Border Cave is a rockshelter located near the crest of the Lebombo Mountains between South Africa and Swaziland, in Kwazulu Natal, South Africa, approximately 400 meters (~1,300 feet) from the border with Swaziland. The cave faces westward from the steep escarpment of the southern Lembobo Mountains: its opening lies approximately 600 m (~2000 ft) above current sea level.
Discovered in 1933 and excavated in 1940 by bat guano miner W. E. Horton, Border Cave's deposits include important Middle to Late Stone Age Transition (ca. 30,000 to 50,000 years ago), and Middle Stone Age Howiesons Poort occupations (45,000 to 75,000 years ago), including human remains. Border Cave was an important part of understanding the age and complexity of the Howiesons Poort component.
Stratigraphy
The cave includes approximately 4 m (13 ft) of deposits, laid down between 200,000 years ago and the present. A long debate and attempts at several different dating chronologies (particularly electron spin resonance (ESR) and amino acid racemization) were mostly resolved in the early 21st century, with most scholars accepting the current chronology.
Scholarly debate continues, however, about the age of the human skeletal materials, some of which were recovered unknown or unclear proviences. The most recent electronic spin resonance dating (Grün and colleagues 2003) puts at least one of the human bones at 74,000 ± 5000 years before the present, which is very early for an anatomically modern Homo sapiens.
Stratigraphy within the cave is somewhat problematic, due in part to the early date of the excavations: but layers of ash extending over large areas (WA) have allowed scholars to nail down consistent occupation levels across the cave. An area of some 25 m2 has been excavated over the years.
Chronology
- Layer 1BS, Early Later Stone Age, 41,000-30,000 years BP
- Layer 1WA, white ash deposit ~38,000-40,000 BP
- Layer 2BS, Middle Stone Age 3, 60,000-47,000 years BP
- Layer 2WA, white ash deposit ~59,000 BP
- Layer 3BS, Howiesons Poort, 79,000-60,000 years BP
- Layer 3WA, white ash deposit
- Layer 4BS, Middle Stone Age I (4BS), 87,000-79,000 years BP
Stone Tool Assemblages
The earliest stone tool assemblage (MSA I) is characterized by a high number of trimmmed points, and a lack of backed pieces. The Howiesons Poort assemblage has more backed pieces and fewer trimmed points, with an abundance of blades. Post-Howiesons's Poort assemblages include many more scrapers.
Environmental analysis of the micromammals suggests that at the time of the earliest occupation of the cave, the area was well wooded: later occupations experienced open savannah woodland.
Human Remains
Numerous hominid bones have been recovered from Border Cave. Most are believed to represent anatomically modern humans associated with the Howiesons' Poort levels. Horton's 1940 excavations recovered an incomplete cranial vault and a partial mandible: unfortunately it is out of context. A nearly complete infant skeleton buried in a shallow grave with a perforated Conus shell was recovered from the 1941 excavations. A nearly complete adult mandible was found at the base of the Howieson's Poort levels in the 1970s: ESR dating on this last returned a date of 74,000 years ago.Redating the Later Stone Age
According to a report published in 2012 (d'Errico and colleagues), Later Stone Age deposits at Border Cave are reliably dated to ca. 44,000 years ago, and they reflect a consistent tusk, bone and stone industry not identified in the archaeological record of South Africa before ~20,000 BP. These artifacts, which are similar in form to those used by San hunter-gatherers, include bone and ostrich shell beads, bone projectile points, wooden digging sticks, wooden poison applicators and notched bone.
The bone arrow point and poison applicator have residues of ricinoleic poison from castor beans (Ricinus communis). One lump of beeswax contained another poison, Euphorbia tirucalli: neither of these poisons are used by San hunter-gatherers today, who use beetle larvae, snake venom and other plant extracts. But the concept is the same.
What the results of the recent research indicate, say researchers, is to explain away the gap in cultural progression left after Howiesons Poort.
Sources
This glossary entry is part of the About.com Guide to the Middle Stone Age in Africa and the Dictionary of Archaeology.
Avery DM. 1992. The environment of early modern humans at Border Cave, South Africa: micromammalian evidence. Palaeogeography, Palaeoclimatology, Palaeoecology 91(1–2):71-87.
Bird MI, Fifield LK, Santos GM, Beaumont PB, Zhou Y, di Tada ML, and Hausladen PA. 2003. Radiocarbon dating from 40 to 60kaBP at Border Cave, South Africa. Quaternary Science Reviews 22(8-9):943-947.
Butzer KW, Beaumont PB, and Vogel JC. 1978. Lithostratigraphy of Border Cave, KwaZulu, South Africa: a Middle Stone Age sequence beginning c. 195,000 b.p. Journal of Archaeological Science 5(4):317-341.
d'Errico F, Backwell L, Villa P, Degano I, Lucejko JJ, Bamford MK, Higham TFG, Colombini MP, and Beaumont PB. 2012. Early evidence of San material culture represented by organic artifacts from Border Cave, South Africa. Proceedings of the National Academy of Sciences Early Edition.
Grün R, and Beaumont P. 2001. Border Cave revisited: a revised ESR chronology. Journal of Human Evolution 40(6):467-482.
Grün R, Beaumont P, Tobias PV, and Eggins S. 2003. On the age of Border Cave 5 human mandible. Journal of Human Evolution 45(2):155-167.
Lee-Thorp JA, and Sponheimer M. 2003. Three case studies used to reassess the reliability of fossil bone and enamel isotope signals for paleodietary studies. Journal of Anthropological Archaeology 22(3):208-216.
Miller GH, Beaumont PB, Deacon HJ, Brooks AS, Hare PE, and Jull AJT. 1999. Earliest modern humans in southern Africa dated by isoleucine epimerization in ostrich eggshell. Quaternary Science Reviews 18:1537-1548.
