Enlarge / Bare, reddish-hued circular patches in the Namib Desert known as “fairy circles” are also found in northwestern Australia. (credit: UHH/MIN/Juergens)
Himba bushmen in the Namibian grasslands have long passed down legends about the region’s mysterious fairy circles: bare, reddish-hued circular patches that are also found in northwestern Australia. In the last 10 years, scientists have heatedly debated whether these unusual patterns are due to sand termites or to an ecological version of a self-organizing Turing mechanism. Last year, a team of scientists reported what they deemed definitive evidence of the latter, thus ruling out sand termites, but their declaration of victory may have been premature. A recent paper published in the journal Perspectives in Plant Ecology, Evolution, and Systematics offers a careful rebuttal of those 2022 findings, concluding that sand termites may be to blame after all.
As we’ve reported previously, the fairy circles can be as large as several feet in diameter. Dubbed “footprints of the gods,” it’s often said they are the work of the Himba deity Mukuru, or an underground dragon whose poisonous breath kills anything growing inside those circles. Scientists have their own ideas.
One theory—espoused by study co-author Norbert Jürgens, a biologist at the University of Hamburg in Germany—attributed the phenomenon to a particular species of termite (Psammmotermes allocerus), whose burrowing damages plant roots, resulting in extra rainwater seeping into the sandy soil before the plants can suck it up—giving the termites a handy water trap as a resource. As a result, the plants die back in a circle from the site of an insect nest. The circles expand in diameter during droughts because the termites must venture farther out for food.
Read 8 remaining paragraphs | Comments