The Mystery of African Desert 'Fairy Circles' Might Have Just Been Solved
A new theory helps explain the cause of the odd patterns in the Namibian desert — and can even help predict them.
If you fly over the Namibian desert, on the west coast of southern Africa, you will see one of nature's great mysteries. Vast expanses of the landscape are pocked with circles of bare patches of earth. These strange patterns - two to 35 meters wide - stretch for miles and, until now, no one was sure why.
On Wednesday, a team of scientists from universities around the globe with expertise that ranges from plant biology to termite physiology and behavior to data gathering and analysis and modeling - brought together by a National Science Foundation grant - published a theory in Nature that finally explains, and can predict mathematically, this mystery.
This study may also offer insights into familiar phenomena worldwide. Organized vegetation patterns are widespread in nature. But, even after debunking theories involving aliens and fairies, scientists have long disputed what causes them. Some believe they are created by plants engaged in a feedback loop caused by competition for limited resources. Others suggest that the patterns are caused by the subterranean activities of termites, ants or rodents. Neither explanation completely answers why the patters are geometric and worldwide.
But according to the research of this multidisciplinary team, the answer is a bit of both: The plants and animals engaged are in an ecosystem dance - expansion, competition, die off, rebirth - that results in a repeating pattern of death and renewal.
"We developed a general framework that can be used to understand many of the regular vegetation patterns around the globe as the result of the interaction between fauna and vegetation," explains Juan Bonachela, an assistant professor at the University of Strathclyde. "You can adapt our framework to the specifics of other patterns by changing details about the territorial animal and vegetation that are interacting and the environmental conditions."
Previously neither the plant nor animal scientists could reliably predict these patterns.
"But by applying a multidisciplinary approach to the problem - combining ground and satellite data, computational models, and statistical analyses," Bonachela said, "we found that only by including the dynamics of both termites and vegetation and their interaction can we replicate all the main properties reported for Fairy Circles, including the fact that they are born and die, their timing, and the properties of the vegetation between fairy circles."
This settles a debate that has raged among scientists for many years.
"Each side tried to explain the phenomenon according to what, for them, were the most reasonable scientific arguments," says Bonachela. Neither was wrong - or completely right. "The fact that their arguments are to some extent included in our comprehensive explanation tells you that the mechanisms they identified indeed are important for the emergence of fairy circles. But those mechanisms are not mutually exclusive, and considering the dynamics of their interaction at multiple scales provides the most complete description of the ecosystem."
The explanation of the theory and the mathematical models that predict it, were published Wednesday in Nature.
But, while this explanation is satisfying and predictable from a scientific point of view -and settles a heated debate - repeatable mathematical models will probably will not satisfy those who subscribed to the myth of the Namibian fairies, mass landings of UFOs or top-secret desert experiments.
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