From 2014 to 2020, we compiled radiocarbon ages from the lower 48 states, creating a database of more than 100,000 archaeological, geological, and paleontological ages that will be freely available to researchers through the Canadian Archaeological Radiocarbon Database. Here, we discuss the process used to compile ages, general characteristics of the database, and lessons learned from this exercise in “big data” compilation.

In the Wyoming Basin, archaeological sites dating from the Early Archaic to Late Prehistoric are often found associated with or adjacent to dense populations of Cymopterus bulbosus (springparsley), a nutritious geophyte that would have been an important food source for prehistoric humans living in the region. Experimental data have shown that the caloric return rates of C. bulbosus were enough to support seasonal exploitation by foragers, yet there has been no direct evidence for the use of this geophyte from the archaeological record. In this study, we examine starch granules from 10 ground stone tools excavated from two stratified, multicomponent archaeological sites in the Wyoming Basin to determine if C. bulbosus was collected and consumed in the past. Taproots of C. bulbosus were collected from two populations in the immediate vicinity of the archaeological sites in order to develop a modern starch reference. Identification of Cymopterus starch granules is based on a systematic study of those reference granules. The presence of Cymopterus starch on the ground stone artifacts suggests that prehistoric foragers were collecting and consuming these geophytes. These findings support previous hypotheses about geophyte use in southern Wyoming and therefore have implications for increasing human populations as well as settlement and subsistence decisions.

Fremont societies of the Uinta Basin incorporated domesticates into a foraging lifeway over a 1,000-year period from AD 300 to 1300. Fremont research provides a unique opportunity to critically examine the social and ecological processes behind the adoption and abandonment of domesticates by hunter-gatherers. We develop and integrate a 2,115-year precipitation reconstruction with a Bayesian chronological model for the growth of Fremont societies in the Cub Creek reach of Dinosaur National Monument. Comparison of the archaeological chronology with the precipitation record suggests that the florescence of Fremont societies was an adaptation to multidecadal precipitation variability with an approximately 30-plus-year periodicity over most, but not all, of the last 2,115 years. Fremont societies adopted domesticates to enhance their resilience to periodic droughts. We propose that reduced precipitation variability from AD 750 to AD 1050, superimposed over consistent mean precipitation availability, was the tipping point that increased maize production, initiated agricultural intensification, and resulted in increased population and development of pithouse communities. Our study develops a multidecadal/multigenerational model within which to evaluate the strategies underwriting the adoption of domesticates by foragers, the formation of Fremont communities, and the inherent vulnerabilities to resource intensification that implicate the eventual dissolution of those communities.

With generous support from the National Science Foundation, we have spent the past four years developing an archaeological radiocarbon database for the United States. Here, we highlight the importance of spatial data for open-access, national-scale archaeological databases and the development of paleodemography research. We propose a new method for analyzing radiocarbon time series in the context of paleoclimate models. This method forces us to confront one of the central challenges to realizing the full potential of national-scale databases: the quality of the spatial data accompanying radiocarbon dates. We seek to open a national discussion on the use of spatial data in open-source archaeological databases.

Over the last decade, archaeologists have turned to large radiocarbon (14C) data sets to infer prehistoric population size and change. An outstanding question concerns just how direct of an estimate 14C dates are for human populations. In this paper we propose that 14C dates are a better estimate of energy consumption, rather than an unmediated, proportional estimate of population size. We use a parametric model to describe the relationship between population size, economic complexity and energy consumption in human societies, and then parametrize the model using data from modern contexts. Our results suggest that energy consumption scales sub-linearly with population size, which means that the analysis of a large 14C time-series has the potential to misestimate rates of population change and absolute population size. Energy consumption is also an exponential function of economic complexity. Thus, the 14C record could change semi-independent of population as complexity grows or declines. Scaling models are an important tool for stimulating future research to tease apart the different effects of population and social complexity on energy consumption, and explain variation in the forms of 14C date time-series in different regions.

Sum probability and Bayesian modeling of a substantial series of radiocarbon dates from a former extensive lake area in NW Belgium, known as the Moervaart area, allow important hydrological changes to be synchronized with Greenland Interstadial lb (or Intra-Allerød Cold Period). It is postulated that the disappearance of nearly all open water systems (Moervaart lake, anastomosing gullies, and dune-slacks) in response to this short but abrupt cooling event was responsible for a nearly total retreat of hunter-gatherers already some centuries before the start of Greenland Stadial 1 (Younger Dryas).

Lithic armatures have been widely noted as key evidence for interpreting the role of indigenous Mesolithic traditions in the spread of the Early Neolithic Linearbandkeramik (LBK) culture, and therefore early agriculture, across temperate Europe. Their role as evidence for the continuity of Mesolithic ‘identities’ has been emphasized without the use of a unified, systematic recording methodology of armatures from both Late–Final Mesolithic (LM–FM) and LBK sites that places armatures in their broader context as part of projectile technologies of late hunter-gatherers and early farmers. In this paper, we present the results of recent research in the southern North Sea basin that utilized a systematic and unified recording methodology to analyse armature assemblages from LM–FM and LBK sites on an inter-regional scale. We report that there is much more inter-regional variability in armature assemblages during the LM than traditionally considered in efforts to interpret similarities and possible cultural transmission processes between Mesolithic and LBK populations. This paper calls for a reassessment of inter-regional LM variability in the construction of Mesolithic-LBK contact models and a focus that places armatures in their broader social and technological contexts.

In this debate the authors tackle a problem fundamental to researchers and resource managers in the Mesolithic period: what sort of prehistory do flint scatters represent?