Blombos: The Earliest Modern Humans?

Does this cave in South Africa hold evidence of the first behaviorally modern humans?

At first blush, there is nothing extraordinary about it. Carved out of a limestone cliff by nature millions of years ago, Blombos Cave is set picturesquely above a rugged seascape along South Africa’s Southern Cape Coast.  Waves crash against jagged rocks below it.  Similar cave scenes can be seen along coastlines of California and Oregon in the U.S.  But unlike most other caves like it, there is something uniquely notable about this one.  It may be without argument one of the most important locations yet discovered that holds evidence, with secrets perhaps yet to be revealed, bearing on the origins of modern humans. Here lived, according to many scientists, small contingents of humans who, for the most part, may have resembled us in both anatomical appearance and basic behavior — but who lived over one hundred thousand years before the first signs of agriculture and collective society emerged anywhere in the world.

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Location of the Blombos Cave, South Africa. Vincent Mourre, Wikimedia Commons

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Blombos Cave interior panorama view. [Image courtesy of Magnus Haaland]

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The significance of the cave was first discovered in 1991 when Professor Christopher Henshilwood of the University of the Witwatersrand in Johannesburg, South Africa, and others began serious investigations of the cave features. Systematic excavations were carried out beginning in 1997 with Cedric Poggenpoel and a team of excavators. It soon proved to be a goldmine of evidence that could potentially rewrite the scenario of when and where behaviorally modern humans emerged.  

Most scientists at this time had assumed, based on evidence uncovered in the prehistoric cave sites of Europe, that modern human behavior, the ability to think and express abstractly, innovate, cooperate and communicate with symbolic expression, was born up north, in or near the Ice Age environs of present-day Europe, among anatomically modern humans who coexisted with their stalky, robust but perhaps less cognitively endowed Neanderthal cousins. But with the work of Henshilwood and others it was now beginning to appear that there was another story — a southside story — a story that played out far earlier in time near the southern Cape of South Africa. Scientists had unearthed 75,000-year-old pieces of ochre engraved with abstract designs, 75,000-year-old beads made from Nassarius (sea tick) shells, and 80,000-year-old bone tools, as well as human teeth with crown diameters that suggested that the people in the cave were likely anatomically modern. Moreover, evidence of shellfishing and possibly fishing had been discovered, dating to about 140,000 years ago. The engraved pieces of ochre have been regarded by many scientists as the oldest known artwork. According to Henshilwood and his associates, the use of abstract symbolism as demonstrated on the engraved pieces of ochre and the presence of a complex tool kit suggested that a Middle Stone Age (MSA) people [280,000 – 25,000 B.P.] were behaving in a “cognitively modern way” and may have exercised syntactical language, the rudiments of modern-day language communication, at least 80,000 years ago.

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Deposit layers at Blombos Cave, South Africa. Kari Janne Stenersen, Wikimedia Commons

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The Finds and What They Mean

Since the earliest investigations beginning in 1991, teams of researchers at the cave have revealed evidence bearing on at least several elements of human cultural activity. For recording and analysis purposes, they divided the stratigraphy (sediment layers) into sub-levels known as M1, M2, and M3, occupation of which has been dated to 72.7 ± 3.1 ka, 84.6 ± 5.8 to 76.8 ± 3.1 ka, and 98.9 ± 4.5 ka, respectively: 

Stratigraphy and dates of the west section of Blombos Cave. The “hiatus” sub-levels contained no cultural features or artifacts. C. Henshilwood, Wikimedia Commons

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Hunting and Fishing

Researchers under the direction of C. Villa and Henshilwood studied the manufacture and use of dozens of Still Bay points (a toolkit named for a site nearby Blombos, characterized by bifacial points with elliptical bases) and other stone tools and fragments which were excavated from Blombos Cave between 1993 and 2004. These lithics all came from the M1 and M2 layers, and most were made of silcrete. Because these researchers were unable, in over a decade of survey and excavation, to find a single source of silcrete closer to Blombos Cave than the alluvial deposits in Riversdale, approximately 30 kilometers away, they inferred that raw materials had been collected in river basins and transported back to the cave for manufacture. The large number of unfinished tools at the site (which comprised more than 80% of the sample set and were found in varying stages of production) allowed the Villa team to physically replicate the manufacturing methods of Blombos Cave’s prehistoric occupants. Their experimental flintknapping revealed that the lithics at Blombos Cave had been constructed by first removing large flakes from a core with a hard stone hammer, then refining the tip and edges by using a softer hammer to remove more delicate flakes. Villa’s team hypothesized that if the lithics at Blombos Cave had been used for hunting, at least some of the tools present would exhibit physical evidence of hafting and of use for cutting meat; morphometric analysis, using comparative collections, revealed that this was indeed the case. The team concluded that the preponderance of lithic evidence, particularly when viewed in conjunction with the other types of artifacts present at this site, is indicative of socially complex hunting behavior, including extensive cooperation and possibly even language and geographic toolkit specialization.

