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In 2015, which marked 35 years since Beaumont had worked at the site, we renewed excavations at Border Cave. Our primary aims were to reassess the stratigraphic context of the sedimentary and cultural sequence, gain insight into site formation processes, make a detailed study of organic remains, identify long term cultural trends, and characterize expressions of complex behaviour and innovation. This contribution serves as an update on activities conducted in 2018 and 2019 and provides an overview of our research findings to date, placing them in the broader context of the Middle Stone Age in southern Africa. New luminescence ages based on feldspar grains in the sedimentary sequence are in broad agreement with the previous chronology established for the site. Geoarchaeology and faunal taphonomy have started to elucidate site formation processes, showing that the members should not be considered as homogeneous units, and that associated formation interpretations established by Beaumont are simplifications that are not representative of the diverse site formation processes active in the shelter. This finding is supported by lithic analysis of the Member 2 WA assemblage that shows differences in technology between artefacts from the top, middle, and lower part of the same member. In addition, the lithic artefacts from the middle and lower part of Member 2 WA show continuities with the lithics from the underlying Members 3 BS and 1 RGBS, which were attributed by Beaumont to a different industry. Grass mats/bedding layers are preserved throughout the sequence, the oldest of which dates to ∼200 ka. The use of ash and leaves with insecticidal properties in the bedding construction reflects complex cognition, as does the cooking of starchy rhizomes that come from layers dated to 170 ka. In addition to a rich mammal fauna found in all of the deposits, the remains of a new individual, a 3–4-year-old child, were recovered from Member 1 BS.LR C that has an ESR date of 42.6 ka.

Extraordinary preservation of plant remains provides an insight into the construction and materials of bedding at Border Cave, South Africa. Towards the back of the cave there are particularly thick layers of desiccated and charred grass and our botanical study is from bulk samples of these approximately 60,000 to 40,000 year-old layers (Members 3 BS, 2 WA, 2 BS and 1 BS Lower C). More than one type of panicoid grass was identified, sedge nutlets were present in the older layers and in Member 2 WA particularly, eudicotyledon leaves were preserved. Plant bedding construction may have altered slightly over time with the use of sedges decreasing in favour of grass. A small item that appears to be woven monocotyledon leaf blades was recovered from Member 1 BS Lower C (42,600 years old), potentially making it the oldest evidence of simple weaving. The bedding is generally desiccated rather than burned, and often lies on an ash base. It is possible that the site's occupants burned old bedding to provide an ash base for fresh bedding. The unique preservation of desiccated plant material from as early as 60,000 years ago may in part be due to these ashy surfaces.

In southern Africa numerous Middle Stone Age (MSA) sites document important steps in technological and behavioural development leading to significant changes in the lifeways of modern humans. To assess whether these cultural changes and developments may be related to environmental changes we need to ascertain past environments. To do this we apply a new quantitative method, the GIS-based Coexistence Approach (CAGIS), on fossil plant material from the MSA site Sibudu, KwaZulu-Natal, South Africa. Previous qualitative environmental interpretations of the fossil fauna and flora of the site remain ambiguous. Because much of the material is anthropogenically introduced, it is difficult to distinguish between the effects of natural changes in the local vegetation and behavioural changes of the people that inhabited the shelter. CAGIS can be applied to such biased assemblages and seems to be an adequate method to directly quantify palaeoclimate and vegetation parameters at an archaeological site. The CAGIS analysis shows that during the Howiesons Poort (HP) Industry winters were slightly colder and drier than present, whereas during summer, temperatures and precipitation were similar to today. Post-HP winters were drier and colder than present, presumably colder than during the HP. Summer temperatures remained the same, but summer precipitation decreased from the HP to post-HP. Vegetation cover was less than today, may be even less than during the HP. The late MSA was observably warmer than the older periods, especially during winter. At the same time summer precipitation slightly increased and vegetation became more dense, but still remained generally open similar to today's anthropogenic landscape. Generally, climatic changes are most pronouncedly reflected in winter temperature parameters, especially in minimum winter temperatures, and to a lesser extent by changes in summer precipitation. The observed ecological trends seem to be affected mainly by variations through time in winter temperatures. This refinement of interpretation was not discernible using previous methods for analysing the Sibudu data.