Among the many prehistoric artifacts recovered by scientists bearing on the development or evolution of early human cognition, the evidence of pigmentation, such as ochre, has figured prominently in the search for the elusive threshold, if such can be defined, when our hominid ancestors evolved into what has variously been defined as humans. This is a much-debated topic, and a universally acceptable paradigm may never in the end be formulated. Nonetheless, it is an exploration in ‘big think’ adventure to consider the summary of what we know to date about one aspect of human evolutionary cognition — the processing and use of pigmentation for various purposes — as a salient sign of becoming human in the long evolutionary march. New discoveries will no doubt continue to emerge, shedding some additional light on one of humankind’s greatest mysteries — when the ancestors of our genus truly became human. — Ed.
The origins and usage of mineral-derived pigments
Archaeological evidence shows that the mining of minerals for use as pigments may have begun over one million years ago, at Gadeb in Ethiopia and the Olduvai Gorge in Tanzania, although the evidence for this appears to be non-conclusive. Minerals were exploited by several early hominid species, including Homo ergaster, Homo erectus, Archaic Homo sapiens and Homo neanderthalensis, although the nature and purpose of this exploitation is not fully understood. Indeed, the location of early Stone Age mining sites in East Africa, in general terms at least, reflects the origins of early hominid settlement in East Africa. The location of mining and settlement sites of later date, that also exhibit this apparently ‘modern’ type of human behavior, may reflect the early spread of hominids away from East Africa. The earliest sites showing evidence of pigment (ochre) exploitation, by Homo ergaster, are in East Africa (c. 1.5m–1.1m BP). Homo rhodesiensis/heidelbergensis arose within the southern savannas of Africa some 1.2–1.3m BP and left evidence of the collection of red ochre and specular haematite (specularite), suggesting that this progenitor species had enhanced aesthetic and symbolic capabilities. There are a number of similar sites exploited by Homo erectus in Europe and Homo ergaster, and later Archaic Homo sapiens, in South Africa in later periods.
There is evidence that Neanderthals systematically sourced and processed manganese pigments. If it can be shown that Neanderthals used manganese for symbolic purposes, pigment use would evidently be a non-species-specific behavior; this would suggest that the cognitive prerequisites of modern human behavior existed prior to the emergence of biologically archaic and modern populations. However, the date and location of the emergence of ‘symbolic behavior’ is still being debated and may never be unequivocally resolved.
Twin Rivers in Zambia and Kapthurin in Kenya are among the most well-known archaeological sites to have yielded evidence of pigment use as old as the Acheulean-Middle Stone Age (MSA) transition (c. 200,000 years ago). Five different pigment colors with traces of use were recorded at the Twin Rivers site. Sai Island in Sudan is also an important site from this transition period. At Sai Island, yellow and red ochre were exploited and ground to pigments using shaped mortars and selected chert nodules.
More robust evidence for the early systematic use of pigments comes from Pinnacle Point near Mossel Bay, South Africa. At this cave site, pigment fragments were excavated from layers dated to approximately 164,000 BP. There is also an increase in the collection and use of ochre showing grinding, scraping or scoring marks at other Middle Pleistocene sites, such as Border Cave, South Africa. There is an increase over time in the frequency of pigment occurrence in the prehistoric record, and although it occurs at different times in different regions, it can generally be placed in the context of the MSA/Middle Palaeolithic in Africa and Europe.
It is likely that minerals and naturally derived dyes were used by prehistoric people to paint a wide variety of surfaces, including rock, hides, clothing, beads, tools, ceramics and the human body. Limestone and calcite or crushed shells were used to produce a white color, and limonite was most likely used for yellow. Pyrolusite and charcoal were predominantly used to provide black and manganite was most likely used to produce black or beige, according to recent X-ray fluorescence analyses. However, archaeologists have found that haematite, an iron oxide, or iron hydroxide were the principal pigments used by early hominids. These both produce a red color. To a lesser extent, various other minerals, including maghemite and cinnabar were used to produce reds in prehistory.
Haematite is one of the most abundant minerals on the earth’s surface and in the shallow crust, and is found in sedimentary, metamorphic and igneous rocks throughout the world. Many of the sedimentary iron deposits contain haematite and magnetite as well as other iron minerals. The name haematite derives from the Greek word “haimatitis” which means “blood-red” – it is thought that the red ochre powder found at prehistoric burial sites may represent blood.
Ngwenya Mountain’s Lion Cave, in Swaziland, contains the oldest known haematite mine. The MSA tools found at this site were not confined to the surface layers but were scattered throughout huge depressions which should have been solid haematite. They were lying among and beneath thousands of tons of red iron oxide, to a depth of forty feet or more. Charcoal nodules from some of the more ancient adits at Ngwenya were dated to between 45,000 BP and 43,000 BP. It is thought that these ores were mined until at least 25,000 BP, and that an estimated 1,200 tons of soft haematite ore had been removed at this site in ancient times.
