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Researchers increasingly rely on aggregations of radiocarbon dates from archaeological sites as proxies for past human populations. This approach has been critiqued on several grounds, including the assumptions that material is deposited, preserved, and sampled in proportion to past population size. However, various attempts to quantitatively assess the approach suggest there may be some validity in assuming date counts reflect relative population size. To add to this conversation, here we conduct a preliminary analysis coupling estimates of ethnographic population density with late Holocene radiocarbon dates across all counties in California. Results show that counts of late Holocene radiocarbon-dated archaeological sites increase significantly as a function of ethnographic population density. This trend is robust across varying sampling windows over the last 5000 BP. Though the majority of variation in dated-site counts remains unexplained by population density. Outliers reveal how departures from the central trend may be influenced by regional differences in research traditions, development-driven contract work, organic preservation, and landscape taphonomy. Overall, this exercise provides some support for the “dates-as-data” approach and offers insights into the conditions where the underlying assumptions may or may not hold. 

Abstract A tubular bone bead dating to ~ 12,940 BP was recovered from a hearth-centered activity area at the La Prele Mammoth site in Converse County, Wyoming, USA. This is the oldest known bead from the Western Hemisphere. To determine the taxonomic origin of the bead, we extracted collagen for zooarchaeology by mass spectrometry (ZooMS). We also used micro-CT scanning for morphological analysis to determine likely skeletal elements used for its production. We conclude that the bead was made from a metapodial or proximal phalanx of a hare (Lepus sp.). This find represents the first secure evidence for the use of hares during the Clovis period. While the use of hare bone for the manufacture of beads was a common practice in western North America during the Holocene, its origins can now be traced back to at least the terminal Pleistocene. 

The La Prele site (ca. 12,940 cal BP) is a deeply buried, single-component mammoth kill and campsite in Wyoming (USA). The site was discovered eroding from a creek bank 3 m deep within a 7-m tall terrace scarp, and prior investigations have primarily focused on excavations accessible from the creek bank, using heavy machinery to remove sterile overburden to access the deeply buried deposits. This approach has allowed excavations to occur safely outside of deep pits, but it has limited our ability to assess the total size and density of the site. To determine total site extent, we conducted systematic bucket auger testing of the La Prele site terrace, attempting 189 augers between 1.6 m and 6.2 m deep across the landform. We use a simulation and other mathematical procedures to infer artifact density from auger artifact counts and interpolate artifact densities across the site using GIS. We determine that La Prele is around 4500 m2 in area and likely contains a buried bison bonebed and two additional artifact concentrations comparable to or exceeding the size and density of previously excavated areas. We use these insights to infer Early Paleoindian group size, concluding that around 30 people occupied La Prele. 

ABSTRACT A type II VapB14 antitoxin regulates biofilm dispersal in the archaeal thermoacidophile Sulfolobus acidocaldarius through traditional toxin neutralization but also through noncanonical transcriptional regulation. Type II VapC toxins are ribonucleases that are neutralized by their proteinaceous cognate type II VapB antitoxin. VapB antitoxins have a flexible tail at their C terminus that covers the toxin’s active site, neutralizing its activity. VapB antitoxins also have a DNA-binding domain at their N terminus that allows them to autorepress not only their own promoters but also distal targets. VapB14 antitoxin gene deletion in S. acidocaldarius stunted biofilm and planktonic growth and increased motility structures (archaella). Conversely, planktonic cells were devoid of archaella in the Δ vapC14 cognate toxin mutant. VapB14 is highly conserved at both the nucleotide and amino acid levels across the Sulfolobales, extremely unusual for type II antitoxins, which are typically acquired through horizontal gene transfer. Furthermore, homologs of VapB14 are found across the Crenarchaeota , in some Euryarchaeota , and even bacteria. S. acidocaldarius vapB14 and its homolog in the thermoacidophile Metallosphaera sedula (Msed_0871) were both upregulated in biofilm cells, supporting the role of the antitoxin in biofilm regulation. In several Sulfolobales species, including M. sedula, homologs of vapB14 and vapC14 are not colocalized. Strikingly, Sulfuracidifex tepidarius has an unpaired VapB14 homolog and lacks a cognate VapC14, illustrating the toxin-independent conservation of the VapB14 antitoxin. The findings here suggest that a stand-alone VapB-type antitoxin was the product of selective evolutionary pressure to influence biofilm formation in these archaea, a vital microbial community behavior. IMPORTANCE Biofilms allow microbes to resist a multitude of stresses and stay proximate to vital nutrients. The mechanisms of entering and leaving a biofilm are highly regulated to ensure microbial survival, but are not yet well described in archaea. Here, a VapBC type II toxin-antitoxin system in the thermoacidophilic archaeon Sulfolobus acidocaldarius was shown to control biofilm dispersal through a multifaceted regulation of the archaeal motility structure, the archaellum. The VapC14 toxin degrades an RNA that causes an increase in archaella and swimming. The VapB14 antitoxin decreases archaella and biofilm dispersal by binding the VapC14 toxin and neutralizing its activity, while also repressing the archaellum genes. VapB14-like antitoxins are highly conserved across the Sulfolobales and respond similarly to biofilm growth. In fact, VapB14-like antitoxins are also found in other archaea, and even in bacteria, indicating an evolutionary pressure to maintain this protein and its role in biofilm formation. 

The La Prele Mammoth site (48CO1401), located in Converse County, Wyoming, contains a Clovis-age occupation associated with the remains of a subadult mammoth (Mammuthus columbi). In this paper, we present the geochronological and geoarchaeological context of the site. The La Prele Mammoth site is buried in an alluvial terrace of La Prele Creek, a tributary of the North Platte River, which acts as an important migration corridor through the Rocky Mountains. Archaeological remains, buried by a series of flood deposits, occur within or below a well-developed buried A horizon, referred to as the Mammoth Soil. Bioturbation of the site has resulted in vertical artifact movement, though peaks in artifact density are evident in vertical artifact distributions and likely represent the occupation surface. Radiocarbon dating of this occupation, including several new dates, suggests an age of 12,941 ± 56 calendar years ago (cal yr BP). 

The northern American Southwest provides one of the most well-documented cases of human population growth and decline in the world. The geographic extent of this decline in North America is unknown owing to the lack of high-resolution palaeodemographic data from regions across and beyond the greater Southwest, where archaeological radiocarbon data are often the only available proxy for investigating these palaeodemographic processes. Radiocarbon time series across and beyond the greater Southwest suggest widespread population collapses from AD 1300 to 1600. However, radiocarbon data have potential biases caused by variable radiocarbon sample preservation, sample collection and the nonlinearity of the radiocarbon calibration curve. In order to be confident in the wider trends seen in radiocarbon time series across and beyond the greater Southwest, here we focus on regions that have multiple palaeodemographic proxies and compare those proxies to radiocarbon time series. We develop a new method for time series analysis and comparison between dendrochronological data and radiocarbon data. Results confirm a multiple proxy decline in human populations across the Upland US Southwest, Central Mesa Verde and Northern Rio Grande from AD 1300 to 1600. These results lend confidence to single proxy radiocarbon-based reconstructions of palaeodemography outside the Southwest that suggest post-AD 1300 population declines in many parts of North America. This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.