The fairy circles of the Namib Desert — mysterious bare soil spots dotting the grasslands across around 1,500 miles of the dry region — appear so well-coordinated and intelligent in design. They suddenly crop up, too, making their nature almost always worrisome and unnerving.
But what is happening and these circles, ranging from 6 to 115 feet in width, show up in nature? They are the consequence of a permanent, systemic process occurring beneath the desert, a new study has found.
Termites And Vegetation
Fairy circles have long intrigued scientists. It is still largely unknown what natural process causes them, although factors such as meteorite impact and massive raindrops have largely been ruled out.
There are two likely explanations: regularly spaced colonies such as sand termites, which munch through grass until they get to a “barrier” such as a rival colony. As they eat grass roots, they create well-engineered sandy patches for capturing what little rain the desert offers, the theory states.
Another hypothesis holds that the plants compete for water as well as other resources, creating the barren rings in the process. More deeply rooted grasses, for instance, drain water from the patches and render it impossible for other plants to make it. Thus, plants organize themselves in the regularly spaced circles.
In new findings published in the journal Nature, a team of mathematicians from Princeton used both termite and plant models to explain the existence of fairy circles. They simulated what kind of vegetation patterns would result from each model separately and combined, and then compared the simulated pattern against images of fairy circles in Namib Desert.
It turned out to be a match, particularly a huge-scale hexagonal pattern.
The team also saw a smaller-scale one in the grasses surrounding the fairy circles. Grass clumps that have regular spacing, too, formed their own pattern.
“[T]hat cannot be explained by either mechanism in isolation,” the team wrote. “These multi-scale patterns and other emergent properties … instead arise from dynamic interactions in our theoretical framework, which couples both mechanisms.”
What Experts Think
Botanist and German professor Dr. Norbert Jürgens agreed that both hypotheses can explain the fairy circle phenomenon together. He is skeptical, however, of plants’ ability to control patterning on a massive scale in the plant-focused model.
Theoretical ecologist Stephan Getzin, on the other hand, is skeptical of the new findings. Favoring the plant model, he pointed out to Christian Science Monitor that the team pursued a model “where the gap pattern of fairy circles solely emerges due to insect activity and colony establishment.”
An integrative model, he explained, would account for the existence of both termites and self-organization. Getzin also previously cited fairy circles in the Australian Outback, in a place where there are no signs of the sand termites.
For the paper’s lead author and ecologist Corina Tarnita, however, this strange arrangement could actually be a natural thing in an ecosystem.
“You realize that you can find these patterns at many different scales. Anywhere from tiny microbial colonies to animal coats to the scale of ecosystems,” she said. “You find compelling patterns and, many times, the same kinds of patterns, the same motifs.”