Funny You Should Ask

The QI elves are a team of writers and comedians who find the answers to impossible questions, doing the research for the long-running QI TV series, podcasts and the spin-off books. For the next little while, we’ll be running some of their finest findings: the weird, wonderful, witty and wise, from their latest book, Funny You Should Ask ... Again.

How does an ant measure distance?

If you want to know how far you’ve walked, there are several ways to find out: you could use a map, a GPS device or perhaps a pedometer to count your steps.

But what if you’re an ant living in the Sahara Desert? Ants there never seem to get lost. They wander about over very similar-looking sandy ground, and once they find a piece of food, they make a beeline straight back to their nest. There aren’t really any landmarks to help them, and the shifting sands destroy any chemical trails left behind from their previous journey.

Ants are able to keep track of the sun, so they know which direction they’re facing, but to navigate their way home successfully, they need to know how far they’ve travelled. Scientists hypothesised that if their stride length is constant, ants might be able to count their steps when moving around and then calculate the distance they’ve covered. A team from the universities of Ulm in Germany and Zürich in Switzerland conducted an experiment to see if ants really do count their steps, testing their hypothesis by fitting some of the insects with stilts.

The scientists set up a nest, and the ants were given a few practice runs without the stilts. They went out, collected food and walked back to their nest without trouble, but once they were given the stilts (made out of pig-hair bristles) they travelled too far, missed the nest and then began pacing up and down looking for it. Because the ants on stilts had longer legs and therefore took bigger strides, when they took their usual number of steps back to the nest, they overshot it.

After being picked up and manually returned to the nest, the ants on stilts were then able to go out and return home just as easily as they had in the past. This suggests they must have a way of counting steps – a sort of internal pedometer – to help them get around. Which is great news, because it’s very hard to find a Fitbit that fits if you’re an ant.

Extracted from Funny You Should Ask … Again, by the QI Elves (Faber, $27.99), which is out now.