Ochre and charcoal were significant pigment sources for the thousands of rock art sites in Africa and beyond. The most commonly used rock art pigments are ochres. The Sahara contains some of Africa’s oldest surviving rock art, made around 12,000 years ago. The paintings of this period include elephants, rhinoceros and other fauna that have long been extinct in the Sahara region.
In later prehistory and the early historical period, a wide range of minerals were being exploited for their color-bearing properties. For example, in Late Period Egypt, in addition to the usage of the principal minerals haematite and goethite, to produce red-hued pigments, a combination of gypsum, calcite, quartz, dolomite and halite were all used to produce pigments used in coffin decoration. Other Late Period coffins from Egypt contain ‘Egyptian Blue’ pigment, often known as blue frit, produced from quartz, lime and copper compounds, as well as atacamite and green frit. Egyptian blue was first produced approximately 5,000 years ago. The use of contrasting shades shows a degree of sophistication in the production process: the result of various analytical techniques on Late Period coffins showed that a dark blue was produced by heating the metal alloy to between 850°C and 950°C, with a high percentage of copper included. A light blue pigment was prepared with a high percentage of quartz. X-ray fluorescence has additionally revealed the use of malachite, realgar and pararealgar to produce pigments in Egypt at this time. Orpiment, the yellow sulphide of arsenic, was used by the ancient Egyptians to produce a bright yellow or gold, whereas realgar was used for bright reds.
Examples of raw mineral material used prehistorically in the production of pigments and rock art. Courtesy Michael McNaughton: African Rock Art
The importance of color
A rich prehistoric record of pigment use indicates that red and black pigments are relatively ubiquitous in Palaeolithic habitation and quarry sites, from the Pleistocene to the Upper Palaeolithic. There is a predominance of black, white and red colours in prehistoric burials and paintings. Many Palaeolithic rock art paintings appear to be expressions of darkness and lightness using only black and white. The use of materials with a black or brilliant white appearance, such as talc, mica, or ilmenite is almost exclusively restricted to the Lower Palaeolithic. Trichromatism, a color vision based on the three primary colors, appears to be an inherent property of human vision shared only with Old World monkeys and one genus of New World monkeys. This may explain, to some extent, the early hominid preferential usage of minerals and dyes that produce the primary colors. Cross-cultural linguistic studies of color terminology provide evidence of this evolution of color usage and perception.
The systematic use of pigments on a variety of media, burials, grave goods and personal ornaments attests to the complex symbolism provided by color, as observed in ethnographically recorded human cultures throughout history. Ethnographic data demonstrates the universal use of specifically selected colors and patterns in body decoration for rituals as well as for practical purposes. Compelling evidence for the early use of pigment in body decoration comes from the discovery of red pigment residues adhering to shell beads, discovered at the Grotte des Pigeons, Taforalt, Morocco, and at Blombos Cave.
Archaeologically, red ochre is reported from two of the world’s earliest modem human burials, at Qafzeh in Israel 100,000 years ago and the earliest burial in Australia, 62,000 years ago. Red ochre powders at Pinnacle Point in South Africa appear to be intended as ingredients for body paints used during ritual performance.
Although there is a growing body of evidence to suggest ochre usage by Palaeolithic hominids in Europe, the Levant and North Africa, and in the MSA in Sub-Saharan Africa, many archaeological associations and contexts that make a compelling symbolic interpretation of ochre usage are from the Later Stone Age onwards, i.e. post-dating 30,000 BP. However, there are also earlier examples of symbolic behavior. In particular, examination of 8,000 ochre pieces from Blombos Cave, dated to 75,000 BP, revealed ochre pieces and bone fragments engraved with abstract patterns. The engraved ochres associated with the remains of Homo sapiens at Blombos Cave may constitute the most ancient irrefutable evidence for symbolic behavior.
There is also geological evidence that red iron oxides were selected in preference to yellow hydroxides from the same source. Consideration of the broader context of pigment use supports the view that early modern humans engaged in various complex behaviors based on networks of symbols. However, an absence of ochre at an archaeological site need not imply a lack of interest in red pigments by the original inhabitants – in the Kalahari, the scarcity of haematitic minerals obliged Khoisan people to employ plant substitutes. Henna is also widely used in the Near East.
