p3k14c, a synthetic global database of archaeological radiocarbon dates.

Archaeologists increasingly use large radiocarbon databases to model prehistoric human demography (also termed paleo-demography). Numerous independent projects, funded over the past decade, have assembled such databases from multiple regions of the world. These data provide unprecedented potential for comparative research on human population ecology and the evolution of social-ecological systems across the Earth. However, these databases have been developed using different sample selection criteria, which has resulted in interoperability issues for global-scale, comparative paleo-demographic research and integration with paleoclimate and paleoenvironmental data. We present a synthetic, global-scale archaeological radiocarbon database composed of 180,070 radiocarbon dates that have been cleaned according to a standardized sample selection criteria. This database increases the reusability of archaeological radiocarbon data and streamlines quality control assessments for various types of paleo-demographic research. As part of an assessment of data quality, we conduct two analyses of sampling bias in the global database at multiple scales. This database is ideal for paleo-demographic research focused on dates-as-data, bayesian modeling, or summed probability distribution methodologies.

Mapping past human land use using archaeological data: A new classification for global land use synthesis and data harmonization.

In the 12,000 years preceding the Industrial Revolution, human activities led to significant changes in land cover, plant and animal distributions, surface hydrology, and biochemical cycles. Earth system models suggest that this anthropogenic land cover change influenced regional and global climate. However, the representation of past land use in earth system models is currently oversimplified. As a result, there are large uncertainties in the current understanding of the past and current state of the earth system. In order to improve representation of the variety and scale of impacts that past land use had on the earth system, a global effort is underway to aggregate and synthesize archaeological and historical evidence of land use systems. Here we present a simple, hierarchical classification of land use systems designed to be used with archaeological and historical data at a global scale and a schema of codes that identify land use practices common to a range of systems, both implemented in a geospatial database. The classification scheme and database resulted from an extensive process of consultation with researchers worldwide. Our scheme is designed to deliver consistent, empirically robust data for the improvement of land use models, while simultaneously allowing for a comparative, detailed mapping of land use relevant to the needs of historical scholars. To illustrate the benefits of the classification scheme and methods for mapping historical land use, we apply it to Mesopotamia and Arabia at 6 kya (c. 4000 BCE). The scheme will be used to describe land use by the Past Global Changes (PAGES) LandCover6k working group, an international project comprised of archaeologists, historians, geographers, paleoecologists, and modelers. Beyond this, the scheme has a wide utility for creating a common language between research and policy communities, linking archaeologists with climate modelers, biodiversity conservation workers and initiatives.

Dispersals as demographic processes: testing and describing the spread of the Neolithic in the Balkans.

Although population history and dispersal are back at the forefront of the archaeological agenda, they are often studied in relative isolation. This contribution aims at combining both dimensions, as population dispersal is, by definition, a demographic process. Using a case study drawn from the Early Neolithic of South-Eastern Europe, we use radiocarbon dates to jointly investigate changes in speed and population size linked to the new food production economy and demonstrate that the spread of farming in this region corresponds to a density-dependent dispersal process. The implications of this characterization are evaluated in the discussion. This article is part of the theme issue 'Cross-disciplinary approaches to prehistoric demography'.

The spatiotemporal spread of human migrations during the European Holocene.

The European continent was subject to two major migrations of peoples during the Holocene: the northwestward movement of Anatolian farmer populations during the Neolithic and the westward movement of Yamnaya steppe peoples during the Bronze Age. These movements changed the genetic composition of the continent's inhabitants. The Holocene was also characterized by major changes in vegetation composition, which altered the environment occupied by the original hunter-gatherer populations. We aim to test to what extent vegetation change through time is associated with changes in population composition as a consequence of these migrations, or with changes in climate. Using ancient DNA in combination with geostatistical techniques, we produce detailed maps of ancient population movements, which allow us to visualize how these migrations unfolded through time and space. We find that the spread of Neolithic farmer ancestry had a two-pronged wavefront, in agreement with similar findings on the cultural spread of farming from radiocarbon-dated archaeological sites. This movement, however, did not have a strong association with changes in the vegetational landscape. In contrast, the Yamnaya migration speed was at least twice as fast and coincided with a reduction in the amount of broad-leaf forest and an increase in the amount of pasture and natural grasslands in the continent. We demonstrate the utility of integrating ancient genomes with archaeometric datasets in a spatiotemporal statistical framework, which we foresee will enable future studies of ancient populations' movements, and their putative effects on local fauna and flora.

