Over the previous 15 years, by way of our scientific research of tracks and traces, now we have recognized greater than 350 fossil vertebrate tracksites from South Africa’s Cape south coast. Most are present in cemented sand dunes, known as aeolianites, and all are from the Pleistocene Epoch, ranging in age from about 35,000 to 400,000 years.
Throughout that point now we have honed our identification abilities and have grow to be used to discovering and deciphering tracksites – a subject known as ichnology. And but, each now and again, 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 not 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 typical origin.
Elephants are the biggest, heaviest land animals. They depart massive, deep, simply recognisable tracks. We have documented 35 fossilised elephant observe websites in our research space, in addition to the first proof of fossilised elephant trunk-drag impressions.
Elephants, like one other group of large land creatures, dinosaurs, could 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 means that elephants possess: speaking by producing seismic waves. These are a type of power that may journey below 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 just lately printed research that we consider 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 way 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 way of the limbs, fall inside the infrasonic vary.
Infrasound at excessive amplitude (it might appear very loud to us if at a barely larger frequency) can journey additional than excessive frequency sounds, over distances as nice as 6km. Elephants have a bonus right here. Lighter creatures can not generate low-frequency sound waves by way of vocalisation. It’s thought that long-distance seismic communication can enable 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 historical 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 attainable 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 state of affairs at De Hoop Nature Reserve, we postulate that vibrations from rumbling travelled down the elephant limb and created the concentric ring options. They’re harking back to a number of the patterns that grow to be evident when sprinkling sand onto a vibrating floor. The floor on which the concentric rings seem will need to have been slightly below the dune floor on the time. The parallel grooves would then symbolize a hint fossil signature of subsurface communication. We’re not but certain how previous the hint fossil is; we have despatched samples for testing.
Rumblings in rock artwork
Elephant seismicity is a comparatively new subject of research for scientists. Nonetheless, those that have lived near elephants will not be shocked on the thought of the animals speaking by way of vibration. Certainly, vibrations from elephant rumblings can generally be felt (somewhat than heard) by the astute observer. And it seems that this information is not only latest.
The rock artwork consultants on our group have recognized and interpreted rock artwork that means the indigenous San folks appreciated and celebrated this information in southern Africa hundreds of years in the past. Elephants had been of profound significance to the San and had been prominently featured in their artworks. 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. Effective crimson strains encompass every elephant; zigzag strains contact the stomach, groin, throat, trunk, and particularly the toes. Many zigzag strains hyperlink the elephant to the bottom. The best strains are closest to the elephants, and each elephant is linked to this set of strains. These are in flip linked to broader strains surrounding the elephant group, which radiate out and away from the elephants as concentric rings.
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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 tune and elephant dance. Strains of power, known as n|om, are thought to be a vibrant life-giving power that animates all dwelling beings and is the supply of all impressed power.
We consider that an understanding of elephant seismicity requires the combination of three our bodies of data: analysis on extant elephant populations, ancestral information (usually manifested in rock artwork) and the hint fossil report.
That elephant seismic communication would possibly depart a hint fossil report 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 embody 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
