If you're an ant in the market for a new nest, you need to make sure you don't get a mansion when you just want a molehill. A new study has added fodder to the debate over how ants do the math that lets them size up potential nesting sites, arguing that they use a simple counting mechanism.
Ants may calculate the area of potential nest sites by counting how frequently they cross their own chemical trails.
CREDIT: COURTESY OF EAMONN MALLON
Since the 1970s, most entomologists have believed that ants pace the perimeter of a potential nesting site to estimate its area. But last year, entomologists Eamonn Mallon and Nigel Franks of the University of Bath, U.K., argued that ants size up sites by wandering about them and counting the number of times they cross their own chemical trails. The smaller the area, the more likely they are to visit the same place twice--a principle mathematicians call "Buffon's needle." Some researchers were skeptical of the idea, however, arguing that ants were actually checking for obstacles when Mallon and Franks thought they were estimating area.
Now the researchers say they have a new piece of evidence that bolsters their hypothesis. In the current issue of Behavioral Ecology, the team reports that when shopping for a new home, the rock-dwelling European ant Leptothorax albipennis always paces out the same-length path on the first visit to a site. The standard path serves as a measuring stick that the ants use on return visits to complete their survey, the researchers argue.
Others are still not convinced. Mathematical biologist David Sumpter of Oxford University, U.K., notes that the researchers also observed that ants sometimes walk the edges of a site, suggesting that they were indeed measuring its perimeter.
