fairy circles fairy circles The circles grow and "die" over decades. (Photo: Wikipedia)

What creates fairy circles, the 'crop circles of Africa'?

Researchers think they've discovered the cause of these ecological mysteries.

For a long time, scientists had no idea what was causing "fairy circles," 20-foot-long barren circles in southwest African grasslands. These mysterious holes range from 7 to 49 feet in diameter, and they grow and shrink over a period of 30-60 years. According to local legend, spirits or fairies make these holes and endow them with magical properties. Or underground dragons breathe poison in the direction of the plants, if you listen to the tour guides.

"Vegetation gap patterns in arid grasslands, such as the 'fairy circles' of Namibia, are one of nature’s greatest mysteries," write Israeli and German scientists studying the phenomenon.

Scientists, who generally eschew local legends and don't believe in fairies (gasp!), decided to figure all this out. This month, they finally found the reason, and it's the oldest biological answer in the book: water.

fairy circlesThe indigenous Himba peoples believe their ancestors created the circles. (Photo: Wikipedia)

Previously, theories ranged all the way from cryptic sand termites chewing away the plants to carbon monoxide under the ground (which still kind of sounds like poisonous dragon breath to us). But for a long time, no theory seemed well-supported by evidence.

That changed a couple weeks ago, when researchers at Ben-Gurion University in Israel and Helmholtz Centre for Environmental Research in Germany, announced that they discovered a clue: For a long time, people thought these spots were only found in Africa, but they've since been discovered in the Australian outback. Since sand termites aren't usually found in Australia, they probably weren't causing the circles.

The researchers used fieldwork, mathematical modeling, remote sensing, model analysis and spatial pattern analysis to discover that our good friend H20 is the key. Apparently, in areas that don't get much rain, plants have to compete for water. The plants self-organize (using their plant brains? fairy dust?), with larger plants sucking the water from the soil around them, creating bare, circular patches.

fairy circlesSome tour guides say a dragon deep underground breathes out poisonous breath, killing the plants in the circle. (Photo: Felix Lipov/Shutterstock)

"This is consistent with model predictions that gap patterns should appear in a limited precipitation range; above this range uniform vegetation prevails and below that range morphological changes to stripe and spot patterns take place," said Israeli Professor Ehud Meron, who worked on the study.

At least, that's the scientists' best guess at the moment. Personally, we're bringing dragon repellant next time we go to Africa, just in case.

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