Mysterious fairy circles may be caused by 'swarm intelligence'

Scientists have debated the origin of Namibia’s mysterious fairy circles for decades, but may now have conjured up the answer.

The phenomenon sees mysterious, circular, bald patches in the dry grasslands on the edge of the Namib Desert.

Researchers from the University of Göttingen in Germany and Ben Gurion University in Israel suggest freshly germinated grass dying inside the circle may be because of a "swarm intelligence" of grass at the edge sucking up all moisture.

Their results show that the grass withers due to a lack of water inside the fairy circle.

Study lead author, Dr Stephan Getzin from Göttingen University’s ecosystem modelling department, said: "By outcompeting and drying out newly established grasses in the circle with their strong root system, the dominant edge grasses maintain the fairy circle as an underground water source in the long term, as the fairy circle never becomes permanently overgrown".

He added: "The large edge grasses follow a kind of swarm intelligence because forming a circle together gives them permanent access to water, which is an adaptation strategy to the extreme drought in the Namib".

A University of Göttingen statement explained: "The topsoil, comprised of the top 10 to 12 centimetres of the soil, acts as a kind of 'death zone' in which fresh grass cannot survive for long. The new grass dies between 10 and 20 days after the rain".



In-depth study

According to the researchers, the fact that it shows no signs of termite damage disproves a competing theory.

For the study, the scientists analysed 500 individual grass plants in four regions of the Namib by taking measurements of root and leaf lengths, carrying out statistical analyses, as well as collecting and comparing photographic evidence. They also took several hundred measurements of soil moisture during or after the 2023 and 2024 rainy seasons.

They said: "In an extensive discussion of the publications on the sand termite theory, we show that so far, not a single field study with systematic measurement data on the root length of dying grasses has shown that termite feeding on the roots of newly germinated grasses create the Namib fairy circles".



Long-held myths

The results are published in the journal 'Perspectives in Plant Ecology, Evolution and Systematics'.

In the myths of the Himba people of the Kunene Region, fairy circles are said to have been caused by the gods or spirits, and their original ancestor, Mukuru, was responsible for the creation of the fairy circles, or that they were the footprints of gods.

Another myth put forth is that the circles are formed by a dragon, and that its poisonous breath kills the vegetation.