A team of scientists from Princeton University has finally solved the mystery of the odd formations in the Namib Desert. The African “fairy circles” consist of vegetation growing in circular patterns, surrounding empty patches. Ecologists had previously failed to provide a scientific explanation for the strange circles but now researchers have a new theory. The findings are in a paper that was just published in the journal Nature.
Fairy circles are barren circular patches surrounded by grasses or other vegetation. They were first discovered in South Africa but have since been found in parts of Western Australia. The patches resemble simple crop circles but without fancy patterns or clear human intervention. Since ecologists had long been unable to explain the origin of fairy circles, some observers began to concoct stories about fairies, dragons, and even aliens.
Researchers investigated two proposed theories that could explain fairy circles. One theory states that activity by termites is to blame—the insects may be killing the grasses that would have normally grown inside the circle. This theory was initially popular but scientists began to question it since the termites in question, sand termites, live below the surface of the ground and rarely cause visible damage. Although these termites were found in the area, that didn’t necessarily link them to the creation of fairy circles. A second theory proposed that the circles were the result of intense competition between grasses. Resources are limited in the desert, restricting the amount of grass that can grow. This could cause barren patches to pop up. The research team considered both theories in their research and collected additional field data to solve the puzzle.
The team found that both theories might play a role in the formation of fairy circles. Termites, highly cooperative insect species, help their own colony but actively compete against enemy colonies. This would result in isolated circular patches—each representing a different colony of sand termites. The odd vegetation growth patterns can be attributed to their unique root systems, which are underground (and out of view) and designed to minimize competition for water. Although the team can’t absolutely prove that these interactions cause the circles, it seems to be the most likely explanation so far.
Fairy circles have mystified both scientists and the public for years. Now we have a possible explanation—a combination of competing termites, limited resources, and organized root systems. Further research might be needed to confirm the theory. Until then, the unexplained circles will continue to be a source of myths and tales.
Tarnita et al. A theoretical foundation for multi-scale regular vegetation patterns. Nature (2017).