You may have had the opportunity to observe one of nature’s wonders: scratch circles, if you have walked on a dune surface after windy conditions have subsided. The extremity of a tethered object is passively rotated into the surrounding sediment, resulting in the formation of these structures. In other words, a fragile frond or blade of grass that is affixed to the ground will sway in the wind, and its slender end will create a perfect circle or arc. The location at which the frond or blade of grass is attached will serve as the center of the circle or arc.
The first formal description of scratch circles was in 1886. In 2018, a detailed summary of their occurrences in the global geological record was published.
In our team’s ongoing investigations of trace fossils on the Cape coast of South Africa, we realised that the Pliocene and Pleistocene surfaces we were researching, dating back as much as 3 million years, provided substantial evidence of scratch circles and scratch arcs. Several phenomena that had not been previously observed were included in this evidence.
After further investigation, we’ve published our findings. We are especially enthusiastic about two critical points.
Initially, the duration of time during which scratch circles or scratch arcs have been previously observed The scratch circles we have discovered may be as recent as 100,000 years old, which significantly broadens their age range and makes them the most recent examples yet identified in the geological record.
In one instance, we were able to identify the likely plant species (a type of sedge) that was accountable for the circular feature. We also documented the first cases of scratch arcs occurring in vertical cliff faces, perpendicular to bedding plane surfaces, as shown in this video by Andre van Tonder.
Secondly, there are two potential explanations for circular patterns with central depressions in Pleistocene deposits on the Cape coast. One is the standard scratch circle or scratch arc, as previously mentioned, which is produced by a plant. The second is an ammoglyph, a pattern made by ancestral hominins in sand that is now evident and interpretable in a rock type known as aeolianite.
We posit that the first variety may have served as the inspiration for the second, and that ancestral humans may have observed these flawless circular forms and devised inventive methods to imitate them. This would be among the oldest known evidence of palaeoart, which are truly ancient, early forms of art, if our assessment is accurate.
Circles in the beach
We already know that the Cape south coast is one of the places in which some of the earliest known palaeoart was created, at sites like Blombos Cave, Pinnacle Point and through the ammoglyphs we have previously described.
The oldest purported ammoglyph that we have dated through a technique called optically stimulated luminescence is approximately 139,000 years old. Sand appears to have been the initial canvas for the earliest artists, as it would have been significantly more convenient and expeditious to draw on than to engrave or sketch on rock walls, trees, bones, or shells.
There is a historical precedent for perceptive ancestral humans to be acutely aware of their environment and to emulate what they encountered. It has been suggested that ochre (a pigmented type of earth) used in body decoration may have originated after people observed the bearded vulture (lammergeier) bathing in ochre and covering its feathers with red pigment. This would serve as an illustration of biomimicry, which involves humans replicating the phenomena they observe in their environment.
Scratch circles in sand, with clear evidence of their formation, would have been evident on the Pleistocene dune surfaces of the Cape south coast. Our hypothesis is that ancestral humans observed these circular forms in pristine condition, inferred their origin, and realized they could attempt to replicate them in sand. This can be accomplished by anchoring one end of a forked stick in the sand and subsequently rotating it, thereby inscribing a circle with the other end. It’s a behaviour we’ve written about in previous research about ammoglyphs. This natural curiosity about and replication of circles has recurred in art through the ages.
A human origin
Drawing circles in sand is not exclusively accomplished through the use of poles in the manner we have described. One may also kneel, position their elbow in the sand, and rotate their forearm with their finger to create an arc. However, due to the impact of the wrist’s flexion or extension on the symmetry, this might not produce a precise arc.
The De Hoop ammoglyph, which is a pattern on the coastline of the De Hoop Nature Reserve, suggests this method of creation. Our team’s investigations with sand have further supported this theory. In reality, the imperfection of the arc is one of the characteristics that corroborates a human origin; the forked stick technique and scratch circles manufactured by plants are considerably more precise. The length of the forearm of the artist of the De Hoop ammoglyph can be estimated; it is consistent with that of a juvenile or adolescent (or very small adult) artist.
It is a wonderful coincidence that the beaches and dunes in the region where humans first began to think and behave as we do (and create art in sand) have become cemented, preserving this record of palaeoart in stone. This offers us a perspective on the activities of our progenitors that may be impossible to ascertain through any other means.
Scratch circles, it seems, are not just spectacular in their own right but might have also set in motion a chain of events that led, for example, to the splendours of Chauvet Cave in France 34,000 years ago and other subsequent masterpieces. The results indicate that our species’ ability to observe with astuteness and then imitate may have enabled us to advance and establish the foundations of what we now recognize as art.
