letters
to an unknown audience
-----------------------
~
Our Entomological Correspondents/  /May 17, 2007

Things I learned today in a talk about long-distance navigation in desert ants:

  • This kind of ant can find its way home or to food, without pheromones, for millions of steps across a flat desert with no significant visual landmarks. This is "like a person walking for 14 hours and then knowing how to get home."
  • The theory is that they do this through "path integration," that is, they keep track of where they are in their heads by adding up all the little movements that they make, one step at a time, and they know the direction of each step by making use of the polarization of the light from the sky.
  • Navigation by robots without landmarks is called "dead reckoning."
  • Robots tend to do it poorly because any error in measuring single steps will be magnified enormously over a large number of steps. This means that a robot trying to get home this way would have a large error in any direction, and would be likely to end up anywhere in the general (or not-so-general) vicinity of where it started.
  • But remarkably, these ants have a consistent bias to one side when returning home. The theory is that this makes it likely that he'll cross his outbound path, thus possibly re-encountering any visual landmarks, which might be useful after all.

In a nutshell: ants are awesome!

Keep Reading >

Post a comment