June 29, 2006 | David F. Coppedge

Ant Pedometer Discovered

Ants have dumbfounded scientists again.  It appears they count their steps when they walk, and keep track how far they have gone.  Reporting in Science,1 a trio of German and Swiss scientists tested desert ants by making some walk on specially-designed stilts and others walk on stumps of cut-off legs.  The first overshot their target, and the second group undershot it by the amount proportional to the change in leg length.
    Another amazing fact is that the ants can use their mental pedometers to reckon how far they are from home, then take a direct route back.  That would seem to require mathematical skill beyond just counting steps.  Indeed it does; not only do the ants have a sophisticated onboard navigation system, but also celestial navigation equipment.  The team explained,

Foraging Saharan desert ants, Cataglyphis fortis, use a mode of dead reckoning known as path integration to monitor their current position relative to the nest and to find their way home.  This enables them to return on a direct route, rather than retracing the tortuous outbound journey performed when searching for food items in their flat desert habitat, which is often completely devoid of landmarks.  The path integrator requires two kinds of input information: about directions steered, as obtained via the ant’s celestial compass, and about distance traveled, as gauged by the ant’s odometer.

See also Live Science, National Geographic and New Scientist.  The team also found that the ants could learn to adapt to their new circumstances.  Regarding the surgical procedures used in the experiment, the scientists were quick to explain that ants don’t feel pain at having their legs amputated.


1Wittlinger, Wehner and Wolf, “The Ant Odometer: Stepping on Stilts and Stumps,” Science, 30 June 2006: Vol. 312. no. 5782, pp. 1965 – 1967, DOI: 10.1126/science.1126912.

There was no mention of evolution in this paper.  Only in evolutionary theory would someone attempt to say, with a straight face, that celestial compasses, path integrators and odometers are the result of a blind process lacking a navigation target.
    This discovery is all the more reason to get the kids an Uncle Milton’s Ant Farm (03/16/2006).  It might stimulate a good science project, too.  If stilts, why not pogo sticks?  or how about a treadmill or moving sidewalk?  or a rotating table?  Don’t let students be cruel to the little puzzle-solvers, but use it as an opportunity to reverse-engineer the amazing GPS software embedded in their tiny heads (not referring to the students’ heads, of course, but to those of the ants).

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