Namibia’s fairy circles: Has one of nature’s great mysteries been solved?

By Thomas Page, CNN
4 minute read
Published 5:26 AM EST, Tue January 31, 2017
Strange barren dots -- rimmed with tall grasses -- sprinkle a 1,100-mile stretch of Namibia's desert.
Strange barren dots -- rimmed with tall grasses -- sprinkle a 1,100-mile stretch of Namibia's desert.
Courtesy NamibRand Nature Reserve
Known as fairy circles, these dots have long posed a mystery to scientists.
Known as fairy circles, these dots have long posed a mystery to scientists.
Courtesy NamibRand Nature Reserve
Over the years, several theories have been batted around. The main hypotheses have pointed to gasses, poisons and social insects as the cause -- though none have been proven.
Over the years, several theories have been batted around. The main hypotheses have pointed to gasses, poisons and social insects as the cause -- though none have been proven.
Courtesy NamibRand Nature Reserve
Last year, a paper was published in Science by professor Norbert Juergens claiming that fairy circles were the work of a species of sand termite, psammotermes allocerus. Juergens argued termites created an underground oasis for themselves by eating the grass roots and killing it, thereby causing a subterranean water trap (without vegetation, water doesn't evaporate and remains underground).
Last year, a paper was published in Science by professor Norbert Juergens claiming that fairy circles were the work of a species of sand termite, psammotermes allocerus. Juergens argued termites created an underground oasis for themselves by eating the grass roots and killing it, thereby causing a subterranean water trap (without vegetation, water doesn't evaporate and remains underground).
Courtesy NamibRand Nature Reserve
Though many experts found his findings interesting, many remain unconvinced. Stephan Getzin, a scientist from the Helmholtz Centre for Environmental Research in Leipzig, Germany, recently put forth another theory with colleagues from Israel. Getzin argues the circles are formed by a process known as "self-organization."
Though many experts found his findings interesting, many remain unconvinced. Stephan Getzin, a scientist from the Helmholtz Centre for Environmental Research in Leipzig, Germany, recently put forth another theory with colleagues from Israel. Getzin argues the circles are formed by a process known as "self-organization."
Courtesy NamibRand Nature Reserve
In arid climates, where water is scarce and soil nutrient-poor, plants face stiffer competition for resources. As a result, they 'organize' themselves at a distance to maximize what limited resources are available --ultimately forming strongly ordered patterns on the landscape.
In arid climates, where water is scarce and soil nutrient-poor, plants face stiffer competition for resources. As a result, they 'organize' themselves at a distance to maximize what limited resources are available --ultimately forming strongly ordered patterns on the landscape.
Courtesy NamibRand Nature Reserve
On January 19 a team led by Princeton University researchers released a study detailing findings which unified both theories. Potentially, they say, the "termite theory" and the "self-organization theory" are not only both true, but rely upon one another.
On January 19 a team led by Princeton University researchers released a study detailing findings which unified both theories. Potentially, they say, the "termite theory" and the "self-organization theory" are not only both true, but rely upon one another.
Courtesy NamibRand Nature Reserve
Sand termites kill vegetation creating bare patches, which are evenly spaced in a hexagonal formation reflecting territorial battles with neighboring colonies. In doing so the earth accumulates more water.
Sand termites kill vegetation creating bare patches, which are evenly spaced in a hexagonal formation reflecting territorial battles with neighboring colonies. In doing so the earth accumulates more water.
Courtesy NamibRand Nature Reserve
Plants surrounding the termites' territory are able to utilize the extra moisture through extensive root growth, growing taller vegetation than their neighbors in drier soil.
Plants surrounding the termites' territory are able to utilize the extra moisture through extensive root growth, growing taller vegetation than their neighbors in drier soil.
Courtesy NamibRand Nature Reserve
The team's computer models were able to map the fairy circles' hexagonal layout and visualize their life cycle, which can span from a few years to more than 200.
The team's computer models were able to map the fairy circles' hexagonal layout and visualize their life cycle, which can span from a few years to more than 200.
Courtesy NamibRand Nature Reserve
In the Namib Desert it takes approximately 20 years for a fairy circle to close up after the death of a termite colony, the study found.
In the Namib Desert it takes approximately 20 years for a fairy circle to close up after the death of a termite colony, the study found.
Courtesy NamibRand Nature Reserve
The team behind the paper say marrying the two theories could have wide-ranging implications.
The team behind the paper say marrying the two theories could have wide-ranging implications.
Courtesy NamibRand Nature Reserve
A combination of insect colonies, regular formations and benefiting vegetation have been identified all over the world.
A combination of insect colonies, regular formations and benefiting vegetation have been identified all over the world.
Courtesy NamibRand Nature Reserve
The fairy circle mystery
CNN  — 

For years fairy circles have been one of nature’s great, enduring mysteries. A defining feature of the majestic Namib Desert, Namibia these dusty patches of earth, ringed with tall grass and dispersed evenly across 1,100 miles have eluded explanation and confounded scientists.

Like the Bermuda Triangle, or until recently the sailing stones of Death Valley, speculation has been rife. Explanations for the circles, which can be from 10 to 65 feet across, have ranged from alien invasion to poisonous gasses. A paper from 2001 says people have claimed they’re the impact sites of meteorites, rolling spots for zebra or even localized radioactivity.

However a group of biologists and mathematicians in a Princeton-led study claim to have solved the curious case of the fairy circle – and in the process, hope to unify the scientific community on the subject.

Before this month’s study, published in the journal Nature on January 19, scientists were bitterly divided.

A lifetime in the field

One camp, backed up by research from the 1990s and 2000s by Eugene Moll, Carl Albrecht and Norbert Juergens, argued for what’s best summarized as “the termite theory”: that the bare patches of earth were the result of hungry underground termites eating vegetation in the area surrounding their colony. This theory was originally derived from the proposal of ecologist Ken Tinley in 1971, who suggested fairy circles were fossilized termite mounds.

On the other side were proponents of self-organization: that vegetation naturally formed circles under the right conditions in order to make the most out of available moisture and soil nutrients. This theory was first applied to fairy circles in 2004 and expanded upon in 2008, explains Corina Tarnita from the Princeton team. In 2014 Stephan Getzin advocated strongly for self-organization, debunking the termite theory when speaking to CNN.

“The termite theory is very appealing to people, because it’s relatively easy to understand,” Walter Tschinkel, a biology professor at Florida State University, quipped at the time.