Beyond broad strokes: sociocultural insights from the study of ancient genomes.

In the field of human history, ancient DNA has provided answers to long-standing debates about major movements of people and has begun to inform on other important facets of the human experience. The field is now moving from mostly large-scale supraregional studies to a more local perspective, shedding light on socioeconomic processes, inheritance rules, marriage practices and technological diffusion. In this Review, we summarize recent studies showcasing these types of insights, focusing on methods used to infer sociocultural aspects of human behaviour. This approach often involves working across disciplines - such as anthropology, archaeology, linguistics and genetics - that have until recently evolved in separation. Multidisciplinary dialogue is important for an integrated reconstruction of human history, which can yield extraordinary insights about past societies, reproductive behaviours and even lifestyle habits that would not be possible to obtain otherwise.

Author Correction: Amplitude of travelling front as inferred from 14C predicts levels of genetic admixture among European early farmers.

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

Amplitude of travelling front as inferred from 14C predicts levels of genetic admixture among European early farmers.

Large radiocarbon datasets have been analysed statistically to identify, on the one hand, the dynamics and tempo of dispersal processes and, on the other, demographic change. This is particularly true for the spread of farming practices in Neolithic Europe. Here we combine the two approaches and apply them to a new, extensive dataset of 14,535 radiocarbon dates for the Mesolithic and Neolithic periods across the Near East and Europe. The results indicate three distinct demographic regimes: one observed in or around the centre of farming innovation and involving a boost in carrying capacity; a second appearing in regions where Mesolithic populations were well established; and a third corresponding to large-scale migrations into previously essentially unoccupied territories, where the travelling front is readily identified. This spatio-temporal patterning linking demographic change with dispersal dynamics, as displayed in the amplitude of the travelling front, correlates and predicts levels of genetic admixture among European early farmers.

Space competition and time delays in human range expansions. Application to the neolithic transition.

Space competition effects are well-known in many microbiological and ecological systems. Here we analyze such an effect in human populations. The Neolithic transition (change from foraging to farming) was mainly the outcome of a demographic process that spread gradually throughout Europe from the Near East. In Northern Europe, archaeological data show a slowdown on the Neolithic rate of spread that can be related to a high indigenous (Mesolithic) population density hindering the advance as a result of the space competition between the two populations. We measure this slowdown from a database of 902 Early Neolithic sites and develop a time-delayed reaction-diffusion model with space competition between Neolithic and Mesolithic populations, to predict the observed speeds. The comparison of the predicted speed with the observations and with a previous non-delayed model show that both effects, the time delay effect due to the generation lag and the space competition between populations, are crucial in order to understand the observations.

Millets across Eurasia: chronology and context of early records of the genera Panicum and Setaria from archaeological sites in the Old World.

We have collated and reviewed published records of the genera Panicum and Setaria (Poaceae), including the domesticated millets Panicum miliaceum L. (broomcorn millet) and Setaria italica (L.) P. Beauv. (foxtail millet) in pre-5000 cal b.c. sites across the Old World. Details of these sites, which span China, central-eastern Europe including the Caucasus, Iran, Syria and Egypt, are presented with associated calibrated radiocarbon dates. Forty-one sites have records of Panicum (P. miliaceum, P. cf. miliaceum, Panicum sp., Panicum type, P. capillare (?) and P. turgidum) and 33 of Setaria (S. italica, S. viridis, S. viridis/verticillata, Setaria sp., Setaria type). We identify problems of taphonomy, identification criteria and reporting, and inference of domesticated/wild and crop/weed status of finds. Both broomcorn and foxtail millet occur in northern China prior to 5000 cal b.c.; P. miliaceum occurs contemporaneously in Europe, but its significance is unclear. Further work is needed to resolve the above issues before the status of these taxa in this period can be fully evaluated. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00334-008-0187-1) contains supplementary material, which is available to authorized users.