In Buffalo Seek Consensus and Other Tales of How Animals Decide Things, Sharon Begley looks at how groups of social animals, including insects, make decisions:
The Manyara buffalo of Africa begin stirring from their postprandial rest just before dusk. Each beast raises its head higher than usual and gazes into the distance.After much shuffling around, the herd treks toward a new grazing ground, but not in the direction — north-northeast, say — that a majority have set their eyes on. Instead, the buffalo compromise. They perform the bovine equivalent of vector algebra, biologist Herbert Prins of Wegeningen University, the Netherlands, has found, choosing a direction that represents the weighted average of the directions the members of the herd have ‘voted’ for.
Compromise, consensus, plebiscite: When it comes to decisions, the animal world is as diverse as the human one, providing a menagerie of approaches that scientists believe can illuminate decision-making in groups of people.
In contrast to the buffalo’s compromise strategy, Cuban leaf-cutter ants are more likely to follow the crowd. When placed in a box with two exits, the ants use each about equally under normal conditions. But if scientists drop insect repellent into the box, the panicked ants follow the herd: An average of 75% try to get through only one exit, scientists at the University of Havana reported last December in American Naturalist. When people do that, as when fire breaks out in a crowded room, the result has been multiple deaths.