Over the previous 15 years, by means of our scientific examine of tracks and traces, we’ve recognized greater than 350 fossil vertebrate tracksites from South Africa’s Cape south coast. Most are present in cemented sand dunes, referred to as aeolianites, and all are from the Pleistocene Epoch, ranging in age from about 35,000 to 400,000 years.
Throughout that point we’ve honed our identification abilities and have turn out to be used to discovering and decoding tracksites – a subject referred to as ichnology. And but, each from time to time, we encounter one thing we instantly realise is so novel that it has been discovered nowhere else on Earth.
Such a second of surprising discovery occurred in 2019 alongside the shoreline of the De Hoop Nature Reserve, about 200km east of Cape City. Lower than two metres away from a cluster of fossil elephant tracks was a spherical function, 57cm in diameter, containing concentric ring options. One other layer was uncovered about 7cm under this floor. It contained no less than 14 parallel groove options. The place the grooves approached the rings, they made a slight curve in the direction of them. The 2 findings, we hypothesised, had been linked with one another and appeared to have a standard origin.
Elephants are the most important, heaviest land animals. They go away giant, deep, simply recognisable tracks. We have documented 35 fossilised elephant observe websites in our examine space, in addition to the first proof of fossilised elephant trunk-drag impressions.
Elephants, like one other group of huge land creatures, dinosaurs, will be considered as geological engineers that create minor earth-moving forces on the bottom they stroll(ed) on. This may be associated additionally to a outstanding capacity that elephants possess: speaking by producing seismic waves. These are a type of vitality that may journey beneath the floor of the Earth.
The function we present in 2019 appeared to replicate simply such a phenomenon: an elephant triggering waves that rippled outwards. After extra investigation and an intensive seek for different explanations, we may report in a lately revealed examine that we imagine we have discovered the world’s first hint fossil signature of seismic, underground communication between elephants.
Elephant seismicity
Because the Eighties, an ever-increasing physique of literature has documented “elephant seismicity” and seismic communication by means of infrasound. The decrease threshold of human listening to is 20Hz; under that, low frequency sounds are referred to as infrasound. Elephant “rumbles”, originating within the larynx and transmitted into the bottom by means of the limbs, fall inside the infrasonic vary.
Infrasound at excessive amplitude (it might appear very loud to us if at a barely greater frequency) can journey additional than excessive frequency sounds, over distances as nice as 6km. Elephants have a bonus right here. Lighter creatures can’t generate low-frequency sound waves by means of vocalisation. It’s thought that long-distance seismic communication can permit elephant teams to work together over substantial distances, and it has been proven that sandy terrain permits the communication to journey furthest.
Learn extra: Fossil tracks and trunk marks reveal indicators of historic elephants on South Africa’s coast
Persevering with the elephant-dinosaur analogy, we thought-about the multitude of publications on dinosaur tracks. We’re conscious of solely a single instance that displays potential concentric rings inside a observe, from Korea, and none that contain parallel grooves. This means one thing distinctive about elephants that generates concentric rings inside tracks and results in the related groove options. Elephant rumbling gives a believable clarification.
In our situation at De Hoop Nature Reserve, we postulate that vibrations from rumbling travelled down the elephant limb and created the concentric ring options. They’re paying homage to among the patterns that turn out to be evident when sprinkling sand onto a vibrating floor. The floor on which the concentric rings seem will need to have been just under the dune floor on the time. The parallel grooves would then characterize a hint fossil signature of subsurface communication. We’re not but positive how previous the hint fossil is; we have despatched samples for testing.
Rumblings in rock artwork
Elephant seismicity is a comparatively new subject of examine for scientists. Nonetheless, those that have lived near elephants will not be shocked on the concept of the animals speaking by means of vibration. Certainly, vibrations from elephant rumblings can typically be felt (reasonably than heard) by the astute observer. And it seems that this information is not only latest.
The rock artwork specialists on our crew have recognized and interpreted rock artwork that means the indigenous San folks appreciated and celebrated this information in southern Africa 1000’s of years in the past. Elephants had been of profound significance to the San and had been prominently featured in their artistic endeavors. A number of rock artwork websites seem to comprise work of elephants in relation to sound or vibration.
For instance, on the Monte Cristo web site within the Cederberg the artist has painted 31 elephants, in a number of teams. They’re in a sensible association. Superb purple traces encompass every elephant; zigzag traces contact the stomach, groin, throat, trunk, and particularly the ft. Many zigzag traces hyperlink the elephant to the bottom. The best traces are closest to the elephants, and each elephant is linked to this set of traces. These are in flip linked to broader traces surrounding the elephant group, which radiate out and away from the elephants as concentric rings.
Join free AllAfrica Newsletters
Get the newest in African information delivered straight to your inbox
That is interpreted because the San artist’s possible illustration of seismic communication between elephants. The sensation of shaking and vibration, which the San name thara n|om, is important to the San therapeutic dances, together with the elephant music and elephant dance. Traces of vitality, referred to as n|om, are considered a vibrant life-giving pressure that animates all dwelling beings and is the supply of all impressed vitality.
We imagine that an understanding of elephant seismicity requires the mixing of three our bodies of information: analysis on extant elephant populations, ancestral data (usually manifested in rock artwork) and the hint fossil file.
That elephant seismic communication would possibly go away a hint fossil file has by no means been reported earlier than, and even postulated. Our findings might have the potential to stimulate multi-disciplinary analysis into this subject. This might embrace a devoted seek for sub-surface patterns within the sand within the neighborhood of contemporary rumbling elephants.
Charles Helm, Analysis Affiliate, African Centre for Coastal Palaeoscience, Nelson Mandela College
