As the years roll by scientists continue to ponder, prove and disprove theories about the existence of fairy circles, the bare, rounded patches of sand that dot the landscape on the edge of the Namib Desert from the north-western Cape to south-western Angola. Yet, the mystery remains. Could it be fairies after all?
Virtually every other year the headline ‘The mystery of fairy circles solved’ appears proposing yet another theory or providing evidence for or disproving an existing one. Well-known scientists and their research assistants spend long hours in the field and after a study period, which could span decades, catalogue their results and publish their papers. Yet at the end of the day, we are still left wondering. A few years later, a similar headline reappears with yet another theory. And, after all this time, scientists still refer to the circles as ‘fairy circles’, for lack of a better name, and that always makes me smile and think. Hmmm, perhaps . . .
Although ideas in the past have included radioactive soil, hydrocarbon seepage, magnetism, gases, the impact of meteorites, UFO landing sites, rolling spots of zebras and footprints of the gods, the most popular theories over the last few decades have been Euphorbia sites, termites and self-organisation, the latter theory gaining the most coverage in recent months.
Milk bushes?
Many desert areas are characterised by the ‘melkbos’ or Euphorbia, a desert shrub with rodlike branches which hold a toxic milky-white latex. A theory initially proposed by GK Theron in 1979 suggests that dying Euphorbia bushes affect the soil below them suppressing the germination of grasses. Prof Marion Meyer from the University of Pretoria’s Department of Plant and Soil Sciences and his students revived the theory, studying the effects of various Euphorbia species, mainly E. damarana and E. gummifera on the soil to determine if they were indeed responsible for inhibiting plant growth. They proposed that with temperature increases many Euphorbias had died over the decades and that the decomposition of the plants and the sticky white latex had altered the chemical properties of the sand, interfering with the bacteria found in the roots of grasses. This hindered the growth of grasses in a circular area around the Euphorbia bush. The latex-infused soil also acted as a water repellent, forcing water deeper into the soil or across its surface.
Sand termites, the beavers of the desert?
Norbert Jürgens, an ecologist at the University of Hamburg, has been studying the effects of sand termites (Psammotermes allocerus) on the soil in the Namib since 2006. After years of testing study sites, he suggested that fairy circles were created by sand termites which eat the grass roots, resulting in the plants dying back from the centre outwards in the shape of a circle. His theory is that the termites create a water trap, in much the same way that beavers build a dam, where rainwater seeps into the sandy soil. This ensures that they have water in the drier times and enables them to maintain a pantry of food by allowing the grass on the periphery of the circle to tap into their water supply.
Organised grasses?
In 2004 researchers proposed that plants in the arid environment may self-organise into circles in their competition for water. The pattern-formation theory was developed by mathematician Alan Turing in 1952, explaining patterns in nature within a mathematical framework. These included whorls of plant leaves, zebra stripes and leopard spots.
Dr Stephan Getzin, an ecologist from the Department of Ecosystem Modelling at the University of Göttingen, and fellow researchers studied fairy circles at various sites in the Namib Desert after rainfall over the last three years. Their conclusions were that the grasses are self-organising themselves, redistributing the soil water to survive in areas with increasing aridity, an escalating condition due to climate change. Getzin explained: ‘By forming strongly patterned landscapes of evenly spaced fairy circles, the grasses act as ecosystem engineers and benefit directly from the water resource provided by the vegetation gaps’. He proposed that the grasses on the fringe of the circle create soil-moisture vacuums around their roots and water is drawn towards them from the inside of the circle. The grasses form these circular patches (the most logical shape to maximise the water available to each individual plant) to make the most of the meagre rainfall and soil nutrients. The barren circles become reservoirs which sustain grasses at the edges.
A combination of factors?
But, the decades-long debate among scientists continues. Perhaps all of the above are factors which play a part in different areas at different times, or perhaps there is a combination of factors at work.
And as there are still doubts and insufficient scientific evidence, the mystery remains unsolved.
But, isn’t this the essence of a mystery after all, that it is never solved? Isn’t it refreshing in the modern world of today to know that nature harbours secrets and mysteries that we only have an inkling of and that they nurture our dreams, encourage the imagination and feed the soul. At the end of the day, I can’t help entertaining the thought that perhaps the fairies are simply messing with us . . . and leading us in a merry dance.
(References: ‘Secrets of Namibia’s fairy circles demystified’, University of Göttingen, Science Daily, 20 October 2022;
‘What causes Namibian fairy circles? – Researchers think they’ve solved a desert mystery’, Ellen Phiddian, Cosmos, 23 October 2022;
‘The surreal mystery of Namibia’s ‘fairy circles’ may finally be solved’, Russell Mclendon, Science Alert, 30 October 2022;
‘The plot thickens – Euphorbia bushes do not cause fairy circles’, Gail C. Thomson, Conservation Namibia, 15 June 2021
‘Visiting the mysterious fairy circles of the Namib Desert’, Joshua Sokol, The Atlantic, 23 May 2018)