Collective intelligence: Ants and brain's neurons
STANFORD - An individual ant is not very bright, but ants in a colony,operating as a collective, do remarkable things.
A single neuron in the human brain can respond only to what the neuronsconnected to it are doing, but all of them together can be Immanuel Kant.
That resemblance is why Deborah M. Gordon, StanfordUniversity assistantprofessor of biological sciences, studies ants.
"I'm interested in the kind of system where simple units together do behavein complicated ways," she said.
No one gives orders in an ant colony, yet each ant decides what to donext.
For instance, an ant may have several job descriptions. When the colonydiscovers a new source of food, an ant doing housekeeping duty may suddenlybecome a forager. Or if the colony's territory size expands or contracts,patroller ants change the shape of their reconnaissance pattern to conform tothe new realities. Since no one is in charge of an ant colony - including themisnamed "queen," which is simply a breeder - how does each ant decide what todo?
This kind of undirected behavior is not unique to ants, Gordon said. How dobirds flying in a flock know when to make a collective right turn? All anchoviesand other schooling fish seem to turn in unison, yet no one fish is theleader.
Gordon studies harvester ants in Arizona and, both in the field and in herlab, the so-called Argentine ants that are ubiquitous to coastal California.
Argentine ants came to Louisiana in a sugar shipment in 1908. They weredriven out of the Gulf states by the fire ant and invaded California, where theyhave displaced most of the native ant species. One of the things Gordon isstudying is how they did so. No one has ever seen an ant war involving theArgentine species and the native species, so it's not clear whether they arequietly aggressive or just find ways of taking over food resources andterritory.
The Argentine ants in her lab also are being studied to help her understandhow they change behavior as the size of the space they are exploring varies.
"The ants are good at finding new places to live in and good at findingfood," Gordon said. "We're interested in finding out how they do it."
Her ants are confined by Plexiglas walls and a nasty glue-like substancealong the tops of the boards that keeps the ants inside. She moves the walls inand out to change the arena and videotapes the ants' movements. A computertracks each ant from its image on the tape and reads its position so she has adiagram of the ants' activities.
The motions of the ants confirm the existence of a collective.
"A colony is analogous to a brain where there are lots of neurons, each ofwhich can only do something very simple, but together the whole brain can think.None of the neurons can think ant, but the brain can think ant, though nothingin the brain told that neuron to think ant."