Pinnacle Point Cave 13B: Shellfish, Ochre and Early Humans

Pinnacle Point Cave 13B, known as PP13B, is a small sea cave near Mossel Bay on the southern coast of South Africa. Excavations from 2000 revealed that people living there about 164,000 years ago collected and ate shellfish, ground red ochre and made small stone blades. These finds are among the oldest evidence of complex behaviour by early Homo sapiens, and they suggest that the coast helped humans survive a long and severe ice age.

Background: a coastline of caves

Pinnacle Point is a rocky headland a few kilometres west of the town of Mossel Bay, in the Western Cape. Its steep quartzite cliffs are riddled with caves and rock shelters, many of which contain deposits left by people during the Middle Stone Age, the period of African prehistory from roughly 300,000 to 40,000 years ago.

The archaeological potential of the area became clear in the late 1990s, when the land was being developed for a golf estate. Archaeological surveys, involving Peter Nilssen and others, identified several promising caves. In 1999 and 2000 Curtis Marean of Arizona State University and Nilssen began a long-term research project, and excavation of Cave 13B started in 2000.

The project grew into a large international effort studying the region’s archaeology, climate, sea levels and plant life, to reconstruct how people lived on this coast over hundreds of thousands of years.

What was found in Cave 13B

PP13B lies about 15 metres above present sea level. Its deposits span a long period, but the most important layers date to about 164,000 years ago, with an uncertainty of around 12,000 years, according to optically stimulated luminescence and uranium-series dating.

In 2007 Marean and colleagues reported three key finds from these layers in the journal Nature. The first was shellfish: the remains of brown mussels, limpets, whelks and other species gathered from the rocky shore. The second was red ochre, an iron-rich mineral pigment, with dozens of pieces showing signs of grinding or scraping. The third was a set of bladelets, small narrow blades of stone that may have been set into handles to make composite tools.

All three had previously been thought to appear much later. The earliest well-dated evidence of regular shellfish eating before PP13B came from sites around 120,000 years old or younger.

Shellfish on the menu

Eating shellfish may seem a small step, but it implies knowledge of the shore and the tides. Shellfish can be gathered safely in large numbers only at low tide, especially during spring tides, which occur around the full and new moon. Marean has argued that the PP13B people must have tracked the lunar cycle to plan their visits to the shore.

Shellfish are also an unusually reliable food, rich in protein and in nutrients such as omega-3 fatty acids. During cold, dry periods, when plant and animal foods inland may have been scarce, the sea offered a steady supply.

At the time, sea levels were lower than today because water was locked in large ice sheets. The shore may therefore have been some distance from the cave, possibly a few kilometres. The presence of shells shows that people were willing to carry food back to their shelter.

Red ochre and early symbolism

The ochre pieces from PP13B have been ground into powder or scraped, producing red pigment. Some researchers think the pigment was used for body decoration or other symbolic purposes, which would make it an early sign of symbolic behaviour. Others note that ochre also has practical uses, for example in adhesives for hafting tools, in tanning hides or as a sunscreen or insect repellent.

The selection of particularly bright red pieces at PP13B has been taken as a hint that colour mattered to the users. However, the purpose of the ochre cannot be proved from the pieces alone, and the debate over its meaning continues. Later sites on the same coast, such as Blombos Cave, have produced ochre pieces with deliberate engraved patterns.

Fire as a tool

In 2009 a team led by Kyle Brown reported that stone toolmakers at Pinnacle Point and other South African sites had heated silcrete, a fine-grained stone, before working it. Careful heating changes the stone’s structure, making it easier to flake and producing sharper, more controlled edges.

The researchers identified heat-treated silcrete at PP13B in layers about 164,000 years old, although the evidence there is limited, and found that the technique became common around 72,000 years ago. Heat treatment requires controlling fire and following a multi-step process, which the authors saw as evidence of advanced planning.

The coastal refuge hypothesis

The 164,000-year-old layers at PP13B fall within a long glacial stage, known to climate scientists as Marine Isotope Stage 6, which lasted from roughly 195,000 to 125,000 years ago. During this period much of Africa became colder and drier.

Marean has proposed that the southern Cape coast acted as a refuge. The region combined rich shellfish beds with a unique flora of the Cape Floral Region, including many plants with edible underground bulbs and tubers. He suggests that a small population of early modern humans may have survived here while populations elsewhere declined. In this view, the coast could have been one of the places where the species weathered a population bottleneck.

The idea remains a hypothesis. Genetic and fossil evidence points to a complex, Africa-wide origin of Homo sapiens, as shown by fossils such as those from Jebel Irhoud in Morocco. Many researchers agree, however, that coastal resources played an important role in the lives of early humans in southern Africa.

Later finds at Pinnacle Point

PP13B is only one of several sites on the headland. A large rock shelter nearby, called PP5-6, contains a long sequence of deposits from about 90,000 to 50,000 years ago. In 2012 Kyle Brown and colleagues reported that people there were making tiny, carefully shaped stone pieces, or microliths, from heat-treated silcrete around 71,000 years ago. Such pieces were probably set into handles or shafts to form composite tools, possibly including projectile weapons.

In 2018 researchers identified microscopic glass shards from the Toba supereruption in Sumatra, about 74,000 years ago, in the deposits at PP5-6 and at a nearby open-air site. The layers show that people on this coast continued to live and work through the period after the eruption, which some had argued caused a global catastrophe for early humans.

Timeline

• c. 195,000 to 125,000 years ago: A long glacial stage brings cold, dry conditions to much of Africa.
• c. 164,000 years ago: People at PP13B eat shellfish, grind ochre and make bladelets.
• c. 100,000 to 73,000 years ago: Engraved ochre and shell beads are made at Blombos Cave, less than 100 kilometres to the west.
• c. 72,000 years ago: Heat treatment of silcrete becomes common on the southern Cape coast.
• Late 1990s: Surveys connected with coastal development identify the Pinnacle Point caves.
• 2000: Excavation of Cave 13B begins under Curtis Marean.
• 2007: The shellfish, ochre and bladelet finds are published in Nature.
• 2009: Evidence of heat-treated stone is published in Science.

Why it matters

PP13B moved the earliest well-dated evidence of shellfish eating and ochre processing back to around 164,000 years ago, close to the early history of Homo sapiens. It shows people adapting to a harsh climate by using the sea, planning around the tides and processing pigment. With sites such as Blombos and Sibudu, it has made South Africa’s coast central to the study of how modern human behaviour developed.