Ants don’t make decisions on the move

Mathematical analysis shows the insects stop to consider their next step

Temnothorax unifasciatus

SINGLE-MINDED  While exploring a new environment, some ants stop walking to plan their next movements. This think-first, walk-later behavior may limit mental strain on busy ants like the Temnothorax albipennis observed in a new study, or the Temnothorax unifasciatus (pictured).

Ihagee86/flickr (CC BY-SA 2.0)

Ants are hard workers, but they’re not multitaskers: They have to stop to think.

Temnothorax albipennis worker ants typically need a pit stop to change their travel plans, researchers in England report January 13 in Royal Society Open Science.

Active ants alternate between moving and resting. While charting new territory, workers leave behind chemical messages about their environment. Releasing ants one at a time into an enclosed arena, the researchers watched as solitary ants responded to information left by their predecessors, varying the average speed of their next movements.

But exploring ants didn’t make these adjustments en route.

While exploring, a Temnothorax albipennis worker ant (shown in slow motion) alternates between moving and pausing. An ant processes incoming chemical information only while stalled, a new study suggests. Edmund Hunt/Univ. of Bristol
Mathematical analyses of the ants’ behavior suggest that the length of ant movements are determined before an ant even lifts a leg. So ants probably process chemical cues while paused between motions, the researchers say.  

It’s possible that ants save mental energy by halting to think, the team says. 

Editor’s Note: The title of the study cited in this story was updated January 13, 2016, to reflect a change made by the authors.

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