Africa: Fossilized circles in the sand on the coast of South Africa may be the work of art of our early ancestors

If you’ve walked on a dune surface after the windy conditions have subsided, you may have been privileged to recognize one of nature’s wonders: scratch circles.

These are structures formed when the end of a tethered object is passively rotated into the surrounding sediment. In other words, a flimsy leaf or blade of grass attached to the ground will blow in the wind and its loose end will inscribe a perfect circle or perfect arc, the point where it is attached becoming the center of the circle or arc.

The first formal description of scratch circles was in 1886. In 2018, a detailed overview of their occurrences in the global geological record was published.

In our team’s ongoing studies of trace fossils on the Cape Coast of South Africa, we realized that the Pliocene and Pleistocene surfaces we examined, dating back as far as 3 million years, provided significant evidence for scratch circles and scratch arcs. This evidence included several phenomena not previously observed.

After further investigation, we have published our findings. We are particularly excited about two key takeaways.

First, the time span in which scratch circles or scratch arcs have previously been identified varies from about 600 million to 60 million years ago. The scratch circles we have found may be as little as 100,000 years old, making them the latest examples yet identified in the geological record and significantly expanding their age range.

In one case, we were even able to identify the likely plant type (a type of sid) responsible for creating the circular feature. We also documented the first cases of scratch arcs occurring in vertical rock faces, perpendicular to bedding planes, as shown in this video by Andre van Tonder.

Second, there appear to be two possible explanations for circular patterns with central depressions in Pleistocene deposits on the Cape Coast. One is the typical scratching circle or scratching arc as described above, made by a plant. The other is an ammoglyph, a pattern made by ancestral hominins in sand, which is now distinct and interpretable in a rock known as aeolianite.

We speculate that the first type may have been the inspiration for the second, and that ancestral humans may have seen these perfect circular shapes and found innovative ways to imitate them. If we are right, then this would be among the oldest known evidence of paleoart (really old, early forms of art).

Circles in the sand

We already know that the south coast of the Cape is one of the places where some of the earliest known palaeospecies were created, in places like Blombos Cave, Pinnacle Point and through the ammoglyphs we have previously described.

The oldest alleged ammoglyph that we have dated through a technique called optically stimulated luminescence is approximately 139,000 years old. It seems likely that sand formed the original canvas for the earliest artists, as drawing on it would have been much faster and easier than engraving or drawing on rock faces, trees, bones or shells.

There is a precedent for wise ancestral humans paying close attention to their environment and imitating what they encountered. It has been suggested that ocher (a pigmented earth type) used for body decoration may have originated after people observed the bearded vulture (Lammergeier) bathing in ocher and coating its feathers with red pigment. This would be an example of bio-mimicry – people copy what they saw in the world around them.

Scratch circles in sand, with clear evidence of how they were formed, would have been present on the Pleistocene dune surfaces on what is today the south coast of the Cape. We assume that ancestral humans noticed these perfect circular shapes, deduced their origin, and realized that they could try to replicate them in sand. This can be done by anchoring one end of a fork stick in the sand and then spinning it, thereby inscribing a circle with the other end. This is a behavior we have written about in previous research on ammoglyphs. This natural curiosity about and replication of circles has recurred in art throughout the ages.

A human origin

Using sticks in the way we describe is not the only method for drawing circles in sand. One can also kneel down, place one’s elbow in the sand, and rotate one’s forearm with one finger inscribing an arc. However, this may not result in a perfect arch – bending or extending one’s wrist would affect the symmetry.

We have found a pattern on the coastline of the De Hoop nature reserve (which we call the De Hoop ammoglyph) that suggests this creation mechanism, subsequently supported by our team’s experiments in sand. In fact, the imperfect arc is one of the characteristics that supports a human origin – scratch circles made from plants are much more perfect, as is the forked stick technique.

We can estimate the length of the forearm of the artist of the De Hoop ammoglyph; it seems consistent with a child or adolescent (or very young adult) artist.

It is extremely fortunate that an area where humans began to think and behave as we do (and create art in sand) happens to be exactly where the beaches and dunes they inhabited have been cemented and preserve this record of paleospecies in stone. This gives us a window into the activities of our ancestors that we may not be able to discern in any other way.

Scratch circles are apparently not just spectacular in themselves, but may also have set in motion a chain of events that e.g. led to the splendor of the Chauvet Cave in France 34,000 years ago and other subsequent masterpieces. The findings suggest that our ability as a species for keen observation, followed by imitation, may have allowed us to leap forward and develop the beginnings of what we now know as art.

Charles Helm, Research Associate, African Center for Coastal Palaeoscience, Nelson Mandela University

Jan Carlo De Vynck, Honorary Researcher, Department of Evolutionary Studies, University of the Witwatersrand