I. Randolph Daniel

The Population Ecology of Hunter-Gatherers and Their Prey

Abstract In this paper we combine foraging theory and population biology models to simulate dynamic relationships between hunter-gatherers and their prey resources. Hunter-gatherer population growth responds to the net marginal rate of foraging; prey population growth responds logistically to exploitation. Thus conceived, the relationship between forager and prey biomass is time-dependent and nonlinear. It changes from stable equilibrium to damped and stable cycles with modest adjustments of input parameters. And, it produces the largest sustainable human population at intermediate levels of individual work effort. At equilibrium the forager takes all prey types with a pursuit and handling rate greater than or equal to its maintenance foraging rate. The structural properties of the model compel us to reject standard anthropological interpretations of the carrying capacity concept; they provide new insights on old issues such as original affluence and intensification. Analysis of the interaction of human population, diet selection, and resource depletion requires microecological models in part because the relevant processes occur on time scales largely invisible to both ethnography and archaeology.

Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago

Significance We present detailed geochemical and morphological analyses of nearly 700 spherules from 18 sites in support of a major cosmic impact at the onset of the Younger Dryas episode (12.8 ka). The impact distributed ∼10 million tonnes of melted spherules over 50 million square kilometers on four continents. Origins of the spherules by volcanism, anthropogenesis, authigenesis, lightning, and meteoritic ablation are rejected on geochemical and morphological grounds. The spherules closely resemble known impact materials derived from surficial sediments melted at temperatures >2,200 °C. The spherules correlate with abundances of associated melt-glass, nanodiamonds, carbon spherules, aciniform carbon, charcoal, and iridium. Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies, including microspherules, nanodiamonds, and iridium. Distributed across four continents at the Younger Dryas boundary (YDB), spherule peaks have been independently confirmed in eight studies, but unconfirmed in two others, resulting in continued dispute about their occurrence, distribution, and origin. To further address this dispute and better identify YDB spherules, we present results from one of the largest spherule investigations ever undertaken regarding spherule geochemistry, morphologies, origins, and processes of formation. We investigated 18 sites across North America, Europe, and the Middle East, performing nearly 700 analyses on spherules using energy dispersive X-ray spectroscopy for geochemical analyses and scanning electron microscopy for surface microstructural characterization. Twelve locations rank among the world’s premier end-Pleistocene archaeological sites, where the YDB marks a hiatus in human occupation or major changes in site use. Our results are consistent with melting of sediments to temperatures >2,200 °C by the thermal radiation and air shocks produced by passage of an extraterrestrial object through the atmosphere; they are inconsistent with volcanic, cosmic, anthropogenic, lightning, or authigenic sources. We also produced spherules from wood in the laboratory at >1,730 °C, indicating that impact-related incineration of biomass may have contributed to spherule production. At 12.8 ka, an estimated 10 million tonnes of spherules were distributed across ∼50 million square kilometers, similar to well-known impact strewnfields and consistent with a major cosmic impact event.

Stone Raw Material Availability and Early Archaic Settlement in the Southeastern United States

The band-macroband Early Archaic settlement model has had widespread use in Southeastern North American archaeology since its introduction some ten years ago (Anderson and Hanson 1988). Nevertheless, the model has undergone little critical testing. New data from Early Archaic assemblages in North Carolina and South Carolina are used to test the models posited settlement range and site types. At issue is the role played by the limited distribution of high-quality knappable stone in Early Archaic adaptations. Contrary to the band-macroband model, it is suggested that high-quality tool stone played a more significant role in settlement adaptations than previously recognized. In particular, group mobility incorporated the geological occurrence of preferred tool stone. Moreover, it is argued that the level of tool curation in Early Archaic assemblages is telling us less about forager or collector site types than it is about the differential use of stone raw material. Last, a new settlement model is proposed whereby settlement ranges were not restricted to particular watersheds along the South Atlantic Slope; rather, settlement ranges “mapped on” to an area that varied annually across the landscape according to food availability but generally included regionally significant stone quarries.