A study led by C. Tribolo and a team in 2006 performed thermoluminescence dating on five silcrete and quartzite lithics from level M1. The internal dose rates were calculated by using delayed neuron activation to measure the concentrations of uranium, thorium, and potassium radioisotopes in the core of each sample, and the external dose rates were measured by a series of dosimeters planted in the stratigraphy for almost one year, as well as by a series of field gamma spectrometer measurements taken throughout the cave. Their results yielded a mean age of 74±5 to 78±6 ka, fairly consistent with the 72.7 ± 3.1 ka date derived from optically-stimulated luminescence of M1 sediments taken by Z. Jacobs and other researchers that same year.

Faunal finds indicated that the MSA people of the cave likely exploited a broad range of animals. This included large animals, such as the eland, and smaller, such as tortoises, mole rats and hyraxes. There was also evidence of seal, dolphin, whale, fish and shellfish in the cave. 

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Bifacial silcrete point from Blombos Cave, South Africa; scale bar = 5 cm. Vincent Mourre, Wikimedia Commons

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Faunal chart of Blombos Cave. C. Henshilwood, Wikimedia Commons

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Personal Adornment

In a study by Francesco d’Errico of the University of Bordeaux, researchers used several methods to study 41 Nassarius kraussianus (sea tick) shells, 39 of which came from level M1 and two of which were from M2. Their goal was to determine whether the wear pattern on these shells–which appeared to have been intentionally perforated and strung together, as for personal adornment–could possibly have formed due to natural processes. Taphonomic analysis indicated that no natural predators of N. kraussianus were present at Blombos Cave during the MSA, and wear use analysis indicated that the condition of the shells was too intact to have been deposited by severe weather patterns. In addition, the mouth of the cave, at 35 meters above sea level, would have been out of reach of ocean waves even during the MSA, and the consistently large size of the shell samples indicates that they were purposefully selected for this attribute. Cost-benefit analysis indicated that the amount of meat yielded by N. kraussianus did not warrant the time required for their collection, leading to the conclusion that sea ticks likely would not have been brought to Blombos Cave as a food source. Experiments with several bead-making techniques revealed that the perforations present in the Blombos Cave shells most resembled the results of intentional piercing with a bone awl or crab claw, and the observed wear use was found to be consistent with friction from rubbing against thread, skin, or other beads. Based on this evidence, the team concluded that the shell artifacts found were anthropogenic in origin and most likely used as necklaces, belts, or other forms of personal ornamentation. The abstract, or symbolic, reasoning inherent in this behavior further attested to the presence of “modern” cognition during the African Middle Stone Age.

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Detail close-up of Blombos shell beads showing intentional perforation. Chris Henshilwood & Francesco d’Errico, Wikimedia Commons

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Bonework

D’Errico and Henshilwood also analyzed bone artifacts from the Cave – which included complete awls and awl tips, projectile points, a tool shaft, and three unidentified fragments with possible engravings – in the interest of dating them and confirming or rejecting anthropogenic modification. It is worth noting that only one of these bone artifacts was found in level M3, and its provenience has thus been attributed to turbation processes. D’Errico and Henshilwood used a scanning electron microscope to examine the use wear and markings on the Blombos Cave bones, comparing these findings to various designs and bone wear patterns that they had produced experimentally. They concluded that the bone tools at Blombos were formed by scraping a piece of bone vigorously against a course surface or existing tool to form a point, and that some of the bones were intentionally heated to increase their strength before knapping. (Because animal behavior can sometimes result in similar wear patterns, the researchers were careful to consider the taphonomic evidence at Blombos Cave, which in its entirety revealed few animal-induced bone modifications.) The use of morphological comparative collections revealed that the bone tools at this site were used as piercers, scrapers, hafted spear points, and even lithic retouchers, and that their surfaces were smoothed by intensive use. The grooves and lines found in the surfaces of the three unidentified fragments served no clear functional purpose and could not be attributed to any known natural weathering mechanism; the researchers therefore inferred a deliberate and symbolic purpose behind them, even suggesting a similarity between these markings and the engravings of ownership added to arrowheads by contemporary San populations, a practice documented ethnographically.

Art?

Blombos Cave represents the single known incidence of man-made abstract images dating earlier than 40 ka, including two ochre pieces which were unquestionably engraved and another seven which are suspected to be so. Ochres are considered to be among the earliest pigments used by humans, derived from natural clay containing mineral oxides. The two definitive pieces were found adjacent to a small hearth, with no evidence of turbation present. They each feature a series of cross-hatched lines bound by sets of thicker parallel lines, creating a discrete, recurring geometric pattern. Experimental production techniques revealed that the engraved surfaces were first prepared by grinding against a rough surface, and that the cross-hatched design resulted from at least two separate tool positions relative to the ochre surface, achieved by rotating the ochre during the engraving process. This led to the conclusion that these engravings could not have been the result of accidental or natural processes, and that their origin was categorically anthropogenic.

