the dating process, from sampling to AMS measurement. With new AMS systems providing much better precision and accuracy for the final stage of the process, we need to review the process as a whole to test the accuracy of reported results. A new High Voltage Engineering Europa (HVEE) AMS system was accepted at Oxford in September 2002. Since then, the system has been in routine use for AMS dating and here we report on our experiences during the first year. The AMS system itself is known to be capable of making measurements on single targets to a precision of better than 0.2% for the 14 C/ 13 C ratio and better than 0.1% for the 13 C/ 12 C ratio. In routine operation, we measure known-age wood to a precision of just above 0.3%, including uncertainties in background and pretreatment. At these levels, the scatter in results is no higher than reported errors, suggesting that uncertainties of ±25 to ±30 14 C yr can be reliably reported on single target measurements. This provides a test of all parts of the process for a particular material in a particular state of preservation. More generally, sample pretreatment should remove as much contamination as feasible from the sample while adding as little laboratory contamination as possible. For more complex materials, such as bone, there is clearly more work needed to prove good reproducibility and insignificant offsets in all circumstances. Strategies for testing accuracy and precision on unknown material are discussed here, as well as the possibilities of one day reaching precisions equivalent to errors of <±20 14 C yr.

' (Movius 1960: 355). The passage of time is equally vital for a proper understanding of the prehistoric sequence in Southeast Asia. While the cultural sequence is agreed by most scholars, its timing is not. The ancestors of the first rice farmers in Southeast Asia probably lived in the Yangtze Valley to the north (Liu et al. 2007), and spread south, via the coast and the major rivers, to enter the broad riverine plains of Southeast Asia. They brought their Austro-Asiatic languages, and a way of life that centred on settled village communities incorporating widespread exchange in exotica, a sophisticated ceramic industry, weaving, and a mortuary tradition that involved both extended inhumation and interment in lidded jars. This Neolithic settlement phase was followed by the adoption of copper-base metallurgy, in which copper and tin were alloyed from the earliest known contexts. The transition into the Iron Age has not been precisely dated, but it is known that early states were forming by the fourth to fifth centuries AD. The timing and the degree to which Iron Age communities developed social and technological sophistication prior to the rise of early states is poorly documented: Noen U-Loke is the only extensively-excavated Iron Age site in Thailand to be published ). A new chronological framework for prehistoric Southeast Asia, based on a Bayesian model from Ban Non WatWe do not know when the first farmers reached Southeast Asia and there remains a basic uncertainty over the date for the inception of copper-base metallurgy in Southeast Asia. This has generated a lack of understanding of the social changes that occurred with the early Bronze Age. As Muhly (1988: 16) In retrospect, the causes of controversies over chronology are readily understood (Solheim 1968;1970;Bayard 1972 Bayard , 1979Gorman & Charoenwongsa 1976;Bayard & Charoenwongsa 1983;Higham 1983;Loofs-Wissowa 1983). Radiocarbon determinations have virtually all been derived from charcoal, with its problems of 'old wood'. Only very rarely has the species of tree been specified, a practice that needs to be addressed in future dating programmes. No recognition was given to the unreliability of mixed samples (Ashmore 1999). In many cases, the relationship between a charcoal sample and the event being dated was unreliable. Major cultural changes, such as the beginning of copper-base metallurgy, have been dated on the basis of only a handful of determinations. When a sample of dates was available, the construction of the site's chronology followed procedures now shown to be importantly wrong (Bayliss et al. 2007: 9).Resolving this situation first requires a prehistoric site with a cultural sequence spanning the early Neolithic to the end of the Iron Age. Such sites are very rare in Southeast Asia. Phases within such a site would need to be ordered in terms of a relative chronology, and we would then require a sufficient number of radiocarbon determinations, preferably generated on the basis of samples with no inbuilt age, to provide dates for the su...