Adventures Among Ants - Mark W. Moffett [54]
Then again, remembering how the basket-laden people walking from Nigeria to Cameroon paused to chat with their returning friends—perhaps to compare notes on the value of the goods they had sold—I wondered whether the ants were sharing information. Through signals I could not recognize, returning ants might inform the nest of a raid’s success in acquiring food or finding a new nest site. Fresh troops would then depart for the raid with updated knowledge of the colony’s current requirements. This feedback might draw more ants into a raid, or lead to its retreat or to the start of a migration. If information does flow between raid and nest, that might help explain evidence for day-to-day differences in the duration and distance of raids.12
For societies as large as an army ant’s, this hypothesis seemed reasonable. As I saw for the springtail-catching trapjaw ants, the care with which workers in small colonies conduct their business can reflect their limited operating budgets. A large ant colony almost invariably shows more frenzied activity and a faster tempo than a small one. Both ant and human societies can be more productive per capita as their size increases, despite all the mad rushing about: in large cities, people interact with numerous others, exchanging and creating ideas at a high rate.13 There’s a payoff for all their “type A” behavior. Workers in large ant colonies likewise glean information from the crowds around them. In the seed-harvester ant of the southwestern United States, for example, unemployed workers perceive how many of their compatriots are devoted to different tasks by the scent each passerby has picked up from her environment, which reveals the job she is performing—one of several known instances where ants show a capacity to accumulate evidence before making a decision. The workers then adjust their efforts accordingly, shifting, say, from nest maintenance to foraging when foragers are in short supply.14 Some individuals’ rough assessment of the labor situation may be mistaken, but a large colony can afford errors, and the “foraging for work” method enables ant societies to redistribute labor effectively without the need for a supervisor.
Among ants, who are acting without a leader, each individual responds based on the small amount of information available to her. But by gathering all those bits together, the superorganism as a whole behaves sensibly. The raid’s features emerge from the collective decisions of the incompletely informed masses, each ant contributing so infinitesimally as to be essentially irrelevant to the outcome. Indeed, the organization of a swarm raid has been accurately re-created by a computer just by modeling the ants in terms of a single, simple set of behavior rules.15
Under many circumstances this wisdom-of-the-crowd is characteristic of humans, too—a valuable feature of human democracies. The average of a large number of decisions, even by individuals who are poorly informed, often turns out to be surprisingly smart and accurate. The U.S. military, for example, located a lost submarine with scant information by averaging the guesses of a variety of experts as to its fate, even though no individual guess was close to correct. This has been put forward as a reason to avoid, in the way ants do, an overdependence on a few leaders or “experts,” whose judgment can be less reliable than that of a crowd.16
One result of the greater information flow in large societies is that larger colonies are more homeostatic than small ones, which is to say that they are more stable in their internal interactions and their relation with the physical environment, in much the way the health of a human body is maintained by a flow of information through our tissues generated by our endocrine glands and nervous system.17 Large ant societies tend to have a more dependable influx of food, for example, and