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Bifacial points, engraved ochre and bone tools from the c. 75 –  80,000 year old M1 & M2 phases at Blombos Cave.  C. Henshilwood, photo by Henning, Wikimedia Commons

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But perhaps the most significant recent discovery bearing on abstract or artistic expression came during more recent excavations: 

An Art Workshop

In 2008, Henshilwood and a team of associates discovered a remarkable assemblage of artifacts while excavating the Cave. The findings included an assortment of lithic hammers and grindstones, and two abalone (sea snail) shells that had evidently been used as containers to hold and store a red, ochre-rich paint mixture that was also mixed with ground bone and charcoal. Ochre, the prime ingredient of the ancient paint, produces the yellow or red color so often associated with the ancient paint and seen to embellish drawings and other works of prehistoric art. It was possibly used for other purposes, such as body decoration. The sediments in which the ochre containers were found were dated to about 100,000 years based on Optically Stimulated Luminescence (OSL) dating. 

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Karen van Niekerk excavating the Tk1 toolkit with abalone shell in the 100,000 year old levels at Blombos Cave in 2008. Image courtesy Science/AAAS. 

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An ochre-rich mixture, possibly used for decoration, painting and skin protection 100,000 years ago, and stored in two abalone shells, was discovered at Blombos Cave in Cape Town, South Africa. This shows the various elements of the toolkit as discovered. Courtesy Prof. Christopher Henshilwood, University of the Witwatersrand, Johannesburg 

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Inside of the Tk1 abalone shell (Tk1-S1) after removal of the quartzite grindstone. The red deposit is the ochre rich mixture that was in the shell and preserved under the cobble grinder. [Image courtesy of Grethe Moell Pedersen] 

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The use of the ancient paint in human history is well documented only after about 60,000 years ago, which means that the Blombos Cave finds may push back the use of the paint to earlier periods. The finds also indicate that humans as far back as 100,000 years ago were methodically producing and storing the material, representing a critical point in human thinking within the context of human evolution.  “The recovery of these toolkits adds evidence for early technological and behavioural developments associated with humans and documents their deliberate planning, production and curation of pigmented compound and the use of containers,” said Henshilwood. “It also demonstrates that humans had an elementary knowledge of chemistry and the ability for long-term planning 100,000 years ago.” 


The Earliest Behaviorally Modern Humans?

D’Errico, Henshilwood and Tribolo have all noted that while no single line of archaeological evidence at Blombos Cave is conclusive enough to shift our understanding of behavioral modernity and its origins, the implications become clear when the scope of inquiry is widened to the site in its entirety. Systematic lithics production, extensive shell bead manufacture with probable decorative intent, production of bone tools for both practical and symbolic functions, and abstract ochre engravings and a painting “workshop” or tool assemblage: all work in conjunction to challenge the traditional belief that modern thought and behavior patterns were out of reach of Middle Stone Age populations, or that early Europeans were responsible for the rise of human thought as we know it. According to these researchers, the assemblage at Blombos Cave provides ample reason to suspect that this site’s MSA population possessed a spoken language, resided in the cave in social groups, and relied on cooperation for survival. (See the video below).

But they have tempered their interpretation with a cautious consideration of the evidence. As noted by Henshilwood and D’Errico: 

……..However, the recent application of high resolution dating techniques to the archaeological data suggests that symbolic material culture occurs only sporadically after 75 ka and is a regular feature only after 30 ka. This evidence contradicts the idea that symbolic behaviour, once acquired, became a regular feature of human culture. This punctuated pattern has been attributed to the relatively small number of excavated sites in Africa. Another possibility is that the variable climates that characterised the Late Pleistocene had a major effect on the continuity of key cultural innovations. The adaptive responses of Homo to changing climates is however poorly understood; researching the role of climate in shaping the cognitive evolution of H. sapiens is therefore a priority. [1]

To this end, Henshilwood, now also with the Department of Archaeology, History, Cultural Studies and Religion at the University of Bergen, along with d’Errico, have created an interdisciplinary research team in Norway, France and South Africa to combine existing and new archaeological data with palaeoclimatic results derived from the use of innovative methodologies.

“A key aspect of the project,” they report, “is examining how environmental change may have affected the behavioural patterns of Homo sapiens and Neanderthals in southern parts of Africa and Europe during, respectively, the Middle Stone Age and Mousterian/Chatelperronian.” 

Penned the “Tracsymbols Project”*, they hope to be able to explore the emergence of key behavioral innovations among modern humans in southern Africa and the Neanderthals in Europe, and how climate change has impacted this between 180,000 and 25,000 years ago. 

In the end, to be sure, all the answers will never come from one, or even a large number, of caves. But ongoing and future research holds the promise of getting us a bit closer to a clearer understanding of when and where humans became humans, clearly distinct from their primate cousins.

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[1]*http://tracsymbols.eu/about/ 

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Visit the website for more information about the Tracsymbols Project.

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