If you’ve ever seen an ant in quest of food, you probably thought that it was just covering territory at random. But according to a study published today in the journal iScience, at least one species of rock ant doesn’t move at all randomly. Instead, their search consists of deliberate wandering mixed with random walks.

“Previously, researchers in the field assumed,” as explained by Stefan Popp of the University of Arizona, Tucson, “that ants move in a pure random walk when searching for targets of which they don’t know their location.” 

When scouting the region surrounding their nests, rock ants, Temnothorax rugatulus, exhibit a distinctive, dependable meandering pattern, according to their research. 

This implies that ants alternate left and right turns on a pretty consistent length scale of around three body lengths.

He says that he and his colleagues call the behavior “meandering” because it resembles the pattern created by a meandering river. Additionally, their research indicates that the ants’ wandering may make their search more effective than it would be if they were just searching randomly. This is due to the fact that ants less commonly examine the same area again when they meander since they tend to cross their own trails less frequently than random walk tracks.

The objective of Popp’s team was to determine how ants respond to nestmates and surface structure on a colony-wide scale. They transferred an entire colony into the lab where they could easily monitor all ants mechanically and under continuous circumstances since it is difficult to follow ants in their natural surroundings.

They quickly noticed the ants’ meandering pattern as they went around. It immediately prompted the question: Could the patterns they were seeing be the result of random squiggles without any established rules? Or did the ants make more orderly, non-random movements? They compared the ant tracks with artificial random walk patterns to find out.

“We wanted to make sure that we are not just seeing patterns where there is none,” Popp adds. “We then used a simple statistical method of detecting regularity in movement tracks to get a simple answer.”

According to their research, 78% of ants exhibited a substantial negative autocorrelation at a distance of 10 mm, or about 3 body lengths. This indicates that after an approximately consistent distance, turns in one direction were often followed by turns in the other direction. They claim that because the ants can remain near to the nest without continually examining the same regions, it probably makes their search more effective. The extraordinary shapes that the ants’ patterns may take from these basic principles, according to Popp, is what most fascinated him.

“Parts of some tracks look like the curled threads one can pull out of a piece of clothing, and in some it looks like the meandering path meanders itself,” he adds, “creating a seemingly fractal structure. It reminds me of some space-filling curves we know from math!”

According to the authors, the current research is the first to discover proof of effective search via predictable meandering in a freely roaming animal. It also suggests that ants have further difficult behaviors to master.

Popp says that he is most interested in questions about the rules in an ant’s brain that make it possible for it to search in such complicated ways. In addition, he argues that the ants have solved the challenge of collective search throughout the course of evolution in a manner that may be used to create autonomous swarms of search robots or drones for usage in disaster zones or unknown regions.

Image Credit: Getty


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