“Wolf and Whittlinger trained a bunch of ants to walk across a patch of desert to some food. When the ants began eating, the scientists trapped them and divided them into three groups. They left the first group alone. With the second group, they used superglue to attach pre-cut pig bristles to each of their six legs, essentially putting them on stilts.
The third group had their legs cut off just below the “knees,” making each of their six legs shorter.
After the meal and the makeover, the ants were released and all of them headed home to the nest while the scientists watched to see what would happen.
The regular ants walked right to the nest and went inside.
The ants on stilts walked right past the nest, stopped and looked around for their home.
The ants on stumps fell short of the nest, stopped and seemed to be searching for their home.
It turns out that all the ants had walked the same number of steps, but because their gaits had been changed (the stilty ants, like Monty Python creatures, walked with giant steps; the stumpy ants walked in baby steps) they went exactly the distances you’d predict if their brains counted the number of steps out to the food and then reversed direction and counted the same number of steps back. In other words, all the ants counted the same number of steps back!
UPDATE 25 Nov 2009:
The story ran on the air today, and added a fascinating coda.
The next day, they had all three groups of ants go out for food again, and this time, they all correctly found their way to the food, and found their way back to the nest. The ones with long legs didn’t overshoot or undershoot the destination, and neither did the ones with short legs.
They all had to walk a different number of steps than they did the day before, so if they all had to work 20 paces to get there the first day, the long-legged ones only had to walk 10 paces the second day, and the short-legged ones had to walk 40 paces. No matter, they all figured it out.
If it wasn’t convincing already that ants do some form of pedometer-counting, this seems like a pretty good confirmation to me.