Watch an individual ant meander across your kitchen floor for a few minutes, and you'll quickly realize that she isn't too bright.
But organize a few thousand of them into a colony, and, if you know what to look for, you'll witness feats of engineering, agriculture, and even animal husbandry of a magnitude comparable to just one other animal – H. sapiens – except that ants have been at it for tens of millions of years longer than we have.
A mathematical analysis of how ants find food offers further proof of ants' collective intelligence. A team of researchers from China and Germany observed ants as they searched for food, and concluded that an ant colony is, in the words of one of the researchers, "more efficient than Google in processing information about their surroundings."
When a solitary, dumb worker ant goes foraging, she – all worker ants are female – wanders around in an apparently random fashion. (Of course, as the social scientist Herbert Simon famously pointed out, it's really the environment that's random, not the ant's cognition.)
If she fails to come across some food, she eventually returns to the nest to rest and eat (Aesop's fable notwithstanding, ants actually spend most of their time apparently doing nothing). But if the worker finds food, she'll pick up a piece of it and try to find her way back home, depositing behind her blotches of a smelly chemical called a trail pheromone. Then, other ants will pick up the trail and follow it back to the food source.
So far, so good. But given that the initial scent trail was laid down by a dimwitted individual ant, it is unlikely to be the most efficient route (which is why you never hear about people making an antline). Ants who pick up the trail will usually follow it, perhaps occasionally straying from the path, while other ants from the colony will continue to wander aimlessly, with some of them inevitably stumbling on the food source. The result is lots of different pheromone trails between the food source and the nest.
But trail pheromones evaporate rather quickly, which means that all else being equal, the shorter the trail is, the stronger the chemical will be. This prompts more ants to follow the shortest route, causing more pheromones to be deposited along that route, causing more ants to follow it. The less direct trails evaporate, and the route is optimized. In short order, haphazard wandering transforms into efficient food transport.
“The ants collectively form a highly efficient complex network,” said study co-author Jürgen Kurths, a German physicist and mathematician with the Potsdam Institute for Climate Impact Research, in a press release.
The researchers also found that ants aren't quite as spectacularly doltish as once thought. Over time, ants develop knowledge of their nest's surroundings, so the older ants' foraging was more purposeful. The younger ants' foraging behavior was more about learning the lay of the land than actually securing food, note the researchers.
The researchers say that their mathematical model applies to any animal that has a home that it must return to, such as albatrosses. It can also be applied, they say, to patterns of human behavior, including Web searches and transportation systems.
"Chaos-order transition in foraging behavior of ants" appears in the current issue of the Proceedings of the National Academy of Sciences.