The ancient preference for the selection of minerals that produce striking or brilliant reds has been widely recognized. The majority of MSA ochre crayons from South Africa appear to have been selected because of their strong reddish hue. Based upon an examination of MSA ochre and rock art in the Cederberg area of South Africa, there seems to be a definite preference for saturated reds. The Cederberg evidence suggests that an active selection of an ochre nodule based on its color also implies a secondary passive selection for its streaking quality and vice versa.
Although MSA and later archaeological sites show a preference for red hues, African MSA contexts also comprise yellow limonite, black manganese, green, yellow, pink, grey and purple shales, white kaolinite and brown goethite, often in significant quantities. In addition to the strength of the color there was a strong preference for the ‘brilliant’, lustrous appearance provided by micaceous specularite, which yields a dark blue or purple hue. The considerable distance that people were willing to travel (or trade) for such minerals seems to add to the evidence that they were highly sought after for their intrinsic qualities. Many minerals would also have been chosen specifically for their hardness, which would determine the practicality of their application to surfaces.
In terms of the use of mineral-derived colors in Palaeolithic art, it is possible that white paint was frequently used, but, since it was less durable than other colors, it was not preserved. As a general rule, only mineral-derived colors are preserved for significant periods of time, which could explain why there is such a scarcity of color in prehistoric art.
There is significant evidence of the utilitarian and symbolic use of color in existing human societies, for example as a material proxy for language. Red, in particular, has a symbolic significance that crosscuts cultural boundaries. Red seems to be frequently associated with life, success, and victory in African, Australian, and native North American societies respectively. The Europeans who first encountered the indigenous people of North America called them ‘Red Indians’ because of their practice of painting their bodies with red ochre. This practice could also have provided protection against the cold in winter and against insects in the summer. Red may have been used due to its ability to make warriors appear more ‘fearsome’. Red may also have been associated with energy, anger, danger, power, passion and desire.
Polychrome, schematic cow facing left. Cow has red body, broad neck with vertical bars, and very small, rectangular head with white horns. Udder with four teats. Below cow’s neck, faded maroon symbolic, animal’s body with four white, vertical fingers, two of which tipped with red points. Small, vertical shape with white bars between middle fingers. Patch of faded white pigment to left of fingers. Left rock face, polychrome, barred design above red cow with white horns facing left, front left superimposed by red square. Las Geel, Somaliland. Credit: Trust for African Rock Art.
Two dark maroon men, one wearing headdress, riding horses with fancy manes and tails separated by man on foot. Jrid Wadi, Mauritania. Cedit: Trust for African Rock Art.
Detail, head and shoulder of red kudu outlined in white, and swimming figure. Mashonaland, Zimbabwe. Credit: Trust for African Rock Art.
Ethnographic accounts illustrating the use of red ochre as a cosmetic substance have been reported for southern African San hunter-gatherers and agro-pastoralists. These examples relate largely to the intermittent topical application of red ochre in purely symbolic contexts. The foremost modern examples of the habitual use of red ochre as a body cosmetic include the Cushitic-speaking Hamar in southern Ethiopia and the Ovahimba of northwestern Namibia and southwestern Angola. Ovahimba women are renowned for covering their bodies, hair and personal attire with a red ochre-based substance known as otjise, comprising clarified butter and red ochre powder. Otjise features prominently in initiation ceremonies and is applied by men when they are to be wed or are about to undertake long journeys. It is also applied to human corpses prior to interment. Ethnographic interviews recently conducted amongst the Ovahimba reveal that, besides the intrinsic social and inexorably symbolic significance of otjise, it can fulfill several secondary functions, including its use as a topical sun-protection element or sunscreen. The habitual use of red ochre as a sunscreen may have presented an advantage for populations that migrated from higher into lower latitudes and it is theorized that increases in the amount of ochre used may coincide with periods during which amplified rates of ultraviolet radiation may have posed an increased risk to human health.
Ethnographic analysis of the contemporary Khoisan hunter-gatherers of southern Africa shows that redness and ‘brilliance’ are likely to have been perceptual qualities exploited for ritual display since prehistoric times. For example, red ochre was and still is used to change skin color and is used in initiation rituals. It is also thought that red ochre was used to demonstrate a ‘sham menstruation’, which was intended to signify a ‘sex strike’ during menstruation. Social pressures to enact this sham menstruation may have become most acute between 160,000 and 140,000 years ago, at the height of the Penultimate Glacial cycle. This behavior would theoretically ensure male attraction to a larger number of females and is potentially an early example of ‘symbolic’ behavior.
In order to complement the archaeological interpretation of sites and artifacts, geochemical, quantitative and experiment-based analyses of mineral source materials and any modifications they have been subject to is essential. This will inevitably lead to a better understanding of where and when ochre and other mineral pigments were mined and used in prehistory, as well as their functional and symbolic significance.