Michael Toffolo, a researcher at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), is co-author of two papers published in the South African Archaeological Bulletin about the Damvlei and Lovedale sites, located in Free State province in South Africa, which help us better understand human occupations in the central interior of South Africa during the Pleistocene and Holocene. The CENIEH laboratories of Electron Spin Resonance, Thin Sections and Archaeometry also participated in both papers.

The first article, which describes the Damvlei site on the left bank of the Modder River, supports a scenario of permanent human presence in the grasslands in the center of South Africa during the Holocene, in the period known as the LSA (Late Stone Age). It also draws the conclusion that occupation at the end of the Late Pleistocene might have been ephemeral and restricted to the courses of rivers like the Modder, while permanent presence would have been confined to the better-watered highlands in the east.

The combination of methods such as micromorphology, infrared spectroscopy, phytolith analysis, and the study of faunal remains and stone tools, has provided data on the vegetation, climate, fauna and chronology of the site. These analyses show that Damvlei was an environment of open grasslands that was relatively more humid during the Early Holocene, with drier conditions in the Middle and Late Holocene.

The CENIEH laboratories of Electron Spin Resonance, Thin sections and Archaeometry have collaborated in the study of these sites.

“Thanks to this microarchaeological approach, we were able to reconstruct the formation processes of the site, which offer a more complete vision of the end of the Pleistocene and Holocene in this region,” explains Toffolo, who participated in these papers as part of his Ramón y Cajal 2021 project: The evolution of Homo sapiens in southern Africa during the Middle and Late Pleistocene.”

In this context, the human occupation took place near the bank of the river, probably as a series of short visits, which made use of the exposed surfaces close to the water. The presence of tools made of banded ironstone, a rock whose nearest source is in the Kuruman Hills, some 230 km to the north-west of the site, supports the interpretation that these groups had extensive social networks.

The Lovedale site

Only 1.5 km from Damvlei lies the Lovedale site, the subject of the second <second paper. Samples of antelope tooth enamel from Lovedale were analyzed to confirm the chronology of the stratigraphic sequence.

The new dating, obtained using the method of Electron Spin Resonance with uranium series (ESR/U-series), indicates that the minimum age of the fossils is 64,000 years, thus in agreement with the chronology previously established by Luminescence (OSL) for the sediments and ESR/U-series for dental samples from small antelopes, which placed its age in the range 56,000 - 77,000 years.

The enamel samples were characterized using the Fourier Transform Infrared Spectroscopy (FTIR) method. This procedure offers a correlation between the state of preservation of the enamel and its uranium content, with the less preserved teeth being the richest in uranium, which is incorporated during burial in sediments. In addition, extensively altered teeth are also prone to uranium loss, which affects the accuracy of ESR/U-series dating.

Therefore, FTIR spectroscopy analysis can be used as a screening method for teeth to exclude the more altered specimens and thus enhance ESR/U-series dates. “This entails a major improvement in the dating method and its accuracy, as well as a better comprehension of the processes affecting the loss of uranium during the time the remains were buried,” adds Toffolo.