Namibian fairy circles are large barren patches of earth ringed by short grass dotting desert-like craters on the moon or giant polka dots. No one knows how they formOIST

Mysterious circles of barren land found in African grasslands and skin cells have been related in a study that revealed remarkable similarities between the two.

Researchers at Okinawa Institute of Science and Technology Graduate University (OIST) in Japan have found that the pattern of distribution of the two unrelated systems are uncannily similar.

"It's a completely amazing, strange match," said professor Robert Sinclair, who heads the Mathematical Biology Unit at OIST.

The distribution of fairy circles throughout the Namibian desert may look random, but that is not the case. Like the skin cells, the fairy circles too have six neighbours in most cases.

Going a step ahead, the percentage of fairy circles with four, five, six, seven, eight and nine neighbours is essentially the same as the skin cells.

"I didn't expect it to be so close," Sinclair said. "We spent a lot of time checking because it really looked too close to believe."

The research was recently published in Ecological Complexity.

The team could not state why the two unrelated systems are similar, but they suspect it could be because both the skin cells and fairy circles are fighting for space.

If this can be established, scientists might one day be able to glean information about systems just by analysing patterns. This could be useful in searching for signs of life on other planets where images will probably be the only data available.

To conduct the analysis, Sinclair and his team took satellite images of fairy circles, and a computer drew lines halfway between each pair of circles to designate invisible boundaries, much like cell walls.

The computer then counted how many neighbours surround each fairy circle.

Mystery of fairy circles

Fairy circles are among the many unsolved puzzles on the planet. Some are just a few metres in diameter, while some can reach up to 20m.

Various theories ranging from termites to underground hydrocarbons to resource competition among plants and vegetation have been suggested but none are able to explain the mystery satisfactorily.

Scientists are now developing mathematical models attempting to explain the origin of fairy circles.

"These models have to incorporate our results," said Zhang, a PhD student in the Department of Statistics at Iowa State University, who assisted Sinclair.