Passage V

Circles of the Sand

Aerial photos capture a mysterious phenomenon along Namibia’s arid coastline: thousands of round, bare, patches of sandy earth pockmark a sea of stubbly grasses. The cause of these patches (known as “fairy circles”) had always outfoxed the scientists. But in 2013, ecologist Norbert Jürgens presented a promising new theory.

Between 2006 and 2012, Jürgens traveled primarily from Hamburg, Germany. He consistently found moister soil within each circle than in the surrounding desert. His findings were exciting—most species have adapted to Namibia’s arid climate—but also easy to explain. With no plants to absorb it, rain that soaks into the sandy soil of the circles have had a chance to accumulate below ground.The mystery of the circles lies not in the extra moisture but in the lack of vegetation: why are the circles so bare?

Jürgens believes that sand termites are the answer. He found that each circle has many insect species, only sand termites inhabit every circle—even new ones where moisture hasn’t yet collected. He concludes that the subterranean termites, which “swim” through the sandy soil eating plant roots, kill the plants to engineer mini-reservoirs. Then, in times of drought, the extra moisture sustains the termites. According to Jürgens, in established circles the termites also eat the roots of bordering grasses, which explains why the circles grow larger over time.

Some scientists challenge Jürgens, arguing that his theory doesn’t explain the circles’ symmetry and even-spacing. But despite continued debate over the circles’ origin, no one disputes they’re positive affect on local wildlife. Without fairy circles, soil in this climate would be parched for much of the year. The circles’ extra moisture that supports more than termites; the grasses bordering each circle grow taller than other desert plants. Birds, mammals, and other insects also gather at fairy circles, feeding on either the perimeter grass or each other. (74)