Emma Loftus

New Radiocarbon Dates and Bayesian Models for Nelson Bay Cave and Byneskranskop 1: Implications for the South African Later Stone Age Sequence

The southern African Later Stone Age sequence is widely considered to be well dated based on radiocarbon dates from dozens of archaeological sites, and apparently shows more or less synchronous cultural shifts across an extensive area. Yet, closer examination reveals the inadequacy of many of the decades-old and uncalibrated individual site chronologies that underpin this regional chronology, making robust comparisons of the chronology of technological change across this region impossible. Here, we present 26 new AMS 14C dates and Bayesian modeled chronologies for two important archaeological cave sites in southernmost Africa, Nelson Bay Cave and Byneskranskop 1. The results provide more robust age estimates for these cultural and paleoenvironmental sequences and revise interpretations of these sites in several instances. This project demonstrates the necessity of redating key sites, and the value of currently underutilized methods, including calibration and Bayesian modeling, for southern African archaeology.

Atmospheric CO 2 effect on stable carbon isotope composition of terrestrial fossil archives

The 13C/12C ratio of C3 plant matter is thought to be controlled by the isotopic composition of atmospheric CO2 and stomatal response to environmental conditions, particularly mean annual precipitation (MAP). The effect of CO2 concentration on 13C/12C ratios is currently debated, yet crucial to reconstructing ancient environments and quantifying the carbon cycle. Here we compare high-resolution ice core measurements of atmospheric CO2 with fossil plant and faunal isotope records. We show the effect of pCO2 during the last deglaciation is stronger for gymnosperms (−1.4 ± 1.2‰) than angiosperms/fauna (−0.5 ± 1.5‰), while the contributions from changing MAP are −0.3 ± 0.6‰ and −0.4 ± 0.4‰, respectively. Previous studies have assumed that plant 13C/12C ratios are mostly determined by MAP, an assumption which is sometimes incorrect in geological time. Atmospheric effects must be taken into account when interpreting terrestrial stable carbon isotopes, with important implications for past environments and climates, and understanding plant responses to climate change.The effect of CO2 concentrations on 13C/12C ratios in C3 plants, comprising most of Earth’s vegetation, is currently debated. Here, using ice core records and plant and animal fossils, Hare et al. find evidence for a pCO2 effect, with implications for palaeoecology and plant responses to climate change.

An isotopic generation: four decades of stable isotope analysis in African archaeology

ABSTRACT The application of stable isotope analysis in African archaeology has a long and distinguished pedigree. Many new developments were inspired by questions in the archaeology of the continent, helped considerably by the availability of African landscapes as natural laboratories for providing the essential underpinning of isotope ecology systematics. Stable isotopes are now regularly built into multi-disciplinary archaeological projects spanning the very long temporal and geographical span of human history on the African continent. On the fiftieth anniversary of Azania: Archaeological Research in Africa we evaluate these endeavours — the achievements, problems, constraints and potential of stable isotopic research in African archaeology. We begin with a discussion of the continents role in developing understandings of stable carbon, nitrogen, oxygen and strontium isotope systematics, as used to interpret change in the archaeological record. We discuss the application of these principles within several areas of archaeological research, drawing on case studies from among late Pleistocene/Holocene hunter-gatherers, early food producers, complex societies of the African Iron Age and the individual life histories of the African slave trade. There is clearly much potential for further application in African archaeology.