Smells, Gases Keep Order in Ant Colonies

ByABC News
May 6, 2003, 1:03 PM

May 7 -- When she first started looking at ant colonies in the Arizona desert 20 years ago, Deborah M. Gordon wasn't just interested in ants. She wanted to know if the ants could help answer some of the most difficult questions confronting scientists in a wide range of fields.

"I was interested in what is now called complex systems," says Gordon, now an associate professor of biology at Stanford University. "That's a system in which the units don't know globally what's going on, there's no central control, there's no hierarchy, there's nobody in charge, and yet somehow all those fairly simple units working together do something interesting."

The ants were supposed to serve as the vehicle for studying far more important issues, like how a brain works, but somewhere along the way the ants swept Gordon off her feet. She became so fascinated with these little critters that she has turned out one discovery after another, including a recent finding published in the May 1 issue of Nature.

Gordon and a fellow researcher, Michael J. Greene, used some highly sophisticated equipment and a little bit of trickery to figure out how ants know what they are supposed to do when nobody is in charge.

Odor Order

It all comes down to an extraordinary sense of smell, the researchers say. Ants that go out looking for food, called "patroller ants," emit a distinctive odor when they return to the nest, thus telling other ants, called "foragers," to go collect the bounty. It's not an order, Gordon says, but the foragers know what to do when ants return to the nest at the right pace, smelling like patrollers.

"That tells them the conditions are right," Gordon says, and the foragers go forth to do their thing without needing to be told to do so.

It's a little like how a brain functions, or how an embryo grows into a distinct organism.

In the human brain, Gordon says, "neurons don't know how to think," but billions of these crucial "units," working together, "manage to think and remember."