Bayesian chronological analyses consistent with synchronous age of 12,835-12,735 Cal B.P. for Younger Dryas boundary on four continents.

Significance A cosmic impact event at ∼12,800 Cal B.P. formed the Younger Dryas boundary (YDB) layer, containing peak abundances in multiple, high-temperature, impact-related proxies, including spherules, melt glass, and nanodiamonds. Bayesian statistical analyses of 354 dates from 23 sedimentary sequences over four continents established a modeled YDB age range of 12,835 Cal B.P. to 12,735 Cal B.P., supporting synchroneity of the YDB layer at high probability (95%). This range overlaps that of a platinum peak recorded in the Greenland Ice Sheet and of the onset of the Younger Dryas climate episode in six key records, suggesting a causal connection between the impact event and the Younger Dryas. Due to its rarity and distinctive characteristics, the YDB layer is proposed as a widespread correlation datum. The Younger Dryas impact hypothesis posits that a cosmic impact across much of the Northern Hemisphere deposited the Younger Dryas boundary (YDB) layer, containing peak abundances in a variable assemblage of proxies, including magnetic and glassy impact-related spherules, high-temperature minerals and melt glass, nanodiamonds, carbon spherules, aciniform carbon, platinum, and osmium. Bayesian chronological modeling was applied to 354 dates from 23 stratigraphic sections in 12 countries on four continents to establish a modeled YDB age range for this event of 12,835–12,735 Cal B.P. at 95% probability. This range overlaps that of a peak in extraterrestrial platinum in the Greenland Ice Sheet and of the earliest age of the Younger Dryas climate episode in six proxy records, suggesting a causal connection between the YDB impact event and the Younger Dryas. Two statistical tests indicate that both modeled and unmodeled ages in the 30 records are consistent with synchronous deposition of the YDB layer within the limits of dating uncertainty (∼100 y). The widespread distribution of the YDB layer suggests that it may serve as a datum layer.

Widespread platinum anomaly documented at the Younger Dryas onset in North American sedimentary sequences

Previously, a large platinum (Pt) anomaly was reported in the Greenland ice sheet at the Younger Dryas boundary (YDB) (12,800 Cal B.P.). In order to evaluate its geographic extent, fire-assay and inductively coupled plasma mass spectrometry (FA and ICP-MS) elemental analyses were performed on 11 widely separated archaeological bulk sedimentary sequences. We document discovery of a distinct Pt anomaly spread widely across North America and dating to the Younger Dryas (YD) onset. The apparent synchroneity of this widespread YDB Pt anomaly is consistent with Greenland Ice Sheet Project 2 (GISP2) data that indicated atmospheric input of platinum-rich dust. We expect the Pt anomaly to serve as a widely-distributed time marker horizon (datum) for identification and correlation of the onset of the YD climatic episode at 12,800 Cal B.P. This Pt datum will facilitate the dating and correlating of archaeological, paleontological, and paleoenvironmental data between sequences, especially those with limited age control.

SIFTING THE SANDS OF TIME: GEOARCHAEOLOGY, CULTURE CHRONOLOGY, AND CLIMATE CHANGE AT SQUIRES RIDGE, NORTHEASTERN NORTH CAROLINA

Abstract Since 2000, East Carolina University has conducted archaeological research in the Tar River valley in the northern Coastal Plain of North Carolina designed to address poorly understood aspects of the region’s culture-history. In particular, survey and excavation along a portion of the Tar River have focused on problems related to Coastal Plain chronology, typology, and geoarchaeology. Here we provide an overview of testing done at one site, Squires Ridge, that contains stratified Woodland and Archaic period remains in a 1-m deposit of largely aeolian sandy soils. We suggest that the formation of the archaeologically stratified portions of sand ridges along the Tar River reflect millennial-scale climatic cyclicity representing regional manifestations of climate change during the Early to Middle Holocene. Sand ridges along the Tar River likely represent proxies of climate change, while the archaeology contained within them manifest human adaptations to such change.

Early Eastern Archaic

Relative Time Period: Follows the Late Paleoindian tradition and precedes the Middle Eastern Archaic tradition.