Blombos Cave is a cave in a calcarenite limestone cliff on the Southern Cape coast in South Africa. It is an archaeological site made famous by the discovery of 75,000-year-old pieces of ochre engraved with abstract designs and beads made from Nassarius shells, and c. 80,000-year-old bone tools. Some of the earliest evidence for shellfishing and possibly fishing has been discovered at the site and dates to c. 140,000 years ago.
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Excavations carried out since 1991 at Blombos Cave provide snapshots of life in the African Middle Stone Age (MSA) in the southern Cape, South Africa. Three phases of MSA occupation have been identified and named M1, M2 and M3. Dating by the optically stimulated luminescence (OSL) and thermoluminescence (TL) methods have provided occupation dates for each phase: these are about 71,000 BCE for the M1 phase, about 78,000 BCE for the M2 phase, and between 100,000 and 140,000 BCE for the M3 phase.[1]
The evidence indicates periods of relatively brief occupation separated by long periods of non-occupation, including a separation between occupation during the Late Stone Age (LSA) and the Middle Stone Age.[2] Bone tools, marine shell beads, and engraved ochre were found in the M1 phase, bone tools in the Upper M2 phase, and considerable quantities of ochre and associated ochre working tools in the M3 phase.[1]
Blombos Cave is some 100 metres (330 ft) from the coast and 35 metres (115 ft) above sea level. The cave is a wave-cut bench in Mio/Pliocene Wankoe Formation aeolian deposits. Interior cave deposits, including those in recesses, cover more than 80 square metres (860 sq ft). About 20 square metres (220 sq ft) of the MSA has been excavated to a depth of about 2 metres (6.6 ft) below the original surface. The depositional history of the MSA levels is complex. Probably just prior to the accumulation of the M3 phase large calcrete roof blocks up to 3 metres (9.8 ft) thick were dislodged creating a variable and uneven floor surface. Further rockfall onto the MSA deposits occurred after the M3 phase occupation at circa 130-140 ka.
Subsequent human occupation left debris scattered over and around these blocks up to a height of more than 2 metres (6.6 ft). Compaction has caused deposits to drape over and around large spalls with some examples of near vertical layering. Near the rear and side cave wall MSA deposits have in some instances shrunk leaving a gap that later filled with LSA deposits. In places large rocks have shifted or broken causing shearing of deposits and infills. Despite these anomalies most MSA deposits are in situ and undisturbed. By identifying and excluding material from contaminated areas archaeologists are confident of the integrity of more than 95 per cent of recovered MSA material.
Principal markers of the M1 phase are bifacial foliate points, typical of the Stillbay, both complete and in various stages of manufacture. More than 400 have been recovered. Silcrete is the dominant raw material and the nearest source is circa 30 kilometres (19 mi). Large numbers of small flakes occur indicating on-site production of these artifacts. Some of the points show fractures which were interpreted as the result of their use as spear points.[3] According to an experimental study of the points, shaping of the points could have been achieved through pressure flaking, a technique that was previously believed to appear first in Europe 20,000 years ago as part of the Solutrean toolkit.[4]
More than 60 beads manufactured from Nassarius kraussianus gastropod shells have been recovered. Twenty-seven of these beads may derive from a single personal ornament. Two chunks of ochre engraved with geometric patterns and more than 15 bone tools come from the M1 phase. M2 phase markers are the more than 20 bone tools and a marked reduction in bifacial technology. In the M3 phase bifacial flaking and bone tools disappear. Silcrete is still dominant but there are fewer retouched tools. Striated ochre, particularly in large chunk form, is common in these levels. Ochre processing tools include lower and upper grindstones and hammerstones. Dense shellfish middens characterize the lower layers with very large hearths.
Faunal remains from the three MSA phases show that a wide range of terrestrial resources were exploited. More than a thousand fish bones, many from large fish, marine shells, seals and dolphins attest to extensive exploitation of aquatic resources and suggest exploitation patterns not dissimilar to that of LSA people in this region. Nine human teeth, mostly deciduous, have been recovered from the MSA levels but no other human skeletal material. The teeth probably derive from fairly gracile individuals and are similar to samples recovered at Klasies River Caves and De Kelders.
The Blombos Cave people engraved pieces of ochre[5] are regarded as the oldest known artwork[6] but very much simpler than the cave paintings and figurines found in Europe after 40,000 BP.[7]
The date of engraved ochre is now firmly established. The use of abstract symbolism on the engraved pieces of ochre and the presence of a complex tool kit suggests Middle Stone Age people were behaving in a cognitively modern way and had the advantages of syntactical language at least 80,000 years ago.
Human remains from the cave include four teeth found in 1998, of which two are heavily worn deciduous teeth and two are incomplete permanent premolar crowns. Marks on the premolars may indicate the use of toothpicks.[8][9] Another five dental specimens were unearthed in the cave during 1999–2000 [10][11]
In 2010, a study headed by Vincent Mourre under the auspices of the University of Toulouse found evidence that prehistoric humans had used the technique of pressure flaking to shape stone into tools.[12][13] The researchers said that the remains of stone points, likely used as spear points or knives, that were carved using pressure flaking had been found that were around 75,000 years old.[12] Previously, it had been believed that pressure flaking had only been invented around 20,000 years ago, in parts of France.[12] The study examined 127 separate artifacts, all made from silcrete, a difficult material to work with, especially compared to flint, which was the rock in which previous evidence of pressure flaking had been found.[12] Out of the 127 points found, around three-fifths appeared to have been produced using pressure flaking.[12]
According to an official at the University of Colorado Museum of Natural History, Paola Villa, the French team's discovery was "important because it shows that modern humans in South Africa had a sophisticated repertoire of tool-making techniques at a very early time."[13] However, Curtis Marean, an archaeologist from the Arizona State University, said that although the results are plausible he remains unconvinced that the researchers had based their conclusions on mathematical data, expressing concerns that the results were too reliant on more subjective observations of the tools discovered.[12]
Mourre's University of Toulouse study follows upon the earlier 2008 Stillbay study by Zenobia Jacobs, of the University of Wollongong, Australia who dated Still Bay silcrete tools at 71,000-71,900 years BP (Before Present), pushing the culture's advent back a further few thousand years if Mourre's team's dating is accepted.[14]
The M1 phase (oxygen isotope stage 5a/4) occupation occurs during a period of falling sea levels (c. 60–70 m/200–230 ft below present sea levels and 10–25 km/6.2–16 mi from present coastline) that is arguably colder than during M2. Donax serra, a sand burrowing white mussel, occurs in the M1 phase suggesting beach conditions in front of the cave. Densities of shell are lowest in this phase (17.5 kg/m3 or 29.5 lb/cu yd) probably because of the distance of the coast from the cave. M2 phase occupations fall within OI 5a with sea levels circa 25 metres (82 ft) lower than present and a coastline less than 5 kilometres (3.1 mi) from the present shore. Intermediate densities of shell occur in M2 (31.8 kg/m3 or 53.6 lb/cu yd). Climatic conditions may have been temperate and warmer than during M1 occupations. The upper part of the M3 phase (CH/CI layers) is a high density shell midden (68.4 kg/m3 or 115.3 lb/cu yd) suggesting sea levels similar to the present. These upper levels arguably fall just after the Eemian period (OI 5d; c. 100 ka. Temperatures were probably 1 to 2 °C (2 to 4 °F) warmer than present with higher sea levels (+3 m or +10 ft). An OSL date of c. 143 ka (OI 6) for a low density occupation level (layer CJ) in M3 suggests the M3 phase may need further subdivision when more dates are available.
